Just curious. I was just reading over at Mazspeed.com that the Miata 3rd member will "bolt in" to an FB Housing. Does this mean that we can change the gear ratios also? (Please forgive me for not yet doing a search on this site, I will do so tomorrow. I was just wondering if anyone here has done this or knows anything about it.

THanks,
Bill.

 

*Sigh*

I'd search up some info for ya, but check the FAQ. I added two threads about rear differentials a few days ago. Aparently some of the miata ones will bolt in, and there's great info in the threads about changing gear ratios. If you pull up any other great threads, repost their links here so I can add them to the FAQ.

PLEASE do not post without doing a search. This forum has thousands of members and if we all posted before doing a search we'd have chaos. Then it gets hard to search for things because you search for what you want and get all these threads saying "I didn't search but I wanna know..." and you have to sift through them to find the threads with the real info.

Jon

 

*Sigh*.

You are right. I am bad poster. Bad, bad poster. I really should have searched before I posted. I am hereby corrected. I stand guilty as charged.....LOL

I figured I would get that answer, but I chanced it anyways and look what it got me: Jon, I just found out by my chancing it that you posted some info in the FAQ section.

And I thank you. And , if , after I do the search, and find some info that you have not previously posted in the FAQ's then I will post them here for ya.

Actually, I didn't ask "how" anyone had done it, or how to do it. I just asked "if" any one had done it, or "knew" about it. So, technically I was correct in my posting the question. But then technically, you are correct in suggesting that I search first, because obviously I was in search of the information, or else I would not have posted it.

But I could say that I was just asking if anyone had done it or knew about it because if the people who had done it or knew about it had read it, they could point me strait away to the thread or website wherein the information was contained......

Or I could just say Ok, and go and do as you suggest and go search for the above sought after information.


Hmmmmmmmm. Sometimes I get into these battles of the wits with myself and it seems to snowball. So sorry. I'll go search now.
Thanks,
Bill

 

wierd.....

 

Yes, it was. Musta been something I ate the other night. Oh well, back to the real issue.
Here is a little info I read over at Mazspeed.com:


Rx-7 Axle Interchange And Upgrades

By Bobrx7


Having answered this question about 20 times, I decided to set up a FACTS article to show all of you the possibilities. I’m including a couple of “neat tricks” that you might consider also.



First, the axle assembly used in 79-80 models cannot be altered to add a limited slip differential. Treat these units as really big paperweights or one more thing to clutter up your garage.

General Swap Information

Any year 1st gen axle will fit in any other year car. The pinion flange was made larger in 83 but will interchange to any axle. This makes matching driveshafts MUCH easier.



All 81-83 housings and third members are completely interchangeable. The LSD 3rd member will bolt right into the drum brake housing, or you can swap in the entire GSL disc brake rear to an S or GS. Use the pinion flange that matches your driveshaft (small flange 81-82, large flange 83). Drum brake axles will not work in a disc brake housing.



The rear axle housings for 84-85 models are unique, as are the 3rd member and will not fit in the earlier housings. Again, the 84-85 LSD 3rd member will bolt right in to the 84-85 drum brake housing if you wish. Keep in mind that the 84-85 SE models have different axle shafts with the larger 4x114.3 mm bolt pattern. The GSL axle uses the 4x110 mm bolt pattern like the S and GS. The GSl and SE axles can be swapped to get the correct pattern for your car. The drum brake axles are different and will not work in a disc brake axle. All 84-85 models use the larger pinion flange introduced in 83.



If you are installing any 81-85 LSD rear end in a 79-80 model, the thread pitch is different for the rear brake hose attachment to the body brake line. An adapter can be purchased at most hydraulic supply stores.



When changing a complete axle assembly, it is vital that all bolts on the suspension links, including the Watts Link, be left loose. Jack the housing up against the springs to bring the suspension to normal ride height and THEN tighten all bolts to spec. Failure to do this will result in; THE MOST EVIL HANDLING CAR YOU’VE EVER DRIVEN!!!! This is because you will bind up all the bushings worse than they already are and it will be like having 400 lb. springs in the rear. Can you say LOOSE? (Thanks Dave D. for learning this lesson for us. Sorry it made your race weekend so crappy.)



Neat Tricks



Last, here are a couple of tricks you may not be aware of. If you like the idea of having a Torsen differential in your 1st gen car, there are two ways to go.



1. The Torsen differential assembly will bolt in to any 84-85 3rd member. They are expensive to buy new (over $800) but finding any 94 and up Miata with the R package or Touring package in the bone yard will yield this VERY nice rear end. Gear sets are interchangeable with the Rx-7.

2. If you want to do a little grinding, the Miata 3rd member will bolt right in to any 84-85 Rx-7 housing. You'll need to remove the upper link mount from the Miata aluminum housing and do some minor grinding to clear the Watts link bracket, otherwise, IT’S BOLT-IN SWAP!!!



Last, whatever swap you decide to make, be sure the bearings are good, the backlash and preloads are fairly close to spec and above all, install all new seals. You’ll thank yourself later.

Happy Rotoring,

Bobrx7



So Maybe you can post some of this on the FAQ page. I'll look around some more and see what I come up with.
Later,
Bill

 

i wonder how many ponies that rearend can handle. I lost my first LSD to grippy tires and a not so stock engine.