Does anyone have pics/build thread for rear big brake upgrade?
 

I know that RESpeed big brake kit is now being reproduced by one member, and offered here:
Mazda Rx-7 First Gen FB Big Brake Kit - Rx2 Rx3 Rx7 12A 13B 20B | eBay

And he will sell just the rear. I have a GSL-SE rear end housing modified for Datsun Roadster with GSL-SE axles but no brakes, brackets, nada. So I'm hoping this kit would work for me. It would really help if there is a build thread anywhere out there with pics so I can visualize how I install in my application. thanks for any links you can provide--I promise I've tried to search but Google no es mi amigo on this one.

I have all the original RE-Speed install pdf files but can't attach them here.

I pm'd you my email address; can you send the files there? Thanks!

I didn't get the PM.

I may have sent it via your email instead; just did again in PM, so hopefully you'll get my email one way or another! Thanks.

Email with pdf files sent.

Thanks much...very helpful.

If you're going BBK, you will need second gen brake rotors/calipers.

I'm just trying to understand the benefit of going to FC calipers for an 84-85 model with the bigger brakes.

The rear brake pad and piston bore size is exactly the same all the way from 1984 to 2002 (except 99> RS/RZ/Spirit R). The only thing that really changes is disc rotor diameter. You get all of a measly 15mm diameter increase going from FB to FC rear discs (258mm to 273mm), the same thickness and both ventilated. Not much of an upgrade at all and makes me question whether it is even worth it, particularly having regard to the actual percentage work contributed by the rear brakes.

If you really need the upgrade and have to go to the effort of custom brackets, spacers etc, surely you go something much bigger.

Is it about availability of parts?

Yes, for me the issue is availability. But with the investigation I've looked at, with the parts I would want, it will be close to $500 for the whole big brake swap ($200 for the rear bracket adapters alone). Unfortunately I can't find GSL-SE calipers and brackets (a pair went for $60 just a couple of days before I looked on the classifieds here--rats!). And unfortunately also, I'm not allowed to post on the classifieds (even wanted!) to alert others I'm looking. But at the price of everything I'll wait a bit more. And if I can find some used calipers and rotors and such, for cheap, I may do the big brake if I can't find the GSL-SE calipers. Maybe I'll get lucky and find an FC donor in the pick and pull for cheap!

The turbo II brakes fit also which are bigger with 4 piston calipers.

Front, but not rear.

The FC turbo rear calipers are virtually identical to s3 GSL-SE rear calipers (in RHD markets, all of the series 3 got the big brakes, so I have to remember that you guys got a specced down models with 13" wheels). They all have the same piston size (34.93mm) and same pad size. The FD rear calipers are exactly the same spec too. The discs on these models are all ventilated and the same thickness (20mm). The only difference is rotor diameter. 258mm (84-85) vs 273mm (86-91) vs 294mm (91-02). The calipers are all just mounted differently but should have the same performance characteristics.

In fact, even the big brake RS/RZ/Spirit R uses the same basic rear caliper with single 34.93mm piston, but is wider to accommodate the thicker 314mmx32mm discs.

So, there is really no performance advantage to be had from upgrading from the s3 GSL-SE type calipers per se. The only thing I could think of was availability, but I understood you can get rebuild kits for s3 rear calipers. If you can rebuild your standard ones, then any bigger disc upgrade could be accomplished by a simple spacer to suit bigger diameter, rather than a full blown big brake conversion.

Yeah it's mostly an availability issue - the GSL-SE rear calipers are incredibly hard to find at this point. The FC parts are much easier to locate.

Lots of good info above by the way :)

Rockauto has the rear calipers but no brackets. So you just need brackets. The rockauto rear calipers are remanned by different places, left is A1 CARDONE and right is RAYBESTOS but they
are both reputable IMHO.

1984 MAZDA RX-7 1.3L R2 Caliper | RockAuto

My bad, the right from Raybestos has the bracket as well.

Unfortunately they don't have with the bracket. If you try to load it, it won't go into the cart. I haven't tried to get just the caliper, as just the caliper doesn't help me.

I was able to put it into my cart no problem. You may have an issue with your
browser and that site or something.

I don't think if you keep going you'll get it. I've had the note back from Rockauto on both the L&R rear calipers/brackets that they are out of stock, and I've signed up to be notified if they get it back in. No longer do those items show up in my search, but for some reason a new searcher still can see them--until they try to buy them.

