Author Topic: Shaking Front Fork! (Read 6166 times)

Bimbam · « **on:** 01 August 2015, 06:26:36 pm »

Hi. i have a problem with my front fork. When i drive from 140 km/h and beyond, the front fork begins to shake (forward and backward) like the wheel is out of balance.
With 190 km/t it is pretty bad. Could it be the wheel? It is worse under acceleration. From 0-130 there is no problem.

darrsi · « **Reply #1 on:** 01 August 2015, 06:53:05 pm »

Have you ever changed the fork oil?

celticdog · « **Reply #2 on:** 01 August 2015, 07:01:15 pm »

Can you tell us all a bit more? Is it Is it vibration/twisting or more of a shimmy? Is there any noise associated with it? Turning, does it get better or worse? Could be wheel bearings, steering head bearings or something as simple as an out of balance wheel, any leakage at the top of the fork oil seals?

Bimbam · « **Reply #3 on:** 01 August 2015, 07:26:15 pm »

Springs and fork oil is changed. Oil seals ok.
About 140 km/h the front fork viberates / shakes +-2 cm forward and backward, total ca. 4 cm. My Gps on the handbar almost shakes off.
No probs with turning, small turns and high speed turning is perfect.
Bearing ok when i check it with the bike on the center stand.

celticdog · « **Reply #4 on:** 01 August 2015, 07:34:15 pm »

Quote from: Bimbam on 01 August 2015, 07:26:15 pm

Bearing ok when i check it with the bike on the center stand.

Hi Bimbam, which bearing, are you talking about the front wheel?

Bimbam · « **Reply #5 on:** 01 August 2015, 07:59:38 pm »

Yes, front wheel and back is ok as well.

celticdog · « **Reply #6 on:** 01 August 2015, 08:25:07 pm »

Next I'd take a look at the steering head bearings. Put the bike on centre stand and check for play both forward to back and left to right. Get someone to put their weight on the rear, to raise the front wheel. With a single finger on the handlebar check the free movement, feeling for any stiff spots or notchiness. Balance the bar central and let it fall, don't matter if to the left or right but they should fall all the way on their own.

darrsi · « **Reply #7 on:** 01 August 2015, 08:26:04 pm »

Whatever it is I would seriously stop doing those speeds again until it's sorted out!

Bimbam · « **Reply #8 on:** 01 August 2015, 09:46:26 pm »

Head bearings checked, no probs. Nice free movement on the handlebar and no stiff spots.The bar falls nicely both ways.
So i guess it must be the wheel thats out of balance.

Frosties · « **Reply #9 on:** 01 August 2015, 10:26:52 pm »

What condition is the front tyre in? Starting to square off? Cheap brand?

darrsi · « **Reply #10 on:** 01 August 2015, 10:34:51 pm »

You're saying 2cm, that is A LOT of play?

Bimbam · « **Reply #11 on:** 02 August 2015, 05:38:33 am »

Tyre is Metzler Roadtec Z8 110/70 ZR17 and it is to be changed soon.
I have done 15.000 km on the tyre and mabye the shaking is getting worse.
I got the bike last sommer and i dont drive above 130 km/h, but sometimes it is fun to have a full acceleration and some speed.
Darrsi; When it shakes so much at high speed, it dosent feel safe

darrsi · « **Reply #12 on:** 02 August 2015, 11:36:28 am »

Who actually changed your fork oil?

There are 2 levels listed in the manual, the 98/99 bikes need more oil than the 00/03 ones as they don't have preload adjusters on them.
Is it possible that you don't have enough oil in the forks?

I've not really ever had a wheel so out of balance that it violently shook, but i s'pose that it's very possible. Just make sure they balance it when you change the tyre.

If you ever consider checking your oil out, or next time you replace the oil, use 15w instead of 10w, it firms up the front end very well.

celticdog · « **Reply #13 on:** 02 August 2015, 07:27:05 pm »

That's a very good call from Darrsi, definitely check the fork oil levels.
I've assumed that it's more likely to be the steering head bearings, as the free play is forward & backwards not up and down. Anyway, other than replacing the fork oil, front tyre, and wheel/headrace bearings, It's well worth your time re-torqueing everything at the front end, those vibrations won't have done you any favours!

Bimbam · « **Reply #14 on:** 02 August 2015, 08:02:38 pm »

Oil changed and correct level checked.
The shaking was there, before and after.
I used 20W and it helped a bit.
Everything is re-torqued exept the headrace bearings.
I think, i will start with a new tyre.

Frosties · « **Reply #15 on:** 03 August 2015, 09:44:30 am »

Quote from: Bimbam on 02 August 2015, 08:02:38 pm

Oil changed and correct level checked.
The shaking was there, before and after.
I used 20W and it helped a bit.
Everything is re-torqued exept the headrace bearings.
I think, i will start with a new tyre.

Good call - come back and let us know if the issue's still there

Good luck

Frosties · « **Reply #16 on:** 12 August 2015, 08:48:53 am »

Any update fella? Still shaking?

Bimbam · « **Reply #17 on:** 12 August 2015, 09:48:23 am »

Hi. I am getting a new tyre next week.
I'll be back

Bimbam · « **Reply #18 on:** 19 August 2015, 04:43:43 am »

New tyre fixed the problem!.
I got new Metzler SportsTec M7RR, front and rear.

darrsi · « **Reply #19 on:** 19 August 2015, 05:29:38 am »

Quote from: Bimbam on 19 August 2015, 04:43:43 am

New tyre fixed the problem!.
I got new Metzler SportsTec M7RR, front and rear.

As tyres wear from new they will become slightly unbalanced over time, even more so if they're not wearing evenly for whatever reason.
Having a tyre/wheel balanced again half way through the tyres life would make perfect sense to compensate for the general wear and tear, but nobody ever really does this.
At least it's sorted now, and you got new tyres out of it too.

celticdog · « **Reply #20 on:** 19 August 2015, 11:40:04 am »

Excellent Bimbam! That's good news, I'm glad it fixed the problem for you.

Frosties · « **Reply #21 on:** 19 August 2015, 12:17:44 pm »

Quote from: Bimbam on 19 August 2015, 04:43:43 am

New tyre fixed the problem!.
I got new Metzler SportsTec M7RR, front and rear.

Nice one fella.