How To Change Clutch Packs On Ford 7.5 Traction Lok

The principal reason to take a limited slip differential in your rear axle is to maximize traction on glace surfaces, such every bit snow, ice, or mud, which tin be exacerbated with an open up differential. Another important reason is to help distribute the torque to the wheels from a high-performance engine and manual combination. The limited-slip differential transfers torque to both wheels fifty-fifty if one wheel is spinning. This is a huge comeback over the traction-limited open differential. Limited sideslip differentials also maximize acceleration of the vehicle.

This Tech Tip is From the Full Book, HIGH-Performance DIFFERENTIALS, AXLES, AND DRIVELINES. For a comprehensive guide on this entire discipline you can visit this link:

Larn MORE ABOUT THIS BOOK Here

SHARE THIS Commodity: Please feel free to share this article on Facebook, in Forums, or with whatever Clubs you participate in. You can copy and paste this link to share: https://musclecardiy.com/performance/how-to-rebuild-factory-express-slip-differentials/

Determining Limited-Slip vs. Open up Differential

To make up one's mind whether your vehicle has a limited-slip or an open up differential is 1 of the easiest driveline checks. The outset step is to place the vehicle on a apartment and level surface, cake the front wheels, and raise the rear wheels off the ground with a jack. Equally always, practice safety showtime and place the vehicle on jack stands. Shift the manual into neutral and make sure that the parking restriction is released. At present only rotate one rear wheel in the forrad direction and pay attention to the rotation direction of the other wheel.

If it rotates in the aforementioned direction (forward), the rear end has a limited-slip differential. If the other cycle rotates in the reverse direction, then the rear end has an open up differential. It is that simple.

Still, in that location is one exception: An extremely worn clutch-plate-way limited-slip differential may act similar an open up differential because the plates are and then severely worn. So it'southward not a totally foolproof exam. But this method works for most cases.

You may wonder why one wheel rotates in the opposite direction. There is a lengthy engineering reason for this, but information technology can exist summed up by the following simple equation:

2 x North_carrier = N_left + N_correct

Where:

N_carrier = rotational speed of the differential carrier

N_left= speed of the left side gear, which rotates at the same speed every bit the left tire

N right = speed of the right side gear (or right tire)

If the carrier speed is zero, which basically means that the pinion and prop shaft are non rotating, the left side of the equation is equal to goose egg.

Yous rotate one side; allow's say the left, at 10 revolutions per minute. In society for this equation to work, the other wheel, in this case the right, must rotate at the same speed merely in the opposite direction:

ii 10 0 = 10 + (-10)

0 = 10 – x

0 = 0

The equation is satisfied. Basically the differential gears are free to rotate relative to one some other inside the differential case while the differential instance is stationary.

If a limited skid differential is in the vehicle's rear axle, a preload should exist applied betwixt the side gears, which would cause both gears to rotate in the same direction (until the torque generated past the friction of the preload has been overcome). One of 2 things can happen. The clutch plates tin can sideslip relative to the differential, and the differential example would non rotate. If the differential case does non rotate, the hypoid ring gear and the pinion will not rotate. Basically, it would be the path of to the lowest degree resistance. Hopefully, the ring and pinion rotation torque is lower than the torque to sideslip the clutches, and therefore, the pinion rotates.

If this sounds confusing, don't worry. This is a footling difficult to understand and is only meant as additional information. The most important thing is to understand how to test for the presence of an open up or express-slip differential.

With the bike adapter tool y'all can rotate the torque wrench at the centerline of the beam shaft. Y'all just need the right commodities pattern and nut welded in the center. This abode-fabricated tool is round and spans all five lug studs; a triangle-shaped plate that spans three of the studs works fine also.

The express-slip checking tool simply fits over the wheel studs. You lot but need to cease the other wheel from rotating.

With the tool in place and the torque wrench in place, you can rotate the tool and tighten the bolt. You just demand to read the torque values for suspension-away and slipping torque.

One time yous have determined that you have a limited-slip differential, you lot can check the preload or intermission-away torque relatively easily. You will need to fabricate an adapter to allow your torque wrench to line up with the center of the wheel bolt pat-tern. This bootleg tool can be as unproblematic every bit a steel plate with the bolt pattern drilled in, and a large nut welded in the center that is aligned with the center of the beam shaft.

Now stop i cycle from rotating (such as jacking only one tire off the footing), remove the other bicycle, and put the adapter over the lug studs. Make sure that the parking restriction is not applied; you don't want to be fighting the brakes at this stage. At present just put your torque wrench on the large nut in the center of the adapter and take a reading of the torque before the beam begins rotating. This can be accomplished with either a beam-manner or click-type torque wrench. If you use the beam style, information technology is helpful to take an banana read the numbers. If you use the click type, ready a torque of 100 ft-lbs initially. If the axle does not rotate, proceed increasing the torque until it breaks away.

Typically, if the breakaway torque value is below l ft-lbs, the differential needs to exist rebuilt or simply re-shimmed. A good range for street use that yet provides decent performance is between 110 and 140 ft-lbs of torque. If the clutch pack is shimmed tighter, it produces poor on-route manners during slow, tight-turning maneuvers. These poor manners are exhibited past tire wind-up during a depression-speed, tight turn maneuver (such as pulling into a parking spot). Also, the differential will act more than similar a locked differential and the vehicle can tend to under steer or plow.

