front forks problem on paralever

[owain]

Can anyone help? my front forks make a knock when I go over ruts at low speeds. Seems to come uop throughthe bars but sometimes feels as if it is under the seat. rear shock fine (WP). have tightened head bearings so they are perfect- they were loose. new fork oil- no change. Wheel bearings are good and everything is tight (caliper etc).
Any ideas?

 

[B Murr]

Have you had the bike long? Did it always make this sound from 1st day you had it. Are the fork seals weeping? Front wheel bearings OK? Have you done anything which might have damaged the bike, hard off roading etc.

 

[Bill-H]

Petrol tank loose / missing rubber support ?

 

[MickDB1]

Sit on yer bike and get someone else to flick yer centerstand down and back up with clunk
you may get the same sensation

 

[nud1e]

you could check the front disc, it is supposed to float in and out, but the mounting bobbins wear and the disc begins to move fro and aft on the bobbins with a rattle or clunk.

 

[owain]

I've had the bike for 12 years! Have ridden it to Cape town (97-98) but other than that, its had an easy life. Fork seals are dry, wheel bearings ok. I've checked centre stand "bounce"- no not that. Tank is solid and mountings are good. I will se if the disc has got any movement- pretty sure it is all tight though. Any more ideas...?

 

[VAL. H.]

I've had the bike for 12 years! Have ridden it to Cape town (97-98) but other than that, its had an easy life. Fork seals are dry, wheel bearings ok. I've checked centre stand "bounce"- no not that. Tank is solid and mountings are good. I will se if the disc has got any movement- pretty sure it is all tight though. Any more ideas...?

Sounds like you need to replace the fork bushes to me.

Failing that you should recheck the head bearings. Simply tightening them won't solve the problem if they are worn. You need to strip, check and regrease or replace.

The noise you hear is the result of the forks being pushed up, and forward at the top giving a knock.
This will occur in the top head bearing as the bottom bearing is pushed into the worn grooves of the needles under compression. Not always spottable when the bike is on it's stand.

With the forks; the bushes ware (become oval), allowing the fork leg to become laterally unstable in the form of forward backward movement, also side to side. Lots of scope for wheel wobble and interesting tank slappers too.
The knock is the top bush hitting the back of the stanchion when under compression. Also not necessarily easy to spot when the bike is on it's stand, and is unlikely to affect the seals at this stage.

Two relatively easy jobs, and will transform the bike completely 'especially the fork bushes'

Val.

 

[B Murr]

I've had the bike for 12 years! Have ridden it to Cape town (97-98) but other than that, its had an easy life. Fork seals are dry, wheel bearings ok. I've checked centre stand "bounce"- no not that. Tank is solid and mountings are good. I will se if the disc has got any movement- pretty sure it is all tight though. Any more ideas...?

Go on, tell us about the cape town trip. Any pics, any mods to the bike, problems encountered etc etc.

 

[owain]

Thanks for this Val. I will investigate fork bushes- wasn't aware of these but haynes may shed some light? I am about to have the forks stripped to look inside and will replace springs with hagon progressives. The head bearings were very loose when I first investigated and i've tightened them up so there is no notchiness whatsoever but the bars move freely side to side. From what you are saying, despite this feeling right, the bearings may still be knackered?
Owain

 

[VAL. H.]

Thanks for this Val. I will investigate fork bushes- wasn't aware of these but haynes may shed some light? I am about to have the forks stripped to look inside and will replace springs with hagon progressives. The head bearings were very loose when I first investigated and i've tightened them up so there is no notchiness whatsoever but the bars move freely side to side. From what you are saying, despite this feeling right, the bearings may still be knackered?
Owain

In most cases, if the head bearings feel smooth with free movement and are well lubed they will be fine. But with old bikes and well used bikes it is possible for other underlying issues to be the route cause of the problem. One such thing is the possibility of the bearing cups to become worn where they are pressed into the frame. This is a very rare thing indeed, but if you bike has been running with loose headstock bearings it is quite possible for the movement in the bearings to cause movement in the cup seat. This can also cause the cup to distort, becoming crisp shaped. These are however usually only found after extreme neglect or abuse.

With reference to the fork springs; firstly if you pulling them apart anyway, do the bushes as part of the rebuild. It would be a wast not to.

In the many years I've been riding motorcycles, both professionally and for fun. I have come to learn that there are two Manufacturers of common use motorcycle after market parts that IMPO should be avoided at all cost.
EBC and Hagon. They both do the job and both offer low budget alternatives. Sadly they also both fall far from the functionality claimed, and become a false economy and a regret.

I personally would look at the Hyper-pro or even TT and Wunderlich springs before committing to the Hagons.

Val.

 

[owain]

What about my rear shock- it is a second hand White Power unit and gives a stiffer ride than the boge original. The knock from underneathis like bottoming out which I am only now beginning to think could be a possibility; the WP has been so good and strong. There is no sign of oil though- i guess it is a gas one (it has a piggy back reservoir at the top of it and the two lock nuts for adjustment of spring load, with two black dials , one at top and one at bottom which are rebound and compression i guess. ) Do you have any comments on these too I wonder? I am looking at having it stripped and re-built if it is bottoming.
Owain

 

[B Murr]

If you can't track down the noise try to go for aride with an oversized helmet or an old one which has loosened up a lot. When I was scouting about for my airhead I used to wear an old loose helmet for the test rides as I could hear an awful lot of what was going on with the mechanicals whereas a new helmet deadens the noise. deeper clunky sounds are harder to trace (which is why you can pretty much place a subwoofer anywhere in a room as deep sounds dont just reach the inner ear via the outside of the ear, they go through the flesh/skull too easily and hence our brains find it hard to discern which direction the come from) so every little bit, like a loose or non existent helmet, helps.

 

[AliBaba]

What about my rear shock- it is a second hand White Power unit and gives a stiffer ride than the boge original. Owain

Good point!
I had a WP where the bearing at the lower mounting-point (bevel-drive) failed, it made a metallic noise.
Put the bike on the main-stand and try to lift the wheel when you watch the shock.

 

[VAL. H.]

What about my rear shock- it is a second hand White Power unit and gives a stiffer ride than the boge original. The knock from underneathis like bottoming out which I am only now beginning to think could be a possibility; the WP has been so good and strong. There is no sign of oil though- i guess it is a gas one (it has a piggy back reservoir at the top of it and the two lock nuts for adjustment of spring load, with two black dials , one at top and one at bottom which are rebound and compression i guess. ) Do you have any comments on these too I wonder? I am looking at having it stripped and re-built if it is bottoming.
Owain

Good point!
I had a WP where the bearing at the lower mounting-point (bevel-drive) failed, it made a metallic noise.
Put the bike on the main-stand and try to lift the wheel when you watch the shock.

I've not used WP shocks myself, but the obvious things to look for are bushes as said by AliBaba above and the rebound damping. This if it has failed will allow the spring rebound rapidly without any damping giving an obvious clonk as it reaches it's full extension.

As for your thoughts on the spring compressing too much; you would probably notice this quite easily, because you'd firstly notice the bike sagging more than normal when you get on it. Also you'll get a sea-sawing motion as you ride the bike and a jarring clunk over bigger bumps.

I'd stick with the forks for now, or you going to get confused. Be systematical in your approach, ie starting at the front eliminating things as you go.

It's also worth noting that clonks can come from other places on the bike as well, from swing arm bearings, loose sub frame, unsecured fuel tank, seat, tool box or even something bouncing around inside your panniers and more.

Val.