Warped rotor or?..

El Guero

El Guero

V4 *****
Joined
Apr 11, 2010
Messages
193
Location
Iowa City, IA
Bike
1995 ST1100
Alright, I'm pretty sure my rotors are warped but I threw a cautionary "or" in there as well. When braking I get some feedback from the front end like I'm running over washboards. Pretty sure that's warped rotors, but I've never dealt with them on a bike before. I also recently changed my fork oil and springs and did stainless steel lines for the front brakes.

Given my brakes are warped, what all do I need to replace? Pads and rotors?
 
If they are indeed warped, then new rotors are in order. Depends on how the pads look, if I'd replace em. Rotors could have a hard spot on them. That would present the same symptoms. I would take the calipers off. Attach a fixed object close to the rotor. Then spin the wheel. If they are indeed warped, you will see it. If they are not, see if a machine shop will surface grind em. If they have enough material that is. Good luck.

Shalom
Michael
 
Before you buy new ones, be sure its not just transfer of brake pad material. Remove the rotors, run over the braking surfaces with a sanding disc or some other abrasive. The ST1100 is not noted for truly warping the metal, good chance you'll be able to save them.
 
CarSalesman said:
Before you buy new ones, be sure its not just transfer of brake pad material. Remove the rotors, run over the braking surfaces with a sanding disc or some other abrasive. The ST1100 is not noted for truly warping the metal, good chance you'll be able to save them.
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You know what, I think you may be on to something here... My brake pads have been sticking to the rotors when the bike sits and some crap has stuck to one of the rotors. I will see if that comes off with some sand paper.
 
Tried cleaning the rotors and I sanded down the brake pads a little, the handlebars still chatter when I get on the brakes. Is there anything else that could cause this besides warped rotors? Tire balance? The Anti-dive system? Bueller?
 
Rotors are the likely cause. You now neeed to determine which one(s). That is done with a dial indicator to measure runout. Any auto mechanic will have one. Important to measure and confirm the problem before buying new rotors. Given that the rotors are expensive and the pads are cheap, I would replace the pads at the same time.
 
I have a machine for grinding brake rotors for bikes, if your interested in going that route. The rotor would need to be checked to determine how much material needs to be removed to correct the problem. When you get the cost to replace them, taking a couple thousandths off and making them right is a good option. PM me if your interested.
 
Highrider said:
I have a machine for grinding brake rotors for bikes, if your interested in going that route. The rotor would need to be checked to determine how much material needs to be removed to correct the problem. When you get the cost to replace them, taking a couple thousandths off and making them right is a good option. PM me if your interested.
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Definitely going to PM you when I am closer to figuring this out!
 
I spent the last couple days sanding on the rotors and spraying them with brake cleaner, and it appears to have made a big difference. I took a quick spin tonight and noticed much less shaking in the handlebars under braking. I can still feel some, but at this point it is hard to decide if it is a problem with the brakes or Iowa tarmac :p I will probably get more brake cleaner and spray them down again.
 
What grit are you using ?

I found 100 grit in a palm sander has been effective for old rusty ( car ) rotors from junkyards .
 
I was using something finer than that... I think I went with 220 grit, no coarser than 150.
 
Good results can be had if glass shot is used in a sand blasting cabinet. Use glass not sand! It really cleans out the pores of the metal. The first few times you use the brakes it will definitely be noticeable until they bed in.

I have bent rotors before when breaking the tire bead with an old HF bead breaker and not watching what I was doing when pressing down on the wheel/tire. Now I remove the rotors when changing tires. Could this be something similar?
 
Pepe' said:
I have bent rotors before when breaking the tire bead with an old HF bead breaker and not watching what I was doing when pressing down on the wheel/tire. Now I remove the rotors when changing tires. Could this be something similar?
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Doubtful, I haven't changed the tires in over a year.
 
Since you changed to BSS lines, you may be feeling things now that were "absorbed" by the rubber brake lines before, but there should not be any real pulsing in the lever.

If you have the front wheel up in the air and can spin it freely, us a screwdriver or awe, held against the fork leg, and put the point to where it just lightly touches the rotor. Spin the wheel and note if there are high/low spots. If you can see/feel any changes here then no need for a dial indicator.... you've got a warped rotor. If it's difficult to detect this way and you have access to a D/I, by all means use it to check runout.

Ma Honda is VERY proud of her replacement brake rotors; quick check at BikeBandit (sometimes a fitting name) shows $458.53 EACH!! YIKES!

Some aftermarket parts are available (including some chinese knock-off rotors for a much-reduced cost) along with fleabay for used. Maybe contact freeSTyle Don to see if he has some available??
 
sirepair said:
Since you changed to BSS lines, you may be feeling things now that were "absorbed" by the rubber brake lines before, but there should not be any real pulsing in the lever.

If you have the front wheel up in the air and can spin it freely, us a screwdriver or awe, held against the fork leg, and put the point to where it just lightly touches the rotor. Spin the wheel and note if there are high/low spots. If you can see/feel any changes here then no need for a dial indicator.... you've got a warped rotor. If it's difficult to detect this way and you have access to a D/I, by all means use it to check runout.

Ma Honda is VERY proud of her replacement brake rotors; quick check at BikeBandit (sometimes a fitting name) shows $458.53 EACH!! YIKES!

Some aftermarket parts are available (including some chinese knock-off rotors for a much-reduced cost) along with fleabay for used. Maybe contact freeSTyle Don to see if he has some available??
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I may try this out... I went out for another spin and it was really weird. If I got up to 60mph or so and then got on the brakes a little, it wouldn't start shaking right away but then after it had slowed down a bit it would start to chatter a bit. It definitely wasn't shaking as bad as before and it isn't a big deal unless you are really getting on the brakes, but it is definitely still there. I guess the rotors still look like the likely culprit, I guess I can get a new (used) set off of ebay for $90 or so.
 
I have straightened rotors on my 600 before. If they have an aluminum carrier you can straighten them with a dial indicator (or good eye. thats what I used) and a flat screwdriver to adjust the carrier. Oh and patients. It worked for me.
 
I tried the screwdriver check but I am not sure I actually learned anything. I guess I should find somebody to check the run-out for me...
 
Not sure why but I'm straying away from the warped rotors idea. You should feel that at all speeds and even when the brakes are lightly applied. I'm thinking suspension or maybe even front wheel install as it sounds like it happens when the weight transfers forward.
 
schlep1967 said:
Not sure why but I'm straying away from the warped rotors idea. You should feel that at all speeds and even when the brakes are lightly applied. I'm thinking suspension or maybe even front wheel install as it sounds like it happens when the weight transfers forward.
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This is what I've been wondering about - I haven't had the front wheel off in a while but I did just change the springs/fork oil. Could it be something stupid like an air bubble in the antidive? I guess it is probably not steering head bearings though...
 
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