The above information is true for all traditional mill type-differentials. You lot should continue in mind that the helical style differential behaves like an open unless the torque bias ratio is very loftier.

Tear-Downwardly Process

Every rear end has a differential (see Chapter i). There are many types bachelor, but I will concentrate on the nigh common types, which are the open (or standard) differential and the limited-slip differential.

Every manufacturer has its ain unique proprietary name for these express-slip rear ends, but all of differentials essentially role in the same way. I chose the Ford Traction Lok equally an example to rebuild, but go along in heed that it is very like to the GM Eaton-fashion differential and others. These are relatively uncomplicated mechanical devices that are quite effective when compared to an open differential. If your limited-skid differential is worn out, you volition end upwardly laying down ane of the near monstrous, single bicycle peels possible.

The outset step is to remove the differential from the axle housing (as outlined in Chapter 3). Consider removing the ring gear for the rebuild process. Some differentials can be rebuilt with the gear still attached (depending on gear ratio and manufacturer), but the differential is a chip heavy and bulky, and the ring gear only adds to that. Additionally, the ring gear can partially block the already modest differential case windows. Commonly the tear down is much easier than the re-assembly process because in well-nigh cases the clutch pack is worn and loose.

In one case the differential is removed from the axle and the ring gear is off, the side by side step is to remove the differential pin bolt and push button the differential pivot out. The differential pin commodities is the v/xvi-inch head bolt with the long shoulder on information technology that keeps the differential pin from falling out.

Information technology is also a good thought to replace the bolt, if possible, or at to the lowest degree re-utilise a thread locker before final installation.

Next, remove the preload jump. To make it easy, utilize a hammer and soft punch or suitable slice of wood to tap the jump out.

Be careful equally you lot button the last portion of the Ford S-fashion spring out. It tends to follow the differential side gears' tooth path and may shoot out of the housing. To minimize the take chances of the leap flight out, identify a rag over the opposite end of the differential instance window.

Once the spring has been removed, take note of how much play there is in the gears. Keep in mind that the thickness of the clutch packs and shims controls the position of the side gears. If the clutches are worn, the side gears are allowed to motility farther outboard and the gears have more backfire or clearance between the teeth. (This is the aforementioned blazon of backfire or clearance that nosotros volition check when setting up the hypoid gears in Chapter 6.) A typical acceptable backfire range is 0.005 to 0.015 inch.

Since we are talking virtually loftier-performance rear axles, you should shim the pack tighter for your hot rod and driving preference

Earlier you remove the internal gears and clutch pack, mark and proceed track of the side gears so they can be returned to the same position or purposely swapped if excessive habiliment is visible. This is not absolutely necessary, only you want to make certain that you keep rails of the parts and have enough of bench space to lay out the parts.

As you lot inspect the gears for wear, don't mistake machining marks for wearable. Revacycle is an older machining process for producing the tooth contour, and it produces machining marks from the within diameter of the tooth face to the outside diameter. This process is still used today but is non very common.

The differential pin retention bolt threads into the differential instance to hold the pin in identify.

The differential pin retention bolt threads into the differential case to hold the pin in identify.

Drive out the Ford-style S-spring between the side gears and through the differential window. The bound will pop out the opposite side. As it is under some compression, be sure no i is standing in front of it when information technology finally releases.

In order to prevent the jump from shooting across the store, a rag is placed over the end of the differential case to catch the spring. This sounds like common sense, simply many folks forget it and the spring flies across the store. More importantly, you don't desire to gamble injury.

With the gears in place with the clutch, we tin cheque the backfire with a punch indicator.

The Revacycle gear is a cutting gear as opposed to a internet-forged gear. There are serrations from the cutting process on the gear molar surfaces and there is no webbing on the inside or outside of the gear.

A internet-forged side gear has a much smoother molar surface. Since the tooth profile is forged in place and not cutting, it allows for webbing to increase the force.

Only like sometime bearing races, these tin exist helpful every bit printing tools. Former axle shafts tin can be used to aid rotate the side gears. Here we cutting the shaft down in length and welded a plate to the stop.

Nosotros can too utilize a complete axle shaft; we just demand an old bike to bolt to it. This takes up more than space in the shop, but is easier if you do not have access to a welder.

The differential pinions have spherical washers on the ends. These washers are very of import to help with wear, so be conscientious non to misplace them.

Once we are prepare to rotate the differential housing, we tin use the differential pin for this purpose. Nosotros partially install the pin and rotate the housing to walk the gears out.

Once the pinions are out of the differential, the side gears can exist removed as well. Advisedly remove the clutch pack and shims with each side gear. Annotation that the last shim tends to stick in the housing, from the lube film.

Using either net-formed or forged-tooth profiles is a more electric current process, and this process does not have signs of machining on the gear teeth. The cyberspace-formed procedure is becoming the standard for all new differential gears. The procedure allows for additional webbing in the gear profiles and therefore stronger gears.

The differential pinion gears (a.k.a. spider gears) tin be rotated out. At that place are a few methods to practice this. If the clutch pack is worn, information technology can be as piece of cake as merely rotating the side gears, and the pinion gears volition turn relative to the side gears inside the differential case and "walk" toward the window.

