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front end knocking noise

Posted: Sun Jul 19, 2009 11:19 pm
by brido
Hi all went riding my nc30 this afternoon and noticed every time that I went over any rough parts in the road or any holes that I heard a knocking sound from the front end, I'm thinking steering head bearings myself but was wondering what anyone on here thought it might be???
cheers all...

Re: front end knocking noise

Posted: Mon Jul 20, 2009 3:42 am
by greggo
There be a couple of things this could be...

First make sure you have checked nothing is loose around the clocks/lights etc...

Knackered steering head bearings will usually result in the bike 'falling' into the turn and feeling uncertain at lean angles.

If you have a front stand, get the front wheel off the ground a look for freeplay at the headstock. Grasp the front wheel and try to rock the whole front end back and forth. You're steering will be notchy if the bearings are knackered when you turn the wheel from side to side, and you would feel some movement at the front wheel if your head bearings are loose.

If you don't have a stand sit on the bike, pull on the front brake, and with your other hand place your fingers between the bearing cap and frame, then pump the forks up and down. You'll 'feel' a clicking if your head bearings are loose. Takes a bit of practice to get this right and detect any problems.

Depending on how long it has been it could be worth repacking the steering head bearings anyway. I do mine every 6 months. If you ride on rough roads especially....

Other potential things it could be
Knackered wheel bearings - you'll get some evil handling if this is the case
Fully floating discs - the disc has a few mm of freeplay on its rivets. No big deal
Could be the pads moving in the calipers from tired spring clips - no big deal, racers run without these.
Worn front forks - could be the bushes, lost oil, knackered compressed springs....if none of the other things find/fix the problem its time for a front end rebuild. And at the age of these bikes, they need it. Last front end I pulled apart came off a road bike and the oil was grey, lumpy, and the consistency of snot.

Re: front end knocking noise

Posted: Mon Jul 20, 2009 9:28 am
by CMSMJ1
Could also be a loose mudguard.... ;)

Re: front end knocking noise

Posted: Mon Jul 20, 2009 11:55 am
by royster81
CMSMJ1 wrote:Could also be a loose mudguard.... ;)
i had this and two rings of PVC tape as graeme france said put a stop to that ...

Re: front end knocking noise

Posted: Mon Jul 20, 2009 12:00 pm
by Spike16
I had this when going over some speed bumps by my house which are down hill or a pot hole especially when trailing a bit of brake, also thought it was the headstock as I got alot of vibration through the bars when it happened, I rebuilt the front forks with some new oil and never heard it since + bike feels much better round corners much more planted

Re: front end knocking noise

Posted: Mon Jul 20, 2009 5:00 pm
by brido
Cheers lads thanks for the replies and the possible causes, I will just go through the list of probable causes and see what turns up. So thanks again :smile: