Pulsing brake pedal

Post by **tobzman** » 12 Apr 2006, 19:00

Right I know this one has been asked before, read the thread but still looking for more possible solutions.

My van was in the garage today to have my longer rear studs fitted. Now when I'm braking the pedal pulses up & down like it would with a warped drum or disc. However it was fine before the drums were removed so I find it hard to believe this is the cause.

Are there other likely causes that could occur when just removing and refitting the drums???

Cheers

Toby

Post by **TechtroT25** » 12 Apr 2006, 19:07

Have the studs been driven home fully into the hub they could be rubbing on something

Post by **philippacman** » 12 Apr 2006, 19:11

have the drums been refitted properly,dont take any chances with brakes take it straight back to the garage and tell them the same as here,if it was right befor it should be right after , simple as

Post by **Diamond Hell** » 12 Apr 2006, 23:02

If you've fitted alloy wheels and the drums were fitted back on with the securing 11mm headed bolts then the wheels might not be sitting square on the drums - lose the bolts.

From what you've said it does sound like the studs haven't been pulled through square.

Post by **tobzman** » 13 Apr 2006, 08:21

Right, after looking at the exploded diagram of the rear brakes in my haynes last night I think I might understand what is going on.
At the moment my steels are back on but with the spacers to clear the unthreaded section of the longer studs. The two 11mm bolts have therefore been left out. This means the drum is relying on the wheel studs entirely to ensure it is perfectly centred on the hub. I think it's possible that it could shift about a bit as the wheel is tightened up.

My plan is to drill some extra holes in my spacers to enable me to refit the two locating bolts. Does this sound like a valid theory???

Cheers for the replies.

Toby

Post by **Horza** » 13 Apr 2006, 08:33

Not really. My wheels are on without the bolts and despite having other reasons to wobble there is no pulse!! Loads of other folk on here have no bolts because of wheel choice, I bet most of theirs don't pulse. If the studs are fitted right and all the nuts are done up right then the whole shebang should be true.

Do like they said, the garage broke it, the garage fixes it.

Post by **tobzman** » 13 Apr 2006, 08:58

Gonna have a look at it over the weekend Euan and see if I can work out what's going on, if not it will be going straight back to the garage.

Stef I notice it was you that posted exactly the same problem a while back, what was the solution for yours in the end???

Post by **HarryMann** » 13 Apr 2006, 09:56

Possible scenarios to look for...

1) The drums are usually hard to get off, sometimes very difficult, particularly if the drums are well worn (stepped) and the self adjusting rod has seized as well, and can't be adjusted back from the access hole in the backplate (never easy anyway, due ratchet pawl)... This means various persuasion methods must be used, but with care, skill and experience if the drums and shoes are not being replaced.

It's possible a drum(s) has been distorted or dented where it matters by such actions.

2) The small retaining screw holes are sometimes used for levering the drum off, bit by bit, using a long thin screwdriver or similar. Both the hub and the inside of the drum can be burred by this action, and if they aren't de-burred before replacement can slightly offset the drum..

3) Similar to 2), a foreign body might get trapped between the hub face and drum face during replacement, particularly as when removing drums, there's usually a lot of dust and rust flakes around, requiring a good old cleanout... sometimes requiring shoe removal to clean up backplates as well.

4) Less likely - One or more brake shoes are not located properly; not sitting nice and flat against the back-plate's pressed out supports or the shoe retaining springs and cupwashers are screwed up somehow.

You might check the brakes after a decent run for overheating, if you haven't used them in earnest, spit on the drums should not sizzle, though if they're modulating the brake pedal, this is unlikely.

Unfortunate fact is... unless they're known to have been serviced in your records, they could need a better look at. Certainly a good de-dust and make sure that self-adjuster-rod is working freely and adjust up..

Post by **Diamond Hell** » 13 Apr 2006, 10:06

LIke Euan said - it were OK when it went in, it ain't OK now.

Don't dick about with it, or when you take it back you'll get 'it was fine when it left here' and they'll accuse you of doing something since - get it back there NOW.

dick - heheh I wrote d i c k - surely that's not rude enough to warrant a swear filter?

Post by **tobzman** » 13 Apr 2006, 14:04

Well, after getting the general jist both on here and from the guys at work I took the van back to the garage this morning.
They called at lunch to say Im had a possibly warped drum so I popped in for a look. They had put the drum on the wheel balancer and said the inner edge wasn't running true.
HOWEVER they also fired it up in gear on the ramp with the drums removed and one of the hubs is running VERY slightly out of true.
The drums slid off real easy, both those and the shoes don't look like they've been on there any time at all so I don't think there was much leverage used initially to remove the drums.
The guy has ordered two new drums which will be fitted on tuesday, he says if it doesn't cure it he'll simply take them off and return them.

Is it normal for a hub to run very slightly out of true??? I'm still suspecting the hub as it's been off and under a press etc etc
Does anybody know how much a new hub is? Got the VW part number as it's not listed on JK, GSF, ECP etc

Grrr simply fitting some alloys is turning out to be very costly!!!

Post by **HarryMann** » 13 Apr 2006, 14:19

A new hub is over £100

A 2nd hand one could be whatever you can negotiate?

Hubs don't run out of true unless they been bent!

Draw your own conclusions

Oh, good luck, call one of the spares dealers on here asap and get that hub in the post!
They should at least apologise and reftit the studs to new (straight) one for you.

Post by **Horza** » 13 Apr 2006, 14:20

You're going to pay them to remediate the things they caused not to work? You were the one that said your brakes were fine before you took it in and are not fine now!!!

It was stories like this that stopped me using mechanics in the first place.

Post by **tobzman** » 13 Apr 2006, 14:40

I certainly wont be paying for any of the labour for the remedial work. As far as the drums go if they solve the problem I will be expecting a massive discount. If it turns out it's the hub then there's only one way that got bent.......under their press, it will be a case of entering negotiations at that point.
Believe me I don't usually use mechanics these days, I'm happy to spanner away myself. However on this one I didn't have the breakerbar/socket for the hub nut and had heard the studs could be very stubborn without a press.

Post by **HarryMann** » 13 Apr 2006, 14:43

This solves problem No. 1 (works for me, anyway)...

Details:-
http://www.club80-90.co.uk/wiki/index.p ... ut_spanner

Post by **tobzman** » 13 Apr 2006, 14:57

Cheers Harry think I'll have to invest in one of those for any future hub work.
Just spoke to my local VAG dealer and that hub is indeed a whopping £110!!!
I still have a feeling this story will be ending in a replacement hub

One other thing is there a list of traders who use this site??? I've checked on the wiki but there's no entries on that page.