If the approach of rotating the gears with your fingers doesn't work, there are tools available to help practice this. In fact, you can make your own tool. An old beam shaft, with the spline end cut off and a square plate welded to information technology, is a good makeshift tool.

Another way to accomplish this (if you don't accept an axle shaft that you are willing to destroy) is to place the axle shaft from the vehicle vertically in a bench vise and identify the differential over the splined terminate. Y'all can even take the original axle shaft and bolt it to the wheel. Then just set the wheel on the ground with the beam pointing vertically upward.

At present that the differential side gear is essentially locked to the demote vise via the splined connection, rotate the differential case. The pinion gears will walk around inside the differential case, assuasive you to remove them from the admission window. In add-on, pinion thrust washers are typically located betwixt the pinion gears and the housings and normally these come up correct out with the gears. If you don't see them immediately, expect closely, as they may be stuck to the pinions or inside the differential housing from the lube picture show.

If, for some reason, the differential case won't rotate by paw, do not worry. Some of these can be very tight. I recommend partially installing the differential pivot into the differential example. Install it just plenty to appoint the housing, but not the inside diameter of the pinion gear.

The pinion gear needs to be gratuitous to rotate relative to the instance, and the pin restricts that if inserted too far.

You tin can put a "cheater bar" on the end of the differential pivot to get boosted leverage. Be very careful; the pin is hardened and the instance is just cast iron. Never pound or bang the pin during this process. Evenly pull on the bar until the pinions rotate. If you lot yank and bang on the differential pin, at that place is a expert gamble that the differential pin hole will be damaged.

In one case the pinion gears have been removed, the peak side gear and clutch pack will want to fall out of the case because the differential is vertical. Be prepared for this and catch the gear and the clutch pack. Again, note the order of these parts and their condition; you don't want these parts falling and bouncing all over the shop. Make certain that the shim betwixt the clutch pack and differential instance has likewise come out.

Now the other side gear, clutch pack, and shim tin be removed. At this point, the differential example should exist completely empty. This is the perfect time to clean the differential case, either in a parts washer or rinsed thoroughly with brake cleaner.

Checking the Parts for Vesture

Lay out the gears and clutches on a bench, in the exact order that they came out of the differential. Just remember which side went toward the ring gear flange side of the case and yous are all set.

In my discussions with the axle and differential experts at Drivetrain Specialists (DTS), they reported observing wear on the side gear teeth. Have a good, long wait at the surface of the teeth and look for signs of article of clothing. The wear is usually concentrated on one side of the teeth because the teeth are loaded more severely in the bulldoze management relative to opposite. If the gears are worn on only one side, you can switch them from left to right and that will load the other less-worn side of the teeth in the drive direction. Your other option is to replace the differential gears.

Take a good await at the clutch plates and reaction plates. The tabs on the outside diameter of the clutch plates easily place them, and you lot should be able to encounter friction material bonded to them. Likewise, inspect the differential pinions and the thrust washers. If wear is observed in the thrust washers, check the beveled surface between the thrust washers and the differential case for signs of habiliment or scoring due to a seized thrust washer that has spun in the example. At that place are new thrust washers avail-able, and you should replace them during your rebuild anyway.

The reaction plates are the steel plates with the spline on the inside diameter. These plates absorb almost of the heat generated during slip events. This heat is prodigal in the gear oil and the differential instance.

I tooth is really chipped on this excessively worn side gear while the others prove pregnant amounts of pitting and wear.

Here is a typical tabbed-way clutch plate, which happens to have woven carbon fiber as the friction cloth. The carbon-fiber material resists wear and can handle higher temperature when compared to traditional paper-based friction.

The reaction plates commonly have an internal spline, special coating, and surface finish for proper interface with the friction material. These plates should not be mixed with different friction materials, the surface coating and preparation on a microscopic level has been optimized to work with the mating friction cloth.

The Ford 8.eight-inch differential gears are really painted at the mill, so they can exist hands identified in the manufacturing plant. This side gear has a clutch pack with the latest carbon-friction-cloth-plates installed.

On the left is the typical amount of wear that you will find on the start and second plates. The plate on the right shows very little sign of article of clothing.

Depending on the mileage and usage of the differential, the clutch pack probably shows signs of wear and scoring. It is a safe bet that the entire clutch pack should exist replaced, especially if the differential, when assembled, had excessive play. This is the best style to restore proper function to the Traction Lok differential.

This is a great time to upgrade to the carbon friction plates that are used on the 2003 to 2008 SVT Mustangs. This is Ford part number Thou-4700-C, and this kit comes with a new preload bound.

The Ford stock-type clutch pack rebuild kit is role number G-4700-B. For some reason, the carbon style clutch pack rebuild kit does not include a friction modifier; the stock-mode plate kit does include information technology. A friction modifier is required and needs to be purchased separately for the carbon-style pack. Likewise, both of these packs come with the correct clutch pack top and shims to friction match the manufactory specifications.

