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Discussion Starter · #1 ·
I have DHX Coil on my 6.6, and the rear end tosses me off the seat even with the rebound set to a molasses-slow setting when I push down on the seat. I'm running a 600lb/in spring. Can anybody tell me what spring the DHX is shimmed for? I've got a 7.785x2.25" shock. The shock doesn't really toss me any more with a fast setting, so something is obviously wrong with the shimming. Question is, should the rebound shim be a bit stiffer or softer? I can't seem to work my mind around it, it just doesn't make sense.


Ole.
 

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noMAD man
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Yeah, it sounds like it could be a defective rebound circuit. I'm surprised to hear that the 6.6 uses a 7.875 shock. I thought it would be more akin to the Nomad which uses an 8.5 X 2.5 shock to produce basically the same travel. On a couple of bikes that I've had the DHX coil installed, you could get the rebound damping to be so slow as to practically lock the rear down on compression. These bikes were using 400-450 lb. springs, but you wouldn't think a 600 spring would overwhelm such strong rebound damping capability. The 7.875 X 2.25 shock is a fairly common size. Do you know anyone who'd let you do a quick comparison check? Do you get any variation in the rebound action from minimum to maximum adjustment?
 

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TNC said:
I'm surprised to hear that the 6.6 uses a 7.875 shock. I thought it would be more akin to the Nomad which uses an 8.5 X 2.5 shock to produce basically the same travel.
Sorry to hi-jack the thread but just a quick question TNC, what effect would that normally have. I was also surprised when I heard the shock specs were different for the same travel on the Nomad and 6.6.
 

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Ole said:
I have DHX Coil on my 6.6, and the rear end tosses me off the seat even with the rebound set to a molasses-slow setting when I push down on the seat. I'm running a 600lb/in spring. Can anybody tell me what spring the DHX is shimmed for? I've got a 7.785x2.25" shock. The shock doesn't really toss me any more with a fast setting, so something is obviously wrong with the shimming. Question is, should the rebound shim be a bit stiffer or softer? I can't seem to work my mind around it, it just doesn't make sense.

Ole.
How much boost valve pressure are you running. Having too much in there can cause the rear end to feel like it wants to jump. I found 100 psi to be good at making the rear end most compression sensitive.

Otherwise your shock is blown or you have your fork rebounding too slow. Make the fork rebound faster and you will not feel like going over the bars.

I have a DHX 5 coil with a 600lb spring. I have never once had an issue with the rear tire leaving the ground. Mine has kept me planted like its got roots.
 

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99 YARDS
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Check that your sag is set right... Preload is a cool adjment. The 6.6 and the 5.5 are made to be affective with 3/4" of stroke sag.Remember even with rear suspenion your legs provide you with damping.Check tire psi as well.The above coment about your front end is a valid point.Doze the frame fit you right?What fork are you useing, whats the amount of travel, how tall is it.How much do you weigh. You could call Fox and let them know how much you weigh, and see if that is the right sping for you.Hopefully we Replyers have helped good luck.
 

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noMAD man
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Suspension quality.

BanzaiRider said:
Sorry to hi-jack the thread but just a quick question TNC, what effect would that normally have. I was also surprised when I heard the shock specs were different for the same travel on the Nomad and 6.6.
This is by no means the absolute do-all, end-all to suspension quality and performance, but generally two bikes with the same suspension design but different length/stroke shocks to produce the same amount of travel...the one with the longer stroke shock is easier to tune, lasts longer, and usually yields a smoother suspension action. That's been my experience. The difference between the 6.6 and Nomad isn't horrific, but it's a little out of the more common practice lately from most manufacturers.
 

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Elitest thrill junkie
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Ole said:
I have DHX Coil on my 6.6, and the rear end tosses me off the seat even with the rebound set to a molasses-slow setting when I push down on the seat.
This is kind of hard to understand. If I set my rebound molasses-slow, my bike would kick me off too because the rebound would be so slow that the shock would already be compressed when it hit the next bump, and it would feel like a hardtail on that bump and throw me forward because of this.

When I have it set fast (I run my rebound pretty fast) it will feel "bouncy" at slow speeds, but at high speed it will be able to absorb the bumps without doing what I described above. No one should really be running rebound "molasses slow", there's no benefit to it and it makes the suspension work like crap.

