front end wobble

[giant81]

I definitely have a front end wobble going on with the C14.  It only happens when I brake.  I plan to order new pads and tire this week, but could it be the rotors?

I've heard that the stock pads can sort of deposit material on the rotors and make it feel like a warped rotor.  This would be what it feels like, it's a vibration that's directly proportional to the speed I'm going when I brake.  If that's the case, how do you clean the rotors to get rid of that material?  If I need new rotors, should I look at something better than stock? 

Any suggestions on what else I should look at?

Thanks!

 

[Freddy]

Yes & yes.  I've found that the only way to successfully remove pad material is to have the discs bead-blasted at an eng recon shop.

 

[gpink]

year and miles?

 

[zarticus]

Brake cleaner & a scotch bright pad will clean the rotors  :beerchug:

 

[giant81]

year and miles?

sorry

'09, 40,200mi  I put about 600/week on so expect that to climb.  I currently have a Metzler roadtech 01 on the rear with about 1600mi on it, and the shinko x16 front with about 7600 on it.  I plan to replace the front tire and brake pads here in the next week or so.

When I do the tire, I'll try to check the rotor for being true, and clean it with a scotch bright red + brake cleaner.  I don't have a gauge to test true, but is that something you could see with the naked eye while balancing? 

 

[gpink]

Might check steering neck bearings.

 

[Freddy]

year and miles?

sorry

'09, 40,200mi  I put about 600/week on so expect that to climb.  I currently have a Metzler roadtech 01 on the rear with about 1600mi on it, and the shinko x16 front with about 7600 on it.  I plan to replace the front tire and brake pads here in the next week or so.

When I do the tire, I'll try to check the rotor for being true, and clean it with a scotch bright red + brake cleaner.  I don't have a gauge to test true, but is that something you could see with the naked eye while balancing?

Absolutely not.  You need a dial gauge and have the bars tied to a full lock position with the gauge mounted on a piece of rail iron (that's what I use) to get a precise reading, plus a micrometer to measure thickness variation, which can also be the cause.

Hope you've been bleeding/flushing the fluid to prolong ABS life if it has it.

 

[giant81]

I do have the ABS and I have flushed everything once, I do wonder though how to know if I've actually gotten enough through the ABS to give it a good flush.

I can say with certainty that the ABS still works perfectly on dry pavement  had a teen on lunch break pulling out of a DQ without looking help me test them out.  Normally when I test the abs, I take it to my parents house.  They have a long gravel driveway, you can safely test abs at lower speeds. 

I'm curious about the steering head bearing.  While I now this is something tire related, how do I know if the steering bearing is going out? 

 

[Deepseamdv]

At 40k miles unless you routinely pull wheelies and drop back down hard your neck bearings are probably fine. Put the bike on the center stand and have someone push down on the back. Grab the forks near the bottom and pull forward. If there is ANY movement have the bearings checked and greased. If you do it yourself be careful, most people get them to tight. Overtightened neck bearings can cause a high speed weave. To loose and it just feels wonky.

 

[yachtjock1]

I just had the same problem and the rings that hold the inner and outer rotor together where stuck so I put an bolt alignment drift into it and rolled them around to loosen them up problem solved.

 

[Tim R]

I also have n 09 but with a few (very few) more miles. If I let go of the bars, I had a handle bar wobble down hill on deceleration and got worse at 35 mph. The Fix? I tried new tires a couple of sets even. Front wheel bearings turned smooth but were hard to turn with fingers. had new front bearings installed. Ah Ha! that was it. Bearings should be easy to turn and no more handle bar wobble if I let them go.

08/09 Front brake disk. Lots of 08/09 owners had rotors replaced due to perceived warp. It is my belief the felt "warp" was actually built up pad material transferred from the pads to a hot disk. For instance. using the brakes then holding the bike from moving with the front brake. Hard to do with rear while stopped. I believe this is when the transfer of pad material occurred. Sanding the disk would remove the pad material and the disk would no longer feel warped.

It appears in 2010 the front disk metallurgy was changed to a softer material similar to the rear disk. I base this on the "lip" that appeared on my rear brake disk. I noticed the rear brake seemed to not brake as well as it had and discovered the lip. I had replaced the rear pads some time before thinking new pads would improve stopping power but it did not. After I found the lip from disk wear. I replaced both the rotor and pads with the braking ability returning like it did.

Some how with the front wheel off a disk carrier was bent. The disk would scrape on the side of the pads....so I bought some nice looking front brake rotors off ebay. But these too had a wear lip. The original disk did not have a lip even after 50K on the bike. I cleaned and spun the carrier buttons in an effort to get things back in line but was of no help. I changed the bent carrier disk with one of the ones bought off ebay. and saved the original disk. At some point I plan to put it back on when I get the proper tools to straighten the carrier. The front brake even with the mixed year disk seem to be working just fine. So not a big worry at this point.

I have not had a chance to try my theory yet as I have not had the chance to stop on a hill with hot rotors and hold the bike with the front brake. At some point I should be able to test the theory. I currently am using EBC front pads and was having pad material transfer with these pads too.

I hope everyone has a happy Thanksgiving. Tim

 

[bobct]

I'm not sure if you got this sorted out. If you don't have a dial indicator, you can put zip ties on the forks and cut or push the remaining end of the zip tie near the rotor surface and get the front tire off the ground then spin the front tire to get an idea if the rotor is warped. Feeler Gage's could be used to get a general idea of how for the space is to determine the runout.

 

[Tim R]

I'm not sure if you got this sorted out. If you don't have a dial indicator, you can put zip ties on the forks and cut or push the remaining end of the zip tie near the rotor surface and get the front tire off the ground then spin the front tire to get an idea if the rotor is warped. Feeler Gage's could be used to get a general idea of how for the space is to determine the runout.

That's too much work. A rubber mallet with a wood handle and one can beat stuff back into submission. The rubber part for moving the carrier and the end of the handle for fine tuning. No joke, that's what I did. Worked on it till the rotor was turning smoothly through the brake pads. No felt vibrations of any kind and stops really well. Nothing like a little poor boy's ghetto engineering huh?

 

[Konehead34]

Necessity is the motherhood of invention....

 

[Just Cliff]

Lots of 08/09 owners had rotors replaced due to perceived warp. It is my belief the felt "warp" was actually built up pad material transferred from the pads to a hot disk. For instance. using the brakes then holding the bike from moving with the front brake. Hard to do with rear while stopped. I believe this is when the transfer of pad material occurred. Sanding the disk would remove the pad material and the disk would no longer feel warped.

This has always been my thought also, always found it hard to believe there was that many warped rotors out there. 1st time I ever noticed the pulsating I scrubbed my disc abrasively & it went away. I now do it at every tire change which averages 4 times a year & it's never occurred again. Brake cleaner & scotch brite pad does wonders.

 

[bmidd]

This has always been my thought also, always found it hard to believe there was that many warped rotors out there. 1st time I ever noticed the pulsating I scrubbed my disc abrasively & it went away. I now do it at every tire change which averages 4 times a year & it's never occurred again. Brake cleaner & scotch brite pad does wonders.

I also do it at tire changes on my bikes. I use a green scotch brite pad, it makes all the difference in the world. 2009 with original rotors and 34k miles.