| Author | Message | ||
     Saszta |
Has anyone experienced the front brake grabbing? More noticeable at slow speeds. What happens is when slowing down with slight pressure on the brake lever, it feels as if the piston is slightly stuck and with a little more pressure on the lever it finally moves out but very quickly and causes grabbing of the rotor. Not too safe, especially if there is any oil on the road. I had a friend with what seemed to be a seized rear caliper on a Suzuki Bandit but the dealer he brought it to just "cleaned" it and it worked fine after that. He didn't rebuild it but just cleaned it. I'm guessing it was some product that lubricates the piston. Not sure how that's done, if anyone has done it, please let me know what the procedure is. thanks. | ||
| Blake |
Get some new pads and try cleaning the disk with some abrasive material. | ||
| Saszta |
So you think it's the pads and disk? I'm assuming you're thinking that there's something stuck to the disk and by sanding it'll remove it. I don't think it's that since I experience a stiffness when pulling in the brake lever and it seems the brakes are not really working. Like something is holding back the piston(s). Then with a little more tension the lever moves past that stiffness and the brake grabs hard. I'll take off the caliper this weekend and lube up any moving parts with brake fluid and see if that solves it. Just wouldn't mind some advice from someone who may have already went through this and can give give me some tips. Hopefully I won't have to remove the pistons. | ||
| Docktor |
Hmmm, Ya bikes only 3 years old,it sounded like the fluid was clagging up. possibly but unlikely.I would recommend a fluid change and definately pop the pistons out. The front does heaps of work,so ya want to know u can trust them.Dont stress, a tube of rubber grease and compressed air is all ya need. Obviously use the air to pop the pistons free,take it easy removing the seals,wipe clean with brake fluid, and dry , then coat with a film of rubber grease. Clean the piston and running area with metho or a mild solvent.Slip the pistons in squarely and re bleed the system. Doc | ||
| Saszta |
Thanks for the advice Docktor, will do all you mentioned this Saturday and post the results. Never used rubber grease before. Would I be correct in assuming that I can get it from an auto parts store? | ||
| Blake |
Sorry, I misread. Sounds like the doc is on the right track. Change/bleed brake fluid, clean/lub lever and mechanical linkages, ensure nothing is interfering with lever. | ||
| Henrik |
I'm thinking, if you have the pistons out, replace the seals. Your description of the "notchy" feel to the brake also makes me think the lever itself could be a touch stiff and in need of a cleaning and lubing. I've had that happen on my SV. Henrik | ||
| Saszta |
I was thinking the same thing about the brake lever myself. Only way to know is check it all out. That'll have to wait a bit as my girlfriend's mom just passed away last night. But, I will get to it eventually and post results. Thanks guys. (Message edited by saszta on October 08, 2006) | ||
| Saszta |
Ok, back at the bike. I've taken the whole system apart and the entire system is relatively clean. The caliper pistons had some brake dust/dirt on the exposed rims but apart from that all looks pretty clean. I've cleaned the caliper pistons and piston o-rings well and re-inserted. Master Cylinder: It seems that the piston within the master cylinder is not moving smoothly. The 2 rubber o-rings on the piston shaft seem fine except the outer one is stiffer than the inner one. I'm guessing that it has a bigger job to do so it's a little more tough. I'm also wondering if this is culprit. I plan to clean the running area with methol alcohol, the piston o-rings with brake fluid then thinly coating the o-rings with white all purpose grease (I hope this is what you mean by rubber grease). The only thing I'm not sure about is having a layer of grease on the o-rings. Would it cause any problems like contaminating the brake fluid? | ||
| Bosezone |
I think you found the problem. What you describe is most likely the delayed piston action in the master cylinder. I would NOT put grease on the O-ring, It will contaminate the brake fluid and could clog up the small opening in the master cylinder. Order new O-rings. The brakes are too important and too stressed to mess around with. Clean it, blow it dry, install new O-rings. If you still feel anything strange with the master cylinder replace it with new. | ||
| Henrik |
