Can someone tell me how a LS differential works? I was under the impression that if one wheel spins, it shifts power to the other....is this correct? I did a VIN# search and know I have a LS diffy. Today I got stuck in my driveway probably a 1% incline. I have Toyo G-02 open country tires with 10/32 tread on them and the right wheel kept on spinning while the left wheel did nada! I bought the truck this summer, and I know it's not a 4x4, but I'm really discouraged with the snow traction so far, even with 600 lbs of sand in it.

Thanks
Itch

 

As far as I know it's supposed to power both tires when one starts spinning.. maybe there's an issue with your limited slip?

 

Next time it happens lightly apply the brakes, that should kick it in.

 

If one wheel is spinning the non-spinning wheel should have 20 Ft Lbs. of torque applied to it.

Operation

The pressure between differential clutch packs (4947) opposes differential action at all times. When the vehicle turns a corner, the differential clutch pack slips, allowing normal differential action to take place. Under adverse weather conditions, where one or both wheels may be on a low-traction surface such as snow, ice or mud, the friction between the clutch plates will transfer a portion of the usable torque to the wheel with the most traction. Thus, the wheel that is on ice or snow will have a tendency to operate with the opposite wheel in a combined driving effort.

CAUTION:
Extended use of other than matching size spare tires on a Traction-Lok® rear axle (4001) could result in reduction in effectiveness (bias torque). This loss of effectiveness does not affect normal driving and should not be noticeable to the driver. However, extended usage will reduce the ability of the rear axle to provide added traction on slippery surfaces.

 

Jack up both rear tires and with the transmission in neutral, spin one tire. Both should turn the same way. If the other side spins the opposite way, you have a problem with your limited slip.

I had to replace my clutch packs at about 190K. Not a hard job at all other than removing and installing the spring.

 

There are several different designs of limited slip differentials. Most use a pack of clutches held together by springs, the clutches allow a certain amount of slip to occur when going around corners. Other types (older Mopar) used cones. Both of these types require friction modifiers to be added to the gear old to allow the clutch systems to engage/disengage properly.

The type of differential that switches traction to the the spinning wheel is the Torsen type, which uses an arrangement of gears which can transfer traction to whichever wheel needs it.

Another type is the Detroit locker, which uses a noisy ratchet type system. It locks both axles firmly when full power is applied, giving the best traction.

Yet another type is the air locker type differential (which I had on my Jeep Rubicon), which allows you to lock the differential as needed at the flip of a switch.

Most limited slip diffentials are somewhat expensive and complicated to install. If you have an 8.8 differential in your truck, you might thing about putting a Lock Right differential in it. The Lock Right is an inexpensive Detroit locker style differential that is installed in place of the spider gears in an open (non LS) differential. It requires no special set up or friction modifiers, and can be installed in your driveway with hand tools. It took me about 2 hours to put one in my old 72 K5 Blazer.

 

either your limited slip aint working or you dont got any because its supposed to spin both tires when one tire is slipping

 

My 87 has a LS, it almost always spins both rears but now and then when it don't I dab the brake pedal and it grabs. Saved me many times from having to get out and lock the hubs.

 

The factory setup of the differential clutch packs is heavily biased towards slip to minimize tire wear, and as the friction material wears over time it only gets worse. These clutch packs are pretty easy to rebuild and restack for much more positive action, and can also be shimmed tighter for even more preload. Sounds like your diff needs this rebuild.

 

Thanks for the feedback everybody. Will try the brake dab and see what happens...if not will look at the clutch pack.


thanks again
Itch

 

I know what you say is true but in all this time I have never noticed a loss in its action on my 87's LS, must have got a real good one from the get go.

Not necessary very often but I noticed if one does spin without the other hitting the brakes tricks it that both tires have equal traction on the ground and it then grabs and powers both wheels the same.

Sand has always been the worst for it for some reason, one will try to sink out of sight while one wheel just sits there.

Gravel, snow and ice it always spins both wheels. Nice for doing donuts!

 

Yep.. like everything else mass produced, sometimes you get a jewel, sometimes a lemon. Both my F150s were pretty average when I got them, the diff would growl under power in slippery conditions as the clutchs rapidly grab and release. The result was you could make progress and the diff was limiting the amount of slip so it was working as advertised, but in situations where 1 wheel has little traction it was easy to get stuck. The solution was easy. Remove the clutch packs and restack them with alternating friction and pressure plates(this is not how the factory stacks them BTW). You end up adding an extra friction plate per side and I went further and shimmed the stack tighter for more preload. The result, I got both wheels driving everywhere all the time, and with any torque applied the rear axle is essentially locked.

 

I took the truck out today, to try the brake dab test. Low and behold, the LS engaged without having to hit the brakes. I tested it for a good 10 minutes, looking in the rearview mirror and had both wheels turning once one started to slip. No idea why this did no happen the other day.

Paul is this what I need to replace? http://broncograveyard.com/bronco/i-...clutch_set.htm
Do you need special tool for this job? The only diagram on the 10.25 I can find doesn't have LS, so I'm not sure where to start.

Itch

 

That's part of the clutch pack but those look like the pressure plates despite what the link says. No special tools required, but I usually replace the pinion shaft locking bolt with a new one when I do this job.