Weird vibration under very heavy braking
 

So as I'm getting more confidence on the bike and braking ever harder, I'm starting to get the vibration back in the bike under really, really hard braking (at the point of stoppying) which I thought was gone when I set the suspension up.

There is about 5 mm left on the fork under really heavy braking, maybe I'll increase the preload, but it tends to be when the rear brake is on hard as well. I braked very hard 3 times in short succession and the bike only vibrated when I had the rear brake on too. This lead me to think it's the back hopping about, any harder on the rear brake and it slides.

However, when I brake very hard on the front there is a slight click felt through my arms, although I think that's the clipons, as when I grip hard with my knees there is no click. Also there's the occasional cluck under braking on uneven surfaces.

I might make the ride a bit firmer, but I think it's one of four things:

1 - Front forks having enough (gsx-r750 front end) and rebounding up at their base
2 - Stock rear shock topping out
3 - Rear wheel skipping
4 - Head bearing.

With regards to the head bearing, I don't have a paddock stand/way to take weight off the front, but at slow speeds moving the bars slowly results in no notching at all.

I thought I'd post to the mighty 'org to see what's going on; thanks in advance.

Re: Weird vibration under very heavy braking
 

Vibration through the bars or is the lever 'pulsing'?

If it's the lever, you probably have warped discs.

Re: Weird vibration under very heavy braking
 

Lever isn't pulsing at all, vibration is through what feels like the whole bike, it's tough to say but I'd say I feel it most through the seat.

Re: Weird vibration under very heavy braking
 

Check everything is tightened up correctly, check the bearings and check the wheels are balanced.

Re: Weird vibration under very heavy braking
 

+1 make sure everything is all tight etc...and as it should be.

;)

Re: Weird vibration under very heavy braking
 

Will give it a go - what do I need to look for to tighten?

Re: Weird vibration under very heavy braking
 

http://www.apriliaforum.com/forums/s...d.php?t=161457

This may help you. I also get something similar, can deffinatly feel its from the front though. Its as the brakes grip and then let off a little as the grip goes on the disc because of the muck and grime causes a little vibration.

Anyway read it and see what you think. :D

Taa.

Re: Weird vibration under very heavy braking
 

5mm left ... USD or RWU? sounds like you night be getting coil bound .... that is not good .. =;

Re: Weird vibration under very heavy braking
 

USD - and what does coil bound mean? I was doing some more very scientific testing and it happens only when I stamp on the back brake.

Re: Weird vibration under very heavy braking
 

Thanks very much, that's very interesting, it's definitely only on the back brake that it happens so who knows?