i jacked up the rear and spun the tires.... and both spun the same direction (LSD) cool! now... i ask the experts.. is this an rx3 or rx7 3rd member? TIA

 

1st gen (identical with teh RX-3 SP) as it appear to be a short pinion shaft and based on diffy flange

 

short pinion shaft? cool! now does that mean if i was rich.. i could head down to racing beat and buy a 4.44 gear set?

 

Buy it from racing beat if you have $$$ to burn. I have other ways to get 4.44 or taller gears. Come over and I will let you test drive my 75 wtih 4.78

 

4.78? do you even use 1st gear? haha....

 

wacky is the coolest

 

Damn, that's the third member I'm after. Those are getting harder to find these days.

 

Old post I know, but care to explain wacky?

 

the kia sportage 4x4's front diffy are either a 4.44 or 4.78. the ring and pinion are direct swap to all pre-86 mazda RX-7s, including RX-3 and RX-2. Not sure on R100 but definitely know it wont work on a RX-4. Just look for them at the junkyard for 1/3 of RB prices

 

Thanks Wacky. Good to know.

 

Here's the problem I have. About 5 years ago I bought a "slightly" used Guru diff that came in the 3rd member with ring and pinion all assembled. I was told it was off of a first gen.

For simplicity, I'll refer to the Guru installed third member as "Guru", and the gslse third member as "gsl-se". Tonight, I decided to swap it into my gsl-se rear end. Well after I pulled the axles and removed the bolts connecting the driveshaft to the "Gsl-se" diff, I realized that the flange on the 3rd member containing the "Guru" has a different bolt pattern than the flange for my "gsl-se" 3rd member! It's hard to explain but the "Guru" 3rd member's flange bolt holes are THREADED and the space between the 4 holes are not the same (like an Rx-3 im guessing maybe?). It's like on the "guru" the holes are the same spacing one direction but the other direction, the holes are closer together. On the "gsl-se" flange, all 4 holes are EXACTLY equal spacing, and the holes are NOT threaded.

Assuming this "guru" diff is from either an older RX7 or maybe Rx3/2, would the ring and PINION splines be the same as and 84-85 Rx7? So can I just take the flange off of the "gsl-se member" and stick it on the "guru member"?

My friend and I are decided what would be the easiest fix, just change the flange over if the pinion splines are the same (and have to worry about getting it tightened down properly with the right amount of load????) or take the Guru diff out of one housing and put it in the other (but worry about any other adjustments so to speak)?

thanks for any help! I figure if I respond here, those of you who have responded to this thread and subscribed will get an email notification.

note: My big 84-85 axles fit into the diff fine so I'm ok there

 

^^^thats your best option. I dont think your guru came with the right flange as the bolt hole spacing on all pre-86 RX (7, 3, 2) diff flange are the same and the only difference is that the newer flange (S3 RX-7) bolt holes are not threaded.

Why not come over and try a 4.44 diffy that I pulled out off my son's FB. you may like it

 

Thanks Mel! I'd love to try it but this is for my street driven turbo car. If my car was N/A I'd jump on that offer in a heartbeat but I think with the turbo, I'm going to have a hard enough time hooking up as it is.

I don't supposed you have an extra s3 larger diff flange lying around? I was just thinking that I don't really feel like tearing apart my perfectly good gsl-se diff if I could find just the flange. I may have no choice though, I might have to just take it off of the old one.

How good are you at setting the pre-load on the pinion? I've never worked on a diff before and don't feeling killing a practically new guru. My friend who's helping me has taken apart a few lsd toyota diffs but he said without the proper tools, tightening that nut on the flange is kinda like guessing when setting preload. He usually just tries to count the threads before removing the nut but I don't know how accurate that would be.

 

http://gearinstalls.com/

All preloads are critical. Tighten the flange nut to factory specs. You measure the preload on the pinion nut with an inch-pound torque wrench then stake the nut. Very precise. Now is a prime opportunity to replace the bearings.

 

Thanks for the info! I deffinately don't want to screw up the diff.

 

How did you feel about the 4.78's ??

 

ok, mine is done. I'll hope for the best. Thanks