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Old 05-14-2007, 09:23 PM
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Disc Brake w/out booster question

I'm hoping someone can help me with an issue I've run up against. I've recently purchased a 31 model A that's been chopped and lowered. All of the mechanical work was started and completed by the original owner, 2 owners ago from me. I believe it has around a 1970 chevelle under the car, with disc brakes on front and drums on rear. The original owner didn't put a booster on the brakes, and they are somewhat spongy. Anybody have any solutions, other than putting the booster on. I'm up against a space issue as well, not a lot of room left to put one. Thanks in advance
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Old 05-14-2007, 09:29 PM
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Did you try bleeding the brakes? We tossed the vacuum booster because of clearance issues on a Datsun 210 and went to manual disc/drum brakes and a master cylinder with the largest diameter piston we could find. It worked great. Of course the car only weighed 1850lbs so stopping was still fairly easy.
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Old 05-15-2007, 12:07 AM
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Well, going larger on the master cylinder is the wrong way.
When you drop the power booster you will need a SMALLER M/C piston, not larger. Smaller amkes more pressure, larger moves more fluid. Common mistake.

Double check the bleeding first, then probably drop to a smaller M/C.
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Old 05-15-2007, 04:42 AM
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Quote:
Originally Posted by spike62
I'm hoping someone can help me with an issue I've run up against. I've recently purchased a 31 model A that's been chopped and lowered. All of the mechanical work was started and completed by the original owner, 2 owners ago from me. I believe it has around a 1970 chevelle under the car, with disc brakes on front and drums on rear. The original owner didn't put a booster on the brakes, and they are somewhat spongy. Anybody have any solutions, other than putting the booster on. I'm up against a space issue as well, not a lot of room left to put one. Thanks in advance
Many questions. Proportioning valve? Residual valves? Type of MC? Location of MC? (under floor?)

A good start would be here:

http://www.mpbrakes.com/technical-su...igurations.cfm

Find your configurations and see how it should be plumbed.
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Old 05-15-2007, 08:50 AM
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The booster (or lack thereof) has nothing to do with spongy brakes. My 1970 Olds 442 W-30 came with manual disc brakes from the factory. You either have air in the lines or a bad master cylinder.
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Old 05-15-2007, 09:05 AM
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Purchase some self bleeders and do a really good job of bleeding all four corners.

Vince
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Old 05-15-2007, 12:14 PM
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re: Disc Brake w/out booster question

Ditto on rebleeding the brakes.
We have a 28 sedan disc/drum setup. No booster, no need.
Works fine. We had a killer time bleeding the brakes. Finally took the calipers loose and turned them with the bleeders straight up and bled them. If the calipers are not set perfectly with the bleeder at the absolute top, a tiny bubble in there is hard to get out.
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Old 05-15-2007, 04:35 PM
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A big Thanks

To all that replied, a big thank you. I will try bleeding them again and more aggresively this time. I'ts been a little difficult coming in the late innings of the restoration and try to get up to speed on something someone else has done. But wouldn't do it if I didn't enjoy it.

Next problem I found out today after it went to be aligned is that I'm out on camber on the Lt. side and no adjustment left, so my local body shop/alignment guy tells me. Any thoughts?


Thanks again to everybody on the brakes. I'm hitting them as soon as time allows.

Spike
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Old 05-16-2007, 12:17 AM
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If the MC has been installed below the level of the calipers, you will need 2 lb. residual valves on front and rear circuits to prevent fluid drainback from the calipers.
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Old 05-16-2007, 04:37 AM
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Quote:
Originally Posted by KULTULZ
If the MC has been installed below the level of the calipers, you will need 2 lb. residual valves on front and rear circuits to prevent fluid drainback from the calipers.
I have always thought that front disc/rear drum requires a 2lb valve for front and 10lb for rear.
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Old 05-16-2007, 05:42 AM
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Quote:
Originally Posted by heyjude076

I have always thought that front disc/rear drum requires a 2lb valve for front and 10lb for rear.
IF the MC is mounted below the fluid level in the calipers/wheel cylinders, the fluid will drain back towards the MC. Simple gravity. The 2# valve restricts that. A 10# is used on drum brakes (regardless of MC mounting) to keep the brake shoes slighly extended for faster application and also to prevent the return springs from slamming the pistons together upon pedal release.
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Old 05-16-2007, 10:48 AM
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Quote:
Originally Posted by spike62
Next problem I found out today after it went to be aligned is that I'm out on camber on the Lt. side and no adjustment left, so my local body shop/alignment guy tells me. Any thoughts? Spike
You haven't told us if you have a ifs or beam front axle.
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Old 05-18-2007, 11:09 AM
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Beam Front Axle

Thanks for the responses. It's a beam front axle. Also KULTULZ may have hit on the brake issue as well. My MC is under the floor, and is close to being the same elevation as the calipers. Sorry for the sporadic responses, we've just hit ball season with a vengeance, and my kids take precedence over the rod rebuilding.

Thanks, again. spike
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Old 05-18-2007, 02:53 PM
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Quote:
Originally Posted by spike62
Next problem I found out today after it went to be aligned is that I'm out on camber on the Lt. side and no adjustment left, so my local body shop/alignment guy tells me. Any thoughts? Spike
Obviously your alignment guy is not schooled in old beam axles. If you are out of adjustment range you will have to have the axle bent in the middle. Any large truck alignment place will be able to do it.
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Old 05-18-2007, 03:37 PM
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re: Disc Brake w/out booster question

What HomeBrew said. Plus I'd be real spooky about an alignment guy who told you there was no adjustment left. There never was any to begin with.
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