• Ciao Guest - You’ve landed at the ultimate Guzzi site. NEW FORUM REGISTRATIONS REQUIRE EMAIL ACTIVATION - CHECK YOUR SPAM FOLDER - Use the CONTACT above if you need help. New to the forum? For all new members, we require ONE post in the Introductions section at the bottom, in order to post in most of the other sections. ALWAYS TRY A SEARCH BEFORE STARTING A NEW TOPIC - Most questions you may have, have likely been already answered. DON'T BE A DRIVE-BY POSTER: As a common courtesy, check back in and reply within 24 hours, or your post will be deleted. Note there's decades of heavily experienced Guzzi professionals on this site, all whom happily give endless amounts of their VALUABLE time for free; BE COURTEOUS AND RESPECTFUL!
  • There is ZERO tolerance on personal attacks and ANY HYPERLINKS to PRODUCT(S) or other competing website(s), including personal pages, social media or other Forums. This ALSO INCLUDES ECU DIAGnostic software, questions and mapping. We work very hard to offer commercially supported products and to keep info relevant here. First offense is a note, second is a warning, third time will get you banned from the site. We don't have the time to chase repeat (and ignorant) offenders. This is NOT a social media platform; It's an ad-free, privately funded website, in small help with user donations. Be sure to see the GTM STORE link above; ALL product purchases help support the site, or you can upgrade your Forum profile or DONATE via the link above.
  • Be sure to see the GTM STORE link also above for our 700+ product inventory, including OEM parts and many of our 100% Made-in-SoCal-USA GTM products and engine kits. In SoCal? Click the SERVICE tab above for the best in service, tires, tuning and installation of our products or custom work, and don't miss our GT MotoCycles® (not) art on the BUILDS tab above. WE'RE HERE ONLINE ONLY - NO PHONE CALLS MADE OR RECEIVED - DO NOT EMAIL AND ASK QUESTIONS OR ASK TO CALL YOU.
  • Like the new V100, GuzziTech is full throttle into the future! We're now running on an all-new server and we've updated our Forum software. The visual differences are obvious, but hopefully you'll notice the super-fast speed. If you notice any glitches or have any issues, please post on the Site Support section at the bottom. If you haven't yet, please upgrade your account which is covered in the Site Support section or via the DONATE tab above, which gives you full site access including the DOWNLOADS section. We really appreciate every $ and your support to keep this site ad-free. Create an account, sign in, upgrade your account, and enjoy. See you on the road in 2024.

Clonk sound from front forks

NPS

Cruisin' Guzzisti
GT Contributor
Joined
Dec 11, 2008
Messages
262
Location
Churchdown, Gloucester, UK
Just wondering if other owners experience a heavy clonk sound going over sudden or deep bumps? My bike is 2005 Breva 1100.

I rebuilt my forks last year. I have noticed a clonk sound that seems to come from the headlamp cluster.
I'm not sure if the sound is from here or is a shortwave been transmitted through the front suspension.

Last week I removed each suspension unit and stripped to check over. I found nothing that did not seem out of the normal condition. I use standard fork oil of 10 viscosity with 400cc in each leg. The adjusters have been screwed in and recently far out with no difference.

I have checked the steering head bearings for play and there is nothing to speak of.

The sound seems to happen near or at the far out of fork travel. Perhaps I should try using less oil to reduce the air compression to lower the height slightly. I think this works. I certainly has the opposite affect if too much oil is added.

Does anyone have any thoughts?
 
Heavier grade fork oil.

Also use some zip tires on the forks just above the sliders.
When the fork compresses it will push the zip tie up.
Now you can tell how much fork travel is happening.
Easy way to see if the forks are bottoming out.
 
Heavier grade fork oil.

Also use some zip tires on the forks just above the sliders.
When the fork compresses it will push the zip tie up.
Now you can tell how much fork travel is happening.
Easy way to see if the forks are bottoming out.

Its on extension that the clonk is happening. But I will certainly consider trying heavier oil.
 
My personal experience is my forks seem to better with 15 weight fork oil. I have no strange sounds and the feel/handling is pretty good.
 
I drained and refilled the forks with 15 weight oil today (380cc per leg as not dry inside). Before replacing plastic pre-load tube and spring I pumped to remove the air. The feeling was as I thought it should be. Easy to push down and hard on pulling out.

I went for a ride. The clonk is still there on hitting a pot hole either on compression or extension against the spring stop in the damper. It is hard to tell which but not full compression of the fork.