RX7 Brake Rotor Sizes

Front 5-bolt 275.5mm
4-bolt 249.7
GSL-SE 250
GSL 227

Rear 5 bolt vented (T2) 272.9
5 bolt solid 261
4 bolt solid 261
GSL-SE solid 257
GSL solid 236

If you have the GSL brakes in the back with 236 mm diameter rotor you definitely need to upgrade to bigger rear brakes to keep things balanced. If you have any of the bigger rear rotors you are probably close enough.

I can tell you from personal experience that the 275mm fronts will not work with the 236mm rears. You will reduce your braking capability significantly because ALL the work will be done with the fronts. If you are just driving around on the street you might not notice the problem until you have an emergency stop and can't stop in time because the front brakes are locking up. On the track it will be immediately obvious as a serious downgrade.

They are 258mm diameter and ventilated, not solid. They are also the same thickness as the TII rear rotors (20mm new, 18mm minimum thickness).

As to the rest of your comment, I think that's sensible advice. If you have the smaller style rear, an upgrade makes sense. But IMO it's not the size of the disc that causes any imbalance/bias issues as much as the smaller piston caliper and master cylinder. The GSL also had the smaller ID master like the s2 from memory (13/16" instead of 7/8"). GSL-SE got the same size as the s4 T2 (7/8"). In s5 and onwards, Mazda went up a size again (15/16"). The small master, combined with the factory brake proportioning valve, means that braking bias and pedal effort is drastically altered once you stick bigger 4 piston calipers up front. If you work off a GSL-SE base with the bigger rear caliper , then simply upgrading to TII or FD front calipers will not result in drastically different pedal effort or bias - it's more or less as specified for the FC and FD.

What I didn't appreciate is that GSL-SE brakes are hard to come by for you guys. Here and in other countries, all model variants for the 84/85 model years, including the lower spec versions, got the 4x114.3 wheels with bigger brakes. Same deal with our FCs: no 4 bolt wheels with smaller brakes, even the NA models got the same brakes as the TII.

any idea which handbrake cable I would use on my rear caliper? specifically the passenger side

I have a 1982 chassis with the 84-85 rear end with a 5x114 axle. The hand break cable I bought didn't fit (was not correct length) I've actually bought 2 maybe 3 cables from various stores and sites. None are the correct length.

would a picture help figure it out?

Based on the info you posted, you would need to 1984/85.

I finally decided to go with the FB BBK, got the brackets from the member on the forum. I ordered the rear vented rotors from Rockauto not knowing that the vented only came in 5 lug. Can these rotors be safely redrilled to the 4 lug pattern?

Yes, just place an old 4-lug rotor on top of the new 5-lug rotor, align the center bores, clamp them together, put on a drill press, drill.

Lots of good info in the thread.

is the forum member still selling these kits?

I have a 1982 GS and am starting to piece together a rear axle swap and front hubs/brakes/rotors.

So far I have:
GSL -SE rear axle housing, axle shafts, retaining plates.
Rear calipers, missing brackets....
Diff carrier, no diff...
4.076 ring /pinion
Drive shaft flange, redrilled to accommodate any FB flange (small or large)
Ebrake cables


I am looking at MSF Racing in Australia, they sell custom front hubs, so I could still use my S2 spindles which have already been welded for coilovers. They have a front brake kit so I could redrill S5 rotors and run 4pot calipers. This saves me sourcing GSL -SE spindles and having to get new coilover brackets, machining, welding etc.

Rear I want to use a Miata diff and the standard GSL - SE rotors,calipers. For miata diff I think I can increase the spline engagement by omitting the rear axle bearing spacers and use a small spacer between the rear rotor and axle mounting face. I emailed Moser and they do not have any idea about GSL - SE axles which is strange because many people say you can just go and buy axles from them. In that case you can get slightly longer axles for proper spline engagement.

My GSL - SE axles do not have any centering feature, I was assuming they would have a spigot that centers the rotor and wheel? Anybody can comment on that?

Lots of info to hunt down to get everything to work.

Still need to determine what are good wheels to run with clearance for the FC front calipers....

someone on a fb group posted some rx7s in a junkyard in CO.. 1 or 2 of them were gslse's