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Power Brake Problem

Posted: Tue Apr 25, 06 11:22 am
by Trigger_Andy
I cant remember if I have posted about this problem before?

OK, since I fitted my header's I have had no brakes at all. To fit the header's I had to move the master cylinder outta the way.
I should have paid more attention to what I was doing because I think I may have lost a seal. If my memmory serves me right it was a foam based seal that disintegrated what it was desterbed? The seal went between a white plastic bit and a metal spacer that goes between the master cylinder and the brake booster. I can post pictures if required.

Does anyone know if you can get spares or know of a suitable alternitive?

Posted: Wed Apr 26, 06 7:31 am
by latil
I think that is just a gasket to keep dust etc out of the joint.I made a new one from laminate floor underlay which appeared to be the same foam.

Posted: Wed Apr 26, 06 8:02 am
by Matt
I don't think the item you're talking about is a seal - it's a little foam air filter which is sandwiched in the upper part between the white plastic clip-on plate and the cast metal plate . Both plates fit between the booster and the master cylinder. As far as I can gather, this vents the side of the booster that faces the master cylinder. I just use a small piece of open-cell foam cut to fit.

Posted: Wed Apr 26, 06 9:15 am
by Trigger_Andy
Thanks for the responce.

OK Steve, I tried to suck on the vacuum hose and it dident hold vacuum. I could suck but with effort :oops: .

I looked ansd felt inside the output rod side of the booster and could not find and tear's/holes in the rubber seal. The seal face for the Snandwich plate is in tact too. Should I be checking for a posable leak path?

Posted: Wed Apr 26, 06 9:21 am
by Matt
what do you mean ' no brakes' ?

does the pedal not move , or does it go to the floor ?

Posted: Wed Apr 26, 06 9:25 am
by Trigger_Andy
Hi Matt,
I get a very short burst of brake effort then no force at all. I still have a solid pedal and have to push like mad to get a fraction of the brake effort I had before. Basicly I have to trundle to junction's.

And this is all since I moved it in various stages to get my headers's in. #-o

Posted: Fri Apr 28, 06 9:47 am
by Matt
Steve - good point , but , (going from memory here , feel free to argue) the construction of this part of the assembly is such that it is absolutely not meant to be airtight .

The cast plate behind the master cylinder seals the rim of the booster's internal rubber seal to the booster body - this is where the airtight seal is - there's quite a few raised ribs on it to ensure a good seal. however , I don't think the section of the booster from which the pushrod emerges is subject to vacuum. Hence the need to vent from between the cast plate and the master cylinder as the internal volume of this part of the booster will change with pedal travel.

I'm not actually looking at the manual or a booster here, and could be talking real rubbish - could someone who actually knows put me straight if I am ? :)

Posted: Fri Apr 28, 06 11:08 am
by Matt
Andy - sounds like you've got vacuum initially , but it's disappearing once you've pressed the pedal .
First thing to check is that the vac hose from the carb/intake manifold to the booster isn't kinked or hasn't collapsed internally . (Had a perfectly good looking one collapse internally once - exactly the symptoms you describe) . Is the check valve where the hose meets the booster working OK?

Otherwise you could have an internal booster problem?

Posted: Fri Apr 28, 06 6:57 pm
by Trigger_Andy
Thanks for all the reply's guy's. Food for thought.

I will have to look into a few of the points that have been brought up when I get home. Like I said before I can suck through the Vacuum line from the inlet manifold but it takes some effort. I have had a good feel inside the rubber element and cant find any tears or nicks, though it was very grubby and rusty. there's a circular rubber piece with triangle shaped metal wedges that fit inside the booster and the output rod sits inside of it, one of these wedges are missing. But it was like that before so I guess its of no importance. Is there anywhere I can buy a manual that will cover this?

Posted: Sun Apr 30, 06 12:17 pm
by Trigger_Andy
I have found a company that sell's remanufactured Booster's on the net. Not bad at $130 each. If I fail to find/fix my problem this look's like the next step.

javascript:ol('http://replacement.car-stuff.com/parts/ ... part=Brake Booster&returnurl=null&dp=true&showdc=true#top');

Unless anyone know's anyone who sell's repair kit's?

Posted: Mon May 01, 06 1:55 pm
by Anonymous
Whatever you do Andy don't bodge it as suddenly being without power brakes wouldn't be nice..... just ask Wildman who very nearly took out a petrol station cos he couldn't stop.

Harmless Bodge and brakes do not mix

If you get stuck for a booster I can do one

Posted: Mon May 01, 06 6:28 pm
by Trigger_Andy
Cheer's Will, PM me with a price when you have time.