Sudden brake failure in mk3 VW Golf

Adrian wrote in news:Xns98D1D502A443Fadrianachapmanfreeis@204.153.244.170:

AFAICS, either brakes - front or rear, will increase the likelihood of a spin, assuming that the vehicle isn't travelling in a perfectly straight line. I'm quite happy to be corrected on this, 'cos I ain't no professor of physics :-)

This, of course, does not apply to modern vehicles with ESP fitted, where the individual wheel brakes are utilised in order to neutralize some of the lateral force and maintain forward motion. I've attended I demonstration of this and I have to say it's bloody good. I fully agree with Thatcham's stance that all mass producing manufacturers should fit it as standard to all models produced. The downside is that less talented drivers may become dependent upon it, and this is when dangers could arise in the event of a system failure.

Absolutely. Anyone who's had occasion to practice handbrake turns

*cough* will understand that the main objective is to get enough force on the brakes to lock them. Once this is achieved, surprisingly little steering lock is required to initiate the swapping of ends ;-)

Stu

No, because all the brakes are working.

Which is what we're talking about there.

At high speed, with any significant

Yes, it's irrelevant to this case. Did the OP mention high speed or significant amount of steering? I don't think so. We're talking about a golf trying to stop at the lights.

But not in this case. We're talking about a car rolling forwards, gently decelerating, and applying the handbrake. That is not going to cause a spin.

I would argue that it is your appreciation of the OP's situation that is lacking.

Steve

So if the car is travelling backwards and the front end is stopping and the rear not, how does that make it spin, where does the turning force come from?

It is indeed a shame, but that doesn't alter the fact it was the right thing to do. I suspect she was simply unable to apply a sufficient amount of force.

Steve

Perhaps you can clarify something for me. How much engine braking do you get on an automatic? Are there any Mk3 Golf autos about?

Not yet. And I didn't say "Only on a DS...". Mind you, real powerd braking systems have mushrooms. Pedals are for wimps.

Ian

You are right. I was thinking of truck test, I know when I used to go in with my cargo, the rear service brake was tested first, then the parking brake applied, and he tried to turn the rollers. It twisted the chassis and the whole truck rocked violently.

It doesn't alter my point though,the handbrake is designed for parking.

Steve

On some cars, yes. On a DS it's the emergency brake as well, and it is designed to slow the car if the powered system fails.

Not quite. If you lose the assist on almost all cars - if the engine conks out, say - then the foot brake will still work. It will take more effort with the feet, but it will still stop the car.

On the DS the foot control is simply a hydraulic valve (actually it's a bloody complicated hydraulic valve which also distributes front/read braking according to loading) so if the engine goes then after about five full applications the accumulators is flat and you need the emergencybrake. Which is a handbrake on manual DS's and ID's and a footbrake on semi-automatics, by the way.

Then you should have written "The handbrake isn't meant to provide braking ability for a moving golf..." and not "The handbrake isn't meant to provide braking ability for a moving vehicle..."

Ian

Then every MOT station I have used for as long as I can remember has been doing it wrong. Turning wheels, every one of them.

Ian

The Bugatti Veyron handbrake has a completely seperate ABS system, to safely bring the car to a hault. I suspect nobody here has one though.

The brakes and handbrakes are almost completely seperate systems, only having common points at the brake shoes/drums that the handbrake actuaytes.

If you had caused the rear brakes to fade, due to overheating, due to the handbrake being partially on, you would still have had some braking or even most from the pedal. The handbrake may however not have been as effective as it might otherwise have been.

You're the second one to say that. I didn't say lose the assist, I said lose the service brake, like the OP stated.

Why? The handbrake isn't meant to provide braking ability for a moving vehicle, whether it's a golf or not. It's a parking brake. It can be used in an emergency for an attempt at retardation, hopefully more succesful than the OP, but it's still a parking brake. I mentioned " it's a golf" in an attempt to get back to the real world as in the OPs problem, but it applies generally.

Citroen will have put a "bloody powerful" handbrake on the DS because they know they're indeep shit if/when the hydraulics fail, and they're covering their backs.

Steve

Hi,

You hinted at the problem in one of your messages.

If the fluid has not been changed regularly it will collect water. If for any reason your brakes become warm/hot (as by having the handbrake on) the water will evaporate and become steam. At that moment your brakes have air in them and they will not work. Period. Within 20-30 minutes they can cool down enough to feel normal again.

Regards Charles

PS. It happened to me because of a seized brake and this is how I grasped the importance of fluid changes.

.

TBH I notice little difference in normal driving between a manual in top gear, and an auto. Of course you'll get more engine braking in a manual if you change down, but then you can do the same in an auto to get a similar effect if you wish. Personally I don't think engine braking is an issue worth considering. The only disadvantage of an auto IMO, is that overall they can use 5-10% more fuel. The advantages, especially in the sort of stop-start motoring that is common in cities these days, more than makes up for the slight increase in fuel consumption, but having said that, the urban fuel figures for an auto, can be better than those of the similar engined manual version.

I've seen a Mk3 1.8GLX auto advertised, so unless it's a mistake it would appear they are available. Mike.

So, let me get this right. You reckon that ...

1) Using the footbrake, which does almost all of the braking at the front, is fine but that

2) Using a front emergency brake will instantly cause disaster, especially

3) In a Citroen, despite the evidence of those of us who own Citroens?

As a matter of interest, have you done many handbrake turns?

Ian

You have some rather odd ideas about the effect of accelerating and decelerating forces on cars. Which end on high performance cars is driven? Which end does the braking?

Ian

A friend of mine has an Alfa Spider 2000. A couple of years back, the MOT tester discovered that the rear brakes weren't working. Not just "jammed" not working but "disconnected" not working. There was no hydraulic pipe to the rear brake system.

He had been driving it like that for ten years and never encountered the uncontrolled spinning which Mr Shazzbat is so sure must happen with front only braking.

Ian

PS It had also passed ten MOT's in that time, of course, in various places, which shows how assiduous MOT testers are about the special procedures for cars with limited slip differentials ...

However, you also said that the handbrake isn't designed to slow awn from speed. Which is wrong, because on some cars it is.

How many times do how many people have to tell you? On hydraulic Citroens the emergency brake /IS/ meant to provide braking ability for a moving vehicle.

Precisely. On the DS the handbrakes are a pair of massive cable-operated calipers working on the front disks. They are far, far bigger than a mere parking brake.

Ian

Bing!

Ian

shazzbat ( snipped-for-privacy@spamlessness.fsnet.co.uk) gurgled happily, sounding much like they were saying :