*xke*
New member
Has anyone ever had a problem with brake handle going all the way down temporarily and then coming back to firm, no-problem feel after cool-down? I was making timed 500' & 700' runs all day (clutch tuning) and the brake was definitely hot. Right after the last run it was fine, 5 minutes later when trailering, the brake handle went all the way down with no resistance. 2 hours later when unloading, the brake was totally fine. Squeezed as hard as I could and held it 1+ minute, no loss of resistance. Fluid level normal, no leaks, rotor/pad thicknesses within tolerance. It's fine now. Could this be caused by the fluid in the caliper "boiling" or getting too hot? I've searched for similar threads but found none. Thanks alot guys...I need that brake to be 100% (which it is now, but for how long?).
Yamidude59
New member
hydralic brakes fade, usually fade at least if your using the brake alot at the end of your timed runs....
horkn
New member
How old is the brake fluid?
Unless it is Dot5 (maybe 4 as well), it is hydrophyillic. That means that it likes water, and brake fluid that is dot 1 or 2 will soak up water. If it is old fluid, it can get quite a bit of water in it, without even noticing it. Water lowers the boiling point of the brake fluid, and will cause the issue you have seen.
IME, most sledders never change their brake fluid, and that is scary. I usually change the brake fluid in my sleds every 3 years with DOT 5 as well.
I change my brake fluid in my bike every 2 years (and I use dot 5) , as I do track days at Road America and such, plus, having no brakes on a bike is downright scary, even more so than on a sled.
Unless it is Dot5 (maybe 4 as well), it is hydrophyillic. That means that it likes water, and brake fluid that is dot 1 or 2 will soak up water. If it is old fluid, it can get quite a bit of water in it, without even noticing it. Water lowers the boiling point of the brake fluid, and will cause the issue you have seen.
IME, most sledders never change their brake fluid, and that is scary. I usually change the brake fluid in my sleds every 3 years with DOT 5 as well.
I change my brake fluid in my bike every 2 years (and I use dot 5) , as I do track days at Road America and such, plus, having no brakes on a bike is downright scary, even more so than on a sled.
I had brake fade on my 700sx one day, perfect trails, tight and twisty, lot of full throttle to hard braking then got a bit hot, used my parking brake untill it cooled off then back to normal.
I changed the fluid just to be sure. It has only happen to me once. But we were riding really hard.
Tod
I changed the fluid just to be sure. It has only happen to me once. But we were riding really hard.
Tod
*xke*
New member
Brake fade or boiled fluid?
The fluid is DOT 4, factory original, ten years old.
I've experienced brake fade before and this wasn't it. This was like the line had been cut. With fade, there's still resistance to the brake handle (or pedal) but the brakes don't really work very well, or at all, but there's still resistance. This was literally no resistance until the handle went down to the handlebar.
Can the brake system on a 98 SRX be upgraded to DOT 5 just by completely bleeding it out or are there seals that have to change.
i\I use the silcone stuff (DOT 5) for kart racing but never have in my sled.
Thanks for the feedback.
The fluid is DOT 4, factory original, ten years old.
I've experienced brake fade before and this wasn't it. This was like the line had been cut. With fade, there's still resistance to the brake handle (or pedal) but the brakes don't really work very well, or at all, but there's still resistance. This was literally no resistance until the handle went down to the handlebar.
Can the brake system on a 98 SRX be upgraded to DOT 5 just by completely bleeding it out or are there seals that have to change.
i\I use the silcone stuff (DOT 5) for kart racing but never have in my sled.
Thanks for the feedback.
It sounds like the master cylinder is on its way out.
9801srx
Member
i had the same thing happen to my 98'.i just changed the fluid and it never happened again. like horkn said water absorbed by the fluid over time really lowers the boiling point and will cause this type of problem.
*xke*
New member
DOT 5 brake fluid changeover
So does anyone have anything for the DOT 5 brake fluid changeover? Are there any seals that have to be replaced or can I just completely bleed out and change the fluid? Thanks for the help.
So does anyone have anything for the DOT 5 brake fluid changeover? Are there any seals that have to be replaced or can I just completely bleed out and change the fluid? Thanks for the help.
make sure the disk is not out of round ....sometime at high speed if its out of round well the disk push back the brake inside the caliper and the first shot you hit the brake well woooohooooo no brake till you hit the second time cause you pump the caliper piston out so brake will be apply...my friend got that problem with is mack 1 eatch time he did a past a full speed well no brake at the end ..he change pads and never got back the same situation .. but i'm scared for him loll
*xke*
New member
Good insight
Yeah, I never really thought of that (caliper pistons getting pushed in). That would definitely explain the symptoms I experienced. The rotor and pads are within spec-barely. I'll try new pads and if it happens again I'll definitely look at the pad to rotor clearance to see if it opened up. Thanks!
Yeah, I never really thought of that (caliper pistons getting pushed in). That would definitely explain the symptoms I experienced. The rotor and pads are within spec-barely. I'll try new pads and if it happens again I'll definitely look at the pad to rotor clearance to see if it opened up. Thanks!
800
New member
If it was bad when it was hot and OK when it cooled down the only thing that changed was the temp of the fluid, so it needs to be changed, I have DOT 5 in my sleds and it works fine. Fluid temp and fade are aggravated in in the sleds because that caliper gets hotter than you think, and the system is very small. Also, how much pad do you have left, the thinner the pad, the further out the pistons are and there is more fluid in the caliper which aggavates the problem.
pipdviper
Member
yep, you boiled the fluid. Make sure if you do change over to dot 5 you get ALL the dot 4 out. There not compatable. You would probablt be fine just flushing and staying with the dot 4 I Was going to change mine over and the dealer talked me out of it.
horkn
New member
*xke* said:
just drain all the old stuff out, and put in dot5. it is that simple, but I bet simply putting new dot4 would fix it.
But why put in dot4 , when dot5 barely costs any more? It is completely compatible (the caliper, lines and MC), as long as you get as much of the old stuff out as possible.
*xke*
New member
Temporary brake failure-and the answer is...
And the answer is...
The rotor/jackshaft key became deformed and was allowing WAY too much play. The brake rotor would flutter a little at certain RPM's and that would push the caliper pistons out. When I grabbed the brake, I first had to take up all the "slack" in the system and pump it up the same way you do when you install new pads into fully compressed pistons. The first couple pulls have no resistance to speak of and there is no braking power. Made a new key to fit (shaft keyway was opened up about an extra .008"; too sloppy), greased the shaft/rotor hub area, flushed the system and changed over DOT 5. Done.
Root cause: No grease on shaft/rotor junction allowing for excessive wear on key and keyways.
And the answer is...
The rotor/jackshaft key became deformed and was allowing WAY too much play. The brake rotor would flutter a little at certain RPM's and that would push the caliper pistons out. When I grabbed the brake, I first had to take up all the "slack" in the system and pump it up the same way you do when you install new pads into fully compressed pistons. The first couple pulls have no resistance to speak of and there is no braking power. Made a new key to fit (shaft keyway was opened up about an extra .008"; too sloppy), greased the shaft/rotor hub area, flushed the system and changed over DOT 5. Done.
Root cause: No grease on shaft/rotor junction allowing for excessive wear on key and keyways.