Breakdown of MS3 front strut

[zenit]

So, I bought a set of stock springs for a future bilstein setup which came with a set of blown front struts. Since I planning on tossing them anyways, I decided to dissect them.






I'm going to go from outside to inside here:

This is outside tube in our twin tube shock, it also has the spring perch for the macpherson setup. It's cut in the center to remove the inner tube.


This is the lower half of outer tube. You can tell that it's not the tube that contains oil piston and shaft, due the rough texture of the tube.



This is upper half of the tube. Two things here: there's a circular depression on the inside of the tube where the spring perch sits, also, there's a dent running laterally along the tube. I'm guessing that it's there to keep the shock head and seal in the tube, just in case things loosen up.



Next we have the inner tube, where the shaft, piston/mid-valve and base valve sit, and shock head sit.



On the right side is the shock head and shaft/head seal, on the left is the base valve.



The interior of the tube is very smooth and unlike exterior tube.



The top side of the base valve.



The bottom side of the base valve.



The base valve taken apart.



The shock head, without seal. Notice the shaft seal- it's not a rubber "u" seal like I expected. It's a hard plastic ring with a very tight fit with the shaft.



With the seal.



The seal not only seals the shaft, but the exterior tube too.



The shaft, piston, midvalve, rebound spring.



Close up on the piston/midvalve. The piston seal is like the shaft seal in the head- it's hard plastic, a tight fit with inner tube.







So what does all this mean? I was curious to see if it was possible to rebuild a shock like this.
In short, probably not. The shaft seal/shock head seal looks pretty specialized, I'm not sure you could find a replacement for it.
Also, the piston seal I have no idea how you would replace and the shaft seal is pressed into the shaft head, with no easy way to disassemble.

Also, the base valve sits against the bottom of the strut, which would have to cut open to drop the inner tube/shaft for rebuilding or revalving. You would have to find a way to reassemble the strut such that it could withstand a hit from the shock bottoming out. Or redesign the shock head that so it could be taken apart from the top. Also, the base valve isn't screwed together, although it looks like it. It's pressed together.

One last thing I just noticed. Although it's a twin tube design, there isn't a nitrogen bladder like I expected. It doesn't look like there's anything separating the oil and nitrogen, which means it's an emulsion shock.

• Share
  • Share this post on
  • Digg
  • Del.icio.us
  • Technorati
  • Twitter

---

Last edited by zenit; 06-29-2013 at 06:53 PM.

[Ace Protege]

That's interesting.

[Rokusek]

Nice work. Very informative thats for sure.

[zenit]

Anyone have a blown/bent/unwanted rear stock shock for dissection?
I'll pay shipping.

[helmetface]

@Nliiitend1; @Tomas;

[Rokusek]

@2.0t03speed; has two rears

[2.0t03speed]

ugh i just threw out my rears a few weeks ago when i did some garage cleaning. i think i still might have my front's though. i need to check tonight when i get home.

[Rokusek]

what happened to the full stock suspension i gave you? please tell me you still have them...

[zenit]

If anyone wants shim stack specs, I have the tools to measure them.

[Tokay444]

I have a blown rear.
We can split shipping from the states, or I can disassemble and post up here.

[zenit]

I'm biased towards doing it myself

But it's your shock.

[Tokay444]

well, if you want to split shipping from canada i can have one out by end of the week.

[anavrinIV]

I have a full set of stock shocks just sitting in my garaged, boxed and ready to go if your'e interested. I don't want any of them. They're not blown, just weren't good enough for what I wanted.

[zenit]

@Tokay444; email me. I'll definitely take that rear shock.
@anavrinIV; I might be interested in those stock shocks.

It looks like bilstien won't sell me rebuild/revalve materials or shims, and at this moment I don't want to have to shovel out $1,300 for a set of B8's from FCM. I might look into fabricating some a new shock head.

[zenit]

Thanks to @Tokay444, I have some pictures of the rear shock.

It's a pretty vanilla monotube shock.

Drilled the shock to release the pressure.


After trimming the top of the monotube, the shock head comes out. Pieces of the shock head are broken off because I thought that it secured by circlip.


Disassembled it looks like this:


Here's a close up on the shock head and valve:



The valve uses the same kind of hard plastic seal:


The valve part of things is pretty normal.


I was mostly impressed with the shock piston. It's a really dinky plastic piece, with just a o-ring for a seal.

[Tokay444]

and that's why i'm on my 4th in two years. stock ride height.

[zenit]

For what it's worth, the dinky piston didn't look like it leaked at all. The shock head o ring looked good too.
The shaft seal was shot though, allowing air in and oil out.

[Rokusek]

Thanks again Brother, this is definitely an awesome bit of information.

-PJ