Where to find 2nd Gen RX-7 5.12 diff gear
- Thread starter Doncan
- Start date
mbuskuhl
New member
In my recent research on this topic, Mazda made a 4.30 gear. The 4.88 and 5.12 are custom one off fab'd R&P's (please correct me if wrong!). Due to the work that goes into them, they take a long time to get, are hard to come by and fetch a good sum of money. ISC Racing has one on it's site right now ready to go. www.iscracing.net
Mazdatrix goes to a 4.30 is all http://www.mazdatrix.com/g7.htm
Mazdatrix goes to a 4.30 is all http://www.mazdatrix.com/g7.htm
actually, the ring and pinions are from the 1st generation rx-7s. Buy the gear ratio you want from mazda motorsports. Then you send ISC racing your new short pinion with your used long pinion (2nd generation rx-7) and they will machine/graft the end so you end up with a long pinion with a 5.12 or 4.88 ratio.
What the above responses are saying is true. The 5:12 & 4:88 gears are available from MAZDA Competition
and if you are a registered member (all you have to do is supply a photo of your car and results from two races annually). The pinion gears has to be lengthened. This is done by providing a pinion from a donor
rearend. Since the pinion you purchase with the ring gear new is short (originally, manufactured for a truck or 1st genration car) you have to cut the two at a proper point, machine the two to fit with a tapered female/male press fit beveled edge area at the joint to be welded by an experts, then machined back to tolerance with very minimal run-out. Because of the tedious process and exacting specifications most
machine shops will not do one of's. Most want a minimum of 5 to to do at one time since the set-up of the
fixture and the jig for one is time consuming.....I have searched at great expense, to find a source to to all of the above and do it with all the expertise of company that builds stock car differentials/rearends. I can get yours done. Call me if you have and interest as I am getting an order up now for the process. You may call me at 843-222-2897. You are not going to find either of these gear ratios in a junk yard or used as they
are special purpose built. I've already been through this lots of time and energy.....by the way this is the most reliable performance you can buy.
and if you are a registered member (all you have to do is supply a photo of your car and results from two races annually). The pinion gears has to be lengthened. This is done by providing a pinion from a donor
rearend. Since the pinion you purchase with the ring gear new is short (originally, manufactured for a truck or 1st genration car) you have to cut the two at a proper point, machine the two to fit with a tapered female/male press fit beveled edge area at the joint to be welded by an experts, then machined back to tolerance with very minimal run-out. Because of the tedious process and exacting specifications most
machine shops will not do one of's. Most want a minimum of 5 to to do at one time since the set-up of the
fixture and the jig for one is time consuming.....I have searched at great expense, to find a source to to all of the above and do it with all the expertise of company that builds stock car differentials/rearends. I can get yours done. Call me if you have and interest as I am getting an order up now for the process. You may call me at 843-222-2897. You are not going to find either of these gear ratios in a junk yard or used as they
are special purpose built. I've already been through this lots of time and energy.....by the way this is the most reliable performance you can buy.
Andy Bettencourt
Super Moderator
ISC and Speedsource aren't making any more of these new IIRC. We just had 2 built with a local supplier.
Oh ya, PM sent too. If that's a Torsen, it ain't selling for $750.
EDIT: We are out - no torsen.
Oh ya, PM sent too. If that's a Torsen, it ain't selling for $750.
EDIT: We are out - no torsen.
ITS51RX7
New member
Here is some info on the diff for sale.
It is NOT a torsen unit it is the LSD clutch pack version.
It is currently installed in my old 2nd gen that I ran into the wall at IRP last year. All running gear Motor, trans, rear end are fine , but the front frame rails were bent beyond fixing.
I purchased another roller 2nd gen from Chris Ludwig, his car already had a 5.12 rear so I do not need two of these. I swapped the motor and trans over and I am ready to get rid of everything else on the bent car.
I am adding a picture of the car the rear end is still in, I wish it was still in the same condition.
Tom was the first one who wanted this diff, so it is his if everything goes ok.
It is NOT a torsen unit it is the LSD clutch pack version.
It is currently installed in my old 2nd gen that I ran into the wall at IRP last year. All running gear Motor, trans, rear end are fine , but the front frame rails were bent beyond fixing.
I purchased another roller 2nd gen from Chris Ludwig, his car already had a 5.12 rear so I do not need two of these. I swapped the motor and trans over and I am ready to get rid of everything else on the bent car.
I am adding a picture of the car the rear end is still in, I wish it was still in the same condition.
Tom was the first one who wanted this diff, so it is his if everything goes ok.
mbuskuhl
New member
If Tom falls out, I'm still interested even given this information. Do you know if a guy by the name of Greg Sabol built this diff or do you know who did? Does it have the exrta clutch pack plates and springs from Mazdacomp? - I think it's 6 vs. 4 from what I'm told. I have another one lined up to buy tomorrow unless this comes through. I sent a PM earlier with my phone, call me if you want to do the deal. Paypal or your preferred payment method ready.
seckerich
New member
To answer your question--you need to order the complete set from mazda with a matched ring and pinion. You do not want to try this if you have to ask the question. It takes some specialized equipment and fixtures to do it right. If you have never set up a rear gear before I would have that done by someone qualified or you will have some expensive scrap metal after the first race. Not trying to be harsh, just don't want you to make an expensive mistake.
Thanks a lot for your respond and advice. Don't worry because I won't be doing the job myself. I have the mechanic and the machine shop with the necesary equipment to do the job nicely. I just want to know what is the necessary ring and pinion combo to do the conversion for at least a 4.56 or lower ratio. You said I need to buy both ring and pinion set from a first gen RX-7. Do you know from what year and model ?? My car is street driven but I run actively in time trials events and would love to take advantage from the benefits of lower gears.
seckerich
New member
The 4.88 and 5.12 were never in a production model and were sold through Mazdaspeed. They were only made for the early RX7 and other comp vehicles but never for the 2nd gen. Thats why you have to modify them to fit. Options that will fit from cars are a 4.11, 3.9, and a hard to find 4.52. Post on here for a 4.88 if you want a reasonable track gear for the price. Most people started with the 4.88 before we got the 5.12. I sold the last one I had but will see what I can find if you want one.