Typically, the showtime and 2d plates wear the most on any clutch pack. This is considering, when the separating forcefulness from the gears is practical to the clutch pack, the first and 2d plates first transferring the torque offset and and then the other plates come into play. If they transfer adequate torque, the other plates meet less speed difference and subsequently wearable less. If you are going to re-utilize your old plates, which I practice not recommend, you may want to move the showtime couple of plates to the eye of the clutch pack. This should put the least-worn plates in the first and 2nd position next to the side gear.

Rebuild Process

The associates process is the contrary of the tear-downward procedure, but there are a few special things to watch out for. Depending on the type of preload that you want across the differential, you can shim the clutch packs tighter or looser. The tighter the clutch packs are, the more windup and potential churr. You lot tin can also upgrade the bound to an F-150 jump. The F-150 spring is approximately ane/4-inch wider than the typical passenger car spring. Its complimentary summit measures around 1.765 inches, equally compared to the automobile leap at 1.510 inches.

But let's keep in mind that we are building a high-performance rear end, not just a stock rebuild. If you lot cannot assemble the differential by mitt, the clutch pack is too tight.

The start footstep is to soak the friction plates in friction modifier for at to the lowest degree 20 minutes. You lot can still expect a few initial "pops" out of the clutch pack when the vehicle is driven. Normally, you should just hear most a dozen or so. The longer the plates are pre soaked, the less initial popping volition exist present. Overnight would be the maximum amount of time before there is no boosted benefit. There is certainly no need to soak the plates any longer than 12 hours.

Be sure to have a make clean, shallow, plastic or steel pan to concord the modifier and plates in. A cookie sail works great for this, but don't apply it to bake with afterward. You lot are only soaking the friction plates. The steel reaction plates do not require this step.

The friction plates need to be soaked in the correct friction modifier prior to installation. This soaking procedure actually conditions that friction as the modifier is absorbed into the fibers of the material. Here nosotros have iii of the plates soaking for 30 minutes.

Also, if you are going to apply the latest carbon fiber way plates, you should properly dispose of the friction modifier used for soaking the plates and only use fresh modifier when you fill up the axle.

While the plates are soaking, make certain that you have all of the parts you demand and that they are clean and dry. During the assembly process, lubricate all of the parts before assembling them into the unit, making sure that they aren't dry out when you first start driving the motorcar. Therefore, make sure that you have some fresh gear oil nearby (the same oil to exist used for the terminal axle fill).

Lay out the clutch pack assembly in the correct order. You should have a total of iii friction (F) plates, four reaction or steel (R) plates and one shim (S) per side. The order is equally follows: side gear (K), reaction plate, friction plate, reaction plate, reaction plate, friction plate, reaction plate, friction plate and shim (G-R-F-R-R-F-R-F-S).

Some enthusiasts utilize a different order and even install additional clutch plates for a tighter differential. Your strategy depends on your level of expertise and what the vehicle'due south application (high performance, drag racing, route racing, etc.) is. There are even rumors of people grinding the friction plates to get more than in the total clutch pack stack.

I like to stick with the factory society and just shim the pack tight. If y'all are working on an early axle (1980s vintage), notice that the clutch plate tabs are square and the new style has rounded tabs. The square tabs are no longer available. Think of information technology every bit a weight savings and your car will be that much faster.

Also, the social club of the plates has changed over fourth dimension. The order for the 1980s-style differentials as stock was: side gear, friction plate, reaction plate, reaction plate, friction plate, reaction plate, reaction plate, friction plate, and shim (G-F-R-R-F-R-R-F-Southward).

Note: An axle of any vintage should exist rebuilt with the updated clutch pack order (G-R-F-R-R-F-R-F-S). If the friction plate is placed directly against the side gear face, a couple of undesirable things happen. First, wear is imparted to the back face of the gear. 2nd, the clutch friction surface is larger than the mating surface on the dorsum of the gear.

We have arranged the clutch-pack stack and shim so that yous can see the proper order of the steel and friction plates. It is important to go the order right to accomplish the correct performance. This stack requires a 0.020-inch shim.

Close examination of this gear and pack assembly reveal that the clutch plate actually is larger than the gear. The clutch plate hangs over slightly by the gear.

Close test of this gear and pack assembly reveal that the clutch plate actually is larger than the gear. The clutch plate hangs over slightly past the gear.

This smaller area results in a pres-certain increase on the clutch face and more wear occurs on the gear and plate. Some people fifty-fifty effort adding more friction plates to the pack. This does let for more friction surfaces and additional torque capacity in theory. The trouble is that the 1 clutch surface has to run on the back of the gear surface. My opinion is to avoid this altogether and stick with the latest recommended lodge of plates (Chiliad-R-F-R-R-F-R-F-South).

It is likewise very helpful to add gear oil to each plate during the assembly procedure. This makes it easier for the pack to stay together and again alleviates any dry running concerns.

On the assembled clutch, notice the two reaction plates side by side to one some other in the 3rd and fourth position. The principal reason for this odd social club is to provide a practiced heat sink to help out the first clutch plate and to allow for full face contact. Each assembled clutch pack consists of seven plates and the advisable shim.

Now is the perfect time to align all of the friction plate tabs. This will brand it easier to drop the assembly into the differential case. These tabs fit into the pockets in the differential housing. In one case you have one complete side gear assembled with the clutch pack and shim, information technology can be loaded into the differential housing. Double check that the clutch plate tabs are all located in the windows in the differential housing.

