73 RX-2 Brake Master Cylinder?????
 

A friend of mine has a 1973 RX-2, which he bought new, and drives it to work every day (Doesn't want to park his RX-8 in the company parking lot). The brake master cylinder is dying, and the local Mazda dealer shows no listing for the cylinder or for a rebuild kit. Local auto parts stores don't seem to have any listings either. What are you guys doing to keep these things going??? Any one have the answer?? Any help would be appreciated.

You can get 99% of oldschool RX parts in australia. There are several vendors if you search online. Ebay even has some RX-2 amd RX-3 stuff.

Another place to try is an actual real oldschool mechanic, who may be able to rebuild it without the rebuild kit.

I use a 1st gen master in my '73 rx3. It required a little grinding though.

what are some of the aussi web sites please

Yeah, 1st gen master is a nice upgrade with a little change of the hard lines.

Many of them have upgraded to the US rwd GLC with 1" bore for better breaking instaed of the stocker 7/8.

Problem Solved!!!
 

Thanks for all the responses. I found that the RX-2 has the older style coarse thread fittings in the brake system, and that is the same as my old GLC and the 79-80 RX-7. Someone told me about having to change the fittings to install a 81-85 style master cylinder, which has the finer threads. We bought a brand new 79-80 RX-7 master cyl and it bolted right in with no interferences, and has the correct threads. We just rebent the brake lines, straightening out a couple of the zig-zags where they go across the firewall to get a couple inches more length. I then turned the bends upwards so they come in from the bottom. The extra port for the front brake was plugged, using a short 10x1.25 bolt and a copper washer(like a banjo bolt)

The bore is slightly smaller than the stock RX-2 master, about 7/8 inch compared to 1 inch, but my friend says he did not notice any difference in pedal force.

Rebending the brake lines must be done carefully, and is very awkward if you are doing it with the lines and all the other stuff in place. The whole job took us about 2 1/2 hours, including flushing and bleeding.

Nice Solution.

7/8" bore will reduce pedal effort 33% but increase travel a little.
Force=Pressure*Area
F1=P1*A1 ; F2=P2*A2 ; A1=1" ; A2= 7/8" ; Assume P1=P2=any number=100
F1=100*1=100 ; F2=100*7/8"=87.5 ; see F1 is greater than F2 to generate the same pressure.

I'd like to jump in and ask a question too, then, since we have a few experts on-hand. I've got the GSL rear discs and am making new hard lines. What would y'all suggest for a new master on the RX-2?

I looked into the GLC master and it seems like a very good match. Props Wacky.

Here's a pic of the '77-79 glc master. It is 13/16" and has two ports at the bottom. Threads are M10-1.25 coarse.

http://partimages2.genpt.com/partimages/359851.jpg
Napa spec can be found here:
http://napaonline.com/masterpages/NO...Cylinder+-+New

P.S. - I miss-typed in my last post 23% not 33%.

The one I was referring to is the GLC with remote reservoir. I tried using the 1st gen in the RX-3 but the reservoir wont clear the strut tower without mods. Im very conservative when it comes to brakes.

I tenatively vote for using a 79-80 RX7 master(13/16", 3-port, 10-1.25 coarse thread) and any GSL proportioning valve(4-port, 10-1.00 fine thread). You will probably need a double flare tool because several lines would go from coarse to fine. The worst thing is that the rear line will need to be changed from coarse to fine to fit the proportioning valve.

You could use a 81-85 rx7 master (13/16" or 7/8" for GSL-SE, 3-port, 10-1.00 fine thread). The mounting flange has a minor interference issue with the nuts of the booster adapter and will need a little grinding to relieve it. The main reason I suggest the later master is I question how much longer the '79-80 RX7 master will continue to be produced.

http://napaonline.com/ has lots of detailed info on parts great for cross referencing.

I also noticed that they sell '76 RX3 masters.

Can't find that one. :dunno: Is it the mizer?

The reservoirs just pull off anyway. You could probably use your car's stock reservoir with any of them.

Sorry if I got everyone confused. According to Ausrotary, they use GLC. But for me, a 79 RWD 626 with remote reservoir is much better. http://www.napaonline.com/masterpage...linder+-+Remfd

http://partimages2.genpt.com/partimages/71686.jpghttp://partimages2.genpt.com/partimages/358069.jpg

I see. It is bigger. 7/8", 3-port, coarse 10-1.25 thread.

Tell him to drive the 8 to work. It has much better locks and would be much more difficult to steal. The rx-2 locks are primitive in comparison.

Driving the Beater to Work
 

This RX-2 runs very well, but has faded paint, dash pad cracked all to hell, cheesy looking steel wheels - and that is just the way he wants it. No one pays any attention to it. Besides, he only lives two miles from his work. In the rainy Seattle winter weather, he prefers to have the RX-8 sitting in the garage.

He also has a 79 RX-7 which he bought new - first one delivered to his local dealer in June 78. 25 years later he got the first RX-8 delivered to his dealer. He is happy with all of them, says he plans to buy another new Mazda every 25 years!

Our 79 style master had very little clearance from the reservoir to the shock tower, but the reservoir is rubber mounted, moves easily 1/8 inch, definitely not a problem in this particular car. In any case if you have a small interference, remember that is why God invented the hammer.

Just curious...Do you think it is possible to use the old RX2 resevoir with the new RX7 master?

Thats below my standards.

"Just curious...Do you think it is possible to use the old RX2 resevoir with the new RX7 master?"

This RX-2 had two separate reservoirs for front and rear. No doubt they could be made to work with the new master, but I like the convenience of a single fill port. The reservoir is translucent, so you can see the front and rear fluid levels. Also, the unit we used came with a reed switch for low fluid indication, just like your GLC unit shown above. My friend plans to connect this into the warning light circuit that goes to the distribution block on the firewall.

This should be archieved. Don't you think?