Jerky rear brake

[dannymax]

Just finished splitting/cleaning and installing new seals and EBC HH pads in the rear caliper on my '99 & replaced with new Castrol 3/4 synthetic fluid.

The pad pins are lubed with copper grease and seals and pistons lubed with red grease.

The brake lever is very solid, depresses a max of 1" and there are no leaks anywhere in the system.

The problem is about halfway down the pedal seems to stick slightly and need just a bit extra pressure to go further. There is a 'creaking or clicking' as it passes by this spot.

If I hook a finger around the pushrod at the bottom of the master and pull outward from the bike the lever is smooth with no jerking/creeping or noises.

The bike has 17K, the rear caliper bores were in very nice shape needing only a little brass wire brushing and brake cleaner flush to shine....pistons were the same.

This morning I will drain the fluid, pull the master and dis-assemble/inspect....just wondering if anyone else ever ran across this. :ummm:

 

[naughtyG]

Dan-o, have you checked that the brake pedal and all associated linkages are free?

 

[dannymax]

Dan-o, have you checked that the brake pedal and all associated linkages are free?

Yes I have G...all pivot points were lubed with lithium grease and there is no binding anywhere.

 

[dannymax]

I had noticed this jerky thing starting last summer but, with the bike being on the lift for the last half of the riding season, forgot all about it till now.

 

[[email protected]]

I had similar issues with a different bike. The pushrod on my rear brake master was corroded. Couldn't tell from looking at it on the outside but one I pulled the rubber boot on the brake master and looked up inside there it was filled with crud, rust, gunk, blah..... I took he master apart, polished the pushrod, reassembled, and it worked fine for awhile. About a year after the master started leaking. The pushrod was worn bad enough to tear up the seals.

Not saying this is the problem, just something I ran across. Seemed that rubber boot held any moisture in and corroded the pushrod. Ended up buying a good used master for the bike, it was cheaper than a rebuild kit and a new pushrod.

 

[naughtyG]

I guess since you have two bikes, taking the M/C from the other and replacing it would prove that point easily.. I also have an old spare rear M/C still up for sale on fleaBay: http://cgi.ebay.com/ebaymotors/ws/e...512210362&viewitem=&sspagename=STRK:MESELX:IT

 

[dannymax]

I had similar issues with a different bike. The pushrod on my rear brake master was corroded. Couldn't tell from looking at it on the outside but one I pulled the rubber boot on the brake master and looked up inside there it was filled with crud, rust, gunk, blah..... I took he master apart, polished the pushrod, reassembled, and it worked fine for awhile. About a year after the master started leaking. The pushrod was worn bad enough to tear up the seals.

Not saying this is the problem, just something I ran across. Seemed that rubber boot held any moisture in and corroded the pushrod. Ended up buying a good used master for the bike, it was cheaper than a rebuild kit and a new pushrod.

Thanks Mike, I'm thinking once I get it apart the problem should be obvious, just seems odd that pulling outboard on the pushrod smooths it out. :ummm:

I guess since you have two bikes, taking the M/C from the other and replacing it would prove that point easily.. I also have an old spare rear M/C still up for sale on fleaBay: http://cgi.ebay.com/ebaymotors/ws/e...512210362&viewitem=&sspagename=STRK:MESELX:IT

Thanks G, I'm hoping a rebuild kit will fix it but if the barrel is boogered up I may have to get a whole master.

 

[Redbone]

The only other thing I might look at would be the alignment of the brake pedal and the push rod. The piston rod could be slightly bent, mounting point for the brake lever bent, the master cylinder mounting point bent.:confused2:
EDIT: I just reread you previous post stating there was no binding. I was thinking along the lines that when you said that you put outward pressure the problem went away. Hmm, hope the rebuild kit does the trick. :thumbs up:

 

[dannymax]

The only other thing I might look at would be the alignment of the brake pedal and the push rod. The piston rod could be slightly bent, mounting point for the brake lever bent, the master cylinder mounting point bent.:confused2:
EDIT: I just reread you previous post stating there was no binding. I was thinking along the lines that when you said that you put outward pressure the problem went away. Hmm, hope the rebuild kit does the trick. :thumbs up:

I went through the same thinking Brian. And, even tho there is no binding I thought maybe the pushrod had somehow gotten bent so I turned the clevis 180' but it didn't make any difference, the problem still exists.

I'm getting pretty curious now and will be going to the shop shortly to get to the bottom of this!! unk:

 

[gamorg02]

I went through the same thinking Brian. And, even tho there is no binding I thought maybe the pushrod had somehow gotten bent so I turned the clevis 180' but it didn't make any difference, the problem still exists.

I'm getting pretty curious now and will be going to the shop shortly to get to the bottom of this!! unk:

sounds like u'll find some gunk in the bore/ on the piston eh?

 

[dannymax]

sounds like u'll find some gunk in the bore/ on the piston eh?

That will surprise me a little cause when I drained the system to do the caliper rebuild I pulled all the fluid out the bleeder valves with a mity-vac and there was no sign of anything....just clean, clear fluid. :confused2:

But, yeah, there almost has to be something inside the master.

 

[dannymax]

Well....the issue is resolved, but I really don't know why.

I removed the master, totally dismantled and inspected every component. There was a very small amount of dark residue in the threads of the piston, but otherwise looked fine. All parts, with the exception of the rubber seals, were cleaned with denatured alcohol, lubed with new Castrol synthetic DOT3/4 and re-assembled.

The brake lever is smooth, no creeping, jerking or any sign of the issues I mentioned earlier. The lever now travels about 1 1/2" and is firm.

Apparently there was something in the master causing this but I have no idea what. :ummm: But, all's well that ends well!

 

[gamorg02]

glad to hear it danny!

 

[naughtyG]

Nicely done Dan-o!

 

[Redbone]

Good news Dan-o, a little skilled cleaning and assembly goes a long ways! Was the residue gritty or in anyway abrasive?

 

[dannymax]

Good news Dan-o, a little skilled cleaning and assembly goes a long ways! Was the residue gritty or in anyway abrasive?

It didn't seem to be Brian. It's kind of a mystery because the jerky spot was quite pronounced, I expected the cause to be obvious. :confused2:

 

[VMAX1260]

glad to hear you solved the problem. ii had issues with m/c with some old bikes i owned through years. one lesson i learned is that you cant test a M/C with your fingers... the pedals or levers increases the power of the pushrod so much even if you try to push it with a screwdriver or something like that. there is no match in the power .

 

[06VMAXIMUS]

It didn't seem to be Brian. It's kind of a mystery because the jerky spot was quite pronounced, I expected the cause to be obvious. :confused2:

Probably that friggin mod monkey, Danny! I bet he put something in there to make you think you needed all new aftermarket components. Good thing you won this time!

 

[dannymax]

Probably that friggin mod monkey, Danny! I bet he put something in there to make you think you needed all new aftermarket components. Good thing you won this time!

Well, I haven't actually driven it down the driveway yet Bob, he may still have a surprise or two for me. :confused2:

 

[Redbone]

Well, I haven't actually driven it down the driveway yet Bob, he may still have a surprise or two for me. :confused2:

Aw, com'on Danny, give it a test spin, probably to the end of the drive is all you'll need!:biglaugh: