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Old 01-08-2006, 09:23 PM   #1
spfldsti
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Default Inverted Monotube and Monotube

Sorry, guys/gals. I'm quite sure this has been covered here before, but I could not find any solid info related to my question. Which is...

What are the differences, advantage, disadvantages of and Inverted Monotube strut compared to a Monotube design? Please, keep in mind I don't want to start a Name Brand war. Brand X inverted monotube versus its own monotube design and not against Brand Y.

Here is my basic understanding of it. Please flame away, but constructive comments are preferred.


Advantage: Inverted Monotubes keep the oil futher away (higher) from the brake rotor (hot area) effectively helping to keep strut oil, cooler, and running within it's normal operating temperature range. Probably only noticeable during a track day or some very aggressive driving.

Disadvantage: Inverted Monotubes transmit more noise up to the cabin. For those concerned with noise. I don't know how they do this; it just seems to be what everyone says. (Noise is not an issue for me)

I'm really curious to hear what you guys have to say. While trying to do my homework/searching. I noticed that most of the Race type applications use a monotube desing with remote resevoirs. This leads me to think that if spring rates and valving are the same, then oil capacity and cooling are really the only concerns.
Help me out fellaws,
Abdias
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Old 01-08-2006, 10:31 PM   #2
Impreza01
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One of the biggest advantage of inversion of the strut is so there is less structural flexing from lateral loads.
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Old 01-08-2006, 10:40 PM   #3
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I've have read similar statements. If you don't mind can you explain why/how?

Thanks.
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Old 01-09-2006, 08:51 AM   #4
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"Bilstein Gas Pressure Strut/Inserts operate on the same principle as our normal gas pressure shock absorber. In the conventional McPherson strut (which is based on the use of the twin tube shock absorber) the piston rod protrudes above the McPherson strut assembly and attaches to the sprung mass of the vehicle. In this type of application the piston rod has to absorb not only compression and rebound forces but tremendous side loads.

The Bilstein principle is to manufacture the strut/insert with the rod pointing down into the strut tube, thereby utilizing the thicker, stouter body portion of the shock absorber to dissipate side loads...In short, due to the increased diameter and surface of the pressure tube, the Bilstein Gas Pressure Strut/Insert is better suited to take increased side loads when compared with the conventional twin tube strut/insert."

http://www.bilstein.com/tech.php?PHP...9b7b60afae3387
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Old 01-09-2006, 12:12 PM   #5
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Are there non-inverted Monotubes?
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Old 01-09-2006, 01:48 PM   #6
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A very slight advantage of the inverted design is less unsprung weight. But its nothing signifnicant most of the time.
To my knowledge, there are far less inverted designs to regular designs.
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Old 01-09-2006, 05:37 PM   #7
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Quote:
Originally Posted by Noob4life
A very slight advantage of the inverted design is less unsprung weight. But its nothing signifnicant most of the time.
To my knowledge, there are far less inverted designs to regular designs.

And also a "slightly" lower center of gravity with more of the weight toward the bottom of the shock. But it also becomes more difficult to choose dampening levels as inverted shocks will have the adjusters on the bottom. Not too bad to adjust up front, but kind of a PITA in the rear.
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Old 01-09-2006, 06:30 PM   #8
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ripvw- Thanks for the link.

Is it a safe assumption that all other manufacturers use similar or somewhat similar design?

Hope you guys don't mind all the questions. I really want to better understand this subject.


