Front end Chatter

[padgett]

94 fzr600. I've had this bike for about 5 months, always had this problem, even after the stuff i mention below.

On light to medium braking i feel some vibration through the handlebars. I can also look down to the forks and watch them shimmy around at the wheel during braking.

Things i've done so far-
Steering stem baring is new, not too tight, able to swing the front around freely.
Forks have progressive springs, double checked fluid level today and they're right on 4inches fully depressed. 10w oil
Checked torque on front axel, stem nut, fork pinch bolts and brake disc bolts.
r6 front brake setup (master cylinder, lines, calipers) New pads.

I think its the discs, but I want to make sure theres not something i'm missing before dropping that $$$
I never did a fork alignment either, could that be something?


Thanks for looing

[DonTZ125]

The fork can get put back together a bit twisted up. Loosen your axle pinch bolt, loosen the axle, loosen the lower triple clamp pinch bolts. Do NOT loosen the upper pinch bolts, or you get to play "pick my bike up"! Squeeze the front brake, and bounce the front 2-3 times. Tighten the lower clamp pinch bolts, tighten the axle, tighten the axle pinch bolt. Try it out.

[padgett]

Hey Don,

Thanks for the reply. Put the bike on a rear stand and did what you said. Seemed to make it a bit better, but it really seems like the stem is knocking around. Barings are new, but i did have them pretty tight for a few weeks, i doubt thats long enough to ruin them...

Still i might need rotors due to this feeling a bit rotational

[DonTZ125]

If the stem is "knocking around", then the ring nuts came loose. The bearings will seat in if they weren't torqued-in enough, resulting in reduced tension on the stem, allowing the nuts to start drifting.

[padgett]

Hey Don,

Thats definitely what it feels like, but if that was the case it would stand to reason that I could replicate the feeling by having the bike stopped and pumping the forks or trying to get the stem to move around. Can't replicate it anywhere but on the road.

Also when i Installed the new stem baring i definitely had it too tight in order to seat it, then backed it off to the point where the front end could move easily. Although I did inspect the races and they didn't seem bad so I left them in. If I need to do the job again, then so be it. Just want to have an informed next step instead of doing work that doesn't need to be done. And just to note i did look at the stem nuts yesterday and they were still tight, washer still in place.

THanks for your replys!

[M in KC]

What condition is your front tire in.? Perhaps a rebalance could be in order.

[padgett]

so its been a bit. I cut out the old steering bearings and replaced them, this was the thing i for sure thought it was. Nope.

Replaced front rotors, that did make a difference! But problem not totally gone.

I read around here that if the bar ends are changed then some headshake like issues can happen. The ones on this bike i got are not stock, press in rubber ones, not threaded bar ends. I feel it in the handlebars so thats where I'm looking next. We are all tight with mounting points on the clip ons/forks. But let me know if I should go back to stock bar ends, if that'll help the issue possibly.

[willandrip]

The heavy stock bar ends are more for damping out mid rpm vibration.
They are not hard to source, originals are usually cheap and it might be an economical eliminator.
They wont stop "chatter" from the forks/wheel/tyre combination.
Lead ? bar snakes and damper beads are available but are designed more for "long " traditional style bars....(cruisers)

I would have had the tyre removed and spun round the wheel in a different alignment if not replacing it.

What were the brake pad pins condition...you need to inspect them more regularly if a lot of vibration is occurring...it is not unknown for them to prematurely wear or even the R pin to displace and pin/ pads to drop out.

[padgett]

The heavy stock bar ends are more for damping out mid rpm vibration.
They are not hard to source, originals are usually cheap and it might be an economical eliminator.
They wont stop "chatter" from the forks/wheel/tyre combination.
Lead ? bar snakes and damper beads are available but are designed more for "long " traditional style bars....(cruisers)

I would have had the tyre removed and spun round the wheel in a different alignment if not replacing it.

What were the brake pad pins condition...you need to inspect them more regularly if a lot of vibration is occurring...it is not unknown for them to prematurely wear or even the R pin to displace and pin/ pads to drop out.

Thanks for the reply, Willan.

At this point i'm going to give the bike to my mechanic and see what he can think about it. I'll report back.

As far as the pad pins, they're good. When i put r6 calipers on there I cleaned the muck off them and lubed them with synthetic silicone.

[padgett]

Well I hate it when i'm researching something online and people say "i'm gonna take it to the mechanic" then the thread dies. I don't want to do that here.

I took the bike to my mechanic, and all he did was retorque the steering head bearing to get that 'chatter' away.

There were some other things he pointed out taht could have contributed to the problem. One of the front calipers had a ton of drag, the brake pad was angled on the rotor so it wasn't seated on the rotor completely flat. That was due to a helicoiled thread on the caliper that was put in crooked by the last owner. he recoiled it and that fixed the dragging issue.

He also noted that I could probably deal with some heavier weight fork oil due to the rebound he demonstrated to me on a known good bike, vs mine. So i'm going to play around with oil weight a bit.

But long story short, the problem was solved by properly torquing the stem nuts using an actual torque wrench meant for the job, and fixing front drag.

Thanks for your help along the way.

[pnbell]

Thank you for closing this thread with your resolution!

I clicked on this post to recommend tightening the stem nuts because had this issue on a bike a few years ago.

Anyway glad its fixed and thanks again for updating this post with your findings; you've just made the internet more useful!