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Blow off valve powered brake booster...

OldSchoolEuro

New member
Joined
Oct 26, 2005
Hey guys. So I just completed my RX-7 Brake conversion over the weekend and have a couple problems. First off I 'think' I deleted one of the incorrect brake lines for the front calipers. I deleted the lines that were closest to the front of the car so thats why I think my brake failure light is coming on.

Overall my brakes feel really weak in the front compared to the stock setup. But I am also getting this unusual sound when the car is on and I am pressing on the brake pedal...has anyone heard this sound before??

 
And here is the current line setup I have on the car...

ScreenShot2013-03-31at95006AM_zps0618f3c6.png
 
So I believe after further investigating that I may have my circuit incorrect. Brake failure light is coming on when I press on the pedal hard.
 
yeah, fubared. you need to take one of the fronts and put it on the other side so you have a front and a read on each side. then you should be gtg. did you eliminate your rear proportioning valves? with the better front brakes eliminating the rear valves makes the brakes much better still
 
That's what I am thinking too...mine is about 10 years old. Won't hurt to replace it. I think it got fubared when I had a friend accidentally pressed the pedal all the way down to the floor when I was bleeding the system.
 
Hmm very interesting. I might try and switch the line to the other port (switch the lines from the junction block to the passenger side caliper) to see if anything changes. In the meantime I may order another master cylinder just in case.

Does yours make that 'pew pew' sound when your car is on and pressing the brake pedal too?
 
No laser beam sound effects coming from mine. I think I will plan on ordering a new master and take a look at rearranging my lines as well before bleeding it again.
 
Looking at Dave's setup, it looks like I'll have to run new lines since the stock lines won't reach the correct ports. Unless I am looking at it wrong...
 
I remember reading something about running Dave's setup (F/R split) saying that the factory master struggles in that configuration. I need to look up those threads again.
 
Mine are plumbed up just like your illustration and have been working fine for years, none of the funny noises or warning lights you are describing at least.

I was actually looking at it just the other day while under the car and thinking that it didn't seem right that I had both front calipers and one rear being fed off of one end of the valve.

Here is Dave Barton's page on brakes. He is showing the ideal way being to feed the front calipers from one end and the rears from the other, but doing that seems like one of the rear lines would have to be re-made to reach the front port.

I was thinking of trying to find a '93/abs car in the yard to see how those are plumbed, and maybe take the parts from it, but I don't think I'll have much luck finding one where I live now.
 
If its working for you then there must be air trapped somewhere. I'll bleed the system again this week.

As for the remake of the lines, I want to avoid doing that but if this doesn't work then I may have to do it. I heard that the non-abs master doesn't like the setup that Dave has.
 
This might sound dumb but most cars have a rubber bellows on the pedal box and they have a vent hole on them and if it gets blocked or it isn't sitting correctly you can get a funny noise.

I don't know much about Volvos so there is a good chance I am wrong.
Are these normally set up so you get diagonal wheels braking if one circuit fails?
 
That's what I think too, but its weird that the MC and BB would go out at the same time too...

The pedal does feel like I am doing a little bit more work than before to get the car to stop.
 
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