If you set it that slow all the time, I'd expect that it would eventually damage the internals of the shock.
 

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Discussion Starter · #8 ·
Not setup, not faulty.

I'm not running the shock molasses slow, I just tried it to see what it did. I've run boatloads of other shocks, and they don't behave this way. I've also tried other DHX Coils, and they behave the same way. Friends have them on other bikes, and report the same problem.

I'm experimenting with higher IFP pressures, to prevent the suspension from going so deep in g-outs, and that helps some, but the rebound on the DHX Coil still feels funky, very vague and uncontrolled compared to, say, a TFTuned 5th Element Coil or Swinger 4-way Coil, or even a lowly RP3.

I've also got my DHX shimmed a little softer on the compression side, to prevent the spike that many are trouble by. This helped the shock a lot, but the rebound remains the same. I'm wondering if the rebound shim is too stiff. If it was too soft, the spring would open the high speed whenever the shock isn't loaded, thus making it impossible to give it a molasses slow setting when pushing down on the seat.

A perfect rebound shim will always make the shock seem fast when you just push down on the seat, but with the addition of your weight, the shim will stay closed, and give you the nice, calm slowness.
 

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Elitest thrill junkie
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Ole said:
TFTuned 5th Element Coil or Swinger 4-way Coil, or even a lowly RP3.
Hmm, well I've ridden the DHXA and DHXC, and I feel that the RP3 in particular, and the swingers, are "overdamped". I can't turn the rebound down enough so that the bike won't pack up over bumps. Again, it makes them feel harsh to me.

What speed-range are you riding at?
 

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Jayem said:
Hmm, well I've ridden the DHXA and DHXC, and I feel that the RP3 in particular, and the swingers, are "overdamped". I can't turn the rebound down enough so that the bike won't pack up over bumps. Again, it makes them feel harsh to me.

What speed-range are you riding at?
I think Jayem is correct. Your expecting too much from your shock.

I've found that many people like to sit down when they should stand up even though they have dual suspension. Tuning your suspension to keep you planted when sitting down IS ALWAYS going to result in an over damped rear shock in order to keep your ass planted.

The only time I've ever felt my DHX wanting to toss me was when I had my fork set way too slow on rebound and was sitting down when I should've been up.

I've found the DHX has a perfect range in rebound control. It has just enough slow speed damping to keep the bike from feeling jittery on landins and rough sections, yet give in a bit on higher speed stuff to keep the shock from packing up. This helps a lot when you're looking to boost off jumps for extra air time.

For the original poster. There are several things you may be experiencing.

1. Your fork rebound is too slow. Make is faster if possible, or get stiffer spring.
2. Your rear shock is over sprung compared to the fork
3. You're not using your legs at all. DHX doesn't reward lazy riders. It's a race shock.
4. Your seat is too high.

I've found that when the rear shock is too over sprung compared to the fork, it will want to buck you off the bike no matter how slow you get the rebound. Getting your front to rear spring rates leveled out makes more of a difference than any damping.
 

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Rebound shimming

Ole,

The stock DHX does in fact have a bleed hole for low speed and a non-preloaded shim stack for high speed. Generally the FOX dampers come valved on the firm side when it comes to the high speed rebound circuit simply because they don't know what spring rate the end user will end up with. With that being said, we have noticed a trend in both the RP3 and DHX shocks where the stock rebound stacks are significantly lighter.

I'm not 100% sure of your explanantion of what's happening, but if you're getting tossed becasue the rebound speed is too fast, than the shimming would need to be stiffened. If I'm understanding you correctly, the piston stack is opening prematurely.

Sounds like you've had it apart already so if you wanted to run the rebound stack by me I could probably give you some recommendations on where to start.

Darren
 

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Sounds like the high speed rebound shimming is too soft. As others have commented, if you add too much rebound damping to allow you to stay seated on bigger hits, you will lose a degree of small bump sensitivity and traction. You can also risk packing the suspension down over multiple hits. There is one trail in particular I ride regularly that has a series of smooth, multiple wave like undulations a couple of feet high occuring on almost every pedal stroke. They go on for literally mile after mile and I find that a much higher rebound setting is required to avoid being bucked off the seat. However, if I try the optimum rebound setting for these on a rough or rooty trail, I lose traction and small bump sensitivity.
 
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