Catastrophic Brake Failure
Discussion
freddytin said:
The cost of a replacement flexible hose, if indeed it suffered any damage,is negligible.
Only if the damage is noticed.
freddytin said:
The cost and danger of allowing the caliper piston to extend beyond its intended range IMHO is far greater than any safety issues that might arise from clamping the flexi.
The caliper will be designed to be safe when the pads have worn down to the backplate, which is effectively what you will be running with if the lining has fallen off.
May be relevant or not.
This reminds me of a village garage of my aquaintance.
One spring and summer, two years ago if memory is correct, they had many locals coming in with brake problems.
Those problems turned out to be pad friction material becoming detached from the backing plate.
Now why?
Then they remembered that the previous winter the local river had flooded and the locals had had to drive through deep water to enter the village.
Those at the garage came to the conclusion that the driving through the floodwater had caused this.
This reminds me of a village garage of my aquaintance.
One spring and summer, two years ago if memory is correct, they had many locals coming in with brake problems.
Those problems turned out to be pad friction material becoming detached from the backing plate.
Now why?
Then they remembered that the previous winter the local river had flooded and the locals had had to drive through deep water to enter the village.
Those at the garage came to the conclusion that the driving through the floodwater had caused this.
freddytin said:
The cost and danger of allowing the caliper piston to extend beyond its intended range IMHO is far greater than any safety issues that might arise from clamping the flexi.
The caliper will be designed to be safe when the pads have worn down to the backplate, which is effectively what you will be running with if the lining has fallen off.
[/quote]
By wearing the pad down to its backplate you will run the risk of what remains of the pad being ejected completely, or worse still wedgeing itself against the disk.
For sure extended contamination from water will cause premature corrosion of the backing plate and weaken the bond between itself and the friction material
Don - lucky escape. I admit that when I've been cruising for a while and I'm coming to a braking-to-a-stop point, I have a little "feel" with the left foot to make sure that the brakes still work
Of course, I do have confidence really, but like to know for sure when there's still enough road left to go down through the gears. Of course, wouldn't help much if the pad just exploded! Don said:
I'm in a very windy twisty road - bit of a dangerous spot so instead of call from where I was I limp a mile or so at less than 20mph to a nearby pub and call the RAC to get it recovered.
Well, at least I wasn't to blame this time!
When I was much younger I left the handbrake on overnight on a cold night. When I pulled off in the morning to go to work I noticed that the car was sluggish but put it down to the cold. Pulled onto M3 and the sluggishness soon went. Went onto slip road for M25 South and went to just touch the brakes just to scrub a bit of speed before the right hander and found there were none. Went down through the cars to slow down (saying a quick thank you that the traffic wasn't stopped round the corner as was the case half of the time back then). Stopped an called AA who enlightened me that when the manual says don't leave the handbrake on in cold weather they don't just mean Scandinavia as it can freeze on even after handle released and thus boil the fluid.
I think it was the fact that normally you totally and utterly rely on the brakes being there that makes it quiet so scary when they are not
p.s. there is no need to point out how many mistakes I made - but I think there is a very low awareness of at least the 1st of those mistakes
I think it was the fact that normally you totally and utterly rely on the brakes being there that makes it quiet so scary when they are not
p.s. there is no need to point out how many mistakes I made - but I think there is a very low awareness of at least the 1st of those mistakes
Never had this (or anythig similar) happen in a car - but I did have "catastrophic" failure on a mountain bike once. Very slack rear brake, incredible front brake. Braking to a stop at a busy roundabout, lever went slack - cable had snapped.
Cue me going 30mph (pedalling hard, actually increasing speed to filter onto roundabout), with no brakes. Took a hard left - jumped the kerb and coasted to a stop on a soft grass verge. Was not much fun for the few seconds whilst deciding whether to jump off or pedal like hell!
Can't imagine how scary that must be in a car!
Cue me going 30mph (pedalling hard, actually increasing speed to filter onto roundabout), with no brakes. Took a hard left - jumped the kerb and coasted to a stop on a soft grass verge. Was not much fun for the few seconds whilst deciding whether to jump off or pedal like hell!
Can't imagine how scary that must be in a car!
beyond rational said:
Is there any proper advice on how to deal with this? Never used engine braking to stop a car to this extent, how much can you reasonably expect in a do or die situation? (obviously depending on car/clutch)
Depends on the car/engine, I expect.
I can get a reasonable amount of engine braking going on in the cerb, to the extent that I can slow from ~50 (in 4th) down to walking pace using the gears, without using a massive amount of revs, and keeping it smooth by matching the revs on the down-shifts. That works ok where I can plan my "braking" over a reasonable distance, and isn't really much slower than the approach most people take of just lightly braking to a stop.
