Brake Shake

[MPittma100]

1981H Venturer - newly rebuilt front calipers and m/c, original 33 year old pads with 27K on them. When applying front brake, especially at higher speeds, I get a large amount of feedback, chattering, hopping. I am thinking of trying new pads first. I have not checked rotor trueness yet, but intend to.

Has anyone experienced this and what have you found? I rarely use the front brakes, but they need to work when I do.

Mike

[motoman]

1981H Venturer - newly rebuilt front calipers and m/c, original 33 year old pads with 27K on them. When applying front brake, especially at higher speeds, I get a large amount of feedback, chattering, hopping. I am thinking of trying new pads first. I have not checked rotor trueness yet, but intend to.

Has anyone experienced this and what have you found? I rarely use the front brakes, but they need to work when I do.

Mike

Rarely use?.......that's scarey in itself. That front brake IS your main stopping ability. I rarely use the rear, cept adding a bit pressure AFTER applying front brake. That IS the correct braking procedure. Hate to see that back-end scoot out from under you in a quick reaction situation. May not be worth 2cents to ya, but with 45+ yrs. of street, moto-X, hilclimbing, trials and single trac, would guess I've learned something.

[MPittma100]

Rarely

Rarely use?.......that's scarey in itself. That front brake IS your main stopping ability. I rarely use the rear, cept adding a bit pressure AFTER applying front brake. That IS the correct braking procedure. Hate to see that back-end scoot out from under you in a quick reaction situation. May not be worth 2cents to ya, but with 45+ yrs. of street, moto-X, hilclimbing, trials and single trac, would guess I've learned something.

Rarely was a poor choice of words to describe my use. "Less Frequently" is how I use the front compared to the rear. I also use lower gearing for slowing the bike.

Regardless of how I use them, the problem remains in the front with the jumping of the front end when applying brake?

MP

[tcoop]

Does the Venturer have the linked brakes or is LH and the XJ the only ones to have that?

The only time that I have had chattering like that in any vehicle is when the rotors were warped or the calipers were sticking/not working properly.

[MPittma100]

Brak Shake

Does the Venturer have the linked brakes or is LH and the XJ the only ones to have that?

The only time that I have had chattering like that in any vehicle is when the rotors were warped or the calipers were sticking/not working properly.

The brakes are not linked - 2 separate systems. Calipers are rebuilt with ss pistons. I did not replace the pads as they had plenty of material and are the original pads (23K).

I will have to check rotor run out, but can't imagine either of them being warped at 23K miles?

If rotors are ok, I will try some different pads.

MP

[bikerphil]

I ran into a similar problem recently Mike. On my 79 Standard I was getting a shake like you describe. I checked the runout of the rotors and it was about .007" on both rotors which isn't too bad, not bad enought to junk the rotors. What I did was mark the high spot on each rotor and position them the same on the wheel so they would both hit the calipers at the same time instead of one and then the other. Doing this made a definite improvement and I was happy with the result. What really made a huge difference was to replace the master cylinder with a modern unit. After calculating the caliper piston sizes, I went with a 14MM piston MC and SS lines and the brakes have never been better. Good luck, YMMV.

[D0wn5h1ft]

Had this problem on my FZR600. If it's a steady vibration it's probably warped rotors. Also, I know that the kevlar brake pads have a "break in" period where if you stop too hard too often it'll glaze them over and they won't work properly.

Another off the wall guess is that that the pistons are providing uneven pressure because one is getting stuck which would bend the rotor to one side or the other depending.

Lots of things to inspect.

[BA80]

1981H Venturer - newly rebuilt front calipers and m/c, original 33 year old pads with 27K on them. When applying front brake, especially at higher speeds, I get a large amount of feedback, chattering, hopping. I am thinking of trying new pads first. I have not checked rotor trueness yet, but intend to.

Has anyone experienced this and what have you found? I rarely use the front brakes, but they need to work when I do.

Mike

Rotor(s) are warped Mike. BTDT. You can usually see which one or if it's both. There will be uneven coloring on the contact surface.

Had a right front on my SG that was pretty bad and I swapped it to the rear. Then I had the pulsation in the rear.

I machined it on the rotor lathe at work and it chattered a bit and had some chatter marks but it quit pulsating. It's been over a year now and the chatter marks have worn off.

If you know someplace that has the old grinder setup for the rotor lathe that should do a good job on it.

[MPittma100]

Rotor(s) are warped Mike. BTDT. You can usually see which one or if it's both. There will be uneven coloring on the contact surface.

Had a right front on my SG that was pretty bad and I swapped it to the rear. Then I had the pulsation in the rear.

I machined it on the rotor lathe at work and it chattered a bit and had some chatter marks but it quit pulsating. It's been over a year now and the chatter marks have worn off.

If you know someplace that has the old grinder setup for the rotor lathe that should do a good job on it.

I have a local guy that can grind them into shape if warped if they are not too far out. So I will check them and see what needs to be done. I have been using the front brake more and the problem seems to be less than when I first noticed it.

I gave this same guy a (rear) rotor that was too far out of round on my Special. He took an XS11 rotor that he had in stock and ground it true. He also drilled holes in to match a pattern to the two front EBC drilled rotors that I had put on the bike. I will use his services on these if needed.

[donebysunday]

Just a thought, is the bolt going through the forks and wheel set ? Is the pinch bolt tight ?