EVO and Vanila RC questions

[CTYankee]

I finally got my bushings from Fox and was able to put the shock on my Evo ('00 way big 4.0).  I noticed a few things.  
1- If I have not put enough pre-load on the spring I get a 'CLUNK' when I drop the rear wheel.  There is not play that I notice in anything, yet if I drop the back on the ground I get a clunk.  Tighten the spring and this goes away.

2- The shock seems to compress then make a pop like noise.  If I compress the back end fast then it does it.  If I copress it slowly then it does it too, but only when I reach a certain part of the stroke.  Its almost like it compresses the air/oil inside then when it reaches a certain point it starts going through the valves.  I have no idea what the internals are like so I can't imagine what is going on.  If I adjust the red/blue knobs then this too goes away.  But what is it?

3- What do the red and blue knobs do anyway?  The one at the end seems to be a dampener, the one up top seems to adjust air pressure.  OK, how wrong am I?

Thanks for the help.  I've posted this at some shock BB's but figured this site is as good or better than any since so many people have the same setup.

Doug

[GrimJack]

Sounds like your shock has some 'issues'.

The knobs are compression dampening and rebound dampening.

The compression dampening will slow down the suspension as it compresses, the rebound dampening does the same thing as it extends.

[Peter_K2_Bike]

The word is damping.  The red knob is your rebound damping, the blue is your compression damping.

[IFO]

ok, your post is really hard to understand...

first off, you have to run at least enuf spring preload to hold the coil in place... or of course you'll have a noise if you drop teh bike... it would be the sound of the spring "rattlin" on the shock body....

did u buy your shock new or used?

to check both circuits, u need to take the spring off the shock...

next unwind both the compression/rebound damping knobs to teh fully open position...(counterclockwise)

now push the shock shaft all teh way in... it should be easy to push in and come back out/up fast...

next dial on the compression knob fully... try to push teh shaft in... it should be VERY difficult to do so...

next back the compression out again and dial in teh rebound knob fully... push the shock shaft in fully again... it should go in easy, but return VERY slowly...

if either of these arent happening, you have a shock with "issues"....

post back with more info, and i'll try to help out some more....

laters....

[Doug]

OK, this time I'll make sense

The shock seems to be behaving slightly differently now.  When I take the spring off and have compression and rebound dialed out all the way it goes in relatively easy, and returns fast.  When I dial up the compression is goes in much slower and returns just as fast.  When I do this with the reboung it comes out just as fast no matter where the dial is.  No sounds though, the ones I was hearing the other night have gone away.

Now with regard to compression, when I compress the shock about 1/2" it gets much harder to compress for a bit, then goes back to the same level of damping.  Almost like at that point in the stroke the shock gets tight.  If I dial up the compression daming it sort of goes away.  I think the added damping just masks this odditiy.

As for the clunking sound when I drop the wheel, everything is fairly tight.  Shock bolts are tight, there is some preload on the spring, and the shock does not move in any way.  I can tug, pull, push, poke, prod, etc but nothing feels loose.  Even when I drop the wheel and stick my finger in suspect places (spring contact points, bushings, shock mounts) I don't feel anything moving.  When I crank up the spring preload this clunking sound goes away.  

And yes, the shock is used.  The seller had it back at Fox for some kind of repair (still waiting for his reply on what was done).  

OK, that about does it for my diagnosing.  Since it obviosly has problems, it will need to go back to Fox (or the seller if he agrees).  Anyone know how much a rebuild costs?

[IFO]

if the rebound dmping knob makes no difference, then teh rebound circuit is dead...

sounds like your shock has some history the seller didnt quite be so forthcomnig about....

good luck...

it can be sorted out at Fox, but you'll end up payig for it....

[CTYankee]

The seller has agreed to pay for the repair.  I told them it was for the K2, but they said they don't spec those...is there a bike they do spec that should tell them to set it up for?  Titus Locomoto (similar geometry)?  Or call back and get another guy?  The people Iv'e spoken to were not the nicest in the world.

edit...
never mind.  I called fox and they said there is no difference in the shocks.  Now I just need to let me wonderful shop know this after they cautioned me about buying used because they are valved specifically for each bike.  Hmmmm, reminds me of the $20 fee they used to charge for 'setting up' mail order shocks they install (setting them upright to let the air rise to the top of the oil before adjusting it).

[IFO]

one feature FOX can do is called the "bighit" valving...

its a higher compression damping circuit at the end of travel for large drops/hits....

but if you dont ride hard chances are its a wasted upgrade...

good luck, once u get it back, n mounted it'll be so worth the hassle...