THAWA- I don't think I understand your question.
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Old 01-09-2006, 07:27 PM   #9
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The shape will be somewhat similar I suppose, as you can only vary the appearance so much. But there are a lot of ways to differentiate one from another, which are usually not easily visible (materials used, type of valving, type of damping adjustment, etc).
It is definitely not safe to assume that, because one coilover shares some similarities to another (be it in appearance, valving, components, spring rates, etc), it will perform similarly or last as long.
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Old 01-09-2006, 09:10 PM   #10
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Quote:
Originally Posted by spfldsti
THAWA- I don't think I understand your question.
I was under the impression there were only really two different types of oil filled shocks/struts, inverted monotube and twintube (not inverted). I just wasn't sure if there were non-inverted monotube shock/struts.
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Old 01-09-2006, 09:32 PM   #11
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Um, for all of you guys who can't bring a non-inverted monotube damper to mind, think of Whiteline's Group 4 coilovers.
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Old 01-09-2006, 11:16 PM   #12
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Quote:
Originally Posted by THAWA
I was under the impression there were only really two different types of oil filled shocks/struts, inverted monotube and twintube (not inverted). I just wasn't sure if there were non-inverted monotube shock/struts.
Strictly going with what I have seen on some of the manufaturers websites. I believe the ZEAL Funtion B6 is a standard monotube, (non-inverted) and the Whiteline G4's would also fall under that category. I spoke with a Koni represenative (the reason I'm asking all these questions) and he told me, Koni doesn't make any Inverted-monotube shock/struts. He also mentioned, "there are no plans to develop any applications for the STi."

Maybe, I misunderstood something above. Are you saying that an inverted-monotube and a twin tube are two different things. I should have picked up on the obvious.

So the PSS 9= twintube.

ZEAL Function B6, Whiteline G4's= Monotube

Cusco Zero 2R, ZEAL V6= Inverted-Monotube

I never picked up on the Twintube design.
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Old 01-09-2006, 11:24 PM   #13
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Quote:
Originally Posted by Impreza01
Um, for all of you guys who can't bring a non-inverted monotube damper to mind, think of Whiteline's Group 4 coilovers.
yup, lots of non-inverted monotube dampers our there, moton, penske, ast, etc.

one inherent problem of inverted monotubes is stiction. There are more seals and friction to overcome before the piston starts to move. This makes for a less supple acting damper compared to a non-inverted strut. Twin-tubes tend to be the most supple but don't have the fade resistance of a monotube.
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Old 01-09-2006, 11:26 PM   #14
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Quote:
Originally Posted by spfldsti
PSS 9= twintube.

ZEAL Function B6, Whiteline G4's= Monotube

Cusco Zero 2R, ZEAL V6= Inverted-Monotube

I never picked up on the Twintube design.
Pss9 is monotube. I think it's non-inverted but don't hold me to that one. Not all twin-tube designs are bad. Supposedly they're more street friendly. The Cusco Zero 2 and 2e are twin tubes.
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Old 01-09-2006, 11:28 PM   #15
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Quote:
Originally Posted by spfldsti

Maybe, I misunderstood something above. Are you saying that an inverted-monotube and a twin tube are two different things. I should have picked up on the obvious.
yes, monotube and twin tube are very different.

here's a good damper primer:

http://www.whiteline.com.au/faqshocks01.htm
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Old 01-09-2006, 11:39 PM   #16
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Quote:
Originally Posted by Arnie
yes, monotube and twin tube are very different.

here's a good damper primer:

http://www.whiteline.com.au/faqshocks01.htm
Thanks for the link Arnie. I'll be up the rest of the night reading that thing. Which is cool, cause my 3 week old daughter is going to want some formula in about an hour. I promised the wife I would do it.
back on topic...

I'm learning everytime I log-on.
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Old 01-09-2006, 11:41 PM   #17
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Quote:
Originally Posted by spfldsti
I'm learning everytime I log-on.
This board needs more n00bs like you. More inquiring/learning and less spouting and bad info handouts (although you did get caught on the pss9 issue)
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Old 01-10-2006, 12:13 AM   #18
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Quote:
Originally Posted by spfldsti
Thanks for the link Arnie. I'll be up the rest of the night reading that thing. Which is cool, cause my 3 week old daughter is going to want some formula in about an hour. I promised the wife I would do it.
back on topic...

I'm learning everytime I log-on.
Great! Do yourself a favor and read all the FAQ's from Whiteline. You will gain a huge understanding of the way suspensions work, etc.
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Old 01-10-2006, 12:31 AM   #19
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Cool.
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