(MARRS-RX7) Brake issues

Alex C. alexanderanson
Sun May 2 22:56:49 CEST 2010

Nope - didn't bench bleed.  Didn't think too (and actually never done it).
I'll just get someone to pound the crap out of the brakes and I'll get as
much air out as possible.  
As for the differences in cylinders, there is actually a pretty big
difference.  The rear drum setups require you to connect the rear brake tap
from the cylinder to the proportioning valve through a brass fitting in the
cylinder.  I opened this brass fitting and there was a separate internal
spring and plunger for the rear brakes - it shows up in both the Haynes and
Mazda manuals, but looking at advanceauto.com and comparing the two
pictures, the 4 wheel disk brakes do not have this separate plunger system
for the rears - its just a normal hookup.  The Rear disk models matched what
I had on the car and later returned for my core charge.  There is so much of
a difference the core charge for disk brake rear master cylinders is $25,
vs. the $10 for a 4 wheel disk.  

- Alex  

-----Original Message-----
From: spec7-bounces at specrx7.com [mailto:spec7-bounces at specrx7.com] On Behalf
Of Bill
Sent: Sunday, May 02, 2010 4:45 PM
To: spec7 at specrx7.com
Subject: Re: (MARRS-RX7) Brake issues

Quoting alexanderanson at gmail.com on Sun, 02 May 2010:

> Ok, update on my brake issues -
> After removing the cylinder that I had put on a year ago, I noticed a
> difference and went back to the computer to check - I was given the wrong
> one!  I was running a cylinder setup for rear drums and not rear disks.

There is no practical difference between the drum and disk master  
cylinders.  Different on paper, different part numbers, but most  
people with drum cars didn't change them when they went to disks and  
it was no big deal.  I didn't change it or the proportioning valve.

> I know I'm going to need to get help to bleed the brakes, but I figured I
> would fill reservoir with fluid and use my one man bleeder to at least
> some of the fluid through in the front.
>  Is this due to the fact that
> there is still a massive amount of air in the line, or does it seem as
> though I have more of a problem on my hands?

Did you bench-bleed the new master?  If you didn't, it will be  
extremely difficult to remove all the air from the master.  BTDT.  And  
as you said, you will need somebody to pound on that pedal to properly  
clear all the air from the lines.

   - Bill
     SRX7 #77 "Tacit Blue"         Go Racing NOW!
     Forest Hill, MD            http://SpecRX7.com/

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