Long Brake Pedal

You're right, the fact that I've not seen it happen doesn't mean it's not happening, the fact it's not happening means I haven't seen it. It comes up time and time again in this ng to attempt to explain long pedal or various bleeding problems and it's bollocks. If it was happening at all, the pedal, having been pressed once and put fluid between the walls, would be pressed again, which puts more between the walls. Don't forget that it won't be able to leak back at the rate it can be pumped in by someone trying to bleed the brakes. There is no way it could balloon as you seem to believe without leading to total failure of the hose.

But if I'm wrong and it is happening, there will be plenty of evidence, and pictures on the web. Feel free to post a link at your convenience.

Steve

I don't beleive it, I'm reporting it. Why do you think bulging hose has it's own fail code on the MOT?

I've seen it on a mates old Seat. He'd been ages trying to fix long pedal travel and I went along to help him bleed the brakes. He didn't trust me to pump the pedal correctly so gave me the job of loosening and tightening the bleed nipple. The flexible hose expanded to a 3inch balloon when he pressed the pedal and dropped back to normal size a few seconds after he released it. He didn't believe it either and only swapped places to have a look when he had made it very clear that he knew it was a wind up :-)

This was done without the engine running so it didn't need the servo pressure to balloon the rubber hose.

You mean like my clutch hose that ballooned under pressure before it eventually burst. The engineer that replaced it said it looked like it had been ballooning for some time before it eventually went.

gospvg was thinking very hard :

He has checked without the engine (servo) running, hand brake on and found the pedal hard, with little travel and if kept pressed, it doesn't go down further. All seems normal there. With the handbrake off, I would expect a little more movement in the pedal, but assuming it is not a lot - again I would say that is normal.

He has confirmed it does become softer and travels much further when the engine is run - again absolutely normal.

My final on this is -

I think the OP is understandably a little confused. I once remember when much younger, spending days trying to bleed my car after fitting new pads and shoes, because the travel seemed excessive and spongy. I was checking it each time with the engine running, which always does produce more travel and a feeling of sponginess, especially with new pads and/or shoes. The extra travel is due to the massive extra pressure put on components by the servo - pipes expand a little and components spring a little due to sheer pressure. You do not normally apply that sort of pressure on the pedal whilst driving. In addition, until the braking surfaces bed in, the brakes will be poorer than you are used to. Give them a hundred or so miles and they will be fully bedded in.

I'll say again the most likely cause. There is run out (wobble) on one or more discs which is pushing the pads back in when the car is moving. When you apply the brakes you have to take up this clearance before they bite. Could be warped discs or wheel bearing play.

in which case it would not appear to happen if the vehicle is stationary, it would also have shown up at MoT

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "shazzbat" saying something like:

They do.

They check for warped discs?

The only problem I see with that theory is the OP's assertion that after fitting new pads, all seemed well for two weeks.

Chris

oh yes, warped disk give braking variations, the max allowed (on ecah brake)is 20 per cent IIRC which is pretty horrendous shuddering, and even that much makes no noticeable increase in pedal travel

I had a space cruiser in once with an mot falure of excessive pedal travel, but that was caused by pads seized in the caliper holder/seized sliders. I thought at first it needed a master cylinder, but clamping the hoses showed it just needed a strip and clean of both front brakes. Surprisingly the brake performance was good and equal !! But I can't see that in this case, unless the OP changed the pads and has left seized caliper slides?

Years ago there was a proposal that only qualified mechanics could do repairs, but there was uproar at the time and it was dropped. I wonder whether there would actually be any improvement in road vehicle condition if it were implemented. It would obviously take a few years to show up.

That would stop most of the trade doing them then ;-)

but there was uproar at the time and it was dropped. I wonder

As a DIYer, I would resist this very strongly. I believe such a scheme is in use in Italy?

I don't honestly think bad vehicles are a major factor in accident. I would however support an increase in the number of roadside checks carried out.

Chris

Well when the decrease in electrical accidents due to PART P occurs then it might be worth considering.

Yep, it was less than one a year before the regulations...

Chris

That's a somewhat odd definition of an accident you're using there.

Yes, I suppose so. I'll try again.

Statistics show that the number of people killed in accidents attributable to a faulty electrical installation in a domestic situation is less than one a year.

Better?

:-)

Chris

Yes, I suppose so. I'll try again.

Statistics show that the number of people killed in accidents attributable to a faulty electrical installation in a domestic situation is less than one a year.

Better?

:-)

Chris

Since you mentioned MOTs, I waited till today because I had a car in for test this morning, so I could ask my friendly local tester. He tells me he saw one in a blue moon, in the days when he was testing loads of anglias and avengers etc. But hasn't seen one in over 10 years.

So of course one should never say never, but I'm still not accepting it as a viable suggestion as a cause of the OPs problem.

And the below still applies.

Steve