Clunking in forks / steering

[briandneville]

Here's a summary of info gathered from another thread:

My '83 has a clunk in the steering / forks under hard braking.  The sound occurs once during each time the front brakes are used with a lot of force, and there is no subsequent clunk during rebound.

From Kevin G: "The clunk when braking could be the steering head bearings but I would also expect some clunking going over bumps.  I think you mentioned that there were tapered rollers installed.  Mine needed to be re-torqued after riding a short while."

From POD:  "most likely Steering bearings or even loose calipers.
Another possibility is slop in the damper.  I've attached a sheet (in German sorry) about fixing this - a procedure I did on my 400 with great results"

From Jefferson:  "The clunk you mention is most likely the top triple clamp moving on the steering stem. People have used shims to tighten things up to get rid of it. The lug is there on the top triple clamp to drill and slot so the triple clamp could be tightened up on the steering stem, but Yamaha deemed it unnecessary and never finished the machining to put a pinch bolt there. You could try tightening the center nut tighter in case it isn't tight enough, but you must first loosen the handlebar bolts so the top triple clamp will be able to move down."

and:  "If you go through the old newsletters the front end clunk was mentioned enough times it would have had a sticky on modern forums. The culprit is the top triple clamp not being tight enough on the stem. Loosen the bolts that hold the handlebars to the top clamp and then tighten the bolt in the center of the triple clamp. It needs to be really tight. Ride and report back. Oh, and don't forget to tighten up the handlebar bolts afterwards."

I bought my vision from Fiat Doctor who told me there was an article in German about a circlip that could be used to get rid of the clunk.  Sounded like a myth but then POD posted the article.  I have attached that here with an english translation, thank you internet.

Hope this is helpful to someone.

[motoracer8]

 You also might find excessive play in the upper bushings in the fork sliders. They can be replaced but its a pain.

[MikeScoot]

How bad is the clunk? Could you get to like it and live with it? Is it harsh enough to cause serious trouble?

[briandneville]

I would not call it a serious problem and probably not something I need to worry about but if I can address it while I've got the front end torn apart I'd like to.  I don't think I will ever 'like' the sound but it does add character.   Thanks for the thought.

[fret not]

If you can feel the clunk when it happens then it is most likely 'loosness' around the steering head area, but if it is just an audible 'clack' it is likely to be the inner fork springs slapping against the inside of the fork tubes.  This used to be a 'problem' with Honda 750s in the early 70s.  You would hear a clack when going over a bump, but not so much when applying the brakes.

[briandneville]

Well, the problem is now gone.  After reassembling the forks, new oil, seals etc..., rebuilding and reinstalling calipers (not stock Vision parts), and re-torquing the steering column, the clunk is gone.  Seems the likely source was the steering head, for which tightening is more art than science.   I also put new tires on the bike, Avon Roadrider MKIIs, which were kind of pricey but do have a noticeably better feel than the 10 year old Shinkos that were on it.

Mission accomplished!  For now...