+1 on the new O-rings all around. I recently bought piston seals from Buell, and they came with a tiny tube of lube for the seals. May be the same for master cylinder O-rings?? Otherwise I've seen recommended using brake fluid for lubrication during assembly. Henrik | ||
| Bosezone |
I am not sure about the grease, but I would not use it and instead, as you said, use brake fluid. The caliper pistons are not in the "flow" of brake fluid even though they do get exposed to it. What does the manual say about rebuilding the master cylinder? | ||
| Brucelee |
Mine is in the shop for this exact issue right now. I will post when I have a solution. | ||
| Blake |
My good friend Keith had the same thing happen to his XB9S front brake disk. However, after a hard session at the track the deposits were burned off and the brake returned to smooth operation. He later also tried the Lyndal pads and they cleaned the rotor nicely. He's now using the Nissin 804 pads which seem to offer improved initial bite. The stock pads seem to be problematic. Hopefully Buell will soon offer a new version of brake pad that addresses this not too uncommon issue. | ||
| Brucelee |
My dealer proclaims, "this is a normal function of the front brake!" They just checked pads, rotor and head torque and all are normal. I am going to try the "hard braking" fix Blake suggested and then replace the pads at 15K as suggested by my dealer. Does Al at American Sport Bike carry a better pad than OEM? | ||
| Blake |
In my view, your dealer is either being disingenuous or is ignorant of how brakes should perform. I'll be surprised if short of a track day or negotiating a very long steep downhill grade that you'll be able to get your rotor hot enough to match Keith's experience at Oak Hill Raceway. A Scotch Brite pad might be the more reliable/expedient solution.  | ||
| Brucelee |
I'll be surprised if short of a track day or negotiating a very long steep downhill grade that you'll be able to get your rotor hot enough to match Keith's experience at Oak Hill Raceway. A Scotch Brite pad might be the more reliable/expedient solution. Blake, can you say more? Are saying that I should Scotch pad the brake pads, the rotor, or both? Thanks | ||
| Blake |
Rotor. I've refreshed the surface of my brake pads before with good results. I used emory paper on a flat tooled surface though. | ||
| Saszta |
wow, look what I've started! Good to see a bunch of opinions expressed. I love forums like these... Ok, here's the scoop. In addition to the things I've already listed as having done in an earlier post in this thread, I've also: - Cleaned the master cylinder piston o-rings thoroughly with BRAKE FLUID. - cleaned the master cylinder well with brake cleaner - lubed the m/c piston's o-rings with brake fluid and coated the running area with a film of brake fluid before assembling. - lube the entire lever mechanism with white grease - put in new pads, mine were worn enough to warrant a change but that had nothing to do with the grabbing - I'm sure of it Assembled everything and problem is gone. I did not "rebuild" master cylinder since the kit was on backorder and I think the seals are still pretty new and good. The bike is only 3yrs old with 8k miles on it. I'm sure some will disagree but I'm comfortable with just doing an extremely thorough cleaning of the entire system. Having said that, I will order the rebuild kit and install it next time I change my pads. New problem: Spongy brake feel, but I've seen a good post on using a syringe to remove the smallest of air bubbles and will try that next. Spongy feel is not that bad and brakes work fine but I know they can be stiffer. I currently have the lever set to 2nd notch on the free play dial and can stop the bike with one finger. Can probably do a stoppie with 2 fingers but I ain't no stoppie king so I'll just imagine it... Brucelee: You're dealer is full of crap if he tells you that Buell brakes are supposed to grab. Yeah, if you jump on the lever they will grab but if you slowly squeeze they should apply pressure to the disk smoothly at the exact same rate as you squeeze them. Find another dealer. There's a lot of dealers out there who don't take the time to listen to their customers and don't give the service we all deserve. Thank you all for your input. (Message edited by saszta on October 16, 2006) | ||
| Blake |
Steve, Thanks for following up with the good news. | ||
| Brucelee |
Thanks all. I will get on this and report back. | ||
| Henrik |
Steve; you probably know, but spongy feel would indicate you still have some air in the brake line. The syringe bleeding should firm things up. Henrik |
