Rear Shock Shim Stack Order

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Thrahl
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Rear Shock Shim Stack Order

Post by Thrahl »

So I'm an idiot and did the one thing every guide tells you to be super careful not to do, I dropped the shim stack when taking apart the rear shock. :doh:
I didn't realize there were shims on the top and bottom of the piston so i pulled it out and the bottom ones hit the floor.
I found them all but don't know the order they're supposed to go back on.

It looked like it was the smallest shim against the piston followed by the largest shim then progressively smaller but I cant be sure.
I have another identical shock that I can pull apart more carefully this time and see the order, but before i go through that again I wanted to see if maybe somebody knew the order.

Edit: Bike is a 1989 KDX 200
Last edited by Thrahl on 03:28 pm Jul 09 2017, edited 1 time in total.
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Rear Shock Shim Stack Order

Post by KDXGarage »

Thrahl wrote:So I'm an idiot and did the one thing every guide tells you to be super careful not to do, I dropped the shim stack when taking apart the rear shock. :doh:
I didn't realize there were shims on the top and bottom of the piston so i pulled it out and the bottom ones hit the floor.
I found them all but don't know the order they're supposed to go back on.

It looked like it was the smallest shim against the piston followed by the largest shim then progressively smaller but I cant be sure.
I have another identical shock that I can pull apart more carefully this time and see the order, but before i go through that again I wanted to see if maybe somebody knew the order.
"It looked like it was the smallest shim against the piston followed by the largest shim then progressively smaller"

Sorry, but that is wrong.

Here's a handy, dandy, fun fact. Which KDX??? :pop:
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Re: Rear Shock Shim Stack Order

Post by KDXGarage »

As best my info shows from a long time ago when I wrote it down (April 13, 2005):

1989 - 1994 USA KDX200 Shock Stock Valving

Compression (piston face outwards)
38.2 x 6
23.1
38.25
36.25
34.2
30.25
28.25
26.25
24.25
20.25

REBOUND (piston face outwards)
34.2 x 5
23.1
34.25
30.25
28.25
26.25
24.25
22.25
26.25
26.15
24.25
24.25
24.1

The outer diameter is to the left of the decimal. The thickness in TENTHS of a millimeter are to the right of the decimal. If it say "x6", that means there are six of them stacked on top of each other. There may be a little washer in there around 1 or 2 mm thick. That doesn't really count.
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Re: Rear Shock Shim Stack Order

Post by KDXGarage »

And if you need a KYB brand rebuild kit for it, I sell those. :mrgreen: Thanks.
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Thrahl
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Re: Rear Shock Shim Stack Order

Post by Thrahl »

Haha yea I guess it would help if you knew the bike. It's an '89 200 so your info should definitely be helpful. (edited the original comment with that info)
Googling around it looks like the rebound is the "outer" stack closer to the nut while compression is on the inside. Is that correct?
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Re: Rear Shock Shim Stack Order

Post by Thrahl »

Just measured the compression (inside) shims.
My calipers aren't the best so the second number might be off by .05 or so but my shims look like this:

38.15 x 8
36.3
34.3
32.3
30.3
28.3
26.1
25.3
21.1
21.3

So clearly my numbers are way off from yours. When I took the shock apart it looks like someone had already been in there at some point, the nut was already ground down.
So maybe it was reshimmed? Or maybe they dropped it like me and just threw stuff back in there lol.

I'm going to check the rebound stack too and see how that compares to yours.

Edit:
Rebound looks like this
34.15 x 10
22.15
34.3
32.3
30.3
28.3
26.3
24.3
21.3
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Re: Rear Shock Shim Stack Order

Post by KDXGarage »

Someone definitely revalved it.

Compression stack is like you thought, on the bottom. Rebound is on top.
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Rear Shock Shim Stack Order

Post by Thrahl »

Finally got a chance to work on the bike again this weekend. Took apart the spare shock and luckily this one had never been opened up before (still had factory peening on the shaft).
So I just used the shim stack from it.
It actually ended up being a really good thing I had a spare shock because after cleaning up the shock body on the first one I realized the walls were really messed up internally, felt and looked like it may have seized up at some point, or maybe just run too long with too little oil. The spare shock body was in perfect shape so I ended up just using it.

Filled it with 5W oil and a fresh seal head. Piston band looked good still and bladder seems fine.
Getting it charged up today (what a pain to find a shop that could do it, I guess most places just send them out for rebuild).

I'm excited to see if the combo of a fresh shock and new front tire will help my high speed squirlly-ness and terrible sand handling.
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Re: Rear Shock Shim Stack Order

Post by KDXGarage »

Congratulations on getting it going. The bodies will indeed get scored if ran into the ground.

I would imagine that some shops just tell the customer that they don't rebuild shocks. I know the last straw for me was going to the then local dealer and ending up at the service technician's house, where any shock this fairly large dealer did ended up at his house for a charge. The store did not have their own equipment. I thought, JUST SPEND THE MONEY to buy your own equipment, and I did.

Good job on getting it going and checking out the parts.
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Re: Rear Shock Shim Stack Order

Post by david »

I got lucky, here at work our general manager is into Ultra4 racing and he has his own Nitrogen charging setup. I just ran buy his house one Saturday and filled my shock after a rebuild.
'81 KDX 175
'90 KDX 200
'07 Vulcan 2000 Classic LT (totaled 4/25/15)
'82 Honda GL500 (sold)
'96 ZXi 1100 JetSki
'98 STX 1100 JetSki
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