As a (sensible?) preparation for several long holiday journeys this car was serviced by a small independent garage in the local village that in the past has provided a competent service. The car was collected one evening after closing hours, and consequently no paper work outlining work completed or bill etc was available.
The following day a 250 mile journey (with 2 children) was commenced. The driver, who does not have any mechanical empathy, but is observant, noticed that the handbrake had apparently been adjusted, but otherwise the car drove normally. After approximately 50 miles of cross country driving and (fortunately) in an urban situation at approx 20mph the brake pedal went to the floor, with absolutely no braking effort. She fortunately avoided all traffic and, using handbrake and gears, brought the car to a halt avoiding all stationary objects.
She sought refuge in a car park and waited for the AA to appear. After a delay the brakes appeared to regain a relatively normal feel, but on AA advice the journey was completed on Relay with the car being left at a Vauxhall franchise garage to be investigated the following day.
The garage reported that the only thing they could find wrong was that the handbrake adjustment was incorrect and that the rear self adjusters had been 'overtightened'. The supposition was that the rear brakes had been binding, overheated,and caused fluid to boil. The brake fluid was changed and the car has been ok since.
The questions that arise are
Has any one experience of brake fluid boiling as the result of binding rear brakes?
Is this considered a viable explanation? ( I would have expected such overheating to result in a typical hot grease and pads smell which I believe would have been noted).
At only 4 years old water contamination may be an issue if the fluid has not been changed but is this likely in this situation?
Any other possible explanations?
I have never seen a warning concerning misadjustment of rear brakes resulting in potential catastrophic failure although I I can understand that a vapour lock would disable both braking circuits.
PS The independent garage so far have been less than cooperative. They initially sought to minimise any responsibility on their part and wanted the disabled vehicle returned to them (in failed state!). Totally impracticable. Whether they will pursue payment or not is awaited. Holiday absences make it difficult to deal with the matter in a straight forward way.
pmh (was peter)
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Peter,
Given that no fault was really found and the brakes seemed to recover themselves is it possible the driver pushed the edge of the clutch pedal by mistake then panic set in, understandable because the feel of no brakes is terrible.
I'm not sure what the investigating garage meant by the self-adjusters being overtightened. Usually it would be impossible to manually adjust them up once the drums are on, I can't see why anyone would try to do so anyway. If you accept that then the position they were found in would be the position *they* auto set to, not where the servicing garage had left them.
The way these adjusters work they can only go the next step when there is a clearence between the brake shoe and drum with the brakes off, once the brakes come to the ideal adjustment they will not go another click until wear takes place.
I'm not sure either about this situation ever getting the rear brakes hot enough to boil the fluid, if they did the most likely way would be to drive with the handbrake on for miles.
It is hard to blame the servicing garage at this point given that no actual fault has been found to challenge them with.
David W
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David, thankyou for your considered reply. In the interests of brevity (all things are relative) I left out of the initial posting the drivers observation that between the incident, and the AA appearing, the brake feel appeared to partially recover, with extended travel and some apparent braking effort available.(difficult to quantify when parked). This substantiates the driver perception of no braking effort, ie not accidental touching the edge of the clutch pedal.
Like you,I cannot understand 'incorrect adjustment of self adjusters'. I have experience of many other makes but none of modern Vxs. I just wondered if there is omething different about them. I will try to get copy of Vx Garage worksheet, but holidays make it difficult.
pmh (was peter)
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Peter,
The boiled fluid is an entirely plausible explanation, and one I have experienced in the past - with cars we had which were laid up. It is somewhat frightening when you come tanking up to a roundabout and discover the pedal hits the floor, shortly followed by your heart hitting your mouth! This was caused on our cars by seized front calipers / rear shoes (yes, it happened more than once over a couple of years!). On one occasion my Dad was suffering lack of performance (this was a 652cc Citroen Visa, but you could notice, honestly!). He pulled over and noticed that the off side front disc was glowing. However, needing to get to work he kept going. After another couple of miles the performance came back, and gentle pressing of the brake pedal revealed no resistance - the conclusion was the fluid had boiled and freed off the caliper, but left a gas pocket in the line which results in the pedal going to the floor. A couple of quick pumps should bring the pressure up and allow braking, but this is beyond the knowledge of most drivers these days. Normal braking performance was restored when he came to drive home. We changed this caliper (and the brake fluid) soon after....
