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Front fork noise!!!

Started by DB Cooper, November 07, 2010, 08:00:20 AM

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DB Cooper

Every time I hit a bump, I get the typical FJ loud metallic clunk from the forks. I know it doesn't have any effect on the ride, but it drives me crazy. I'm going to re-do the forks this winter, what do I look for while doing the forks to get rid of the noise?
Kevin.
I remember when sex was safe and skydiving was dangerous.

Arnie

I don't know that this noise you describe is typical for FJ's.
There are a number of things that could be causing a "clunk" noise when you hit a bump.
Springs that are too soft if you have too little fork oil will bottom and KLUNK!
If the steering bearings are loose, they could clunk. (most likely culprit)
If the fork bearing metals are extremely worn, they could clunk.

Check, grease, and adjust the steering bearings first.

Avoiding the bumps will help too. :-)

Arnie

Dan Filetti

A weak center-stand spring, will cause the center-stand itself to pull away from the bike momentarily and cause a 'clunk' as it slaps back.  Although this may be far enough away from the forks to be eliminated as a culprit.

Worth looking at though.

Dan
Live hardy, or go home. 

DB Cooper

That's funny, I did a search and found several references to a noise, clunk etc., coming from the front end. It may not be "typical", but  it seems to be "not un-heard of". I don't know how to post a link to another topic, but a search " what the heck is causing that noise" came back with near 2 pages of replies to that one post. There are other refences as well.
The noise only happens when moving and hitting a road crack, or concrete lip like at the entrance to a laneway. I can't seem to duplicate the noise in the garage either. I've tried holding the front brake and rocking the bike to compress the forks, as well as getting it down off the center stand. I've check all the obvious things like instument cluster, tank rubbers, and front fender. All seem to be as they should be.
The head bearings are good, and seem to properly adjusted as there is no play, and the bars move freely from stop to stop with no center notch. I just got the bike this summer, and I do not know if the springs may be worn, what the weight of the fork oil is, or the quantity. The fork seals are a little weak so this is why the I'm going to do the rebuild this winter.
I was just wondering, that while the forks are apart, if anyone else has discovered worn spacers or anything like that.
Kevin 
I remember when sex was safe and skydiving was dangerous.

RichBaker

 I was hearing a clunk from my front end, same thing... only when moving and hitting bumps.  It went away when the back 1/2 of my front fender fell off....   :dash2:
Rich Baker - NRA Life, AZCDL, Trail Riders of S. AZ. , AMA Life, BRC, HEAT Dirt Riders, SAMA....
Tennessee Squire
90 FJ1200, 03 WR450F ;8^P

markmartin

Kevin,

I was getting a similar clunk before rebuilding my forks this spring.  It sounded to me like it was coming from the top of the fork tubes.  The steering bearings seemed good and I couldn't get any noticeable play when suspending the front end and trying to check for worn bushings or any other looseness. My guess was that it was the 3/4" spacer sitting on top of the springs, maybe getting pushed up against the inside of the fork tube when I hit these sharp bumps.   So, when I installed new spacers when rebuilding the forks, I used a larger diameter PVC. (I think it was 1")   The clunk has all but disappeared now. I can't be sure if this was the culprit as I added emulators and replaced the bushings also.

I still get the occasional clunk at the center stand that Dan's talking about when I hit a good pot hole or similar.  Maybe I should get a new center stand spring...?

Mark

simi_ed

FWIW, my feeling is the forks have worn bushings.  I have my stock '89 forks, still with original bushings (about 25,000 mi. on 'em).  I found that there is a a small amount of movement between the tubes and lower legs.  If the leg is clamped in a vise, the tube will wiggle to 'n fro slightly.  My YZF forks have new bushings and no clunk to be found.

-- RKBA Regards,

Ed
===
Ed Thiele 
Simi Valley, CA -- I no longer have SoCal manners.
'89 FJ12C (Theft deterrent Silver/White)


- All that is necessary for the forces of evil to win in the world is for
enough good men to do nothing.

- Edmund Burke

FJmonkey

Quote from: simi_ed on November 07, 2010, 01:56:47 PM
FWIW, my feeling is the forks have worn bushings.  I have my stock '89 forks, still with original bushings (about 25,000 mi. on 'em).  I found that there is a a small amount of movement between the tubes and lower legs.  If the leg is clamped in a vise, the tube will wiggle to 'n fro slightly.  My YZF forks have new bushings and no clunk to be found.
Ed, I still need to get you $ for your clunky forks. Too bad I missed the ride today, the weather was nice and cool, perfect for full leather.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

simi_ed

Forks are here, waiting patiently.  I missed the ride too.  Honey-do list took over ...

Next time!

Ed
-- RKBA Regards,

Ed
===
Ed Thiele 
Simi Valley, CA -- I no longer have SoCal manners.
'89 FJ12C (Theft deterrent Silver/White)


- All that is necessary for the forces of evil to win in the world is for
enough good men to do nothing.

- Edmund Burke

DB Cooper

Thanks for the input guys. I have to agree with Mark & Ed's suggestions.  I swear the noise is right at the top of the forks. And other than fork seals, it wouldn't suprise me if the bushings have never been done. I wasn't planning on emulators, but  I may change my mind later. I'm going to change the springs while I'm in there, anyone have any suggestions as to spring rate or manufacturer? I'm waistline challenged, and I drive enthusiastically, so I'm not sure what to change to. Any help would be good.
Kevin
I remember when sex was safe and skydiving was dangerous.

Yamifj1200

I can highly recomend Traxxon's OMNI springs. I weigh a tad under 200 lbs and the 1.0kg springs are perfect for me..If you decide to replace the fork seals go with the OEM seals, they work best...
http://www.traxxion.com/OmniForkSpringKit.aspx

Hope this helps...

Eric M


http://www.fjowners.com/index.php?topic=14833.0


"All unattended children will be served an espresso and given a puppy"

SlowOldGuy

I think I read somewhere that the springs can bow slightly in the fork tube during compression and cause a clunking sound on some bumps. 

I had a clunk in the fornt end of my '85 that used to annoy me, but for some reason it is now gone.

DavidR.

TRoy

don't forget to rule out the headlamp reflector.. it can rattle around inside the housing and cause a clunk, too  :morning1:
Peace & Love
86FJ 100K+
07Burg650
15Downtown300

ribbert

I have the same "clunk"and always assumed the twin Volvo horns crammed in there with very little clearance were hitting the front subframe. I never gave it much thought. However, I have removed the horns and the noise remains. It's not frequent enough to bother me but I would suggest if you have somewhere close by that regularly brings it on, ride over it with your fingertips resting on top of the fork tubes and if they are the problem you'll definitely feel it. I tried this today after reading the posts, with my "noise detecting" (lining removed) helmet on and, of course, couldn't find the right bump.
"Tell a wise man something he doesn't know and he'll thank you, tell a fool something he doesn't know and he'll abuse you"

DB Cooper

I'm positive it's in the forks now. I was out for a ride the other night and the air temp was +2 Celsius. The fork oil is really stiff at that temperature, and I noticed the noise was a lot worse and definitly near the top of the forks.  I'm thinking more and more it that it's probably the spacers being worn out and banging on the side of the fork tube. I've since talked to the PO and he says that he put progressive springs in, 2 new seals and 15w fork oil. He said that the fork bushings were good at the time so they weren't replaced.  I'll know more when Itear it apart after the snow flies. Good point on the "touchy feely" on the fork tubes. It will make the noise on almost any small bump so it will easy try it!
Kevin.
I remember when sex was safe and skydiving was dangerous.