swaping LSD guts into NON LSD casing

[Ceeker]

would anyone know if there are any differences between the out put flanges from a 4:10 LSD and an open 3:73 Diff?

The outer side bearing retainers seem the same but wondered if the bearing were different between the two?

I have a very clean 3:73 case I want to transplant my 4:10 guts into without having to do any adjustments in terms of torque or lash.

Any help would be great thanks.

[Jaker]

If you're changing the case, you'll need to recheck all those clearances/torques.

[Ceeker]

If you're changing the case, you'll need to recheck all those clearances/torques.

I'm not replacing the pinion bearing or crush washer..

But you're saying still I would need to recheck tolerances?

the only torque spec I would need to be concerned with is the side seal covers no?

[iwantspeed]

you can not do that.


each diff is different.


the side plates have shims bolted in between the pumpkin and the side plate.


that sets the gap between the ring gear and the pinion gear mesh.


you cant just swap diff housings with out setting the gear mesh again.


and the shims are not the same on both sides.


a good diy with current pictures(9/26/2018). on an e21 diff same concept as the e30

https://www.bimmerforums.com/forum/s...ild-(Pic-heavy)
shim is in here

[Ceeker]

OK makes sense..here's a thought.
When they were mass producing these cars in the factory obviously they weren't hand built. So how on earth did they manage to set up each and every diff with a total production run of 2.3 million e30s?

Of course there were a dozen different ones so how did they manage it? I'm just wondering.

[Ceeker]

So what you are saying that if I change nothing and place the same shims in exactly the same order without disturbing the pinion gear It would still need calibrating?

[e30davie]

OK makes sense..here's a thought.
When they were mass producing these cars in the factory obviously they weren't hand built. So how on earth did they manage to set up each and every diff with a total production run of 2.3 million e30s?

Of course there were a dozen different ones so how did they manage it? I'm just wondering.

They would have setup each differential independently. I'm sure there is a retired German person out there that is very proud of the fact that he setup E30 differentials for 12 years straight.

I've played a bit with differentials and every time i have been bitten by incorrect setup, its very finicky. Its good to have an understanding of the requirements, but its one of the jobs that i am happy to pay a pro to do it.

[Ceeker]

Thank's for that link. I guess he got the lash bang on. Never mentioned whether he needed to adjust the lash. However he did mark the flanges and the shims to exactly how they were when disassembled. So I wonder if that helped prevent the trial and error with the shims?

[SkiFree]

The ring and pinion is a matched set, the pinion spacer is typically (8/10) spaced for the pinion, not the housing (so the inner pinion bearing needs to come out). The side to side adjustment needs to be re-shimmed as has been said, but you start by using your total spacer thickness as the fixed total width.

Given your questions, I'm assuming your never taken apart a differential, or transmission, or steering box? Once you get the hang of it, and have some precision tools, it's not too bad. You can do it.

[Ceeker]

The ring and pinion is a matched set, the pinion spacer is typically (8/10) spaced for the pinion, not the housing (so the inner pinion bearing needs to come out). The side to side adjustment needs to be re-shimmed as has been said, but you start by using your total spacer thickness as the fixed total width.

Given your questions, I'm assuming your never taken apart a differential, or transmission, or steering box? Once you get the hang of it, and have some precision tools, it's not too bad. You can do it.

Yes I have never gone that deep into those parts before. I get the jest of it now. I just don't have the time at the moment to do the job nor the proper tools. therefore I think I'm just going to put the 410 back in and call it a day.

I appreciate everyones patience and time they took to explain this to me. Clearly there was plenty I wasn't aware of..lol.

[iwantspeed]

no problem.


maybe take a spare diff apart to practice and see what its like inside.

[82eye]

not sure what you're doing but i've swapped an ls carrier from a 4:10 into a 3:73 to make a 3:73 lsd no problem. i rebuilt the ls unit and swapped crown gears. i built the 4:10 as an open with the spare parts and again no problem at all.

yes you have to pay attention to shims. as long as the shims stay with the original case you should be good. should still be a thread on it over at bf.c depending on how bad crapbucket messed it up.

i did not swap pinions out which really helps the process. have done that in the past and find it's the most difficult part of the job. get an extra crush sleeve if you do. everyone messes it up the first time and over does it.

[SkiFree]

Yikes, bad information alert.

[Wanganstyle]

not sure what you're doing but i've swapped an ls carrier from a 4:10 into a 3:73 to make a 3:73 lsd no problem. i rebuilt the ls unit and swapped crown gears. i built the 4:10 as an open with the spare parts and again no problem at all.

yes you have to pay attention to shims. as long as the shims stay with the original case you should be good. should still be a thread on it over at bf.c depending on how bad crapbucket messed it up.

i did not swap pinions out which really helps the process. have done that in the past and find it's the most difficult part of the job. get an extra crush sleeve if you do. everyone messes it up the first time and over does it.

If you don’t remove the pinion the diff was not rebuilt.

Classic case of r3vtard missinformation and spray paint rebuild of engine also.

[82eye]

lsd rebuild and gear swap.

have done a few others as well. never had one blow up. that one was super simple since i had both cases and left the pinion alone.

shims always stay with original case.