This is topic Torsen Install help.. in forum Spec Miata at Spec Miata Community.

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Posted by W. Bonsell (Member # 14917) on :
Am finally going to replace the VLSD on my '91. Have a torsen on order. Does anyone know where to find complete instructions on making the big change over?

Posted by George Munson (Member # 6376) on :
It's pretty straight forward. Unbolt wheels and pull axle nuts. Unbolt the old axles from the old diff. Remove the diff support arm and drive shaft. You will probably need a puller to push the axle from the hubs. Drop the old diff and start installing the new stuff.
Posted by jwarren (Member # 3749) on :
super easy install! It took me about 45 minutes from start to finish with an impact.

one thing that will help you:

When you are unbolting the diff. from the power pant frame, loosen the two bolts until they are finger tight, then whack one of them (can't remember which one) with a hammer to remove the 'splined' portion that actually fits into the differential. i'm sure you have no clue what i'm talking about but as SOON as you realize the PPF won't come off of the diff you'll know what i mean. Take a look at an exploded diagram of the rear diff and powerplant frame on mazdamotorsports before you do it so you know all of the little pieces that are there.

I hope this helped.
Posted by David Luney (Member # 812) on :
The following is for the Torsen replacement. You would add the axle swap out for an early car.
1. Remove the subframe brace
2. Remove the exhaust pipe.
3. Remove the 4 driveshaft bolts and driveshaft.
4. Unbolt the LR caliper and safety wire it up and out of the way.
5. On the drivers side only, remove the outer upper and lower upright bolts and remove the upright as an assembly by prying the axle from the diff. If you have a baggie, cover the diff side of the axle to keep it clean.
6.If you have a shipping plug from the new diff plug the open axle hole (not required if you drained the old diff).
7. Loosen the PPF bolts almost all the way out. Smack with a BFBH (Brass) and remove the upper press in fastners then the bolts.
8. I use a flat chisel to remove the centering insert on the underside of the rear PPF bolt.
9. The PPF should be free, pry it to the passenger side and safety wire or bungee it out of the way.
10. Remove the 4 12mm nuts holding the diff mount retainer.
11. Support the diff with a floor jack rolled in from the drivers side.
12. Remove the 2 17mm nuts freeing the diff.
13. Pop the passenger side axle out of the diff.
14. Bring the diff down and to the drivers side, sliding the axle out as you go.

Installation is reverse of removal. I pre-fill the new diff on the bench and use the afore mentioned plugs to avoid a 90wt bath during the install.
Posted by Glenn (Member # 2102) on :
I like the idea of only removing one side UCA.

Also add DO NOT OVER EXTEND the CV joints or you will be repair/replacing them. Don't ask how I know, LOL
Posted by Keith in WA (Member # 16099) on :
Good list David...I do think you forgot one step that will keep you from smelling like trans fluid for a week though. [Wink]
Posted by SCCA_Racer (Member # 24816) on :
The axle can be a PITA to remove from the hub unless you bought replacement hubs with the Torsen.
After I removed the diff I reinstalled the uprights and had to use a torch (for heat) and a 4' breaker bar on the axle nut. That was after letting the axle nuts soak over night with penetrating oil. I thought I was home free once I got the axle nut off, but that was not the case. I ended up threading the axle nut back on and using a sledgehammer to drive the axles out. In the end it flatten the axle nut, but they cam out. I still have not decided if I am going to install new uprights with new bearings or try running these after all the abuse I put them through to get everything apart. God luck with your swap.
Posted by Vick (Member # 13121) on :
I think there is a step by step with pictures on
Posted by Glenn (Member # 2102) on :
I ended up threading the axle nut back on and using a sledgehammer to drive the axles out
typical problem with rust belt cars! I have cars all the time that the lower control arm bolt id frozen to the arm and will NOT move. If you come up with a good reliably method of removal please post!