nuhawk

Did you buy the new set from the local shop? If so, they should stand behind them. If they didn't I would go through every barnyard method available to verify 1) the wheel is straight and runs straight. Bad bearings, bent axle, wrong spacers could all play a part, 2) the rotor mounts on the wheel are true, 3) the rotors are true once you have done 1 & 2. You're going to have to disassemble some stuff to do this but it's the only way to eliminate things one by one. My experience with sticky caliper pistons is that they grip and don't give up or they don't grip at all and then lock. I have never heard of one pulsating. There was a post about pulsating front brakes recently. Fish around a bit using the search function and you may run across something that is pertinent to your situation. Otherwise just hang out for a while and the other guys will add their 2 cents.

JamieDaugherty

I have this same problem with mine. Most recently I swapped a CBR954 master cylinder for the stock one - no difference. I need to check the runout on my rotors as that still might be the problem.

History - This is my second VTR. Both were 98's, the first I bought new and paid off in the first year. I had to sell it for the down payment on my house. The one I have now I bought as a salvage. It was wadded up in a little ball when I got it. One fork was ever so slightly bent and has since been straightened. The frame and other parts are ok. Only half of the front wheel was there when I got it, so it and the rotors are good used parts.

My suspicion right now is that something is tweaked with a caliper, mount, both or something else in the system. It's pretty tough to know for sure, but after 13k miles I've not seen any weird pad wear or anything else that would give me a hint as to what's going on. For know I just grab a bigger handful!

Hawkrider

+1 on nuhawk's recommendations minus the axle. The axle doesn't rotate so even if it's bent it wont cause the wheel or rotors to wobble. I suspect a rotor problem. Since the rotors are new I would check the seating surfaces between the rotor and wheel hub and also that the rotor bolts are torqued correctly to 14 ft-lbs. If that is okay then check the wheel runout and disk runout. A bad bearing would give worse symptoms than just brake pulse. You would have lots of vibration and wobble from the front end.

Randman

Greg, you said bearings, I wonder if that is what is wrong with mine now, I put on the RC51 calipers, took her out up and down the street, now along with the pulse action, rather a break slipping kind of feel, I also feel kind of a wobble, or something hard to explain....does not inspire confidence...

so would/could I be getting that effect due to the rotor bolts not torqued properly??

JamieDaugherty

Hawkrider - It absolutely could be the axle. If it's bent it could cause the rotor plate to not be parallel with the caliper plane. That would cause poor braking performance. I've checked mine already and I know it's straight, though it's probably something to check again at this point.

cliffhangerstx - Try checking your runout. If your rotor bolts were loose you would hear rattling noises. The rotors can and will warp, the wobble you describe leads me to think that could be where your problem is.

Randman

Me thinks that could be it as well, I replaced the stock rotor before when I had this problem, then I thought I had her fixed, alas I probably have warped another rotor, so that is why I bought some cbr900rr rotors, then they turned out to be the wrong year....so now I am in search of more....lol....this thing is like a hole in the road that sucks up money...lol oh well...

Hawkrider

Jamie,

I agree with your statement, but he said he gets a pulsating feel at the lever, indicative of a warped rotor. The rotor not being parallel to the caliper will not cause a pulsation.

99Hawk

Nothing like using the right tool for the job, get your hands on a dial indicator one way or another.


If you find one rotor to be the problem you should first remove it and remount it 180° out and recheck the runout. Sometimes you get 'stacked tolerances' where both the rotor by itself and the wheel machining are within tolerance but when the rotor mounts 'the wrong way' you'll have both tolerances add up to be out of spec. You may also find the runout to be reduced if you very carefully clean both rotor and wheel to reduce the possibility of crap on the mount throwing the rotor off.

Most likely if you check + remove and remount the rotor a couple of times you'll be able to reduce the runout enough to a point where you'll be able to live with it ...

seattletwin

Thanks for the advice from everyone. The dial indicator looks like the tool for the job. Add this too the problem, I wonder if this will be more indicative of the problem? When I tried to roll my bike forward in the garage the front wheel was frozen, and only after I tapped on the calipers did the wheel free up. I do live in Seattle so the bike gets wet although it is stored in a heated garage. Seems that I have caliper problems at the least.

Hawkrider

Yeah, you got some caliper problems bro. What I think has happened is that the front caliper(s) are sticking and the excess heat has warped one or both rotors. Still, try to clean them anyway. Remove the calipers and pads. Do one caliper at a time and note which pad goes where so you can put them back the same way. Pump the lever several times to extend the caliper pistons. Don't let them go out too far or they will come right out. When you see clean metal use lots of brake cleaner and some 1000 grit sandpaper strips to clean the gunk off the pistons. Push the pistons back in by hand if you can. If they are clean then you should be able to. They also make tools just for this job, or you can get creative with a screwdriver or Channel-lock pliers.

seattletwin

Finally found some resolution. As suspected I had multiple issues. The rotors were bent. The cause: The wheels were painted by the previous owner. There was over spray around a couple of the holes were the rotor mounts on the wheel. This caused a the rotors to ride out of true and over time the rotors bent. New rotors and clearing the paint from the mounts solved the problem. In addition the seals in the master cylinder where cracked, not sure if that was a contributing cause or an effect.
Thanks for everyones advice and support!
Bike rides great now!

nuhawk

Glad this one worked out. KC996 is still chasing the same problem with his front. Thanks for posting this up!