52 replies to this topic

[bunsenburner]

Mallory Park was bathed in sunshine for almost the whole Saturday. Weather wise I couldn't have been any luckier. Just before the break for lunch I went out for one quick session. 5 laps in the tyres were on and everything was looking good. I got a great line out of Shaw's hairpin and hammered it round Devils elbow onto the start/finish straight .

I was over 120mph when I saw my braking point and stepped on the brakes. There was nothing, absolutely nothing!

The pedal went straight to the floor. I tried to take the corner as wide as possible, but the 888s on the rear were the first to give up. I quickly went to opposite lock which prolonged the time on the tarmac and drooped more speed, but then the grass heralded the end. I just held onto the steering wheel and hoped for the best.

A mouthful of sand and dust later and it all went quiet. Funny how it seems such a long time sat there waiting for the marshals.



Initially I thought it must have been boiling fluid, but even after cooling the brakes were still extremely soft. I gingerly limped home and bled the fluid the next day but I still have the same problem.

The first pedal press is extremely soft with loads of travel and very limited stopping power. If I lift off and then try again straight away the pedal is much firmer and the car brakes better but still not what you'd expect. This pattern repeats itself whether stationary or on the move. I am wondering whether there is a more serious problem with the brake system.

Does anyone know if the pattern of very soft with loads of travel followed by firmer and much less travel when pumping the brakes is a symptom of something in particular?



Now I love a thread with pics, so here are a few, courtesy of my "lucky" passenger.

YOU CAN SEE THE ROUTE IN.....EVEN SOME OPPOSITE LOCK COULDN'T SAVE THIS ONE.




PRETTY DEEP, RESTING ON HER UNDERTRAY.



HEY, LOOK AT THAT FUNNY LITTLE PLASTIC CAR STUCK IN THE KITTY LITTER.



VIDEO OF THE "TOW OF SHAME" .
http://s1237.photobucket.com/albums/ff478/bunsenburner101/?action=view&current=IMG_0138.mp4
EDIT: how do you post a video directly on the post?


BACK IN THE PADDOCK LOOKING A BIT DUSTY.




AND YOU THOUGHT YOU HAD A DUSTY DASH!

Edited by bunsenburner, 12 June 2011 - 08:37 PM.

[Boombang]

Sounds like seals in master cylinder is knackered.

[simsy]

One general thought about some of these reported brake issues; 1\ After stripping part of the braking system we re-fit the braking system and bleed to our satisfaction. All seems well. 2\ At some stage later the brakes FAIL....!!!! One comment I have heard many times on here and talking to normal people about cars is that they never activate their ABS in normal driving, they drive well within their limits and do not push the peddle hard..... I find that the abs in my vx is activated every few minutes in normal driving, because I push the peddle until is stops to 100% of the cars ability. (read heavy handed/footed)... But I know my abs is working well (ish) and I have no hidden air in the system... After owning an elise the brakes in the vx are very servo assisted. I think that trapped air, due to pussy footed driving not activating the asb, may be leading to some of these failures.

[bunsenburner]

One general thought about some of these reported brake issues;

1\ After stripping part of the braking system we re-fit the braking system and bleed to our satisfaction. All seems well.

2\ At some stage later the brakes FAIL....!!!!

One comment I have heard many times on here and talking to normal people about cars is that they never activate their ABS in normal driving, they drive well within their limits and do not push the peddle hard.....

I find that the abs in my vx is activated every few minutes in normal driving, because I push the peddle until is stops to 100% of the cars ability. (read heavy handed/footed)... But I know my abs is working well (ish) and I have no hidden air in the system... After owning an elise the brakes in the vx are very servo assisted.

I think that trapped air, due to pussy footed driving not activating the asb, may be leading to some of these failures.

I hate to be a passenger in your car being thrown about as you actvate your ABS

My VX ABS is never activated either, but thats because it's permanently disconnected.

I expect the failures are purely down to tracking a road car. The modifications made are done because we all know standard parts just won't last the distance.

[NA Jimbo]

Sounds very much to me like another master cylinder on the way out.

[simsy]

Having no brakes at 120mph will not make your passengers happy either..... I find the abs on the vx comes in so easy in the wet on road that its not braking that hard at all.... until its got hot tyres and brakes then it improves. Granted, normal passengers will not be happy in my vx, unless they are so inclinded and know me.... Still think activating abs by driving or electronically to move air about is worth doing for safety. Nice day at the beach, I bet the car was not too pleased...

Edited by simsy, 13 June 2011 - 11:42 AM.

[slindborg]

An Mc test Engine off. pump the brake a few times to bleed down the servo. Then press the pedal gently, if you get some resistance keep pressing and if the pedal drops its the MC seals dead.

[MellowYellow]

Almost every time I drive my car the ABS cuts in, I think it's because I use (and always have) engine braking as well as the brakes, it only takes the slightest bit of gravel, diesel etc on the road to get a little moment of ABS. On the track it was a nightmare first time out especially as it was damp, after taking a lot of rumble strip on the chicanes I had the ABS light come on, once this had happened the brakes were transformed, allowing me to brake deeper into corners and gave a better pedal feel altogether, I'm definitely putting a switch on now. I have suffered complete brake failure once on the track as well, my own fault, old fluid, no cooling down lap and only five minutes before going back on, made the first corner interesting luckily half a (slow) lap later the pedal had come back and everything was fine for the rest of the session. To pin your problem down, it could be fluid/air related, which if it is can be remedied pretty easily with a fluid change and a bleed, if this isn't the case, it will be apparent straight away as the symptoms you have mentioned will still be there. A possible check would be as follows, without starting the engine pump the pedal hard five or six times (this will get rid of any servo pressure that remains in the system), then keep it pressed (hard) and if it starts to go down then it's symptomatic of a leak somewhere in the system, be that a piston seal (will be visible on the caliper), a joint (into the abs module??), a pipe damaged or the fluid leaking past the seals in the mater cylinder, if there are no visible leaks anywhere then a master cylinder would be No1 suspect. Dooh, too late Slindborg beat me to it!!!

