John81

My rear end is toast. Mechanic says looks like I need a complete rear assembly. Any ideas where to find one or alternatives? Thanks.

j_tso

iTrader: (2)

What's broken?

Most of the rear can be replaced or repaired, except if you bent an axle shaft that can be hard to find.

Maxwedge

iTrader: (1)

Yeah, as said, almost every part is available to rebuild it. If the housing itself is bent or damaged then you need to source a "new" one, but they're usually available on the RX7club classifieds, FB or Epay. I threw one in a scrap dumpster at work because nobody replied to my for-sale listing.

John81

Thanks. We’re definitely looking into that option. Right now it’s at a general repair place and he didn’t go as far as to open it up but said it just spins and he hears a lot of clunking inside and is assuming it’s beyond repair. We’re going to have some restoration guys look at it. This is my sons car and he is a teenager. This car is mint, it was literally garage stored and only occasionally driven in the summer before he bought it, but he wasn’t driving it like it’s 40 yrs old and here we are.🙄

j_tso

iTrader: (2)

Could be something in the differential assembly. See what the restoration guy says.

All bearings are available. If the ring and pinion gears are damaged, they're available new but cost a few hundred dollars.
Gears from a 1994-2004 Miata rear end are compatible so a used one should be cheaper but the speedometer would be off a little.

John81

So they said the teeth are broken up so I guess this would mean a new ring and pinion are needed? They are looking for used parts. Doesn’t look like a cheap fix. Any advice?

KansasCityREPU

iTrader: (9)

Certain Miata and Kia Sportage pumpkins will work. Do a search in the first gen technical section and you will find many that have answered which ones fit depending on what year RX-7 this is for.

https://www.rx7club.com/1st-generati...-diff-1158076/

j_tso

iTrader: (2)

Like I said above, 1994-2004 Miata ring and pinion gears can interchange.
Because of the gear ratio the speedometer will read faster than normal, this may help with the son.

Changing them out is time consuming, the labor charge will hurt.

John81

It’s a 1981 rx7

j9fd3s

iTrader: (3)

the 1999-2005 miata 6 speed used the same 3.9 gears as the Rx7.

ATC529R

I have a 1980 disassembled, but I won't part with the ring and pinion. spider gears I will let go if it was those, and I have the axles. If it is opened up enough to see the R+P, they should be able to give you a heads up on that the other stuff looks like.

other tell me the R&P on these rarely go out....

John81

Thanks for the insight. I’ll definitely ask them about it.

ATC529R

Bump to see the outcome. I have clunkage.

Holdfast

I have a 3.9 ring gear and pinion gear in mint condition. Removed from my car years ago to install 4.10. Also have a really low mileage complete 3.9 open diff from a 80 Rx7. Looks brand new. Have pictures if interested.