Hi guys!

Question for you: If the rear differential's clutch pack is completely worn (only the passenger side tire ever spins / drives), does this cause any wasted energy or slippage in the rear end (say, for example, going around a turn when power should be transferred to the other wheel)?

(I don't feel 'slipping', but I could be missing some energy loss)

Or does it essentially lock up the one drive wheel to make it push all of the time?

If you were to do a rebuild on a 1999 8.8", would you just go with the OEM clutch disks?

Thanks for any insightful replies!

Best,

GD

 

If your clutches are completely worn, then your basically running an open diff right? Maybe running clutch pack particulate through your bearings, don't know if that is awefully bad or not. . .

If your curious to find out if its slipping, jack the truck up on stands, so both tires are off the ground, and try and spin them. If its tight, and you have stock tires, you will have a hard time moving it. If its lose, it will spin like an open diff, with a litle drag. I have a L/S in my D61, and moving it around the yard on 38's you really have to give 1 tire a shove to get it to break lose to turn, and this was a used L/S.

An OEM rebuild would probably be fine, there is a way to arrange the clutches/steels to get an extra one of each in there. Don't know right off hand, but it is fairly well documented on the site. . .somewhere

 

I guess I am running an open diff... ? maybe tha's right, and maybe it isn't (which is why i asked here - if you claim it isn't losing power due to slippage, and all the power is just focused on the one wheel, then I'll have to believe ya, as I don't truly know how clutch packs work)

I'm wondering what the best price I can find to have them changed out will be?

I'd do it myself, but i don't want to end up vehicle-less if it goes badly on a weekend.

 

Any power loss would only happen in an open diff if one tire lost traction causing all the power to go to spinning that wheel. If both tires are on the ground and both have traction, then your not lossing power, even going around a corner. . .thats what the differential was designed for, to let one wheel spin faster or slower than the other around a corner (inside tire turns slower than the outside tire) while still putting power to the ground.

A L/S puts friction in the differential to help negate power loss if one tire losses traction. The power will still be going to the tire that is sliping, but it will now have to overcome the friction of the clutch packs which helps send some of the power back to the other tire on the ground (there are exceptions, but this is a pretty good explanation). The more your L/S wears, the less it can "transfer" power until your running an open diff.

Now, I don't know how the 8.8 changed if any in 1999, but here is how a L/S works from a 1996 and earlier 8.8. I doubt the basic setup has changed much though.


Ok, the L/S is for the most part an open differential with a machined reccess behind each side gear. The side gears have rough splines machined into the outside of what would normally be the bearing surface that rides in the carrier. The clutch pack is made up of steel plates with tabs on the outside that lock into the carrier in the reccess. The friction disks have teeth that engage the splines on the side gears. So, if you can imagine having layered frictions and steels sitting behind each side gear, the only way for the gears to move is if a force great enough is applied to those gears to spin the frictions against the stationary steels and the clamping force holding the clutch packs together. The clamping force is apllied by a very heavy "Z" spring inserted between the side gears in the center of the carrier. The spider gears and shaft remain the same as in an open diff.

I do know you can get the "Z" spring out with out removing the ring gear, but I don't know if it will go back in. Takes a big hammer and alot of prying to get it out the way I did it.

I won't even go into price I can tell you it ain't gonna be cheap though Have you tried a search here? Or maybe try your local chapter to see if anyone there might be willing to give you a hand? Its a long shot, but who knows. Good luck with this, if you have anymore questions, just holler

 

A worn out limited slip carrier acts just like an open one. Power is distrubuted basically equally under most conditions, except when one wheel slips. Then that wheel gets almost all of the power.

 

My 1992 F150 Ford Factory Service Manual says that the way to test the Trac Loc limited slip is to jack up one side of the rear axle and then place the transmission in neutral and then take a torque wrench and using a special attachment that connects to three lug nut studs--see if it takes 20 foot pounds or more torque from the torque wrence to get the wheel in the air to turn.

I checked my 101k limited slip Trac Loc and it took 23 foot pounds to turn the elevated wheel. I didnt use the special attachment--I just placed the torque wrench on one of the lug nuts.