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Drum brake upgrade kit, interest?

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Old 10-14-07, 02:38 PM
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Drum brake upgrade kit, interest?

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?
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Old 10-14-07, 07:35 PM
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I like this idea. Of the 10-15 FBs that the scrapper here used to have, there wasn't a single GSL or SE.
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Old 10-14-07, 08:25 PM
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yea its a great ideal I have an 85 GS rear end I will give them.
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Old 10-14-07, 08:26 PM
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I also have an 80 I will give to if they want both.
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Old 10-14-07, 09:42 PM
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i wish i had known about this two weeks ago. i had a 84 drum rearend id of donated to the project.
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Old 10-14-07, 10:12 PM
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iam confused, i have 1980 with drum rear brakes. would this kit work for me switching to rear disc.
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Old 10-15-07, 06:56 AM
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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?
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Old 10-15-07, 07:22 AM
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I'd be interested, except I've got an 83....
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Old 10-15-07, 08:29 AM
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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.
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Old 10-15-07, 08:40 AM
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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
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Old 10-15-07, 08:55 AM
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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...
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Old 10-15-07, 09:15 AM
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Originally Posted by Glazedham42 View Post
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
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Old 10-15-07, 09:18 AM
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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.
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Old 10-15-07, 09:23 AM
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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
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Old 10-15-07, 01:55 PM
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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 ?
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Old 10-15-07, 02:25 PM
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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.
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Old 10-15-07, 02:45 PM
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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.
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Old 10-16-07, 06:45 AM
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Originally Posted by Rogue_Wulff View Post
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.
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Old 10-16-07, 08:20 PM
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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.
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Old 10-16-07, 09:33 PM
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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?
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Old 10-17-07, 12:24 PM
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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
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Old 10-17-07, 08:46 PM
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Originally Posted by vipernicus42 View Post
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.

Originally Posted by Me
Found my parts fiches!

Just thought I'd share with y'all:

S3 (1984-1985 model years)

Casing, Rear axle - Part number FA54-26-020 - Application: Rear drum brakes (S and GS models)
Casing, Rear axle - Part number FA58-26-020 - Application: Rear disc brakes (GSL and GSL-SE models)

Shaft, Rear axle - Part number FA54-26-111 - Application 12A engine (S, GS, GSL models)
Shaft, Rear axle - Part number 8595-26-113 - Application 13B engine (GSL-SE model only)

Bearings, Collars, Oil Seals, and Spacers are all the same...

Housing and LSD unit from the GSL-SE...
Axle shafts and Ring and Pinion gearset from the GS.
Slap on some loaded calipers and rotors and it should be a full 12A LSD disc brake rear.

Lookin like I can cobble together a legal rear axle from GS and GSL-SE parts that I have around already... Sweet!

Only thing that looks like it's still 12A disc brake rear specific is the dust cover/backing plate... Is that really necessary? Wouldn't it result in cooler brake temps if I left that out?
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Old 10-25-07, 06:19 PM
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Bump. Furthering interest in this kit?
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Old 10-25-07, 06:36 PM
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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?
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Old 10-25-07, 07:16 PM
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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.
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