How difficult is it to rebuild a non-LSD differential? Mine is very noisy above 50 mph.

 

It's not the most complex part of the car, but every thing has to be at the right tolerances to work, to much or too little torque, too much or too little shim, too much or too little play, and etc. If one of these specs on one part is off the diff may be even more noisy and wear out more quickly. No to say you shouldn't try it, I tore into a manual trans for the first time last winter and thought I was getting in over my head, but I just followed instructions, took my time, and bought a micrometer to check, double check, tripple check tolerances, and my trans is now working great with no noises or grinds. You can find a link to all the factory service manuals in this thread https://www.rx7club.com/1st-generati...t-link-894736/ and that will give you the "step by step" on a diff rebuild. You also may want to consider just buying a used unit, I have an open diff in my car and I am currently looking for a stock LSD unit, the LSD units go for around $200-$300 which is very cheap for what it is, so open diffs are even cheaper; when I get my lsd unit I'll probably sell my open diff on this forum for at or close to free + shipping. Lastly be sure that it is indeed your diff making the noise, I had a very similar problem on my car and was sure it was the diff, later when I did my V8 swap the car also got a new trans and drive shaft and the noise vanished meaning it was either the trans or U-joint(s).

 

i understand the Mazda diffs are way simpler than a ford/gm, and the ford/gm mechanics have lots of experience rebuilding diffs. so if you find a ford/gm guy, they can literally do a Mazda diff with their eyes closed.

if you want to try it yourself, there are some measurements that are tricky to take, one of the reason the ford/gm guys can do it is because they have enough experience to do it by feel, and then verify by measuring