I'm looking to swap the rear axle on my 1984 rx7 GS so I can get disk brakes all around. I know most people swap out from the 3 letter and above and I have looked into it but finding them has been proving difficult. I was wondering if any one had any suggestions or had experience swapping out an IRS from the fc or fd. My subframe has two different sized holes where the front lower control arm attaches, the bolt I have fits the bushing and the front hole but the rear hole is significantly. Is this normal? I bought this car as a shell and I don't know all the work that was done on it.

 

welcome to the board.

i think this will probably be one those things where you set the money aside and just keep looking, periodically, until you find something. maybe check your Regional forum, here on the board, and see if you can go to a few meets and get plugged in, then see if someone can give you a lead to one.

my unsolicited 2¢ is that you should not go the route of converting to the FC or FD rear subframes just to get discs.

 

I agree with the above. Doing all that work for a disc brake conversion is a waste of time and money and will require you to swap out the front the front spindles over to FC spindles and brakes just so that the rear will match the front. The drum brakes do a great job of braking and in magazine tests from the period cite this.

I use the original drum brake rear on my 85 GS, and that car I put a 13B in and it accelerates nicely. I don't ever worry about braking issues with that car. My 80 Leather Sport RX-7 still has the original drum brake setup. The car is 44 years old and it does a great job of ststopping. Albeit, the brake components are in great shape and the car has not been left unmaintained.

 

You can buy new rear axles to convert your current 1984. You'll still need brake calipers, disc, etc. to complete it. There was a thread here on the forum, I believe this year or last, that list the place that sells them.

Here is the thread. https://www.rx7club.com/1st-generati...-axle-1164911/

https://panicmade.com/axles/p/84-85-...-7-panic-axles

You want the GSL ones to maintain the 4x110 wheels OR get the GSL-SE to convert to 4x114. The harder part is finding calipers.

 

As KanasCityREPU states above if you are intent on swapping out the rear of your GS to get rear disc brakes you search needs to start with finding rear calipers first, otherwise it's will be a waste money sourcing another rear end (unless it comes with the calipers already.). I don't know how many original GSL original owners "opted" for four wheel disc brakes when they bought them however, I can tell you that the rear calipers for the GSL-SE are "non-existent" for the most part. My days of "pic-a-part" shopping are long over, and if you can find them they can be rebuilt but that's pricey too. I searched nation-wide online salvage yards and have come up empty, sadly the advent of online shopping led to people blowing off "core" returns so parts that normally would have been turned-in at a parts store would be sent to vendors who would rebuild them and put them back into the supply chain has resulted in a lot of "NLA" listings. Mazdaverx713 has a very valid point that the rear drums are more than adequate for the job coupled with the front disc brakes, but if your intent on having four wheel disc brakes on your RX7 good luck. Save your money and ensure you have an adequate supply of patience too!