A fiddling trick here to see how tight the pack is without completely assembling the unit is to install the two pinions and cross pivot without the other side gear. Insert a screw-driver between the differential pin and the face up of the installed side gear and lightly pry to simulate the utilize force of the preload jump. With the force applied, advisedly stone a pinion back and forth to cheque backlash. If you take no back-lash, the pack is too tight. If the backfire is much beyond 0.020 inch, the clutch pack is too loose.

These are all of the internal components of a express-slip differential. We have arranged them outside of the differential to show the relationship of the parts. Once installed in the differential example, it can exist hard to meet all of the components.

The clutch plate tabs must marshal with cutouts in the differential casting. This semi-round notch tin exist seen near the bottom of the admission window.

Information technology may be tricky to go ready upward with a punch indicator without an banana. You can await until the entire differential is built without the pre-load spring installed and cheque it again. Of class, if you desire a existent tight differential, you need to shim it tight. A adept range for back-lash is 0.001 to 0.006 inch.

You lot can purchase complete clutch packs that are already shimmed and fix to go. If y'all become that route, be certain to go along everything together every bit packaged. Exist careful not to mix things up while the friction plates are soaked in modifier. This is a quick and easy way to go because you can skip the whole clutch pack shimming and backlash setup.

You can measure the clutch pack assembled height in accelerate to get an idea of how close you lot are. The Ford style's typical range is 0.640 to 0.645 inch. The performance kits tin exist every bit thick every bit 0.655 inch. The easiest method to measure the pack is to lightly clamp the pack with a C-style clench and measure the overall thickness with a set up of calipers or a micrometer. Information technology is besides recommended that the clamp thickness of the left and right packs is kept close to 1 another. If there is too much variation, information technology tin can be difficult to install the differential pivot later in the associates process.

Again, if the pack is too tight, the pinion gears are extremely difficult, if not impossible, to gather. Too, keep in mind that you want backfire or clearance in the differential gears when they are completely assembled.

As stated above, this comes down to personal preference. If y'all are planning on running slicks and racing ofttimes, shim information technology tight. The differential is shimmed too tight if you cannot get information technology put together. The tighter the pack the more windup or bind y'all will notice during depression-speed, tight-plow maneuvers such every bit pulling into a parking spot.

This preload that is existence built into the unit and the strength provided by the S-spring is all static preload. Once the differential gears (non hypoid) begin rotating relative to one another, the separating forces from the gears employ additional thrust loads to the clutch pack to resist this spinning. Equally mentioned before, this is the speed difference as compared to between the left and correct wheels, and not vehicle speed.

The nautical chart shows speed divergence plotted on the horizontal axis confronting torque transferred on the vertical axis. You tin can run into that the line does not begin at the nada point, where there is no speed difference across the differential gears. It is actually offset up on the torque curve. This amount of offset is based on how tight the pack is assembled and the forcefulness practical past the Due south-bound.

There are many "one-time tricks" that work, simply aren't always the best idea. Some folks build the clutch pack tight and omit the Due south-leap. This allows the pre-load to exist nil and the differential will allow speed difference under lite torque easily, just like an open differential. Then, when higher torque is applied, the separating forces from the side gears further compress the clutch packs. In this situation, if one cycle begins spinning on a glace surface (ice, gravel, etc.), the torque is very depression in the arrangement as the resistance between the tire and the slippery surface is very low. Stepping on the gas pedal harder does not produce more torque in this case. The S-spring helps in this specific driving status. If you lot are concerned most too much preload, don't substitute the stock spring with a stiffer jump.

In social club to measure the overall pack thickness, we lightly clamp it together and measure out it with a micrometer. In this instance, nosotros used a pair of vernier calipers to mensurate the overall pack thickness or height.

The Ford service kit comes completely assembled and pre-shimmed. Although this takes the shim aligning office out of the equation, nosotros still need to disassemble the clutch pack in order to soak the plates in friction modifier.

This graph represents a typical preloaded clutch-pack-fashion limited-slip differential. The clutch-pack preload shifts the graph vertically so this is no speed difference across the differential, but in that location is still a resistance to differentiation from the preloaded clutch pack. Once a speed departure occurs, the side gear separating loads applies additional forces to the clutch pack.

The nut and bolt with big washers provide an associates aid. While typically not required, it tin be helpful. Once the pinions are installed, you tin can remove this nut, bolt, and washer arrangement.

Although pinion washers can be difficult to re-install in the differential, make certain to get them in place during the associates procedure.

It is possible to rotate the pinions in place by yourself, but information technology's much easier to have a second person assist. Notice that the pinion washer is correctly in place.

As long equally the pinions are lined up correctly, the differential pin volition slide smoothly in place. It is best to check this alignment now before the ring gear is installed.

It is very piece of cake to install a pinion one tooth off. When this happens, it is impossible to correctly line up both pinions through bores with the differential instance. If this situation occurs, you need to remove the pinions and beginning over.

