Twin chamber spring question and problem...

xenasdaddy

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#1
Well,

First I would like to ask, is there supposed to be approximately 1/4" of "play" between the damper spring and the damper bushings when the bushings are slid down to touch the lower part of the damping assembly, or is the spring supposed to have tension applied on it when the damping assembly is removed from the fork? Does the lower part of the damper assembly on the inner assembly simply get spaced further down the inner chamber by having slack in the spring while the chamber is out of the fork? was that as confusing as it sounds?! sorry but i am likely not using all the correct terminology to describe this.

here is a pic of what i am calling the inner chamber spring assembly:

http://albums.photopoint.com/j/View?u=1409053&a=12886532&p=51540293&Sequence=0&res=high

With the VERY gracious telephone and email help of my local MX-TECH rep and DRN, I was able to change both my shock spring (2000 cr250) and my fork springs. However, I am a bit confused as to if I accomplished my task on the front end. You see, my forks make a "knocking" or "clunking" sound when i compress them fairly hard with the front brake on. This only happens towards the very bottom of the stroke. I DID make sure that there was no binding by following kxvet's and shaggy's advice on tighteneing sequence, etc. it sounds to be coming from both forks near the lower half somewhere. also, it only happens on the compression, not, the rebound of the movement. i have redisassembled the left fork tube and found no obvious (to me) cause. the steering head is fine also.

any suggestions or comments are welcome.

thanks,
xd
 
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#3
The 1/4" or so of play is normal for that piece. During the reassembly process for the inner chamber, the slide bushing assembly will be forced upwards giving the spring a certain amount of preload. I don't think that is what is causing the noise you are hearing. It sound as if the fork may not have been re-assembled correctly. Do you have an owners manual for the bike? If so, I would double check the assembly order on all the components. Unfortunately, there are a number of possible situations that could be occuring if the fork isn't put together correctly and it is very hard to guess at it accurately. Was the fork making this noise before you dis-assembled it?
 

xenasdaddy

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#4
thanks budman.

i spoke with my mx-tech rep. last night and we went over my assembly procedure and came to the conclusion that i did everything right. i do have a manual also and followed it to the "T". I even rebuilt them again last night just to make sure. well, when i bolted the suckers back on and adjusted the clamps , etc. it still makes the same noise. my mx-tech rep suggested that it may be the steering head bearings and that could be possible from the sound i guess. i just have to get someone else to push them down for me so i can listen closer. i will post what we find out. the fork did not make this sound previously but the heavier springs may be causing more load to be transfered to the steering head, thereby causing the knocking sound from what i was told.

thanks.
 
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#5
Do you still have the springs you took out? Perhaps try putting them back into the fork and see if it still makes the noise. At least you will know that the spring is what is causing the noise. Perhaps the "end prep" of the new spring isn't perfect, which may be causing the spring to deflect under load. If the assembly is ok, then lets start examining the things that are different after re-assembly. Worn headset bearings could account for the noise but I'm surprised it didn't show up before. Did you take the triple clamps off the bike? If so, perhaps the headset is just loose. Yet another possibility is that the fork guard is hitting something now. I wish I had more to offer, but I'm a bit stumped.
 

xenasdaddy

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#6
springs are already back in but i have the others. if i can not diagnose the location of the sound with someone else pumping the forks hard, i may resort to putting the old ones back in just to see if it may be the springs as you say. but it does not sound like a metal on metal hit, more like if you drop a baseball onto cement.

triple clamps never came off. steering stem nut is tight. i actually removed the fork guards to make sure they were not hitting.

could it be the front brakes? i think i will remove the caliper from the fork and brace the front tire against a wall tonight and push down and see if i hear the same noise.

also, i just noticed that a few people recommend 16lbs of torque on the fork clamps, but i used the what the manual recommended 20 on the bottom and 22 on the top or vice versa (do not have my manual here at this time).

i do appreciate the help.

xd
 
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#7
Sounds like you have most of the bases covered. If the caliper is loose, it could be the source of the noise. Sorry I couldn't be of more assistance :( .
Good luck!
 

xenasdaddy

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#8
OH MY!

You will not believe this.

After reinstalling my new springs / servicing my forks, and then reservicing the forks because i heard this stupid noise, this is what i found:

well, first I put the front tire against a wall with NO CALIPER and bounced the forks - result = NO NOISE. Then i decided it must be the brake caliper, so i mounted the caliper, put the front tire against the wall and DID NOT sqeeze the lever and bounced the forks - result = NO NOISE. Then i sqeezed the lever with tire against wall and bounced - result = NO NOISE.
Lastly, i backed the bike up, sqeezed the lever and bouced - result = NOISE, NOISE!

Finally I noticed that if I squuezed REALLY HARD (like I had not done before)on the lever and bounced the forks, NO NOISE.

Conclusion, I could actually see my rotor moving very slightly when the noise was being made! It was simply my brake rotor slipping a bit and it ceased when I squeezed the lever harder! I just never expected that a rotor slipping could sound like that, I always thought it would just sqeek or grind.

Thanks for all the help on helping me realize that I am again an idiot!

XD
 

KiwiBird

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#9
Sounds like time to work out those puny nancy arms and get a manly grip ;) . Bet you can field strip your forks blind folded now, eh?
 

xenasdaddy

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#10
lol. yep - i could use a good hundred workouts. i can get both forks completely off the bike, tore down to the internals, cleaned, refilled with measured amount of fluid, torqued back on bike and clickers set in right around a little over an hour and a half now. though i typically go back over everything and make sure it is "perfect".
:)
xd
 

Jeremy Wilkey

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#11
LOL.. I was waiting for that... Brake noice is very common espically on brakes with floating discs.

New springs are often a touch noisey as they need to polish there od's.

Regards,
Jer