Slight clunk in front end

[Erdoc48]

1994 ST- ABS model but really doesn’t matter for purposes here- for a while under relatively heavy braking and only when going over rough surfaces I hear (slightly) and feel (mostly) a clunk vs vibration in the front and through the bars - under normal braking on a smooth surface, nothing abnormal is noted. I jacked up the front end to check the steering head and it feels solid, no stiffness when turning the bars in either direction. Handling is normal, and is not twitchy and no wobble is noted (well, decel wobble with hands off the bars at 45 mph- I have a more recent Shinko Verge on the front, but the decel wobble was not noted with the last 2 tires used: a Metzeler Z8 and Pirelli Angel GT- had a Shinko originally when I got it and had the decel headshake then as well).

One fork was leaking last year and all bushings replaced as well as seals - has Progressive springs up front (done by prior owner) and running 10Wt oil (and this above issue was both before and after the fork rehab).

Relatively new brakes and anti-rattle shims as well (last year).

Stock bearings (not tapered roller)- as far as I know, never changed but I am the 3rd owner of the bike
49,500 miles
This has been present for some time (likely the past few years that I can recall, and maybe I’m just noticing it more in the recent past). My 8000 mile Silverwing has the same thing.

The above is NOT noted on my 2000 which has tapered roller bearings changed early in the life of the bike with me and a fork brace/ Superbrace.

My brother suspects the bearings in the steering stem (but why on an 8000 mile Silverwing as well??).

Questions: Do I: 1) plan to change out the bearings (I assume not serviced so original grease on everything)- if this is the option, I’m not sure I’m up to the task and assume it will be more substantial $$$ to have a shop do it.
2) just buy the spanner and tighten them up a tad

All ideas are appreciated.

 

[SMSW]

IIRC, there is a loaner kit do do this - i.e. replace the steering head bearings. Maybe @John OoSTerhuis has it or knows where it is?

 

[dwalby]

when you had the front end jacked up did you grab the forks and push them forward/backwards towards the bike with the wheel pointing straight ahead. If the steering stem is loose you'll feel a clunking that could be what you're feeling while riding.

another possibility is the anti-dive unit on the fork lower tube. It can clunk under certain circumstances, or maybe it has issues that need to be addressed. I'm not sure exactly how they go bad, but people here have rebuilt them.

 

[Erdoc48]

Thanks for the replies- I did what you said (jacked up the front end and grabbed the forks to check for movement)- very solid, no movement and zero clunking. I can check the anti-dive parts next. The bike runs and rides fine, so I’m not too concerned and not looking for issues that are not there, just making sure (and the 2000 with similar mileage doesn’t have the issue at all).

 

[Andrew Shadow]

Front wheel bearing/s?
I have twice found a clunk similar to what you describe was an early warning of a wheel bearing on its way out.

I also found that the best way to replicate the sound was applying the front brakes while going over a small curb like you would find at the transition between the roadway and a sidewalk at the entrance to a driveway or parking lot. Speeds are low enough to hear it but still fast enough to cause it. When doing this I could hear the clunk. When checked the traditional way there appeared to be no bearing problems.

 

[Erdoc48]

Front wheel bearing/s?
I have twice found a clunk similar to what you describe was an early warning of a wheel bearing on its way out.

I also found that the best way to replicate the sound was applying the front brakes while going over a small curb like you would find at the transition between the roadway and a sidewalk at the entrance to a driveway or parking lot. Speeds are low enough to hear it but still fast enough to cause it. When doing this I could hear the clunk. When checked the traditional way there appeared to be no bearing problems.

Thanks, I’m going to try this. I viewed enough videos and it doesn’t look too hard to swap them out (both for the wheels and steering stem). I have to test a little more. Actually, I had the wheel bearings done when I had the whole bike rehabbed and painted (I had the wheels powder coated so new wheel bearings were a necessity then).