If yous have temporarily installed the pinions and differential cross pin, they demand to exist removed. At present yous can install the other side gear with clutch pack and shim. Double-bank check that you have the clutch pack order correct. This is where things get tricky. Y'all need to concord the side gears in identify while putting the pinions in place and getting all the teeth to line up. You can apply a bolt with large washers to temporarily concur the side gear(s) in place. You can get past with-out this aid, just information technology can be helpful.

Do not forget the spherical pin-ion washers that go betwixt the pinion gears and the differential example. Take your time and be patient; these tin can be tricky to install. At this stage, help from a second per son tin be helpful, although it is not required.

In one case the pinions are in place, you need to rotate 1 side gear relative to the differential case to get the pinions to rotate into identify.

If the gears are all lined up correctly, the differential cantankerous pin should drop right in.

If the pinion teeth are off by one and yep, it is possible one pinion hole may line upwardly correctly, but the other may not.

Unfortunately, in gild to correct this misalignment you need to rotate the pinions dorsum out and index 1 pinion over to the adjacent side gear tooth. This is where the homemade splined axle shaft tool is then helpful. Over again, exist patient and go it right.

Once the gears are in, installing the Due south-shaped pre-load jump is the last step. There are many ways to do it. You can compress the spring in a vise or use plates on either side with a C-style clamp, or but tap it in. I take washed several of these and am comfortable with just tapping them in with a hammer. Exist careful, this is fabricated out of hardened leap steel, and you lot don't desire to scissure or over-shrink it.

Next, I like to put the differential pin in identify and start the cross pivot bolt a couple of threads. This ensures that everything stays together until I am fix to put information technology back in the car. A trick to help align the cross pin bolt is to put the commodities in the pin before pushing the pin in all the mode. Then, use the bolt equally a handle to plow the pin and marshal the bolt with the hole in the differential instance.

The final footstep is to remove the bolt, button the pin in flush, and the bolt pigsty should line upwardly perfectly.

Terminal Assembly and Operation

When you lot get the axle completely re-assembled, don't forget to add the correct amount typically 4 ounces of friction modifier to the lube fill. This is very important to make certain that the clutch remains quiet over fourth dimension. You should plan on using traditional non-synthetic gear oil during break-in. Afterwards you have 500 miles or so on the gear, feel gratis to change the oil and switch to synthetic if yous similar.

If you have replaced the band and pinion gear up, check to meet if the manufacturer has added a phosphate coating to the pinion and/or ring gear to assist the gears break in properly. Think of this similar flat tappet camshaft burglary lube that is added during engine associates. Ever follow the instructions that came with your new gears or differential if they vary from the information in a higher place. Some gear and clutch manufacturers recommend synthetic lube during the burglary process.

The preload Southward-jump can be com-pressed with channel-lock-style pliers or a C-clamp to assist with installation. Once you accept rebuilt several of these units, you develop the feel for how much to tap the spring to get information technology started in place.

Orient the differential pin retention hole earlier the pin is completely installed. We like to employ the retentiveness bolt to aid us visually orient the pin before nosotros button it in all the way.

Once the pin has been completely installed, you should put the retention commodities in identify and lightly first the threads. This will make certain that the pin does not autumn out before you are ready to install the differential.

Now that the Traction Lok is rebuilt and installed, you should no longer have that embarrassing single bike skin. You can confidently put down two black ribbons of tire rubber. Of form, earlier you try this, make certain that the hypoid gears are properly broken in (if they were replaced at the same time as the differential rebuild).

The typical amount of time required to perform the rebuild is four to 5 hours depending on your skills and how many you have done before. It is not a difficult task, even for the beginner. It only takes time and patience.

GM-Style Limited-Slip Differential

The GM-style limited-slip differential doesn't utilize the S-style bound for preload. It instead uses a series of wound-ringlet springs trapped between two steel plates. Eaton Corporation produced these differentials, which are typically referred to every bit Positraction rear ends. The Eaton Posi was first introduced as optional equipment in 1960s-vintage Chevrolet rear axles.

The Traction Lok assembly and disassembly instructions apply except for a few small-scale changes relative to removing and installing the springs and plates. Basically you follow the aforementioned steps until it is time to remove the S-spring. And so you tap the bound pack partway out through the differential housing window with a brass punch (non all the manner, as yous want the pack to remain intact and not fly apart). Usually 1 inch or and so will do.

Many people swear by the Blue Oval brand of friction modifier. The modifier is bachelor in 4-ounce bottles from whatsoever Ford dealer.

With the proper preload across the differential and a good set of clutch plates, the rear axle acts like a spool during hard acceleration. This is axiomatic because both wheels have left a blackness patch during a burnout, and those patches offset at the aforementioned time. If one patch starts before the other, it may exist a sign that the preload is non high enough.

The GM-style limited-slip differentials use four compression springs equally opposed to the unmarried S-manner bound Ford uses. Eaton builds these differentials both as factory-installed and aftermarket units.

The leap pack needs to exist tapped out like the Ford Due south-leap. You desire to make certain that you alternate between the spring plates and do not hit the springs themselves.

One time the spring plates are partially pushed out, you can grab them with a suitable set of pliers. But compress the springs, and the plates and springs should pull out.

The 200-, 400-, and 800-pound spring and jump plates are shown from left to right. The spring plates get thicker every bit the spring charge per unit increases. Besides, the spring wire diameter and number of active coils vary and, consequently, it is like shooting fish in a barrel to visually tell which springs accept been installed in the differential.

