So I got a lsd from a 88 glx automatic 3.9 ratio and I want to go to the 4.1 lsd. Can I pull the ring and pinion gears out of an open 4.1 and put it into my lsd 3.9?

 

Yes you can just swap the ring/pinion gears from your auto onto the lsd since they are both NA. IF your car is open diff 4.1 then just swap the ring gear over before you put the lsd in and be done with it.

 

Ok it sounds like it will work, but let me be clear. Right now I have an 3.9 lsd NA and I want to go to a 4.1 lsd. I figured it would be cheaper and easier to find a open 4.1 NA take the gears out and convert my 3.9 to a 4.1.

 

you'll have to pay a shop to properly set up the pinion gear if you don't find a case with the already 4.1 gears installed into it. it's not an easy undertaking for the DIYer with no experience.

 

I've installed rear end gears before. While I do know it is a bitch to set the torque on the pinion nut. I think I'll be able to handle it. The reason why I'm doing this is because I've installed a T56 camaro 6 speed with a .5 to 1 6th gear ratio. And 6th gear is useless under 80mph. I'd like to think I have a little experience.

Which way do you think would be easier keeping the case I have and putting the 4.1 gears in it. Or putting the clutch pack in the 4.1 NA case. Is that second option even possible.

One worry I do have is staying with a NA diff, maybe I should make the switch to the turbo diff but that would be 5 times more expensive.

 

I would put the 3.9 LSD into the 4.1 case so you don't have to touch the pinion gear, just swap gears and set back lash.

 

I have a 4.1 open rear end sitting around (no sub shafts) if you need one to throw the LSD into...

 

Thanks but I think I'll look for one locally first. I just found a guy selling a diff out of manual glx for $50. I asked him when he turns one axle does the other turn in the same or opposite direction. This might be a steal.

 

the LSD diff carriers are completely different so you only have 1 option, swap the pinions out.

 

You wouldnt swap the pinions, just the LSD it's self. the ring and pinions have to stay together.

he needs to get a 4.1 OPEN diff. carrier and all, and just take the LSD part and remove the ring gear from it, and put the NEW ring gear from the 4.1 and put the 4.1 back togather and use that, then junk the old 3.909 pinion, ring gear and carrier(housing).

right? thats how i understand it....

 

that's probably more accurate, if he can find one locally or have the case shipped. most people won't touch the pinion because they don't know anything about how to disassemble a diff properly.