[bunsenburner]

An Mc test


Engine off.
pump the brake a few times to bleed down the servo.
Then press the pedal gently, if you get some resistance keep pressing and if the pedal drops its the MC seals dead.

That pretty much describes exactly as it is both before and after the fluid change. There are no visible leaks either.

[slindborg]

An Mc test


Engine off.
pump the brake a few times to bleed down the servo.
Then press the pedal gently, if you get some resistance keep pressing and if the pedal drops its the MC seals dead.

That pretty much describes exactly as it is both before and after the fluid change. There are no visible leaks either.

99% likely to be a fcuked MC then.... Doh but atleast you know now

[chrisgold]

An Mc test


Engine off.
pump the brake a few times to bleed down the servo.
Then press the pedal gently, if you get some resistance keep pressing and if the pedal drops its the MC seals dead.

That pretty much describes exactly as it is both before and after the fluid change. There are no visible leaks either.

99% likely to be a fcuked MC then.... Doh but atleast you know now

sh**, no brakes at 120mph, that could quite easily be the death of the car and the driver, lucky there was a big gravel pit....

[bunsenburner]

An Mc test


Engine off.
pump the brake a few times to bleed down the servo.
Then press the pedal gently, if you get some resistance keep pressing and if the pedal drops its the MC seals dead.

That pretty much describes exactly as it is both before and after the fluid change. There are no visible leaks either.

99% likely to be a fcuked MC then.... Doh but atleast you know now

sh**, no brakes at 120mph, that could quite easily be the death of the car and the driver, lucky there was a big gravel pit....

I guess that's why they put one at the end of the straight!

Admittedly it was lucky that I didn't hit anything. Even a low speed collision would cause a lot more damage than a higher speed gravel trap entry.

There was some damage though, but thankfully minor.

1. The rear drivers wheel has quite a few stones embedded between the tyre and the wheel rim (This was brand new only 2 months ago!)
2. The middle under tray has been pulled from the retaining bracket with damage to the 3 fastenings
3. A dusty more dusty dash

Plus the suspect brake master cylinder which caused the failure.

[slindborg]

tyre remount and you will be sorted.

[System-G]

Have you had any work done to your brakes recently (before the trackday)? If so, exactly what was done?

[bunsenburner]

Have you had any work done to your brakes recently (before the trackday)? If so, exactly what was done?

No work has been done on the brakes recently.

If it is the master cylinder then perhaps it just wore out - it's demise quickened by lots of firm braking on track (SC with 888s).

[TheRealVXed]

Ditto to this issues at Bedford Autodrome last week. Boiling fliud = no braking. Think it's put a bunch of air in the system now too. Dot 5.1 and new pads on the way before Anglesey should hopefully cure it. Although not had any issues since so this mine was solely fluid related.

[SteveA]

Gerrards is probably the only place with decent run off at Mallory, someone is looking after you Did you have the ABS turned off?

Edited by SteveA, 14 June 2011 - 11:44 AM.

[System-G]

No work has been done on the brakes recently.

If it is the master cylinder then perhaps it just wore out - it's demise quickened by lots of firm braking on track (SC with 888s).

OK cool. When was the last time you had a fluid change?
What fluid are you using?

It is sounding likely that the MC seals could be knackered, but not ruling out boiled fluid.

[bunsenburner]

No work has been done on the brakes recently.

If it is the master cylinder then perhaps it just wore out - it's demise quickened by lots of firm braking on track (SC with 888s).

OK cool. When was the last time you had a fluid change?
What fluid are you using?

It is sounding likely that the MC seals could be knackered, but not ruling out boiled fluid.

I have only had the car for a couple of months so I'm not sure what fluid is in it or when it was last changed. I changed the fluid on Sunday and I still have the same pedal characteristics.

My first thought was overheating, but when the braking issue didn't go away I figured it must be something else. I thought it could have been air or moisture in the system so decided to bleed the system and replace with some decent fluid, but that didn't cure it.

I've now got a racing DOT4 in it http://www.elise-sho...l-p-502049.html)

The car is off for it's MOT today anyway, so I will leave it to the experts to get to the bottom of the issue.

Interestingly I did overheat the brakes at Donington a couple of weeks ago and so I had ordered the new fluid, RC5+ pads and braided hoses, to minimise the chances of it happening again. Unfortunately I didn't get a chance to fit them so the Mintex 1144s and the old fluid went to the track.

[System-G]

OK - the previous overheating certainly hasn't helped. When you replaced the fluid did you bleed from both the nipple and the hose? as there is a piston each side of the caliper, but only one bleed nipple, I find it helps to bleed from the hose too. Some people remove the caliper and bleed it upside down, but this is a faff. Once you're sure you have all the air out and can get the pedal firm - take the car out and make sure you can stop. Take it for a bit more of a drive andmaking sure no one is behind you, get the ABS to activate (damp road helps). Get the ABS pump going a couple of times. Re-bleed the brakes at both the nipple and the hose. Should be sorted If not, then look at the MC. Once fluid has boiled, it's pretty much useless. Fresh fluid every 3 to 4 trackdays too. Dot5.1 has a tendancy of retaining any moisture in the air so requires more frequent changes. Best to keep with a high boiling point Dot4 (Like RBF600 or similar).