Possible ABS issue after low speed drop

[STPanther]

A while back I managed a low speed drop of my ST while attempting to ride it out of a grassy ditch. I was riding alone and dropped in on its right side at such angle that I couldn't pick her up by myself. After two kind passers by (one on a moto) stopped to help me get the S10 upright, the only damage appeared to be a broken right mirror. The brake lever and hand guard assembly was pushed down, but I was able to push it back up with some effort. I was able to ride (the long way ;D) home which was 130 miles.

A couple rides later I started noticing a slight hickup or stutter feeling in the front brake lever. It happens nearly every time the front brake is applied. No such feeling in the rear brake. Braking still feels smooth and steady, but I am concerned about what I am feeling in the brake lever. It almost feels like what a loose front rotor would feel like, but both rotors look to be plenty tight. The little hickup only seems to happen when the key ignition (i.e. electirc power) is in on position. The ABS sensor looks to be on the left side of the front end, which didn't take the impact of the drop. I wonder if the ABS sensor took a jolt and could be the issue?

Before I take it to the dealer for a look, I thought I would reach out to the forum to see if anyone else has had this issue?
Thanks for any help.

 

[RIVA]

Sorry to hear of your mishap. Check your brake discs for warp.

 

[Don in Lodi]

The floating portion of the disc assembly will absorb any run-out in the disc. That shouldn't be it. Is the stutter you're feeling a feed back into the brake lever? A pulsation under your fingers? Is the stutter a steady thing, every rotation of the wheel steady? If ABS is activating, even accidentally, the light should come on too. Need to check for any dirt imbedded where it shouldn't be. Some high mineral content mud in the sensor ring might screw with things. Some sand or grit in that floating portion of the rotor could stick the rotor into a warp, though this system is used widely now in everything with no real troubles with sand and grit.
The tid-bit that it started happening a couple rides later tends to suggest it wasn't the tip-over that did it though.

 

[STPanther]

The floating portion of the disc assembly will absorb any run-out in the disc. That shouldn't be it. Is the stutter you're feeling a feed back into the brake lever? A pulsation under your fingers? Is the stutter a steady thing, every rotation of the wheel steady? If ABS is activating, even accidentally, the light should come on too. Need to check for any dirt imbedded where it shouldn't be. Some high mineral content mud in the sensor ring might screw with things. Some sand or grit in that floating portion of the rotor could stick the rotor into a warp, though this system is used widely now in everything with no real troubles with sand and grit.
The tid-bit that it started happening a couple rides later tends to suggest it wasn't the tip-over that did it though.

Thanks for your response. Yes the stutter feedback is felt in the brake lever, much like a single pulse under the fingers. It only happens once (not every wheel rotation) after applying gentle brake pressure. No ABS light is eluminated when it occurs. It happens within a second of brake application.

I landed in a grassy ditch and am lucky the hot pipes didn't catch the grass on fire. That would have been disastrous. I will pull the front wheel and see if any grass or bits of dirt are in places that shouldn't be.

 

[Don in Lodi]

Ah. Take apart and clean all the moving parts in the lever.

 

[STPanther]

Ah. Take apart and clean all the moving parts in the lever.

I will look at the brake lever closer too. Interesting thing is that the stutter feeling is only felt with power to the ignition. When pushing the bike in neutral with key on and motor off, the stutter can be felt in the lever. However, then when the ignition key is in off position, the same little stutter isn't felt.

I haven't pulled the front wheel to look for dirt, grass, etc yet. I failed to mention that I am currently recovering from right achilles surgery I had last week. Not due to the drop of the moto. I hurt it playing sand volleyball. Unfortunately, the recovery time will take months and I will be on crutches for 6 to 8 weeks. I hope to be back on the moto before the snow flies.
My friend may be over to help me tonight. He will be happy to test ride my S10 ::001:: Beers are chilled and ready for the bike doctors. ::003::
Thanks again for the reply.

 

[Don in Lodi]

Hmm. My lever sinks clear to the grip by the time I've backed my running bike down the driveway. Doesn't do it while off. Doesn't do it rolling forward. I'd say it's a ::021:: thang.

 

[Glenn C]

Just a thought...

I had a similar thing when I used to park mine after commuting home. I have to do a " back and fill" turn to get the bike turned in the driveway ready for next morning's departure. This is all done at walking speed, as I have to push the bike backwards on opposite lock then forward again etc. The feeling I was getting back turned out to be the steering head assy being a little loose and once I tensioned it up correctly, no more problem. I really thought it was coming back through the front brake lever but it must have been coming back through the handle bars.

Might be worth checking out as I've seen a few references to loose steering head bearings.

Cheers
Glenn

 

[greg the pole]

is it possible that the banjo bolt on your master cylinder got tweeked a bit, and let air in? Air in the system could be a culprit
had a guy on a gs do the same thing, and his brakes did not work at all,