8.8" Rebuild Help

I know ford makes the standard rebuild kit and a kit with carbon discs. other than that, I don't think there are any options.

I would think the kit ford sells will work quite nicely after all your factory 8.8 has worked well up to this point.

or get a locker unit.

The stock limited slip made by Visteon is just a weak unit. It can be rebuilt but is not a very strong unit. The clutch discs are not very durable in design and they use a weak S-spring to preload the packs instead of a spring pack like Eaton or Auburn (cost save). The Auburn is ok but it uses cone clutches and I don't think it is rebuildable. The Eaton Posi is probably the best unit you could put in your car. They use carbon disc material. Unlike the ford discs that look like smooth and paper like. The Eaton discs look woven and extremely durable. They also use a 400lb spring pack. I have built many Eaton units that have gone in very high horespower cars and I have found them to be the best. Look to pay $400 for a new one but if you can get one used they are not too bad to rebuild. Be cautious of lockers on a street car. Lockers are great low-speed performers which makes them perfect for truck that are driving off-road or a car that spends its life at the track. If you are looking for high speed performance and traction then a limited slip is best.

i can't understand why auburn's are so popular for aftermarket posi's. once they are worn they are garbage. eaton is about the same price and perform the same. most five liter gearhead magazine advertisers don't offer them. why i don't know.

I just bought THIS ONE
For my car. I put 03 Cobra wheels with 275 tires and started getting the one wheel peel. Im buying a Detroit Tru-Trac next year though. This is only temporary.

i bought a rebuild kit for 50.00 through my local car quest a week or so ago, they sent me one from northwest differential. it was a better looking kit than stock, and included one extra friction plate for each side and one extra steel plate, two of which i couldent use but it fits in order anyway..the extra plate should help but it caused some problems, i had to remove the steel washers behind the spider gears for them to go back in, and i had to grind those two flat spots in the center pin all the way across the pin so it would slide through the axles after i had the C clips on which moved them slightly inward, not a big deal and it doesn't slip it all, if you can find a phone number or website they shipped overnight, and have a great product IMO

~Mark~

Foxbody1993 said:

I just bought THIS ONE
For my car. I put 03 Cobra wheels with 275 tires and started getting the one wheel peel. Im buying a Detroit Tru-Trac next year though. This is only temporary.

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The Tru-Trac is not a bad unit but there are a few things to consider. The unit is very similar to a Torsen in design and does not use any clutches. It basically creates bias torque (torque applied to the low traction wheel) by the angle of the spiral gears. When there is not any load on the unit it spins free. This makes it function like an open around town. Under acceleration it will bind and create torque to both wheels most of the time. But it will not not give the vehicle any bias if one tire has no traction (one wheel peel) because the gears are not preloaded. This also limits traction during high speed turning because one tire may start to lift from the road surface and the unit will lose its ability to create bias torque. With a clutch style limited slip you will never get to the point were you won't have any bias because it has a pring pack that is always applying force to both wheels. A clutch style is much better for autocross vehicles and will almost always prevent one wheel peel even when one tire has no traction (spring pack creating bias torque). The Tru-Trac is a great unit for off-road vehicles (trucks) that want the vehicle to handle like an open and still give enhanced traction when needed. Not the best for a high speed street car though. In addition, after the Tru-Trac unit has been ran a few hundred miles the unit will lose much of its bias torque because the gears actually become polished.

ronburgundy said:

i can't understand why auburn's are so popular for aftermarket posi's. once they are worn they are garbage. eaton is about the same price and perform the same. most five liter gearhead magazine advertisers don't offer them. why i don't know.

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You obviously know you differentials. I think it has to do with the marketing. I work for Eaton and I have conducted various competive analysis on different units and Eaton is by far the best. Eaton does not spend a lot of money marketing towards the aftermarket. We focus primarily on oem applications because there is just more to be made. Our mechanical locking differential is in GM trucks (G80-option) and is offered in the 8.6, the 9.5, the 10.5, and the 11.5. We have electronic lockers that are standard in the Hummer H2s and H3s. Our hydraulic locking differential is found in the Jeep Grand Cheorekee with Quadradrive on 2005 and up. Our Eaton Posi is standard in the new Trailblazer SS with the 6.0 liter. But other than that the posi is mainly aftermarket and does not get much marketing. Many performance shops know this and use Eaton posis in their customers vehicles.

