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Brakes of death!

A

AngelGrinder

Joined Nov 2010
40 Posts | 0+
Hey all, last month I was doing a trackday at Snetterton, I'd done 2 x 20min sessions then had an hour and a half lunch break then went out again, towards the end of the session, after hard braking into a slower corner, the next corner the level came aloong way back, as the bike had never done this, and the brakes had never faded before I decided to pull off the track, so coasted around the next corner about 50mph and saw an exit lane. I pulled off the track and the lever came all the way back the handle bar and did NOTHING. My rear brake is also useless and I never use it, so this also did nothing. I tried pumping the lever but no help, used my feet and grass to slow down as much as possible, but ended up hitting the barrier head on about 15/10mph, luckily managed to stay upright... although my groin area didn't particularly enjoy it.

After being picked up and taken back to the garage (about 5mins) the brakes seemingly worked fine. I've not ridden it since... as I'm not wishing to die!

I've heard of brake fade, but never experienced it, and wasn't aware it could happen this quickly. The resovoir is still full, and there doesn't appear to be any leakage, pads all have plenty of life left....

So, what could the problem be? I need to thoroughly check everywhere, don't really have the cash to swap everything, so if anyone could narrow down the problem that would be great.

Thanks in advance!
 
Check your discs for warping fella. If one is out it'll push the pads/pistons back & you'll lose the brakes.

HTH
 
Ya bugger! did ya ***** ya pants??? once had brake faliure in a 44t low loader, a pin broke and i ***** everywhere LOL
 
i would sugest you replace the brake fluid, pumping at least 2 reservoirs through each caliper with good quality fluid.
brake fluid is hydroscopic so over time collects moisture, under normal light road use this is not a major problem however under heavy track use the heat created is enough to boil the water and make steam in the brake caliper and lines hence the lever comes back to the bars as the steam is easily compressed.
when everything cools down you have a brake lever that feel relatively normal again.
kev
 
I used 5.1 once, never again, the stuff is ****! it destroys seals that are not designed for it plus I found it "sweats" through the rubber reservoir hoses. System is designed for dot 4 I would use that
 
Scary stuff but agree with the guys on moisture/air in the fluid.
I use Brembo Gold racing fluid but you have to change it at least once a year as it's very hydroscopic.

Bet the soles on your boots took some wear :eek:
 
you're confusing 5.1 with 5. 5.1 is not only compatible with 4 but it is also better, having a higher boil point. 5.0 is siliconic and yes, it is not compatible with any other dot (3, 4, 5.1)
 
Hi angle grinder was that you at the bennets track day ?? , I was next to you in the paddock with carbon fibred Rsv mille

Eddie
 
stress said:
you're confusing 5.1 with 5. 5.1 is not only compatible with 4 but it is also better, having a higher boil point. 5.0 is siliconic and yes, it is not compatible with any other dot (3, 4, 5.1)
Click to expand...

If the above is regarding my comment I'm not confusing the two, I'm fully aware that 5 is silicone & if mixed with 3, 4 or 5.1 your fluid turns to jelly. But 5.1 IMO is still crap & from my own experience I have seen it "sweat" through rubber hoses not designed for it & destroy seals. You may be fine using it, the choice is yours.
 
The other thing about 5.1 is that it absorbs moisture far quicker than dot 4 leading to more frequent fluid changes & moisture was the cause of anglegrinders problem in the first place.
 
it amazes me that some don't prep their bikes before a track day ..... changing to fresh brake fluid would be the least you should do
 
A lot of people mistakenly think that the hygroscopic property of brake fluid is a bad thing. IT IS NOT. Brake fluid is designed to be hygroscopic so that it removes corrosive water from within the brake system. In cold conditions it will also stop ice forming in the brake system.

More hygroscopic = BETTER.

DOT 5.1 fluids are not chemically different to DOT 4 fluids. DOT 5.1 brake fluids cannot damage a braking system designed to be used with DOT 4 fluids.

DOT 5.1 fluids are simply DOT 4-type fluids which meet or exceed the DOT 5 performance requirements.

All brake fluid DOT3/4/5.1 is designed to have a limited life and needs to be changed regularly (in a performance vehicle).

All brake fluid will absorb water once put into a brake system, so the wet boiling point becomes important. The wet boiling point of DOT5.1 is 190 degrees C (DOT 4 is 155 degrees C)

Conclusion/Summary:
Just as with engine oil there are different qualities of product. Given two brake fluids of the same quality the brake fluid meeting the DOT 5.1 standard WILL outperform the DOT 4 fluid.

DOT 5.1 fluids have all the water-absorbing characteristics of the DOT 3/4 fluids while providing very high boiling points and relatively stable viscosity over a wide range of temperatures.

The only 'disadvantage' of DOT 5.1 compared to DOT 4 is the higher price.

Rob :)
 
Last edited:
Go Rob Go! thats the answer.

Buy the way i have just changed all my fluids when i fully serviced my own bike. I replaced it with DOT 4 as it does state on the caps DOT 4 ONLY. unless you are going to be riding on a track at trmendous speed day in day the higher boiling point will make no differance but the higher price will. I can thrash the tits off mine with extreme late hard braking and the little puppies on the front Always pull up.
In my opinion mate, give it a good bleed through as said before by others with standard DOT 4 and all will be tasty.
 
Does sound almost like you might have had the pads pushed out. Did you pump the brake at all when you realised it wasn't working?
Word of advice, get the rear brake working? Whilst you're at it, clean out the calipers and make sure all the pistons are moving freely and bleed the front and back brakes.Check your front brake disc bobbins are moving freely too.
 
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