Front Caliper Rebuild

[boosz]

I really hope someone might be able to shed a little light on this little situation... Here's the problem. I started to get a pulsation from both front and rear rotors last year while riding in Florida last March on vacation. When I got back home, the dealer, of course, informed me that it was from ABUSE.... LOL!! Whatever!! I don't ride like a mad man... only had the front wheel off the ground enough times to count on one hand and even then only enough to just feel it. NO stoppies what so ever, as that was the next reason, excuse, they gave. So anyways... I rode till this year with the problem getting to the point that NOW I have to replace all the rotors and pads and rebuild the calipers.
No problem..... was an automotive mechanic for 15 years, rebuilt lots in the past, only single piston though. Consult the manual and the seals are supposed to have a taper on them and have a specific orientation to be installed.... Only problem is the seals I got have ABSOLUTELY no taper at all... I tried installing them. No problems, sealed fine BUT..... there is never any lever. The pistons come out when the lever is pulled and then they RETRACT when the lever is released. Makes me think that I installed the seals incorrectly. So now I have them all apart again to double check that I didn't just imagine that they weren't tapered. These seals are deffinately NOT tapered.

 

[boosz]

So now I come here... to see if ANYONE may have tried to rebuild these before. The seals came from Suzuki, and were identical to the ones I removed. The originals had NO destinguishable taper to them either. When I soaked two of the seals for 15 or so minutes in brake cleaner the swelled up to double the size and THEN there was an obvious taper. Not about to do that to the new ones though, and it's far to late to contact the dealership. Been apart for two weeks and would like to be back together by the weekend as the kids are away and DAD wants to play!!

lol....

 

[Darkeyce]

Did you ever get this sorted out?

If yes, how did you determine the taper on the new Seals?

 

[boosz]

Unfortunately I haven't gotten this sorted out. I'm gong to seek some help from a friend who races bikes tonight. He's a little baffled by my description of the problem as well.. I will post what I find out.... Which hopefull will also fix my problem as I'm going through withdrawl.... NO busa for the past month trying to get all the repairs done!!!

 

[boosz]

Well....here it is for anyone who is reading this post. Brakes are FIXED!!!

Went to a friend (yes I'll call him that...) to ask advise. He's been racing bikes for years. Even he tried bleeding just in case I missed some air! Nope... not air. SO we decided to remove ALL of the fluid I had put in... btw it WAS DOT4 fluid, new from a sealed container, and replace with, well it was Willwood DOT4, which shouldn't have made ANY difference, but after bleeding ....... I had a brake lever again.

 

[boosz]

The ONLY reason we can come up with for this solution is one or the other reasons or a combination of both that I will explain now....
The new fluid I bought might have been old stock that was sitting on the shelf for a while... not getting rotated properly, and the seal on the container may not have been perfect and allowed some moisture to get in. The second is .... when I was doing all of the brake work, temperatures here in southern Ontario the last week and half of the week before were in the high 30's just touching 40 (high 80's into the low 100's for those in Farenheit) with humidity levels into the 80 percent area... In other words LOTS of moisture in the air!! If you don't already know brake fluid is HYDROSCOPIC!! (it absorbs water) and with the humidity levels as high as they were when I was doing the brakes, this might have been my problem....
Even though I feel a little embarassed about the cause it pays off to have a second set of eyes check out your work sometimes when things just don't work out the way you had planned!

 

[boosz]

The seals were deffinately square cut... NO taper on them at all !!! The taper area is machined into the caliper bore wall which helps the piston to "pull back" away from the pad and relieve pressure on the rotor when you release the brakes.

 

[boosz]

There is one other thing that was suggested that I try and I would like to pass it along to the members as well..... Tie wrap the lever so that the brakes are being applied. Leave it on over night so that any SMALL amount of air that might be trapped in a curve or little nook, can escape out through the master cylinder. In the morning just cut the tie wrap and off ya go! Made sense to me and can't hurt anything to try it. Guess I'll find out in the morning... But for now... I'm off to bed!...

 

[boosz]

After tie wrapping the brakes on....front and rear, over night I thought that I would report back.... The levers are MUCH firmer this morning than they were after bleeding them last night. Even though I bled the air out at the calipers until no more air came out, actually, with the help of a vacuum bleeder so the brake fluid doesn't get all over the rims, they are still better after the tie wrap trick!!
Now if it would only STOP raining!!