Of course, it has the disadvantage of not displaying any brake lights to the vehicles following, so one can't go messing about with that sort of thins when there is a risk a following vehicle might not notice one is slowing down.
A more severe braking effect could (I expect) be brought about by dropping more than one cog at a time, though the revs would have to be matched rather well to prevent a sudden engine braking effect de-stabilising the car.
Take care. beyond rational said:
Is there any proper advice on how to deal with this? Never used engine braking to stop a car to this extent, how much can you reasonably expect in a do or die situation?
It's never happened on public roads, but I've had brake failure on track a couple of times.
It helps to know why it's happening. If you've overheated the brakes (as I had) then stand on the pedal, don't lift off under any circumstances, get what you can from the foot brakes and meanwhile drop down through the gears as fast as you dare, helping with the handbrake. You can change down very aggressively if you use the clutch to avoid over-revving the engine, not particularly nice for the clutch but better than a trip into the scenery. The reason for keeping your foot on the brakes is that if the brakes are close to boiling they are very likely to boil as soon as you take your foot off, so you will immediately lose *all* braking if you try to pump them. I've found that by taking a very deep line through the corner using this technique I've been able to get away with it so far. If you're in serious trouble and really need to scrub off a lot of speed or hit something, a technique that work in karting is to put it sideways. It doesn't matter how cr@p the brakes are, once it is sideways all four wheels will be working hard. In a car you stand a good chance of flat spotting the tyres, and you have lost any chance of steering round the problem, but you will lose speed in a hurry once you have it sideways. In a rwd car, engine braking and/or handbraking it makes it very easy to get it sideways, the challenge in these situations is usually to keep it pointing vaguely the right way. This is the other reason for taking a deep line when the brakes go, because it's usually the fronts that go and the car will try hard to spin.
On the other hand if you know it's not heat related then pump the pedal and see if you can get any resistance.
Edited by GreenV8S on Thursday 8th March 21:02
That all seems pretty sound to me
it was about the worse case scenario - i.e a crash in front blocking road, travelling at 60-70, discover total lack of brakes (we'll assume due to sabotage for this exercise), little/no space for avoidance - so if the car makes it as well, thats just a bonus. I do often wonder if I could react to such a set of circumstances and intentionally damage my own vehicle to avoid or reduce the impact or would I just freeze and slam right in? Hopefully i will never know.
I think I would instinctively go for handbrake as i don't think I would mentally lift off the footbrake (which probably means I would also not downshift in time) and aim towards the path of least resistance.
it was about the worse case scenario - i.e a crash in front blocking road, travelling at 60-70, discover total lack of brakes (we'll assume due to sabotage for this exercise
), little/no space for avoidance - so if the car makes it as well, thats just a bonus. I do often wonder if I could react to such a set of circumstances and intentionally damage my own vehicle to avoid or reduce the impact or would I just freeze and slam right in? Hopefully i will never know. I think I would instinctively go for handbrake as i don't think I would mentally lift off the footbrake (which probably means I would also not downshift in time) and aim towards the path of least resistance.
My wife had this happen on our 307. EMU packed up, brakes went west, she was heading towards a Bentley with a Champions League footballer in between. Standby for insurance meltdown. Luckily she had presence of mind to use the handbrake and drop it into 1st. She point blank refused to drive the 307 after that - we got shot of it the next week.
tgaow said:
My wife had this happen on our 307. EMU packed up, brakes went west, she was heading towards a Bentley with a Champions League footballer in between. Standby for insurance meltdown. Luckily she had presence of mind to use the handbrake and drop it into 1st. She point blank refused to drive the 307 after that - we got shot of it the next week.
Thats bloody terrifying that is. What on earth had caused it?Dunno - it’s the second time the EMU had failed (1st time about a week after we had got it) but in that case it didn't take the brakes with it - the engine just died. Interestingly when we called the dealer the response was "oh another one" - can you wait for the lorry to come back from another pickup? My wife wasn't far from the dealer so picked a courtesy car up from them. Driving back she saw a third 307 on the back of the recovery lorry! I did some asking around about the 307 amongst owners and friends and found some great stories. The best one -a drivers side electric door mirror that moved about on its own and the worst, 70 mph on the motorway, EMU packs up, engine shuts down, rear ended by the car behind.
"Top Gear Top Tip" - don't buy a 307!
"Top Gear Top Tip" - don't buy a 307!
Ho hum, way back when, my Mother paid for her driving instructor, ex Police Class One, to take me out in my first car.
"Slow down without the brakes", he said.
Lots of DDC.
"Really give it revs", he said, "To get those lower gears".