 

[Upt' North]

Erdoc, I'm pretty sure my 98 gave a little sound occasionally just like the one you describe. I checked everything through and could find nothing wrong. Nothing loose or worn etc.
The sound changed or disappeared for a while when the back of the pads were coated with new anti squeal paste. I think I used the LiquiMoly blue stuff. But it might have been my imagination too.
I would ride given that you have checked likewise.
Upt.

 

[Uncle Phil]

One of 97s had a bad clunk like that - it turned out that the low forks were worn out.
I didn't find that out until I had them rebuilt.

 

[rwthomas1]

Mine used to make a clunking noise under very heavy braking, with the forks very compressed. I think the forks were bottoming out, or close to it. I assume there is a "hydraulic" stop at the bottom of travel? I changed out to a set of Sonic springs, now they don't do that anymore and the front end doesn't dive much either.

 

[Erdoc48]

Mine used to make a clunking noise under very heavy braking, with the forks very compressed. I think the forks were bottoming out, or close to it. I assume there is a "hydraulic" stop at the bottom of travel? I changed out to a set of Sonic springs, now they don't do that anymore and the front end doesn't dive much either.

See, this is it! Heavy braking with forks compressed over a rough surface. It’s not horrible, just a bit annoying and the bike otherwise rides and handles fine. I’m really torn on this one- part of me wants to just spend the $$$ and get them switched over to tapered bearings like I have in the 2000 (even if I still note the clunk, at least this eliminates the bearings as the cause). Another cheaper part of me just wants to take the top triple clamp up and snug them up a bit (but not tear the whole thing down). How long do steering head bearings last anyway (and again, I assume factory bearings with the original OEM grease at near 30 years old and 49,500 miles)? I don’t want to overthink this. Thank you all for the ideas.

 

[red one]

See, this is it! Heavy braking with forks compressed over a rough surface. It’s not horrible, just a bit annoying and the bike otherwise rides and handles fine. I’m really torn on this one- part of me wants to just spend the $$$ and get them switched over to tapered bearings like I have in the 2000 (even if I still note the clunk, at least this eliminates the bearings as the cause). Another cheaper part of me just wants to take the top triple clamp up and snug them up a bit (but not tear the whole thing down). How long do steering head bearings last anyway (and again, I assume factory bearings with the original OEM grease at near 30 years old and 49,500 miles)? I don’t want to overthink this. Thank you all for the ideas.

Think mine did that a little one time when my front pads were changed then went away quickly. Pads bedded idk? If it does it under panic braking only I'd leave it alone unless you are ocd. Mine is a 2000 with 86K and has the Oem steering head bearings and they have never been serviced. Don't need it. But I don't ride flying over RR tracks and pot holes and bumps without slowing down like some of you guys. No riding like a senior citizen provide far less wear and tear on ones ride.

 

[kiltman]

Each ST1100 I’ve owned (3) had to have the steering head bearings replaced. I could not detect a notchy spot when the front wheel was jacked up but each one did have shaky bars at low speeds. When the bearings were replaced the bars no longer shook.
For all three bikes I had a mechanic do the job for me and it was a couple of hours labour plus parts. I replaced the OEM bearings with tapered. I have read that when replacing the bearings with OEM bearings the steering head should be retorqued after the initial 1000 miles of use. I assumed that would be true for tapered, but my mechanic said no. I haven’t had any issues on that front, and have ridden 50 k miles on the bikes after bearing replacement.
If the OEM bearings are replaced with tapered, the torque settings are different than with the OEM bearings. They are less than OEM, if you torque the tapered bearings to the value of the OEM units you will experience a low speed weave like you’re riding through a river, it’s very disconcerting. No torque value was given to me other than the taper bearings were torqued by feel and that the bars would rotate through the turning arc smoothly.

