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?

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. :D

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.

Very interested.

The braking is the only thing I feel could be greatly improved.

Not sure about the rears.

I'm sure they could be fabricated. It's just stamped steel.

Is there still any interest in this. I have an 85 GS that i am rebuilding and I Would prefer to put the $ into disks right away rather than redoing the drums then converting. This would be so much easier than getting a GSL rear axle.

GREAT IDEA! if this happens i am in fo sho

i am totally interested!!!

+1

79-83, drum to disk conversion

But this thread is from 07

Sorry if this is a little off topic. I just found respeeds site and saw the 85 big bearing to FC conversion. Does anyone know where I would find out if these would be track legal? I am interested in tracking this car at autocross, or time attack. I am totally new to the race scene and just trying to make sure what I build can be raced. If anyone knows where I can get class Regs that would be great.

Pretty much anything would be legal. But then you are talking about bumping up to a different class.

Also, BUMP! I am interested in the S1-2 Disc rears.

I'm interested in the 84-85 Drum to Big Brake conversion!

any update on this billy?

+1; Drums are gonna start being hard to get at some point! And I am almighty tired of having to adjust them.

My 84 gs would absolutely love a disc conversion, and I'd love to not have to find a raped lsd unit to swap to!

Not to far off. Could use some big bearing drum rear end dimensions if someone has one and a machinist caliper handy.

-billy

Any chance you could make a kit for the 1980 drum rear end I have all the measureing tools needed.

Billy, when you get this ready to go for the SA drums will you address these issues:

- E brake cabling conversion

- Hardline/softline routing and conversion

- Proportioning valve

as either part of the kit or directions for what parts can be used for solving these and advice for implementing solutions?

BTW, you do this and I'm in on it for my next upgrade.

What dimensions do you need. I have a big bearing drum rear sitting along the side of my house..

Yes, 1979-1983 rear disk conversion.

Sending PM.



E brake would be handled by using them form the disk brake car along with the calipers. We have little short SS lines from the hard line to the caliper. Many have used our Rx3 and Rx2 kits without issues using the stock mastercylinder and prop valve. 81-83 cars will be easy due to the disk brake master bolting directly on. SA guys would need to convert the hard lines as well.

-billy

this would be badass
make it

So I went to MAZDA yesterday with my usual cache of parts requests, and one of them was rear drums for an 82 RX7.

His response?

NO MORE.

You have to go to NAPA/Autozone/etc to get them!

http://www.autopartswarehouse.com/de...85c7ab9e&gan=1

rock auto might have them at a lower price

hell yes!
 

+1 for rear disks i got an 82 im doing a 302 swap on a lil extra stoping power would be great lol :icon_tup:

Bump!

Billy, I have an ignorant question to ask you:

Thinking about getting the SS brake lines you guys offer. Considering the car right now is rear drum, would the drum to disc conversion require me to get new rear lines or would I be able to keep my old line? I am 95% sure I will need new ones, but it never hurts to ask!

I can probably answer this one for him ... you'll probably need new ones. I would imagine the whole back brake line would need to be changed because of the way they are desined in the drum vs disc brake.

In the drum brake setup, you have a line going to the driver side and then from there that goes to the passenger side and you only have one bleeder on the passenger side. In order to bleed the calipers properly you'll need a bleeder on every caliper and would have to do something like what the cars that came equiped with disc brakes have. What they have is a machined Y block on the axle (I don't think the Drum axles came with this braket for it) but from that Y you have one line that goes to the passenger side, and another to the driver side.

Rear Drum conversion
 

I have a 1980 S. I would definitely be interested.