Back to basics, split circuits notwithstanding.
"Slow down without the brakes", he said.
Lots of DDC.
"Really give it revs", he said, "To get those lower gears".
Back to basics, split circuits notwithstanding.
Edited by WhoseGeneration on Monday 26th March 19:07
I've had brake failure on two occasions in the past. One was where one of the front calipers was sticking on just enough to cause the fluid to boil, which resulted in the pedal going straight to the floor. This was on the approach to a roundabout after a long flowing section of A road. Fortunately I was able to stop in time by changing down a gear, switching off the ignition (no power steering etc fitted) and pulling the hand brake on. Luckily there was hardly any traffic around.
The second time was only a partial failure - the master cylinder gave up on one circuit, but that was not approaching any major hazard, so it was easy to stop with gentle braking on the remaing circuit.
Not a nice feeling at the best of times.
The second time was only a partial failure - the master cylinder gave up on one circuit, but that was not approaching any major hazard, so it was easy to stop with gentle braking on the remaing circuit.
Not a nice feeling at the best of times.
I had a Clio Cup total brake fail at Palmer Sport event at Bedford Autodrome.
Was unfortnately at the end fo the straight on the North Circuit doing 95 mph just going past 2 cars and probabaly on the fastest lapo I had done there in 4 visits.
No brakes at all and off in a straight line. Both instructor and I were trying our brake pedala nd looking for obstructions under foot although the pedal was actually going down to the floor.
Kept the car striaght and just tried to steer until we hit the perimeter fence 45m later. Actually couldnt steer at all due to soft ground, didnt try the handbrake and later chief instructor said good job as we could have flipped.
So eventually had a front end impact into concrete perimete fence post (couldnt even miss that)at about 30mph and car was a mess.
JP wrote to me explaining it was a mechanical fault that would not reoccur but did not give full fault reason.
Instructor and medical teams were A1 and whole course shut for about 15 mins (4 circuits). Luckily both of us were unharmed.
Was unfortnately at the end fo the straight on the North Circuit doing 95 mph just going past 2 cars and probabaly on the fastest lapo I had done there in 4 visits.
No brakes at all and off in a straight line. Both instructor and I were trying our brake pedala nd looking for obstructions under foot although the pedal was actually going down to the floor.
Kept the car striaght and just tried to steer until we hit the perimeter fence 45m later. Actually couldnt steer at all due to soft ground, didnt try the handbrake and later chief instructor said good job as we could have flipped.
So eventually had a front end impact into concrete perimete fence post (couldnt even miss that)at about 30mph and car was a mess.
JP wrote to me explaining it was a mechanical fault that would not reoccur but did not give full fault reason.
Instructor and medical teams were A1 and whole course shut for about 15 mins (4 circuits). Luckily both of us were unharmed.
Strangely enough, I've just replaced a rear pipe pipe on my Cit ZX. Unknown to me it was badly fitted and had been worn through on the bottom of the car. First I noticed was the brakes felt a bit low when pressed, I thought it was time to adjust the rear drums, the self adjusters being a bit dodgy (French, you see). Next thing the brake light lit up, so I pulled over to check things. The puddle of brake fluid in front of the rear wheel alerted me to a "problem". Filled up the brake fluid reservoir and made for home, about 5 miles away, keeping an eye on the level. Took off the brake pipe to take to up to the local car part place to get a copy made. That was when I noticed a large hole in the pipe, in the middle of the shiny bit that had been rubbing. When I refitted the new pipe, I had to move the mounting bracket a considerable way to make it the same angle as the other side.
Sounds like a horrible situation! Good job it didnt happen at a worse place.
A while ago i started to get a scraping sound from my front offside wheel- sounded just like the pads hitting the wear limit marker. Fine i thought, time to change pads. Bought some pads, went to change them, and found the brake caliper leaning forwards, touching the inside of the wheel!
One of the bolts that held the claiper in place had fallen out, and the caliper had then leaned forward! Luckily, minial damage done to the alloy and caliper, but could have been a lot worse. Imagine if the other bolt had failed? No matter how well you take care of a car, sometimes shit really does happen
A while ago i started to get a scraping sound from my front offside wheel- sounded just like the pads hitting the wear limit marker. Fine i thought, time to change pads. Bought some pads, went to change them, and found the brake caliper leaning forwards, touching the inside of the wheel!
One of the bolts that held the claiper in place had fallen out, and the caliper had then leaned forward! Luckily, minial damage done to the alloy and caliper, but could have been a lot worse. Imagine if the other bolt had failed? No matter how well you take care of a car, sometimes shit really does happen
Gassing Station | Advanced Driving | Top of Page | What's New | My Stuff