Brake Fluid Leak at track??

[geras003]

Dave and all track junkies,

This might sound like a stupid question but.. I noticed after my track days that I lost some (not much) brake fluid in the brake reservoir.. Also it seems like it leaks from under the cap. May be under hard braking/cornering??... I could definitely see fluid on the outside of the reservoir...
I guess it is not normal??? What should I replace? Just a diaphragm on the cap??

Thanks in advance!

[repiv]

Vigorous driving introduces factors that can contribute to losing brake fluid past the cap that would not normally happen under more sedate conditions. You've got the slosh factor for one. Then you've got the fluid heating up as well. Finally, when the brake pedal is pushed hard, you can get some fluid coming up like a small fountain. I've done this with the clutch when I forgot to put the cap on when doing the final pumping after a bleed. It's like a mini-geyser.
Just make sure that rubber diaphragm thing under the cap is fitted properly and fully seated into the cap. Additionally, remember that the cap has 2 positions. Always ensure that the cap is screwed on to its second and final position. This may involve pushing the cap with some slight downward pressure as you turn it on.
Have you seen those reservoir socks? I think Spoon makes them. On the most part, those are kinda ricey, but I suppose they are there to soak up the "sweat". This would tell me that somebody has had it happen and the aftermarket caters to it.

[Goku]

Repiv you kinda on the right track with whats happening. Yes your getting some leaking via just the force and pressure that is in the reservoir, but thats not why your "losing" brake fluid. Your losing brake fluid because your brake pads are wearing down from all the use. Its perfectly normal and expectable while racing. If your just starting out racing, you might hear guys talking about always having brake fluid with them in there supplies they carry. I know I was like "why" when I first started racing. Well this is the answer. As your pads wear down the fluid level will go down too, and you just need to top if off.

The leaking at the reservoir is prolby more from ppl spilling than an actual leak at the cap. Just wipe off the excess and top of the fluid and you will be fine.

I still remember one race I did, 150 miles in one day. Start of day fluid was full around 125miles or so into the day the brake light would flicker while turning. By 150miles brake light was on all the time, and my brakes were about shot. And after a close call under braking, I called it quits for the day. Now I keep a much better eye on my fluids and pads. I need those just as much as I need my R-comps :D

[geras003]

Thanks guys for replies! I'm pretty sure it's a combination of wearing the pads and small leak from under the cap - the reservoir was absolutely dry and clean before the event.. And since I'm running ATE superblue - I can tell it was fluid on the outside.. I will try clean the diaphragm, and filter and see what happens!:) Watkins glen is harsh on brakes....

[SpitfireS]

There is an arrow on the cap too.
It should be pointing.... somewhere :D
IIRC its explained on the cap.
I don't know if you can put it on backwards but its worth checking it I guess.

As pads wear, the fluid level drops.
True.
But you don't need to top it up, not even on the track.
It will not do you any good.
Actually, you have lost the way to see how much life your pads still have as the level isn't in relation to pad thickness anymore.
The level switch won't tell you either as the level is too high, even with worn pads.

You should start with a full reservoir & new pads.
If the level gets below a certain point you need NEW PADS, not more fluid.
The new fluid won't make it to the caliper anyways as the brake system isn't a flow through system.
The caliper is a dead-end.
The reservoir is just that, a reservoir.

I've only been on the track 3 times, the last time on R-compounds.
I did not notice any brake fluid sweating.

:hi:

[Goku]

There is an arrow on the cap too.
It should be pointing.... somewhere :D
IIRC its explained on the cap.
I don't know if you can put it on backwards but its worth checking it I guess.

As pads wear, the fluid level drops.
True.
But you don't need to top it up, not even on the track.
It will not do you any good.
Actually, you have lost the way to see how much life your pads still have as the level isn't in relation to pad thickness anymore.
The level switch won't tell you either as the level is too high, even with worn pads.

You should start with a full reservoir & new pads.
If the level gets below a certain point you need NEW PADS, not more fluid.
The new fluid won't make it to the caliper anyways as the brake system isn't a flow through system.
The caliper is a dead-end.
The reservoir is just that, a reservoir.

I've only been on the track 3 times, the last time on R-compounds.
I did not notice any brake fluid sweating.

:hi:


I will have to disagree with you. I was not implying that the reservoir is somehow a way to tell if your brakes are worn out or not. Toping it off also has nothing to do with getting the new fluid to the calipers. Toping it off is to avoid the chance of pulling any air into your master cylinder. Having a full reservoir also helps with heat in the system. Your reservoir should be at full at all times while racing to make sure your brakes will perform at their maximum. Using your fluid lvl as a way to tell if your brake pads are worn is a poor way to monitor your braking system.

[Goku]

Thanks guys for replies! I'm pretty sure it's a combination of wearing the pads and small leak from under the cap - the reservoir was absolutely dry and clean before the event.. And since I'm running ATE superblue - I can tell it was fluid on the outside.. I will try clean the diaphragm, and filter and see what happens!:) Watkins glen is harsh on brakes....

If you are getting excessive leaking at the cap then yes check it out make sure you have it on tight, and in the locked position. If it still leaks after your next race just replace the cap. Good luck.

[Geo02s2k]

Thanks guys for replies! I'm pretty sure it's a combination of wearing the pads and small leak from under the cap - the reservoir was absolutely dry and clean before the event.. And since I'm running ATE superblue - I can tell it was fluid on the outside.. I will try clean the diaphragm, and filter and see what happens!:) Watkins glen is harsh on brakes....

I had the exact same thing happen the first time I went to the track. I chalked it up to boiled fluid expanding and pushing its way past the seal. (I was running with stock fluid.) I switched to ATE Superblue (well, the yellow equivalent) for the next trip to the track and didn't suffer any leaking fluid. (This is what I was going to suggest at first until I read your second post.) Could have been that my resevoir was just VERY full the first time and only just full the second time.

[SpitfireS]

I will have to disagree with you. I was not implying that the reservoir is somehow a way to tell if your brakes are worn out or not.
The level switch is btw.. and that is "operated" by the brake fluid reaching a low level.
OEM pads have a steel indicator welded on them to tell leftover thickness from the outside.
And, when it starts to touch the rotor you will (or are supposed to) hear it.
http://inlinethumb08.webshots.com/42503/2045641400102826257S500x500Q85.jpg

Toping it off also has nothing to do with getting the new fluid to the calipers. Toping it off is to avoid the chance of pulling any air into your master cylinder.
You mean: you're on your last mm. (0.0039") of pad material, you're still using them on the track, you are braking hard to clip the apex just right and the low fluid level may be pushed away from the pick-up point so you want to avoid getting air in your system by adding fluid?
Allright, you do have a point.
I hope you agree with me that on the track one should not be on their last mm of pad material.
;)
In all other cases:
That will never happen.
There is enough fluid in the reservoir to compensate for pad wear.
The level will never get low enough for air to be drawn in.
Certainly not with the S2000.

Having a full reservoir also helps with heat in the system. Your reservoir should be at full at all times while racing to make sure your brakes will perform at their maximum.
I can't see a full reservoir having any effect on the brake fluid temp in the caliper.
There is al least 1 meter of brake line AND an ABS pump in between.
I just don't think a full reservoir will cool the fluid in the caliper.

Using your fluid lvl as a way to tell if your brake pads are worn is a poor way to monitor your braking system.
Yeah.
The outside pad is easy to check.
If the level is lower than one should expect by looking at the outside pad one might be tempted to remove the wheel to inspect the inside pad and rotor thickness.

:)