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Post by SandStorm on Aug 30, 2017 9:33:15 GMT -5
So, It's just a strange behaviour I'm having with my lovely Gillian anderson, I mean, my red Gilera Stalker.
She runs fine, able to withstand 75 miles trips in a single day, but when it comes to braking (rear is cable and weak, I need new shows, but lazy to do it) she just hates it when it's hot.
Last year I replaced calipers, brake pads (new from ebc) master cylinder, brake line (ok, both master cylinder, calipers and brake line were used but in way better condition than mine) and she brakes fine. Until the outside temperature gets extremely hot.
Then the master cylinder starts sticking.
On cold weather it's all perfect.
So, I suppose, the O rings in the MC piston, may get dilated with the heat and lock it up. What can I do to solve it? I've tried two other pistons I have laying around (used, it's impossible to find grimeca stuff here new) and the same happens with extremely hot weather.
Is it ok to bathe these rubber O'rings in silicon spray? (that helped on my sportscar electric windows that were sticking up in the rubber rails)
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Post by ryan_ott on Aug 30, 2017 10:32:38 GMT -5
Have you tried different fluid?
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Post by SandStorm on Aug 30, 2017 12:25:18 GMT -5
I using dot4 ferodo fluid.
Gilera recommended Agip fluid. I can try to replace with that, but shall buy it online...
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Post by oakleyscoot on Aug 30, 2017 19:31:39 GMT -5
Disk brakes ( or any hydraulic brake) operate by fluid moving in two directions.
1st direction is by the movement of applying brakes, this pushes out the piston(s) in the caliper thus
making the brake pads squeeze against the rotor and stopping you.
The second direction is when brakes are not needed, the piston(s) retract and fluid moves back to the master cylinder.
If your brakes are freezing and not releasing I might suggest one of two things (or both) may be happening.
1. the pistons are not retracting, maybe because of dirt/debris around the piston(s) not allowing them to return
OR
2. The small hole that allows fluid to return is plugged or partially plugged and isn't allowing fluid to
return into the master cylinder.
I believe the O-ring you speak of is probably NOT the cause of brake sticking. ( unless it is the wrong size o-ring or wrong material).
It is there to seal the bore to allow moving fluid to the caliper. It does not have anything to do with
the return of the fluid. Unless like I said it is the incorrect size or material.
and please do NOT put silicone on the o-ring, you will contaminate your brake fluid, not good.
Do not mix Dot 4 with Dot 5.
Do not use Dot 5 in a Dot 4 system. (without complete rebuild of master cylinder and caliper and hoses as the brake system will become contaminated ).
Do not use Dot 4 in a Dot 5 system for the reason stated above.
Dot 4 and Dot 3 are compatible so you can use 4 in a 3 system.
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Post by SandStorm on Aug 30, 2017 20:40:41 GMT -5
Thank you for your info, but my system is dot4 and that's what I keep using. I haven't mentioned other dot specifications.
Yet, it doesn't explain why only happens with extremely hot weather and not on colder weather. If was obstruction, would keep obstructed independent of weather conditions.
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Post by lostforawhile on Aug 30, 2017 21:46:47 GMT -5
dot 4 is mainly used because it has a higher boiling point, under normal street conditions I don't see any possible way of getting even DOT 3 to it's boiling point in these little scooters
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Post by geoffh on Aug 31, 2017 15:48:55 GMT -5
It might be your strange braking style is overheating the front end,try fixing the rear brake,I tend to favour the rear brake and just a little front to bring me to a halt.
geoff
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Post by SandStorm on Aug 31, 2017 16:13:08 GMT -5
I ride the same style either in summer as winter.
It's mechanical problem. I'll just replace everything with new generic material
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Post by 90GTVert on Sept 1, 2017 6:52:05 GMT -5
One clue would be if it brakes fine on your first stops and then starts having problems. If it's fine at first on even a hot day, it's most likely heat related because it would only be happening once the brakes are hot. Getting the rear brake in good working order and using it a little more could reduce the heat in the front brake and improve the issue. Any chance water has found it's way into the brake fluid?
If the brake sucks even from the first time you pull the lever, it may not be heat related. 100F is not really hot for a brake system. It sounds like it has, but just to be sure; has the problem gone away since it started? If the weather got hot and it happened and hasn't been right since, then heat may not be a big factor.
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Post by SandStorm on Sept 1, 2017 19:49:10 GMT -5
Brakes been fine now on the past couple of days.
I don't brake long, just the necessary. I always use engine braking first and then apply both brakes. Problem only arises if she is left in the sun, it's the MC for sure.
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Post by greginisn on Sept 5, 2017 23:32:50 GMT -5
Dump & replace your brake fluid and replace the caliper. Get rear brake working. If you have a wreck with someone that has read this thread, they will crucify you.
Stay safe, Greg
just saying
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Post by SandStorm on Sept 25, 2017 11:50:12 GMT -5
Hallo guys sorry for a long time without saying anything. Vacations started so today took her to the garage. The mechanic said to first replace the oil even if it's around one year old. But probably I may need new rubbers too Regarding the rear brake, it was adjusted. The shoes material is not that good but he warned me that a very strong rear brake is too dangerous if lock up. And that like in a car, it's in the front all the juice should be Now, he can't find new stuff for my Grimeca brakes. Yet. But since my problem, she's been OK. Also, I may adapt some kind of protection rubber between the piston and lever. Mine is missing it Thanks all for the imput  |
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