Front Disc Brakes

smeggy · 06-13-2009, 06:18 PM

The cylinder that forces the brake pad up against the front brake disc does not retract far enough to take all the drag off the disc. Is this a brake fluid problem or something else?

katoranger · 06-13-2009, 06:54 PM

I would flush the fluid out and fill with some DOT 5. Give that try to see if it helps any. If not it is likely that the piston is sticking.

The brake fluid that comes in these bikes is mediocre at best.

Allen

TheRealWorld · 06-13-2009, 11:30 PM

Most of these will have a small drag on the disc at all times. With the wheel off the ground, spin it and if you can get one revolution that is not to far from normal.

You may not be able to turn it at all but I could not tell form your post. If that is the case do what the katoranger said! A great idea on any new china bike.

AZ200cc · 06-13-2009, 11:41 PM

Three China bike rules.
1, If it's a Chinese fluid drain it and replace it.
2, If it's a chinese rubber product, Replace it soon!
3, If the bolt is put in by a Chinese worker, Loctite it and tighten it.

The oil is probably made from whale blubber, The brake fluid is recycled from sewer water and the rubber will melt if it's ever is exposed to anything but it's natural environment....And the bolts fall out to let You know the bike needs love

forchetto · 06-14-2009, 03:29 PM

The job of returning the piston back into its cylinder is the rubber seal around the cylinder. This distorts on purpose and acts like a return spring.

The brake fluid under pressure forces the piston to slide out of the caliper. This action deforms the seal in the direction the piston travels. When releasing the brake pedal the deformed seal will pull back to its original shape and pull the piston with it, this action will release the brake pads from the disc.

katoranger · 06-14-2009, 04:38 PM

I just learned something new. Great.

Allen

phil · 06-14-2009, 05:40 PM

i would also check the pins on the caliper to be sure they are sliding smoothly your auto parts will have some caliper grease or brake grease, dont use regular grease

Ma77 · 06-17-2009, 03:42 PM

at least your cylinder IS forcing the pad onto the disk, no matter what i do to my front brake it never seams to...just......work really :?

smithyUK · 06-22-2009, 10:12 AM

strip the brakes rite down to bits remove pistons springs pins ect clean everything thorghly (spelling lol) bave every thing in petrol rince with water let it all dry then reasemble make sure the pistons are totaly clean grese all pins and moving parts (not the pistons lol) finaly get some proper brake fluid into it
good luck

TheRealWorld · 06-22-2009, 10:26 AM

I might be tempted to skip the water rinse!

06-13-2009, 06:18 PM	#1
smeggy Join Date: May 2009 Posts: 4	Front Disc Brakes The cylinder that forces the brake pad up against the front brake disc does not retract far enough to take all the drag off the disc. Is this a brake fluid problem or something else?
	0

06-13-2009, 06:54 PM	#2
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	I would flush the fluid out and fill with some DOT 5. Give that try to see if it helps any. If not it is likely that the piston is sticking. The brake fluid that comes in these bikes is mediocre at best. Allen __________________ You meet the nicest people on a Honda Clone.
	0

06-13-2009, 11:41 PM	#4
AZ200cc Join Date: Apr 2007 Location: Show Low Arizona Posts: 2,889	Three China bike rules. 1, If it's a Chinese fluid drain it and replace it. 2, If it's a chinese rubber product, Replace it soon! 3, If the bolt is put in by a Chinese worker, Loctite it and tighten it. The oil is probably made from whale blubber, The brake fluid is recycled from sewer water and the rubber will melt if it's ever is exposed to anything but it's natural environment....And the bolts fall out to let You know the bike needs love __________________ <br />2001 Suzuki DR200SE<br />1997 Suzuki RM250 YIKES<br />1995 Yamaha Breeze 125 daughters<br />1991 Honda XR80r Restored<br />maybe a 2003 Yamaha TTR90
	0

06-14-2009, 03:29 PM	#5
forchetto Join Date: Jul 2008 Location: Gijon, Asturias,Northern Spain Posts: 396	The job of returning the piston back into its cylinder is the rubber seal around the cylinder. This distorts on purpose and acts like a return spring. The brake fluid under pressure forces the piston to slide out of the caliper. This action deforms the seal in the direction the piston travels. When releasing the brake pedal the deformed seal will pull back to its original shape and pull the piston with it, this action will release the brake pads from the disc. __________________ Jincheng Monkey JC50Q-7 (two of them) Skyteam Dax replica ST110-6 (two of them) Zongshen ZS125-43 Qingqi QM200GY-BA Super Motard Yamaha Virago XV1100 Triumph Bonneville SE Qingqi QM110GY PGO Bug rider 250 Buggy
	0

06-14-2009, 04:38 PM	#6
katoranger Join Date: May 2007 Location: Altamont, Kansas Posts: 15,103	I just learned something new. Great. Allen __________________ You meet the nicest people on a Honda Clone.
	0

06-13-2009, 11:30 PM	#3
TheRealWorld Join Date: Jun 2008 Posts: 817	Most of these will have a small drag on the disc at all times. With the wheel off the ground, spin it and if you can get one revolution that is not to far from normal. You may not be able to turn it at all but I could not tell form your post. If that is the case do what the katoranger said! A great idea on any new china bike.
	0

06-14-2009, 05:40 PM	#7
phil Join Date: Jun 2008 Location: wise va Posts: 636	i would also check the pins on the caliper to be sure they are sliding smoothly your auto parts will have some caliper grease or brake grease, dont use regular grease __________________ halls auto l coolster, modcycles, yanmar & zongshen, dealer fired roketa,lifan and jet moto and apollo quit me who's next
	0

06-17-2009, 03:42 PM	#8
Ma77 Join Date: Dec 2008 Posts: 53	at least your cylinder IS forcing the pad onto the disk, no matter what i do to my front brake it never seams to...just......work really :?
	0

06-22-2009, 10:12 AM	#9
smithyUK Join Date: Dec 2008 Posts: 77	strip the brakes rite down to bits remove pistons springs pins ect clean everything thorghly (spelling lol) bave every thing in petrol rince with water let it all dry then reasemble make sure the pistons are totaly clean grese all pins and moving parts (not the pistons lol) finaly get some proper brake fluid into it good luck
	0

06-22-2009, 10:26 AM	#10
TheRealWorld Join Date: Jun 2008 Posts: 817	I might be tempted to skip the water rinse!
	0