Odd noise in the front forks

[builder309]

I have a '94 ST1100 with a mere 50K miles on it, and I recent began hearing a clunking noise in the front end. I have checked and re-checked to make sure all the cowling and bodywork is secure and all structural members that support the instruments and headlight. Nothing broken or amiss that I can find. It is seemingly in the suspension. It only makes his noise when I hit a particularly rough spot or small hole, and apparently only on the downward or return stroke of the fork travel. Could it be a broken spring? Suggestions?

 

[Larry Fine]

Loose damper rod?

 

[dwalby]

might be something in the anti-dive system. Broken spring is very unlikely

 

[John OoSTerhuis]

How old is the suspension fluid? I’d pull the forks and do a fluid R&R and overall/general inspection. Damper rod and anti-dive are possibilities. Report back.

You might edit your post’s subject line to include “ST1100.”

John

 

[jfheath]

+1 on the anti dive mechanism on the bottom of one of the fork legs. Which leg depends on whether or not you have the combined braking system. Some parts are plastic and can wear

But there are other possibilities which are related to the brakes and brake caliper assemblies. Pad springs, mounting bolt bearings, SMC pivot mechanism (if you have the CBS model), badly fitting non Honda brake pads, .... . Of course it could be the forks, but it is always worth investigating brake assemblies for odd clunking noises.

 

[builder309]

How old is the suspension fluid? I’d pull the forks and do a fluid R&R and overall/general inspection. Damper rod and anti-dive are possibilities. Report back.

You might edit your post’s subject line to include “ST1100.”

John

I just replaced fork oil a year ago, so I don't think it's that. Will check the other stuff and see.

 

[Andrew Shadow]

Check the front wheel bearings. I had a clunk in the front end of my first ST1100 caused by a worn wheel bearing.

 

[jfheath]

Another possibility - just prompted by @Andrew Shadow 's suggestion is the wheel bearing spacer. A long tube that fits in between the bearings on the axle. It ensures that the bearing are not drawn together when the axle bolt is tightened. But it should be held firmly in place when bearings are installed correctly. If it is loose, you'll hear a clunk when you drop the wheel onto the floor onto its tyre from about 1cm . Or you will be able to stick a finger into the bearing and feel whether or not it is moving about easily. If it is, then the bearings haven't been installed properly, and will probably be due for changing anyway - as they will have been subject to an extra load from the side the axle was tightened.

 

[Uncle Phil]

Another 'far distant' possibility is the lower forks are 'wallowed' out - but that usually does not happen on low mileage ST1100s.
Backstory - I was having my forks rebuilt and one of the bikes had this strange 'clunk' whenever I hit a bump.
Never could figure out what it was - and I looked and looked and checked and checked.
Kent at Atlanta Computrac (a great and honest suspension feller) was doing the work and when he checked the lower forks before the rebuild, they were wallowed at near the bottom of the stroke.
Needless to say, I had to find another set of fork lowers to rebuild.

 

[dtcoleman]

My two cents.
If its a clunk you may want to check steering head bearing.
Lift the front of your bike while on the center stand. I usually use a floor jack n block of wood under oil pan.
Once raised grab the front wheel n check for play. You may notice the clunk at that point. You can also check for that flat spot in the race of that bearing by turning the handlebars left n right.
Hope this helps.
Dave

 

[Sadlsor]

Kent at Atlanta Computrac (a great and honest suspension feller) was doing the work and when he checked the lower forks before the rebuild, they were wallowed at near the bottom of the stroke.
Needless to say, I had to find another set of fork lowers to rebuild.

Regardless of whether this is the actual issue in this case, I continue to consistently hear / read very good things about GMD Computrac.
Have for years now.

 

[Al st1100]

for giggles make sure all the triple tree bolts are tight.

 

[SMSW]

Another 'far distant' possibility is the lower forks are 'wallowed'

What do you mean, Phil? Worn into an oval cross section?

 

[Uncle Phil]

What do you mean, Phil? Worn into an oval cross section?

I didn't 'peer' into the fork bottoms, just watched the measuring instrument.

 

[SMSW]

I didn't 'peer' into the fork bottoms, just watched the measuring instrument.

Ok, but what do you mean by wallowed? Enlarged in an oval or just larger in diameter at the bottom of the tube?

 

[Uncle Phil]

Ok, but what do you mean by wallowed? Enlarged in an oval or just larger in diameter at the bottom of the tube?

'Reverse' leg calipers - the 'needle' showed a great difference in the bottom measurement.
"Wallowed out" is an old country term where I'm from.
I do not have a clue as to the precise shape of the enlargement because it did not and does not matter to me.
And to borrow a line from Forrest Gump - "That's all I have to say about that."