 

[rwthomas1]

See, this is it! Heavy braking with forks compressed over a rough surface. It’s not horrible, just a bit annoying and the bike otherwise rides and handles fine. I’m really torn on this one- part of me wants to just spend the $$$ and get them switched over to tapered bearings like I have in the 2000 (even if I still note the clunk, at least this eliminates the bearings as the cause). Another cheaper part of me just wants to take the top triple clamp up and snug them up a bit (but not tear the whole thing down). How long do steering head bearings last anyway (and again, I assume factory bearings with the original OEM grease at near 30 years old and 49,500 miles)? I don’t want to overthink this. Thank you all for the ideas.

I'm a chronic "over-repairer" that is in remission. I try to only fix what needs fixing. If the steering head bearings are tight, there is no play, and no "detent" feeling then leave them be. Heavy braking on rough surface is exactly when mine would make the clunking noise. Almost like a "groink" sound. I found the forks way too soft with factory springs so I put in Sonic's. They are not progressive, and I've been very happy with them. No more noise.

 

[Andrew Shadow]

See, this is it! Heavy braking with forks compressed over a rough surface.

Just a thought- is it possible what you are hearing is the ABS activating?

On my 2000 ABS ST1100, the ONLY time that the ABS would activate is under heavy braking on a really bad surface. Overwhelmingly, and mostly, it was on heavy washboard asphalt. It would only activate for a couple of seconds, not long enough to even have time to look at the indicator light to see that it was activated. I intentionally and repeatedly performed hard braking on a very washboard stretch of road to figure it out. Because it was planned I could have my attention focused on the light and see if it matched the noise. Otherwise the ABS never activated on that bike, and as a result it was not a familiar sound.

 

[ST1100Y]

Just a thought- is it possible what you are hearing is the ABS activating?

Nah, I've the same significant "...weeep..." when hitting a hump during heavy braking, anti-dive closed and the fork oil is forced through the smaller orifices...

Cluttering in the front end can have a number or causes, likely the LHS caliper<>anti dive linkage, possible the nylon bushing missing/worn off

 

[dwalby]

See, this is it! Heavy braking with forks compressed over a rough surface.

the anti-dive is activated by the brake caliper, maybe you're just hearing it cycle, or maybe something in the mechanical connection between the caliper and the anti-dive unit is worn and slapping around.

On the non-ABS its on the left fork leg, but I think I recall hearing that on ABS 1 bikes its on the right leg since the two types of forks are reversed from the non-ABS.

 

[Uncle Phil]

FWIW, On the ABSII the anti-dive is definitely in the right fork.

 

[Erdoc48]

More investigation on the way. I am getting an estimate from the local shop just to be sure. I do like the tapered bearing function in the 2000. Funny that the 94 started with a Shinko, had decel headshake, then had Z8 and Angel GTs, with no headshake and most recently a Shinko Verge, again with the headshake. Must be the profile of that tire. I have to check the Anti-Dive as well.

I still don’t know why the Silverwing does it as well- can’t be the steering bearings as that only has 8K miles on it. I have to see if that has an anti-dive piece. Maybe I just need to shut up and ride some more.

EDIT: I just checked the anti-dive on the left fork (as the forks on the 94 ABS are the same as the non ABS models)- a little rattle at the lower bolt and the spacer is there in the caliper as well- same as on my 2000, also with the little rattle, but maybe an internal defect. I don’t want to start throwing parts at it randomly, so again, many thanks for your thoughts.

 

[John OoSTerhuis]

JuST another anecdotal data point, but when I R&R’d my 1991 SSMST1100’s fork seals @~55K I found a piece of the seal material on the face of the anti-dive piston at the bottom of that fork tube. 500 miles on the Dempster Hwy might have had something to do with the fork seals and dive failures. The anti-dive function was degraded but I didn’t perceive it. I sure noticed the improvement after I replaced the piston and most of the rest of the unit. FWIW

John

 

[klaproth]

@Erdoc: on my Honda Helix, the head bearings were shot at about 10k miles. It was much older than you SWing, but probably has the same type of head bearings.
I replaced them with tapered bearings, and it was like new again.