The ride was very uncomfortable. I think I'm used to a 5 weight oil. On bumpy roads it was a lot harder to control so mine does need a lighter oil. With the wheel off and the spindle shaft clamped in place I hit it with a rubber hammer. The shock made quite a loud noise. Seemed to be amplified by the mud guard. I heard the LH spring vibrating inside the stanchion tube. Also sound from the headlamp bracket and headlamp area. I'm beginning to think this is a shock wave sound transmitted to the lighter items in the steering that is amplifying the sound. I'm not imagining it and this sound is new since I rebuilt the bike.
The head bearings are tight with no play. The top yoak is tight against the steering head bearing adjuster rings and the large top disk like fastner (with massive hex in the middle) is also tight.

Perhaps I will dismantle the head bearings over winter to check, but not sure what good that will do. Handling is good though (with lighter oil). It is just the clonk noise over pot holes and speed bumps that spoils my enjoyment.
 
Thanks John. I have tried different settings. I had mine fully in for a number of years. Two weeks ago I wound it fully out. Does not make any difference to the clunk.
 
Changed back to 5 weight oil today. removed top yoke to inspect head bearings. All fine.
I have found something that could cause a the clunk. Either side of the headlamp is a u section plastic tube thing. These were just on the headlamp support frame and the obviously have a use. Perhaps to prevent cables wearing on the blunt edges of the headlamp mounts.
I decided to push them forward slightly so they fit between the headlamp and the head lamp supports. I tightened up and the sound when taping the headlamp is very muffled due to these two u section plastic things in the gap. I wonder if this could be it. I will have to have a ride and see.
 
mine is doing the same clonk, I have heavier oil and hyperpro springs .....clonk is much reduced now I have tightened the steering head bearing.
 
  • Like
Reactions: NPS
Changed back to 5 weight oil today. removed top yoke to inspect head bearings. All fine.
I have found something that could cause a the clunk. Either side of the headlamp is a u section plastic tube thing. These were just on the headlamp support frame and the obviously have a use. Perhaps to prevent cables wearing on the blunt edges of the headlamp mounts.
I decided to push them forward slightly so they fit between the headlamp and the head lamp supports. I tightened up and the sound when taping the headlamp is very muffled due to these two u section plastic things in the gap. I wonder if this could be it. I will have to have a ride and see.
Edit: Made no difference.
 
I'm going to take yet another look at my head bearings. Has anyone fitted tapper roller bearings?

Yes I have. Bit of a job taking everything down to get the old rollers out and the tapered in. Customer said he felt the bike handled better after.
 
Just stripped the head down yet again. Roller ball races are completely OK. The races are very good like new. I ordered some tapper roller bearings anyway to fit in over the weekend if they come tomorrow. I just cant see the problem being the head bearings. There was no up/down side to side play that I could feel. Certainly not enough to move to cause a clunk.

While I had the forks off I tried pumping each. There appears to be a distance of about an inch between the compression damping and the rebound damping. Obviously rebound is the more heavy of the damping but there is still some damping on compression of the fork.
This distance at damping change over could be the culprit. Done quickly it does generate a sound. It is roughly the same on both forks.
I didn't have this problem before my rebuild. In the rebuild I replaced both fork stanchion tubes with MG replacement items. Also the top and bottom bushes. Springs and preload tubes are original. The plungers are the originals although I replaced the plastic sealing rings.

I'm using 380cc of 5W oil in each leg. Oil viscosity does not make much difference to the sound, nor does the spring compression adjuster.

If I could upload a video I would. I wonder if it is possible. I will record a youtube video and post the link.

This clonk noise spoils all enjoyment when riding. There must be a solution.
 
Last edited:
Clonk solved. Well 7/8ths of the clonk gone.
New taper roller head bearings. Filled each leg to 450ml 5w oil.
One or both is responsible and I don't know which. I have tired greater than 400ml per leg before but found the ride to hard due to the air compression. I had a 40 mile ride today and I can cope with the firmer forks.
Do I feel a difference with different head bearings. Unfortunately, I made two changes at the same time. The bike does feel quite different. But the clonk has largely gone too. So all very confused and subjective. I do like it though. Moved on considerably and much more enjoyable to ride compared with what I have been used to.

I feel the clonk comes from the movement in the fork between compression and extension. There is a valve in the end of the stanchion tube that the plunger shaft passes through. This valve must let oil through on compression but not on extension. The shutting of the valve causes an immediate change in damping. It is a piece of plastic that shuts against a flat bottom of the stanchion. You would expect it to be immediate in the affect. However, I believe this created a shock wave into the fork and to the steering head. Perhaps the extra metal contact of taper roller bearings over balls somehow modifies this shock transferring it to the frame rather then headlight and instrument cluster (causing the noise). Just guessing but the difference is very positive and will allow me to enjoy the ride again.
 
Back
Top