Next grab the jump pack from the opposite side window of the differential housing. Utilize a pair of locking pliers and remove the entire pack.

Audit the plates and springs for cracks; clean and supercede as required. If you want a higher preload torque, now is the time to replace the spring pack with a stronger set up. Typically for these units, in that location are 3 spring-preload options available: 800-, 400, or 200-pound. The higher the bound force, the college the preload and torque bias ratio.

Spring Forcefulness Math

There are rumors out there suggesting that the advertised forcefulness from these springs is not right. I decided to perform some reverse engineering to verify which is true:

k = Yard x d^iv/ (8 x Northward_a x D³)

Where:

k = spring charge per unit expressed in lbs/in M = shear modulus of elasticity (a constant value of 11,312,516 psi for steel)

d = wire diameter in inches

N_a = number of agile coils. The term active coils or a turn of a compression spring refers to the number of turns of the wire cloth that actually deform during pinch. Nearly springs are designed to have the top and bottom coils footing flat to allow for better seating. The ground section of the spring is not considered active in this example.

D = mean curlicue diameter in inches, which likewise can be found as (inner diameter + outer diameter) ÷ 2

One time we have the leap constant calculated, nosotros can find the force per spring past solving the following equation:

F = thousand (Δx)

Where:

Δx = (spring gratis height) – (bound installed meridian)

We made some estimates for the number of active coils and rounded to the nearest number. We too considered the unlike leap plate thicknesses and came up with the post-obit:

From this nosotros get the spring rates (g) as 80, 364, and 1,485 lbs per inch, respectively.

Now we presume that the total compressed top is 1.32 inches and have into business relationship the 2 leap-plate thicknesses. We used the to a higher place force equation with the following parameters:

This yields forces of 45, 90, and 163 pounds, respectively. Since there are four springs in parallel, nosotros multiply the forces by iv to yield 180, 360, and 650 lbs per inch, respectively.

These are very shut to the advertised values, especially when you consider that nosotros fabricated some approximations for values such as the number of active coils, compressed acme, and wire diameter. Keep in mind that you cannot simply accept the 200-pound numbers and multiply by four to get the 800-pound spring numbers. In that location are differences in plate thicknesses and, therefore, in the compressed heights of the springs.

Differential Gear Removal

Follow the Traction Lok procedure to remove the rest of the differential gears and plates. Always go along track of shims and the order of friction plates and steel plates so you tin reassemble them in the aforementioned lodge. A new friction plate is approximately 0.070 inch thick for this style differential. Also, this mode clutch pack uses pocket-sized hardened caps, upon which the clutch plates ride inside the differential case. These simply foreclose the plates from wearing grooves in the case and inhibit free movement of the clutch pack.

When it is time to re-install the spring pack, you just need to squeeze the pack together between some plates with a C-style clamp and and so tap them in betwixt the side gears. Once the spring pack is started, you can remove the clench and finish tapping the pack dwelling.

As with the Traction Lok procedure higher up, once the pack is in, double-check that the differential pivot assembles easily without interfering with the bound pack.

The clutch pack tabs run on these hardened caps. There are two caps per side-gear-and-clutch combination. Therefore, you demand to install iv caps per differential.

A C-clench with some steel plates tin exist very helpful to shrink the bound pack. And so nosotros can tap the plates in place. Recollect, you desire to tap the plates and non the spring themselves. Make certain that the springs stay aligned on their seats.

The compression-bound-style differentials accept different options for preload springs and clutch-plate quantities too as clutch friction material (equally described in the "GM-Style Limited-Slip Differential" section above). As a result, you can set up dissimilar preload torques. The following describes some of the combinations for this type of differential.

If you lot stick with the typical stock springs that produce a net force of 200 pounds, y'all have a couple of choices: The stock steel plates with a ix-plate pack setup per side (made upwards of v friction plates and four reaction plates), or a seven-plate pack per side setup with carbon-cobweb friction plates (made up of four friction plates and iii reaction plates). The carbon-fiber plates are a great upgrade over the steel plates and significantly reduce, if not eliminate, clutch churr. (Remember as the preload increases, the tendency for chatter increases.)

If you switch to the 400-pound bound setup, yous tin utilise the seven per side arrangement with carbon plates, which is the standard for new Eaton differentials, or you lot can utilise steel with a nine-plate pack per side similar above.

If you switch to the 800-pound jump setup, you can again choose between a seven-per-side carbon-way pack or a nine per side steel-pack system. As ever, the steel pack produces a fair amount of clutch plate chatter. The most aggressive kit is the 11-plate-per-side system with steel plates and 400-pound springs, or carbon plates with 800-pound springs. These 2 arrangements wear extremely quickly and are meant for elevate racing only.

Simply how much bias torque is theoretically achieved from these different arrangements? The torque capacity of any clutch tin can exist represented by this unproblematic equation:

T = μ ten N ten R_m ten F

Where:

T = torque in ft-lbs

μ = coefficient of friction (a dimensionless number, typically 0.10 for these clutch plates in gear oil)

R_m = mean diameter of the clutch plate surface in feet (0.2458 foot for the GM-style plates)

F = apply load in pounds

Northward = number of friction surfaces

Hither are the results of our calculations:

The bias torque value is a linear relationship to the bound strength. As the spring forcefulness doubles for a given clutch pack's total plate count, the bias torque also doubles. (Meet Chapter v for more than nearly clutch pack preload and side gear separating strength.)

