I found out that the ReSpeed big rear disc brake upgrade kit only works with the stock disc brake rear ends...

Any interest in a TII brake upgrade that'll work on a S3 (84-85) GS or S (DRUM BRAKE, LARGE BEARING) rear? It's in discussion with bwaits of ReSpeed. He just needs a drum brake rear to work with.

It should just need different brakets to mount the caliper to the axle and a different stamped steel backing plate...


My thoughts:

The disc brake rear ends are hard to find. Being that most of the RX-7's sold have drum brake rear ends this axle should be plentiful...

I'm only basing this on the fact that I drove three hours one way to get a spare GSL axle for my Spec-7 car and I have four drum brake rears in the back yard ready to go to the scrap metals processor. (They've come out of other cars that've gotten swapped or gone to the scrapper.)

Being that a majority of cars out there have drum brake rears, why go finding a full GSL or GSL-SE axle when all you're after is the big disc brakes. (Okay okay... differential as well, but there are other options for that... Miata, FC (Remove it from the ring gear), aftermarket, welded, etc.)



Anyone in the Georgia have an axle they can part with?

 

I like this idea. Of the 10-15 FBs that the scrapper here used to have, there wasn't a single GSL or SE.

 

yea its a great ideal I have an 85 GS rear end I will give them.

 

I also have an 80 I will give to if they want both.

 

i wish i had known about this two weeks ago. i had a 84 drum rearend id of donated to the project.

 

iam confused, i have 1980 with drum rear brakes. would this kit work for me switching to rear disc.

 

Negatory on rear ends earlier than 84... They changed bearing size in 1984. You'd need a different set of axle shafts...


Then again, would that be all that'd be needed?

 

I'd be interested, except I've got an 83....

 

it seems to me that possibly there'll be more demand for the older axle drum brake rear...

I'm wondering how different the actual axle flanges are between big bearing and small bearing... That should be all that effects caliper mounting... Then the axle shafts would be all that'd be required and I believe that gets contracted out to Moser Engineering.

 

Guys, we would be looking at 3 kits here if enough interest is shown:

79-83, drum to disk conversion
84-85, drum to disk conversion
84-85, drum to big brake conversion.

This will cover all the possibilities. Since the 5 lug axles can only be done for 84-85 housings we do not see doing the 79-83 to big brake.

-billy

 

Billy,

Just need a little clarification. So this means that a 79-83 rear would retain its original 4x110 bolt pattern, just utilizing discs instead of drums? This would be preferable to me over a 5 lug pattern, since I'm already set up for 4x110, as I think many of us are.

What would we be looking at for a price on the 79-83 drum to disc conversion? What calipers and discs would be utilized on the rear? Is it something that could be easily matched to the style of the front discs? I.E. stock if you want, or slotted, drilled, vented, whatever? I'd like to keep the front and rears matching if possible...

 

79-83, drum to disk conversion = 4x110 uses stock 81+ GSL rear calipers and rotors, your stock axles would be retained.
84-85, drum to disk conversion = 4x110 uses stock 81+ GSL rear calipers and rotors, your stock axles would be retained.
84-85, drum to big brake conversion. = 5 lug, uses 88-91 Turbo rear calipers, 5 lug axles would be needed.


Cost? No clue yet. This just came about this weekend.

-billy

 

So a kit for the 79-83 drums to disc would be cool. I'd buy that especially if it used some COT parts so its easy to service in the future.

Ahh. I just saw Billys reply about the parts. Excellent. Sign me up.

 

Billy,

Thanks a ton for the quick info. This is definitely the best avenue. Please let us know about a price whenever you are able to round up that info. If this is half way affordable for my poor man's budget, I'll be all over it.

Jamie

 

So how do we deal with the drum backing plate? Would we have to yank the axles and pull the bearings and remove or somehow reuse it for the caliper mounts ?

 

billy I have 1 80 rear end and an 85 rear end I am willing to give for this great ideal. Like its been said the rear disc is getting harder and harder to find.

 

Billy, would your current rx2/3 rear disc conversion brackets work for the 79-83 drum housings? I have wondered about that from the first time I saw that kit.
I don't know if the RX2/3 rear axle housings have the same bolt spacing as the 79-83 RX7 drum housings.
Personally, I think the proposed kits would sell. I have a freind that would likely want the 84/85 drum to stock GSL brake kit, since he has an 85 drum rearend, and a GSL-SE pumpkin. We had been planning to build our own brackets to do this exact swap. With the greater LSD options available to the 84-85 large axle rearends, I think the drum housing will gain interest with a disc brake conversion kit readily available.

 

Right oh... Like I said, I've got four sitting around in various capacities...

I'm too lazy to pull the axle shafts and ring and pinion gears for spares for the Spec7. Of course that'll change once I bend a few at the track.

 

being able to get disc brake on my 1980 would make my year. so if you ever offer it as a kit id buy it as soon as i got my pay check that week.

 

Just out of curiosity, what would it take to convert my '84 GS to 4pot fronts and rear discs, while retaining the stock FB wheels? Or would that not happen?

 

Wow, I thought the existing kit did this... Good thing I didn't end up grabbing one before we figured this out.

I've got an '84GS and definitely interested in the big brake rear.

Jon

 

Yeah. I was looking at the NON-SE length axles but realized that the differential housings are different when I was going through the parts fiches...

Here's a copy of a mail that I sent to the Spec-7 mailing list when I was getting a little desperate for a spare GSL rear end, but had a GSL-SE axle around for something else.

The difference is at the flange. The drum brake rears have a four bolt flange to hold the backing plate... It needs to be strong to hold the anchor point for the shoes as that's taking on rotational load as you apply the brakes...

The Disc brake rears have a three bolt flange for caliper brackets.

 

Bump. Furthering interest in this kit?

 

heck i want a kit for my gs i can keep auto-x stock class with that. due to disks being available in 85. would the E-brake till work?

 

Pele, I thought the purpose of the backing plates was to aide in the cooling of the rotors by directing air across them. I know there is a kit for the front rotors that ducts air directly on to them.