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Location:
Melbourne
Registered:
March 2003
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My brakes are screwed, why?
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Wed, 29 June 2005 12:16
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Ok i'll just lay down the story first:
I decided that my brakes were getting to be very very crap so I had my pads changed over to some better ones, no problems there. When they were changing over the pad's they found a bunch of things wrong with them that needed fixing.
Rotors under legal limit
rear shoes worn
sticky calliper
leaking rear cylinders
and needed brakes to be bled.
So after a little hills run with my new pad's i decided they were pretty sweet and that i'd go bleed the brakes with my cousins help.
Big mistake. We bled and bled and bled them and their was just so much air coming out of the rear left line, all the others were fine.
anyway when we ran out of fluid we just put everything back and left it as is. their was a crap load of air still left in my lines and only about an inch of pedal play actualy did anything to the brakes, the rest was nothing.
Took my car to the place that did the pad's and had the rear cylinders replaced and a full bleed. It was a little better but nothing like it was before the first bleed. Now i have about 2 inches of pedal play that actualy brakes.
So just what is wrong with my brakes? Theirs no leaks anywhere anymore but they are still crap, could it just be an adjustment problem (we havn't changed any adjustments at the master cyl) or is it something worse?
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: My brakes are screwed, why?
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Wed, 29 June 2005 12:19
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I had a similar problem - needed a master cyl rebuild. air was getting past the piston. (nb: this is only one of many possibilities for these symptoms)
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Location:
Melbourne
Registered:
March 2003
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: My brakes are screwed, why?
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Wed, 29 June 2005 12:38
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that's what happened to mine - was fine before the bleed, but during the extra travel of bleeding (plus new calipers) the seal just disintegrated.
piston was undamaged (luckily, because a replacement couldn't be sourced)
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Location:
Canberra
Registered:
June 2005
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Re: My brakes are screwed, why?
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Wed, 29 June 2005 22:51
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My brakes now are the same.
Working fine at Wakefield Park last time, then I changed the rear slave cylinders to RA23 ones with new kits and went to bleed the lines. Results the same as yours, no pedal at all, will pump up and then fall again.
I agree with prveious replies.
A cylinder with some age on it or one from an import wreck like mine the seals do fail very easily.
I have a new kit to go in the Master cylinder this weekend and I'll update how it went also.
Regards
Rodger
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Location:
Rosanna, Melb
Registered:
June 2002
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Re: My brakes are screwed, why?
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Wed, 29 June 2005 23:38
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I've had people tell me only to use the top 1/2 of the pedal travel if bleeding an old master cylinder. The bottom half of the travel is never normally used and so can get crap/rust/gremlins building up on the inside of the bore. So when you bleed it and push the master cylinder piston seal over this section it gets ripped apart.
May be the cause of your problems, but I wouldn't swear to it.
Hen
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Location:
Canberra
Registered:
June 2005
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Re: My brakes are screwed, why?
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Wed, 29 June 2005 23:50
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Makes good sense to me Hen.
I reckon that is what has happened to my cylinder now that I read your comments.
In the past I have usually completely overhauled the brake system on my cars so had never seen this till now.
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Location:
Sydney NSW
Registered:
July 2004
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Re: My brakes are screwed, why?
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Thu, 30 June 2005 02:47
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I recently replaced all my rotors/pads/rebuilt rear calipers, and after trying to bleed for ages using the pumping technique and we just couldnt get a good pedal(almost right to the floor). Thought the MC was farked.
Took it to the mechanic, and he "apparently" bled the brakes. Charged me money, I got in the car to drive away and they were only marginally better(almost - almost to the floor)
I went to the auto shop, bought a heap more fluid, then set up the car with both rear brake bleed valves running through tubing to two jars 1" full of fluid, so no air could return up the hose. Opened both valves a fair bit, so fluid was running out, then poured more fluid in the MC resevoir. Also gave it a couple of pumps and it sounded like it had a bad case of diorrhoea.
This method, repeated on the front, used heaps of fluid, but got me an even better pedal than i originally had.
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Location:
Melbourne
Registered:
March 2003
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Re: My brakes are screwed, why?
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Thu, 30 June 2005 11:49
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Are the master cylinders for all xa6x the same? or is there a specific type for the ra65?
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I supported Toymods
Location:
Australia
Registered:
November 2003
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Re: My brakes are screwed, why?
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Fri, 01 July 2005 04:04
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| Henn wrote on Thu, 30 June 2005 07:38 |
I've had people tell me only to use the top 1/2 of the pedal travel if bleeding an old master cylinder. The bottom half of the travel is never normally used and so can get crap/rust/gremlins building up on the inside of the bore. So when you bleed it and push the master cylinder piston seal over this section it gets ripped apart.
May be the cause of your problems, but I wouldn't swear to it.
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Yes, that is normally what happens.
This is why I flushed my brakes with Metho before pumping the new fluid through.
It flushed out the bore nicely.
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Location:
Gympie
Registered:
June 2005
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Re: My brakes are screwed, why?
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Fri, 01 July 2005 12:58
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Sadly, brakes are one of those areas where you'll find the adage "if it aint broke, don't fix it" seems to have some truth. This thing is functioning... I know, I'll just poke it in the ribs and see what happens. What sometimes happens is all those things that are working but tired suddenly give up the ghost. With braking systems that have a few years on the clock, you need to be prepared to undergo a bit of a chain reaction. Part A, the obviously tired part gets replaced, and the increase in function puts a bit more strain on Part B, which then fails too. This can go on for some time. Or in your case, I would say that if the MC hasn't gone out to lunch then it probably has started looking at the clock. Also you mentioned rotors being below minimum legal thickness. The new pads will help, and if you are really desperate you could drive on them for a while, BUT, once the pads are partly worn, you will most likely run out of clamping force as the calipers will be at maximum travel. In other words worn rotors OR worn pads you'd get away with, but not both. I'd be planning replacement rotors sometime soonish.
Did you replace rear brake shoes at the same time? Same story, if they are worn, you'll also lose travel.
I used to use a tube to bleed with too, and I also made sure that it went UP from the bleeder, so that it kept any air moving away from the system, and made it obvious when the air was no longer there. If bleeding without a tube then always be sure that the bleeder is fully shut off BEFORE the brake is released, otherwise you're just sucking air back into the system.
Also start bleeding from the nearest brake to the MC and work away to the furthest.
Have Fun
Cheers Richard
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