Richard
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The scenario of overheated fluid causing vapour lock and brake failure is possible. Rubbing brakes will generate heat and this will be transmitted to the brake cylinders and fluid, causing boiling and vapour production in the system, so the explanation is theoretically possible. Following such an event, the brakes could feel quite normal once the fluid has cooled and the vapour recondensed. The older the brake fluid, the more likely this is as it will have absorbed more water. Vx recommend a 2 year brake fluid change interval. Has that been carried out?
DW is correct that auto adjusters cannot be overtightened manually. They are not accessible once the brake drum is in place. One possible explanation is the handbrake adjustment. It is possible that the handbrake cable was overtightened, so that the brakes were applied very lightly even when it was 'fully' released, causing a continuous rub on the rear brakes, and eventual overheating. However, that won't overtighten the adjusters themselves, so I'm confused about that part of the diagnosis.
Regards
John S
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Did he mean that they were over-tightened as in taking in too much slack, or did he mean that the mechanism itself was over-tight and therefore that it couldn`t adjust in either direction as it was not able to move freely ?
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Of course one thing that comes to mind....
This car could well have the problem where rainwater is directed into the master cyl' filler by a daft arrangement of underbonnet seals/shields (look at an unmodded one and you'll see the problem clearly). There was a recall for this (up to '99 models I think) but I reckon loads of cars missed it. The last Astra here hadn't been done and I had to sort it.
Also something on the HJ car-by-car guide I wasn't aware of.......
.....Floor around handbrake mounting and driver's seat mounting can crack (symptom: having to pull handbrake right up). This could be the reason why more than a few Telegraph readers complain of being unable to release the handbrake of Astras with drum rear brakes....
Any connection I wonder??
David W
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Think I'm right in saying that the handbrake cable of an Astra can be maladjusted to give the right 'feel' to the brake lever.
The adjustment is usually made on an unloaded vehicle, and when the car is subsequently loaded the cable shortens enough to cause the rear bakes to bind. Unload the vehicle - no apparent problem.
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Thanks for contributions so far. Has anybody got definitive (Vx dealer?) information regarding Steves comment on the problems of setting handbrake feel when unladen giving binding problems when fully laden?
Thanks
pmh (was peter)
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I would have thought that if the rear brake self adjusters had been 'overtightened' which is virtually impossible, enough to bind and boil the fluid, the driver would have noticed the the considerable drag and resistance to movement of the vehicle. Plus if the brakes had been binding there would have been quite a pungent smell from the brake linings themselves.
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dunno re driver noticing
after a service of a car with disks on all 4 wheels pulled into a car park and got out to see the rear disks glowing red hot
the handbrake had indeed been adjusted so that even when fully off in the cab it was in fact slightly on
driving the car there was no noticable difference, it had been stopping pretty ok, which i put down to most of stopping power comming from front wheels anyways, and the dual cicuit system being set up to cope etc
anyway took it straight back (slowly), had cable slackened a bit, and no problems...
obviously generated lots of heat at the wheels, but whether brake fluid boiled and condensed at wheels i have no idea, brake pedal certainly never showed any symptoms
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and there had been no sensation when pulling away, that is it didnt "feel" like you were pulling away with the handbrake on
i guess this was just because it was only on ever so slightly, and powerful engine masked it totally
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pmh,
Back in 1995 the company I worked for as a mechanic added some Vauxhalls to the fleet. Come the first service we had loads of problems with Astra and Cavalier rear brakes. Usually they were burnt out, shoes disintegated and cylinder rubbers cracked and hardened. The local V/hall dealer accused 'us' of overtightening the handbrake cable. We hadn't - they had, during the Pdi. It also came to light that a badly adjusted cable could apply the rear brakes during suspension movement.
None of the drivers had complained of brake problems such as noise or smells, they just didn't know the problem existed.
Steve
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Update. (And thanks for all earlier contributions).
After a sucessful holiday and about 3000 uneventful miles, the owner of the independent garage has now changed his tune.
He was personally responsible for doing the work on the handbrake and has indicated that he will waive the bill for the service and make a contribution to expenses incurred following the brake failure including the investigation etc by a Vauxhall Franchise. Cheque awaited.
Methinks he has done some homework and has probably been setting up all Astra handbrakes incorrectly in the past!
At least he gets 100% marks for doing the morally correct thing, even if falls short of admission of liability. It would have been nice to know if the brake fluid had been contaminated, but the car has now gone to trade in, partly as loss of of trust and we will never know if the water drain mod had been done.
pmh (was peter)
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