91notchbk said:

The Tru-Trac is not a bad unit but there are a few things to consider. The unit is very similar to a Torsen in design and does not use any clutches. It basically creates bias torque (torque applied to the low traction wheel) by the angle of the spiral gears. When there is not any load on the unit it spins free. This makes it function like an open around town. Under acceleration it will bind and create torque to both wheels most of the time. But it will not not give the vehicle any bias if one tire has no traction (one wheel peel) because the gears are not preloaded. This also limits traction during high speed turning because one tire may start to lift from the road surface and the unit will lose its ability to create bias torque. With a clutch style limited slip you will never get to the point were you won't have any bias because it has a pring pack that is always applying force to both wheels. A clutch style is much better for autocross vehicles and will almost always prevent one wheel peel even when one tire has no traction (spring pack creating bias torque). The Tru-Trac is a great unit for off-road vehicles (trucks) that want the vehicle to handle like an open and still give enhanced traction when needed. Not the best for a high speed street car though. In addition, after the Tru-Trac unit has been ran a few hundred miles the unit will lose much of its bias torque because the gears actually become polished.

Click to expand...

Well now that class is out I probally will just get and Eaton. LOL Thanks for the class. I liked the price on it and figured it couldnt be too bad, Guess I was wrong! Will my current stock diff act alot better after a fresh rebuild and work decent for a year? I pull out and try to accel quickly and it just breaks the rr loose and spins like bastard! Pls PM me any extra info. I really need to understand this.

Foxbody1993 said:

Well now that class is out I probally will just get and Eaton. LOL Thanks for the class. I liked the price on it and figured it couldnt be too bad, Guess I was wrong! Will my current stock diff act alot better after a fresh rebuild and work decent for a year? I pull out and try to accel quickly and it just breaks the rr loose and spins like bastard! Pls PM me any extra info. I really need to understand this.

Click to expand...

The stock visteon unit will probably be good for 20k miles but it really depends on how much horsepower you have. It is really hard to say. The Visteon units do ok but when they start to one wheel peel they will glaze the discs almost immediately. This is because the discs are just slipping and a ton of heat is building up. I have removed limited slips that were spinning only one wheel and the driver just kept his foot on the throttle and really cooked the unit. The oil was black and burnt and the discs were smoked. As long as the discs are holding the wear on the discs is minimal. The problem is the friction material Visteon uses eventually loses its coefficient (poor friction material) and one wheel peel starts to happen. It progressively gets worse because one wheel peel is the worst thing that can happen to a limited slip. Under this condition TONS of heat is built up and the discs will get almost immeditely glazed which means they lose their coefficient (ability to grip) and from this point on it just gets worse. If you rebuild the the Visteon You will probably be ok for a while but eventually the dreaded one-wheel peel will return. Put an Eaton in and enjoy the traction. Attached are some pics of the difference between the Visteon discs and the full carbon disc from the Eaton unit. Notice the larger surface area of the Eaton discs over the smaller Visteon ones. Also, the woven carbon designwhich makes the discs very strong and durable and they will not glaze and lose coefficient like the Visteon discs. Another factor to consider is the Eaton uses a stronger spring pack instead of a weak s-spring.

If you do rebuild the Vsteon make sure you shim the gear packs tight so that you have between .000-.002 backlash between the side gear and pinion gears. Do this by checking one gear pack at a time and draw the gear tight in the housing with a fixture of some sort. This is important for longevity and durabilty and will prevent any play in the rear end. If this is not done and the packs are shimmed loose the unit will have a short life and you may have a small amount of play in the rear end.

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These are picks of an Eaton unit and a Visteon unit (s-spring).

what I like to do when I rebuild the factory Trac-Lock 8.8 carrier assemblys is to install 4 clutck disks per side instead of three. in a sequence of (from sidegear out) friction disk,steel,friction disc,steel,friction disk,steel, friction disk and then shim. and thats four friction disks and three steel disks. do this on both sides and your car will not one wheel peel any more. this lasts a long time, Haven't worn one out yet.

woven carbon material is incredibly durable. gm has been using this in their torque convertors since about 97. they intentionally slip the tcc in order to acheive a smooth lockup. if you can intentionally slip a product and have it last 100k miles or so, you've got a tough material.