Keep in mind that the college the preload torque, the tighter the differential, or the less likely the differential is to unlock and allow a speed divergence across the wheels. The tighter the clutch pack, the more windup and noise tin be expected from the rear axle, especially in slow, tight-turn maneuvers. Basically, the on-route street manners of the vehicle volition exist compromised as clutch pack preload increases.

Cone Mode Limited Sideslip Differential

Chrysler Sure-Grip express-slip differentials are typically institute in 8^3⁄4-inch rear ends. At that place were ii variations available: the plate type (described earlier) and the cone type. Models from 1958 to 1969 used the plate-style Dana Power Lok. Borg Warner originally manufactured the cone type from 1969 to 1974. The cone type cannot be rebuilt; your best option is to buy an aftermarket unit if yours is not working correctly.

The cone-mode limited-slip differential has the same function as the plate-fashion but uses cone-shaped friction surfaces. If yous await closely at the side gear near the round window on the left, you tin see a portion of the cone surface. (Auburn Gear)

The cone-style limited-slip differentials perform the same role equally the plate style. There are just a couple of differences in design. The cone style utilizes a conical-shaped friction surface, much similar a manual transmission synchronizer, and there is typically but a single surface per cone. Borg Warner originally produced them in the 60s and 70s under the name of Spin Resistant. Many of the Large Three vehicles (GM, Ford, Chrysler) used them. In the early 80s, Auburn Gear began manufacturing differentials with the cone-way design and yet produces them today. The units take a set of thrust plates with preload springs between them that look similar to the GM preload springs.

The cone-type surface reacts confronting the differential case and they end up being a matched set. Some enthusiasts mix and friction match different parts from multiple differentials in an try to repair a worn-out unit. This is not recommended and the performance cannot exist predicted. You may get lucky, merely it is not worth the risk. Fortunately, these units are replaceable. Auburn Gear actually offers a direct exchange pro-gram. You can go to the nearest benefactor and, for the typical price of a clutch pack rebuild kit, yous can exchange your worn unit of measurement for a new differential that'due south set to go. A dainty attribute about this program is any updates or improvements to the parts are already included in the replacement hardware at a reasonable cost.

Ford Mustang Differentials

In that location are several differentials that have been offered for the Ford eight.eight-inch axles typically institute in the Mustangs over the years since the introduction of the Fox chassis. I am not going to review all of the older-style (pre-Play a trick on) designs but will cover most of the different combinations that take been available for the 7.five-, 8.5-, and 8.8-inch axles.

The first matter to be aware of is that all of them are two-pinion differentials.

Call up that all 28-tooth-spline side gear differentials require a 3/iv-inch differential pin, while the 31-molar side gear differentials employ a 7/8-inch-bore differential pivot.

The vii.5-inch ring gear axle has a 28-tooth spline and a 10 x sixteen-tooth combination. At that place are 10 teeth on the differential pinions and 16 teeth on the side gears. The typical application for this axle is the Five-6 Mustang.

Hither are the diverse Ford differential gears that are bachelor. From left to right: 7.5-inch 28-tooth spline 10 10 16 tooth combination (blue), 8.5-inch 28-tooth spline 10 x sixteen tooth combination, eight.8-inch 28-tooth spline x x fourteen tooth combination, eight.8-inch 31-molar spline 10 x fourteen tooth combination, 8.8-inch 31-tooth spline ix ten 13 tooth combination.

The viii.5-inch ring gear axle has a 28-tooth spline and a ten x 16-tooth combination besides. Some applications are the Flim-flam chassis (1979 to 1993) Fairmont, Zephyr, Mustang, Thunderbird, Granada, etc., and Explorer/Ranger.

One 8.8-inch ring gear axle has a 28-tooth spline and a 10 x 14-molar combination. This was a hybrid differential. Information technology has an upgraded differential case that is stronger than the previous differential. This is the differential that y'all want if you are not going to upgrade to 31-tooth-spline axles and you lot broke your 8.5-inch 10 x 16 differential. These are found on the SN95-chassis (1994 to 2004) college-powered V-viii applications, such as the Marauder, Bullitt, and Mach i.

Another 8.viii-inch ring gear beam has a 31-tooth spline and a x x 14-molar combination. Some applications for the differential are the F150 and S197 (2005 present) V-8 Mustangs.

The tertiary viii.8-inch band gear axle has a 31-tooth spline and a 9 ten 13-tooth combination. These differential gears are stronger, which results in a slightly heavier differential associates. This differential can exist found on the S197 (2005–present) specialty Mustangs only, such every bit the Shelby GT and KR.

Summary

At this point, you know how to tell the difference between an open differential and a express sideslip differential. And you know why you want a limited skid differential in your vehicle. You should also be aware and confident of how to disassemble and reassemble your limited-slip differential and what areas to look for regarding wear.

Written by Joe Palazzolo and Posted with Permission of CarTechBooks