Had the Polo in for a service and MOT on Friday, and it failed on 4 'excessively corroded/deteriorated' brake flexi pipes. Naturally, I had these replaced, and to do this, the brake system was bled.
When I picked the car up at 5pm, all was well apart from the brake pedal now has an 'abnormally' long travel. I put it in inverted commas because I?m not sure if it really is excessive or its just me worrying over nothing again.
Prior to having them done, the pedal would move about 1cm before they kicked in, with all of the remaining effect taking place in another inch or so. After that, the brakes would always lock. Now, the pedal travels about 1.5 inches (or at least that?s what it seems like) before the brakes work properly, retaining the same feels as they did before, just lower down to the floor. You can press them as hard as you like and the pedal is still well away from the floor (about half the pedals entire travel)
That initial 1.5 inches does give some braking effort, just not a lot, and the pedal isn't spongy (which would indicate air in the system).
What do you people thing, anything to worry about?
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IF you can't bring the feel up by "pumping" the pedal, then I would say all is ok, with new pipes, fluid and being bled the feel has just changed is all.
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Thanks RF.
I haven?t tried pumping the pedal yet, although when I first got in, I pressed the pedal a couple of times in quick succession, (just confirming that the pedal really did move that far) and I can't recall any difference.
I'm going out tomorrow, so I?ll try it then, but if pedal travel is shortened by pumping, this means that there could be air in the system doesn?t it?
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Wholly dangerous idea but have you tried locking the brakes?
I had a similar "problem" in as much that, I could swear I was pressing my brake pedal in a lot more than usual. A marginal detour into a bus queue and the resulting slam on of the brakes soon told me I was imagining it.
(I only hit one nun.)
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Adam
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On a lot of modern breaking systems this method does not apply,if their is excesive travel in the pedal it needs bleeding again and also double check that there is no leak.The maximum travel will be listed in the workshop manual.
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If the Polo has rear drums ( you do not state which model/age you have ) it is likely that the shoes are out of adjustment or the self adjusters are lazy/siezed. I had this "problem" on a mk2 golf. The slop in the pedal is pushing the shoes into contact with the drums. Careful adjustment will reduce the pedal action.
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An old tip for anyone starting to have doubts about their braking power was to use their left foot.
Carefully.
Nearly went through the screen in my Mini!
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I wasna fu but just had plenty.
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Thanks for the replies people.
Got into it this morning, and pressed the pedal before I started the engine and the pedal feel was as it used to be. Started engine, and pedal went to the new feel. So, I pumped the pedal - no change.
Adski - No, I haven?t tried locking the brakes yet, but I gave them a damn good prod on my travels this morning, and braking performance is as good as it used to be, but I?ll do an emergency stop later and see what happens.
Andy - I looked into the Haynes manual, but couldn't find any specs in it. I've got some VAG workshop manuals somewhere, I?ll take a look at those, but I don?t think its specified in those neither.
GWS - Yep, did that on the way home from the garage the other day, and this is how I found out that the initial inch or so does actually give some braking power.
s2driver - The car is a 1993 edition (as per profile), and thus does have drums at the rear. As the car underwent a full service, I would imagine they checked the rear brakes (said they did) so any mal-adjustment would have been rectified. The brakes only got this new feel after the service and MOT, wouldn't lazy adjusters be a more gradual thing?
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The pedal pulldown on starting engine is the servo effect coming in; assuming you kept pressing on the brake as you started engine.
you can check this by switching engine off and pumping pedal repeatedly; as the vecuum is exhausted the pedal will harden up again.
AFAIK this effect occurs on all cars apart from those Citroens which have common fluid for suspension and braking, though why you should notice it after a service I don't know, maybe there was a split in the vaccuum pipe to the manifold which was fixed?
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"Got into it this morning, and pressed the pedal before I started the engine and the pedal feel was as it used to be. Started engine, and pedal went to the new feel."
Good - thats the way it should be, thats the engine powered servo kicking in and providing the extra "push"
" So, I pumped the pedal - no change."
Good thats the way it should be, no air in the system.
Try the emergency stop, if it stops fast, hard and in a straight line then your brakes are all fine and dandy.
Its just the feel has changed due to the new fluid and the new bits.
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.Well, tried the emergency stop, and the car pulled up straight and true with enough power to successfully rearrange all the items in the boot.
Incidentally, I didn't hold the pedal when re-starting the engine. Just pressed when I got in - it was hard, the way it used to be. Let go. Started the engine, tried it again - new feel resumed.
Like I say, no amount of pumping the pedal made it change its position (I haven?t tried pumping it whilst driving, should I?)
There is no sponginess in the pedal neither (which I assumed would also mean air in the system)
Looking in the VAG workshop manual, it states that the maximum amount of free play should be no more than 1/3 of pedal travel. I would say that mine is just within this tolerance, but I really need to go and measure it to be absolutely certain. 'Free play'? I think there is some braking performance in that initial inch or so, but its not a lot and retardation is the same at the start of the inch than it is at the end if you know what I mean! (So is it really free play?) Thereafter, the usual braking feel is resumed.
I?ll try to remember to do a bit of testing and measuring tomorrow, and I?ll let you know how I got on.
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Happened to me on a Passat which had its fluid changed at VW. Got in the car and the peddle went down half way. Not normal I said. Took the car home to try it at their suggestion, but I knew it was not right. They picked it up and bleed it properly. Then it was fine.
It had all disks, so I would suggest a new bleed, and if no better, adjust the rear shoes. This should have been done anyway as a matter of course on such a serious brake service.
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Profile ? I wouldnt count on VW doing a careful adjustment to your rear drums. You can be a whole click out on the adjusters and this will account for the excessive pedal travel....
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Click on someone?s name in the message header and it'll give you their profile (if it isn't hidden)
The car hasn't been to a genuine VW garage but a VW specialist. They did say that the handbrake cable needed lubricating as it wasn't releasing the rear drums properly. Could it be that they have over adjusted them, perhaps over compensating for the seizing cable on the rear drums? But then again, it has automatic adjustment on the rear drums. With time, is it likely that the adjuster will do its job and reduce the amount of 'slop' in the pedal?
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Somebody may correct this, but I think that the self adjusters rely on the handbrake coming off freely. ie a a partially seized handbrake cable may prevent the adjusters from working properly.
Different on many cars, I can remember this applied to one of the cars I have owned, it may have been the Polo.
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pmh (was peter)
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I would be surprised if the rears were adjusted at all.they are supposed to be self adjusting-and usualy are treated as if they do work.I rarely have found them to work,usualy what prevents them from working is dust on the adjuster-so a manual adjustment may be needed after whole unit is cleaned up,But they should be checked cleaned and adjusted at main service-though I doubt this happens??
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Steve
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Right then.
We've managed to establish that there is unlikely to be air in the system, so at least it wont need re-bleeding. (Thanks again RF)
Thus, the most likely cause of the extra travel is incorrect adjustment on the rear drums. This isn't an area I've dealt with before, and the Haynes is little use (having no diagrams, photos or explanations on how to adjust the rears) so I?ll try and get my dad to look at them. Any tips in this department would be much appreciated.
This is the last question, I promise, but is it usual for the servo effect to wear off after a day or so? I left the car for a couple of days and (before starting the engine) the pedal was solid. But yesterday, I stopped the engine and about 5 minutes later just before starting the engine again, the pedal still had the servo feel.
Thanks again everyone
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Normal in my experience. The vacuum resevoir fills up with air or the vacuum leaks out. According to taste.
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I wasna fu but just had plenty.
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