LSD Carrier innards questions

[alcyon]

I will be getting my used OEM LSD soon, so I will be working on it. Since this will be my first time working on such a diff, I have several questions.

1. I heard some people mentioning about removing the side shims installed by the factory that goes between carrier and side gear. Is this a must ? Or could I just swap out any clutch plates (the mickey mouse shaped) and the disc plates in between with the new OE parts. Do I really need to measure the stack in this case?
2. If the stacks are done incorrectly, maybe too loose, what is the worst that will happen ? Will it just behave like an open diff, or will it lose drive on both axles ?
3 What would be the consequence of just reusing the old shims and clutch plates inside ?

 

[Asterix]

Differentials are singularly the most picky thing to put together on your car. Being off by 0.001 will make the difference between a long, quiet life, and whining and grinding itself to powder in short order.

The pinion and ring gears must be aligned just right with respect to each other in 2 dimensions. The tapered roller bearings must be preloaded just right simultaneously. Reusing old shims may be possible, but you have to measure everything.

The clutch plates are rather more forgiving. Toyota even reordered them in later differentials because people complained about noise. If you want actual good lockup, alternate the friction and clutch plates. You may want to consider the Weir spring to make for even more grip. Remember that it's easy to remove grip with oil additive, but to add grip, you have to completely disassemble the differential and increase the spring that squeezes the clutch packs.

There's a write up on rebuilding the differential you should read before starting. You need a press and a few other special tools.

 

[alcyon]

Yes I am very familiar with the ring and pinion setup, and in this case, I will be reusing the the ring and pinion so i will not change pinion depth.
What is the purpose of this procedure ?

I thought with a LSD there is supposed to be some drag ?

 

[Asterix]

Ha! Yea, that step would be for the open differential only. They also don't tell you to put the transmission in neutral.

If you're putting the old ring gear on a different differential case, you should expect to have to change the side shims.

 

[Bru]

I have rebuilt my LSD differential 9 years ago. The 2 shims you're talking about adjusts the backlash of the ring gear. There are also shims inside the LSD case that adjusts the backlash of the side to spider gears. Follow the procedure in the manual. You're going to need some things like a micrometer and a Vernier caliper. You'll also need a dial indicator with a magnetic base if you're going to check backlash. An inch pound torque wrench is used to measure preload of the drive pinion gear bearings. Some of these things can be had at Harbor Freight. Here's a link to the online manual: Click here to go there.

 

[alcyon]

I received the diff today. Still unsure if its a LSD, but it should be.





My observations are :
The diff turns smoothly, and pinion preload is still there, I can feel the preload. I will measure it, but I am kinda reluctant to take it apart, but i guess I have to, otherwise I can't remove the rust, rust proof it and re paint the housing. So I guess I still need to install a new crush sleeve. I need to inspect the bearings, but I guess these have never been changed, but they do feel good. The diff looks untouched, it looks like factory markings are still there.
Also is the left and right outdrives different lenghts, or is it just different length vs the open diff outdrives ?
I will be taking baseline readings and gear pattern before removing the carrier. I am very curious what pinion depth shim is on this and the carrier side shims, to compare against what I have in my open diff.

 

[Bru]

Check the differential gear ratio by putting a piece of tape on the companion flange and another on one of the side gear extension bolts. Count the rotations that the companion flange takes for the side gear extension to make one full revolution or 360°. Differentials, depending on year and application, can be: 3.40 to 1 (non-turbo manual or automatic transmission whether they are LSD or open), 3.91 to 1 (87 to 88 turbo manual), and 3.73 to 1 (89 to 92 turbo manual). If the front seal is not leaking, I would leave that alone. With the side shafts off, make a measurement of the total rotating preload with a beam type inch pound torque wrench. Total preload includes the pinion and side bearings. You can remove the rear cover which should tell you that it's a limited slip or not. Clean the oil off the ring gear splines and apply some type of measuring compound either the paint or a thin coating of grease to a few splines and turn the companion flange clockwise by hand while giving some drag to the ring gear to see what the contact pattern is. Compare it to the online manual. Check each ring gear tooth backlash using a dial indicator with a magnetic base. You can then carefully remove the carrier, being careful not to mix up the 2 adjusting shims. Then take a rotating preload reading of the pinion alone. Compare that reading to the spec and also subtract it from the total preload to get the preload for the side bearings. Compare that to the spec. If the side seals are not leaking, and you don't want to open the limited slip clutch pack, reassemble the carrier and torque it to spec. You can check the breakaway torque of the clutch pack once the differential is back in the car with one wheel jacked up and using a torque wrench on the hub nut. Something like 60 to 80 foot-pounds is healthy. Harbor Freight has a nice screw type jack for removing and installing the differential. The oil I use is Castrol axle limited slip 80W-90. It has the limited slip additive already in it. You'll need 2 bottles. Think the capacity is about 1.4 quarts, or until it just starts to flow out the fill hole, with all 4 wheels on a level flat surface.

Limited slip differentials usually have a LSD sticker above the filter plug.