Brake pulsation!!

[duganc1717]

So for those did not see the previous thread http://www.nestreetriders.com/forum/...ragging-s.html

I bought a 02'CBR F4I and the front brake was squeaking and pulsating. I realized the front wheel was rotating in the wrong direction, turned the wheel around and everything was fine.
No more squeak, or pulsating.

Except the wheel was dragging when I tried to spin it on the front end stand, I swapped the pads in the calipers from the inside to the outside and bled the brakes and the drag was gone.
I rode the bike 80 miles on Wednesday and the brakes were the best they have been.

I left for a trip on Thursday out of Hopkinton, MA and by the time I got to Mt Greylock road I noticed a severe pulsation @ 40mph to 20-25mph with light to moderate brake pressure.

Above 40mph the pulsating is not nearly as severe. The higher the speeds I'm braking from the more the feeling improves.


I rode the bike from Hopkinton, MA to VT gaps to lake George, NY via back roads to home yesterday and there was not a lot confidence in the braking department. Especially on rte 17 in VT.

So WTF gives? Why when I turned the wheel around would the brakes feel fine, then return to pulsating after roughly 100 miles of riding?

[brendanp]

Have you checked to see if the disc's are warped or not flat?

[duganc1717]

I have not. I have eyeballed them and that is it so far.

The only that makes me think they are not, is the fact that when I first turned the wheel around to the correct direction there was no pulsation.

[R7]

I think I know what the problem is, there's a good deal on an 06 R6 on born and you should look into it

[duganc1717]

Found two things, tire seems to be cupped and I don't remember it being like that before the trip. Also front rim is now bent.

[duganc1717]

I think I know what the problem is, there's a good deal on an 06 R6 on born and you should look into it

Most helpful as always.

[j4eric]

have the wheel balanced....if that does not work, change the brake pads and make sure you have the correct tire pressure, you said you just swapped the brake pads inside to the outside, that means the wear is completely screwed up by now.

[schleppy]

Also, if the bike has floating rotors the little buttons surrounding each disc could be "stuck" and full of brake dust. CAREFULLY spray lube around all of the buttons (avoid the disc!), that can help free them up.

[duganc1717]

have the wheel balanced....if that does not work, change the brake pads and make sure you have the correct tire pressure, you said you just swapped the brake pads inside to the outside, that means the wear is completely screwed up by now.

Actually they would be on the correct side of the disc surface since the wheel was rotating in the wrong direction.

[DaveZX6r]

it sounds like the whole thing has alot of different variables going into it. Stupid question but have you checked the pressure in the front tire? I was having a similar problem and found out that i only had about 20 lbs of pressure in front tire. filled up problem solved. But the cupping and combined with bent rim... that ususally only happens if you've got no pressure in the tire. check your pressure.

Either that or the tire is just all sorts of fatiqued from being worn in two different directions :idk

[duganc1717]

Air pressure is good and it was good the night I brought the bike home. So I don't believe that is an issue.

Little update, I pulled the rotors off yesterday and cleaned the shit out of them specifically the button-like part that attaches the carrier to the rotor.
First with brake clean then wheel cleaner, then brake clean and lubed then with WD-40 and PB blaster.

I also place a straight edge on each rotor on both side and they appear to be fine.

Pulsation seem to be gone, I'm going to grab new pads today and see what that does.

[SVRACER01]

if the tire is cupped you probably need a new tire as it wont ever get UNcupped and will increase the feeling you getting now. you could probably put new pads in since they have now been used in 2 different directions (not sure if that will matter). whatever is causing the tire to cup is what your feeling. stuck or warped rotor, unbalanced tire, warped rim. the problem went away when you flipped the wheel because the tire was "good" in that direction and it could absorb the "issue". once the the "issue" stated to wear the tire to its present "cupped" stage...you started to feel it again. pull the wheel and get everything checked at a shop or if you have a dial indicator do it yourself.

[stoinkythepig]

Air pressure is good and it was good the night I brought the bike home. So I don't believe that is an issue.

Little update, I pulled the rotors off yesterday and cleaned the shit out of them specifically the button-like part that attaches the carrier to the rotor.
First with brake clean then wheel cleaner, then brake clean and lubed then with WD-40 and PB blaster.

I also place a straight edge on each rotor on both side and they appear to be fine.

Pulsation seem to be gone, I'm going to grab new pads today and see what that does.

I can't recommend any lubricant on the rotors... I can, however, recommend that you use an EZ out and give the "button-like" parts a few turns to loosen them up.

[duganc1717]

Didn't actually lube the rotors that would be , I'll try getting the buttons to move alittle more freely.

[stoinkythepig]

Didn't actually lube the rotors that would be , I'll try getting the buttons to move alittle more freely.

Any lube on the buttons will fling outward, right onto the rotor surface. Not a good situation, though probably not dire either. The buttons are designed to work dry, I'd keep them that way.

[NEWTREADS]

I have an 04 f4i and had the same problem. It was after an intense braking situation. Passing several cars when the front one made a left with no signal, so I was on the brakes hard. After that I had the same problem. The vibration wasnt as bad at higher speeds, but it was always present. I took a straight edge to the rotors and hit em with a mic. trying to see if one or both were fucked up. They seemed to be fine. I got a pair on ebay and the problems were gone. Oh and for cleaning out the floating disc points I wouldn't use any type of lube. Someone said it earlier. As the wheel spins any excess lube will work its way onto the braking surface. Maybe use compressed air? Brake dust sucks have glasses and a mask if ya try it. Is the tire scalping on the left side? thats normal wear. Change it. I've never had a scalped tire cause vibration in braking situations. Then again I change em once it gets bad. No idea how bad the tire on your bike is. Fuggit changing rotors possibly pads and a tire can cost ya a few bucks, but better than paying the ultimate price.

[tls25rs]

Check your wheel bearings also. My TL was cupping the front tire and after diggin around a bit I found that the wheel bearings needed replacement. I haven't replaced the front tire to verify that the problem is gone but my wheel spins much more freely now.

Joel

[Degsy]

Wirelessly posted (BlackBerry8330/4.5.0.77 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105)

Casey, that's a good point. Those bearings could have been screwed by the wheel being on backwards.

[stoinkythepig]

My new-to-me ebay rotors exhibited a little shudder under hard braking. I put a dial indicator on them and found about 6 thousandths of runout on one, and about 4 on the other. Got them both within 2 thousandths by lightly smacking the aluminim rotor carriers with a small sledge and a drift. Braking smoothness is vastly improved. If anyone needs to borrow my dial indicator and the custom fork leg mount I made, you are welcome to use it.