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RX7 rear axle ???

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nomad

Yoda
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Just curious about fitting an rx7 rear axle to a spridget. Are there any tech articles on this??? Know that a 81 to 83 axle is preferred. I can get a 84 which, according to wikipedia, has a different wheel bolt pattern than the earlier axle. Mainly wondering if the earlier pattern is 4 inch and will bolt up to spridget wheels and how much work is required to narrow the axle?

Kurt.
 
Kurt, I may be wrong but I think the guy that built The Mite used an RX-7 Axle. Google The Mite if you've never been there before. He used something to keep the turbo Miata engine from breaking rear axles. Maybe he adapted a Miata Rear End and a 4 link. Now I've got to go back there and look.
 
There is a guy on the MGExperience that is going to narrow a ford 7.5" since they are cheap and have a wide range of gear ratios. I think he said the shortened axles were going to cost $300, but when he is finished he'll have LSD and disc brakes. He said he'd try to weigh it when he gets it finished.
 
Follow the link in the article on the Mite to Moser and give them a call. They have probably done this conversion several times before. This sort of work is their speciality.
 
Thanks much folks, I've been busy or would have been back quicker. Just daydreaming about building a spridget with a lot more power. Knew I had seen some of that stuff here before. Wish I had a lathe!

Kurt.
 
I wonder if it has to be an rx-7 diff. I is it that much tougher than others? Some of the Mustang II models with the 302 engine had the 9 inch rearend, as did a few with the V6(my 74 model did). I also have a Kia sportage and it has a pretty marrow rearend with a solid axle in the back and weighs in at about 3000 pounds with a 2 liter engine and has been through hades and no diff problems.
 
I imagine it could be a lot of different axles but the RX7 axle has limited slip and disc brakes and is light and tough. One has to consider unsprung weight or handling will go away. I know of a bugeye with a hot rotary and a 9 inch ford rear that goes like stink in a straight line but gets whooped in autocross.

Kurt.
 
apparently, the gearing of most rx-7 diffs is somewhere around 4.11
 
Ah, good call, Trevor. The Mazda wankel would be a high revving engine which would explain the low rear gears. So would the ford be light and make for a good swap? How about other suggestion's--someone mentioned a rear axle from a Subaru. Early 80's is getting pretty old for japanese stuff. Nissan at least does'nt support any of the old stuff. The guy with the bugeye that a friend told me about may have other handling problem's. Higher unsprung weight should only be a factor on rough surface's.
Any pictures from the MG experience guy? I'll see if I can find the site.

Kurt.
 
He hasn't made the swap yet, but based on his other work ... it'll get done and he'll post pictures.
 
I haven't seen Phil on the site recently but he runs an RX7 rearend on his Sprite.
 
nomad said:
Ah, good call, Trevor. The Mazda wankel would be a high revving engine which would explain the low rear gears. So would the ford be light and make for a good swap? How about other suggestion's--someone mentioned a rear axle from a Subaru. Early 80's is getting pretty old for japanese stuff. Nissan at least does'nt support any of the old stuff. The guy with the bugeye that a friend told me about may have other handling problem's. Higher unsprung weight should only be a factor on rough surface's.
Any pictures from the MG experience guy? I'll see if I can find the site.

Kurt.
Click to expand...
The Subee would be an independent rear. That gets a a lot more complicated. I am trying to think of something that might work and have a higher ratio, yet still be light.
 
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