ChasRX

I am doing a rear axle swap in my '81 GS to use an '83 GSL w/ disc brakes. But rather than Hi-Jack Moonchopper's original thread, I thought I'd also start a new one. I've searched this forum and Mazspeed's forum and learned quite abit; however, here's the stage I'm at with questions:

Parts I have include:
1. Entire '83 GSL rear axle with disc brakes (bought on Ebay).
2. SS Brake line kit (for rear disc models) from Mazdatrix.
3. New Rotors and calipers from Advance Auto. (old ones are traded as cores; too rusty!)
4. Bendix OE brake pads from Advance.
5. GSL emergency brake cable assy (soon to arrive).

My questions are:

1. Will I need a new master brake cylinder, too? I've looked on Mazdatrix and learned that there are two different part numbers for both kinds: Drums vs. discs. Not sure what the difference would be. Volume perhaps?

2. Do I have to swap out the proportioning valve?

3. Anyone have recommendations on 'Speed-bleeders'?

4. Is the driveshaft going to be an issue from an '81 shaft-end to the '83 rear end?

Any advise is appreciated. I'm cleaning up the axle, now, for re-painting, so I haven't actually started the swap, yet.

MosesX605

Errr, I think that the driveshaft flange is bigger on the '83 model year cars, so you'll need an '83 driveshaft as well. I did this swap into my '79 and I didn't change either the proportioning valve or the master cylinder. The brakes have plenty of stopping power, but they are a little too rear biased for my tastes. You'd best swap over the proportioning valve, but you can keep your original master cylinder.

As for the speedbleeders, I've never used them, so I can't comment.

Good luck on the swap.

RoyFifo

2 and 3: Proportioning is done internally on the master, get one for disk brakes. The block after the master is a safety valve that shuts off flow to the front or rear if either developed a major leak. (Half your brakes is better than no brakes)

4. you can swap pinion flanges, torque the Pinion nut down to 94 Ft-lb's after changing them. 1982 drive shafts have replaceable u-joints, 83's dont.

Other:
A: Put new wheel bearings and seals in now if you can afford it.
B: Get one of those 1-man bleeder kits. Its some tube, a cap with a magnet off the side and a little bottle. Works on more cars than one set of speed-bleeders.
C: New U-Joints and have your shaft dynamically ballanced to 7000 PRM
D: New rubber in the control arms and watts link since you will be taking them at least halfway out.
E: New Pinion seal if you do swap flanges.

F: Above all, enjoy your new improved traction and stopping power.

ChasRX

Great. Thanks for the tips. I'll swap the pinion flange, then, too. I'm heading down to my local Mazda parts shop, today, and I'll order a pinion seal. I have a local machine shop that has balanced the drive shaft in the past. I like the idea of keeping the '81 drive shaft. Please see pic, below, as I need help confirming the flange seal to be replaced:



Yes, I'd thought about the wheel bearings, too. Actually, I thought about having the axle bearings replaced, too.

boyee

iTrader: (3)

I did not find a thread committed to just brake master cylinders so I thought I'd post the numbers here. When I needed to replace my leaky BMC for my GSL 4-disc brake I had a hard time using online catalogs to find the right part I needed and even a wrong part was delivered to me. So I just decided to make a list of the part numbers people can directly search for so there is no confusion to getting the right or wrong part.

A1 CARDONE 111962
AC-DELCO 18M266
AUTOSPECIALTY M-53103
AUTOSPECIALTY M-53103E
BECK/ARNLEY 072-8108
BENDIX 11962
CARQUEST E105901
CENTRIC 130.45103
CERTIFIED FM2056
DOORMAN M39489
EIS E105901
ITM 25-01102
LUCAS GIRLING 211129
MAZDA OEM FA18-43-400
NAPA (BRAKE) 39489
QUALITEE 66 74 220
RAYBESTOS MC-39489
WAGNER F108037

Remember this is reference part numbers only for 1981-1983 GSL Rear Disc Brake Master Cylinders. Also always verify to whoever you order your parts from that its for a 4-disc brake 1981-1983 RX-7. Hope this helps anybody looking to replace theirs!

Rx-7Doctor

iTrader: (13)

Thank you for taking the time to do this. I'll see if I can find the thread that we have that references to interchangeability and add it to that thread also. :-)

aussiesmg

iTrader: (1)

During 83 the rear ends changed to the bigger bearings and axles, do you know which one you have?

I use Russell Speed Bleeders and love them, so easy, so clean, one person can do the whole car in 10 minutes.

You can also adjust bias by carefully selecting brake pads for there aggressiveness.

Buy a caliper rebuild kit for a few bucks and rebuild those puppies, there are threads in here on this, it's easy and super effective.

aeenox

Hey Guys,

I have a 83 GS with drum brakes, I was wondering if I was able to bolt up a 84-85 drive shaft on to my 83 rear end.
It it safe to say that my 83 is a later model that has a rear end with the big bearing axles like the 84-85?

I am asking because I swapped a 85 GSL-SE rear end, but one of my axles is bent. But I think the 85 rear end housing might have gotten bent too. So I was thinking of getting a new axle and swapping all the parts from the 85 rear end into the 83 rear end housing.

Thanks,
Ernie