Installing a LSD into my 3.8 stock rear end

[Camaroman1221]

i need to rebuild my rear end and replace the bearings, while i am in there i want to install a LSD from a stock SS into my stock rearend, any idea how hard it would be, i have 3.23 gears so i know i have the right carrier to take it. the only thing i am not to sure about is if i can just pull the old one out and install the new one, of do i have to measure back lash and bearing preload and other stuff like that.

[EarlR]

Re: Installing a LSD into my 3.8 stock rear end

I just finished doing exactly the same thing a couple of weeks ago. I already had a used LSD I bought earlier this year, but had never gotten around to installing; but then one of the bearings started making noise and I ended up having to rebuild the whole thing (bad bearing was on the pinion gear). To answer your question; yes, you will have to 'set up' the new diff. Chances are very good the shims from the old diff won't be right (mine weren't) and even if by some chance they are you'll still need to set the backlash & check the gear pattern.

Were you planning to replace the pinion bearings while you're in there? That adds an extra level of PITA, as you will need to have the old bearing pressed off - assuming you don't have a press.

[bigbrian442]

Re: Installing a LSD into my 3.8 stock rear end

In 99% of changing just the carrier, the stock shims work fine.

[Camaroman1221]

Re: Installing a LSD into my 3.8 stock rear end

um.... for now i am just replaceing the carrier and wheel bearings and seals, i work and a automotive shop so i am gonna do the pinion bearing alil later while i am at work, so i am thinking i should be able to pull the old carrier out and slide the new one in after i replace the bearings cause i am keeping my old ring gear in the car along with the only pinion so they should still line up properly

[EarlR]

Re: Installing a LSD into my 3.8 stock rear end

It will be really easy to tell if the old shims work or not - if they will go in with the new carrier (mine wouldn't even go in) there should be some resistance when turning the carrier. Just install the new carrier & shims w/out the ring gear (make sure to keep the races with their respective bearings), install the caps and turn the carrier. If there is some resistance but it will turn by hand then the shims are probably right. If it turns really easily then they are too loose. Conversely, if it is very hard to turn they are too tight. In either of the last two cases just add or subtract shims to get the right preload. There is a tool for measuring preload, but I've always just gone by feel.

One thing to remember though - even if the shims are right you still have to check the backlash, & to a lesser extent the contact pattern. All you need to check the backlash is a dial indicator with a magnetic base. If you work in a shop they will probably have one. It's easy to do and you can really screw up a rear end if you set the backlash either too tight or too loose. The contact pattern can be checked by brushing some white lithium grease on a few of the teeth and turning the pinion both forward and backward to get one full turn of the ring gear. You can see in the grease how the teeth are meshing. If you haven't moved the pinion, and have the right backlash on the ring gear the contact pattern should be good, but it is always a good idea to check this, and it's so easy there is really no excuse not to.