Miller
Part of things
Posts: 87
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Hey There, I was wondering if any of you skilled and knowledgable people could share your thoughts on a rather worrying brake problem on my 1983 VW Polo. Today I was running it down a long steep hill (which there are plenty of in devon) and was rather shocked to find the brake pedal (which I was using to keep me from carreering down said hill) starting to sing into the footwell as I maintained pressure on it eventually hiting the carpet and brake effectiveness disapeering. First intinct was to pump the pedal and this then resulted in the car stopping as it should. This is now happening every time I have had to use the brakes for a prolonged (10 sec or more) time and is rather worrying. I'm sure its not down to heat fade due to the pedal pressure disapearing and my first thought was that the brakefluid level was low - which on inspection was not the case. I don't know much about brakes and was wondering if: A: The brake fluid has been contaminated or there is an air lock B: Brake pipes are perished? C: Fault in one of the caliper pistons? The car is disc front / drum rear non servo configuration so should be easyto pinpoint on inspection but are there any areas I should check first ? Or should I, as my instinct tells me, hand it to the local mechanic to have a look at ?(don't trust my self when it comes to brakes) As I have said this only happens on prolonged periods of braking and the car pulls up on emergancy stops as well as a non servo assisted 1983 polo ever has. Any ideas?
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could be anything to be honest, either fluid loss from somewhere in the system or contamination. however if you've not done any work recently involving brakes, and not had the lid off the resevoir then it would seem unlikely that the fluid has suddenly become contaminated... this would normally be a gradual loss of braking power.
basically just check all components for leaks.... the calipers, the rear cylinders and the master cylinder. does that age polo have a split circuit or is it all on the one?
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Never trust a man Who names himself Trevor. Or one day you might find He's not a real drug dealer.
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air leak somewhere
hoses or m cylinder - not that much ££ and easy to fix
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2001 HONDA CT110 (NOT RCV)
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Miller
Part of things
Posts: 87
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According to my trusty Haynes manual it has a duel circuit split diagonally, and may have self adjusting rear brake shoes (havent checked). The fault diagnosis in the same manual suggests excessive brake travel could be caused by worn rear brake shoes and if this is the case could they be adjusting over prolonged braking making the pedal go down and then resetting when the brake pedal is released? Thanks for your suggestions Miller
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Seth
South East
MorrisOxford TriumphMirald HillmanMinx BorgwardIsabellaCombi
Posts: 15,538
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Could also be one of the flexy hoses has gone weak and is expanding under pressure. You'll need a helper to press the pedal while you go round and check them.
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Follow your dreams or you might as well be a vegetable.
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Miller
Part of things
Posts: 87
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Ahh! Thanks hairnet and seth, hopefully your right and in which case it wont wont be too much to fix - I'm intending to replace the car soon anyways with something a little bit more "retro" so don't wan't to add much more to the £300 I have just spent on it.
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Last Edit: Aug 2, 2006 22:16:18 GMT by Miller
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slater
Club Retro Rides Member
Posts: 6,390
Club RR Member Number: 78
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Eek! Brakes Help?slater
@slater
Club Retro Rides Member 78
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a good trick is to clamp up the brake hoses (hose clamps or mole grips with something to protect them from the jaws)
clamp one up and then try the pedal, if the problem remains after you have clamped the pipe. they you pretty much know the components after where you have clamped it are not at fault. If you clamp one and the pedal goes hard you know the problem is in the part you have isolated with your clamp.
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had a similar problem with my 411 recently. After fitting new callipers there has been loads of play in the brake pedal. Bled them time and time again to see if it was an airlock but the drivers side wouldnt bleed right, only a small amount of fluid was coming through. We checked the flexi hoses first and saw that one had partially collapses so changed that. When we bled the brakes next the problem was still the same. Then we spent an evening removing different parts of the brake system on that side tracing back the fault - ie looking for where the volume of fluid was correct coming through the system. Turned out it was now fine up the to the end of the flexi hose, but then with the final copper pipe section attached there was barely any fluid coming through. Upon inspection of this section of pipe it was full of sh*te, and we couldnt clean it out so that was replaced too. And then when we bled the brakes again we had a good volume of fluid coming through the bleed nipple, but still the brake pedal was hitting the floor. With both wheels failing to lock when the pedal is on the floor it looked like a master cyclinder, and upon inspection there seemed to be a leak with a load of congealed brake fluid around it. Somehow, i have now managed to track one down which should be with me next week and hopefully will sort all my problems! Hope that might help - the flexi hoses were £4, the brake pipe section £5 and the master cylinder £65. If it costs that on a 411, its gotta be less for a polo.
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Stu
Posted a lot
Posts: 2,913
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Sounds like a dodgy seal in the master cylinder to me but I would go round and check the flexi hoses first, looks for leaks, bulges etc. Then adjust the rear drums as per the Haynes manual instructions and bleed the system all round. Does it have a rear brake bias valve on the rear axle? My old Golf with rear drums has one and I know all the GTI's I've had do, can't remember if my old Polo did? In any case, if there is a rear bias valve then check it's moving freely as 9 times out of 10 any airlocks I've had with VW brakes are down to that pesky valve!
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'89 BMW E30 325i Sport, '04 MINI Cooper S, '09 Volvo V70 D5
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I'm with Stu on this one. Look for a leak, if no leak then the seal is going in the master cylinder.
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Davenger
Club Retro Rides Member
It's only metal
Posts: 7,272
Club RR Member Number: 140
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Eek! Brakes Help?Davenger
@dminifreak
Club Retro Rides Member 140
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Had the same problem with my Mini, one of the wheel cylinders at the back was leaking
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