Inverted Struts

[Sp 01]

Can you tell me the main reason for inverted strut design?

Is it for rigidity and durability or is it for "Unsprung Mass" reasons?

I was lead to believe that unsprung mass issue was a priorty in racing design.

[Wojtek]

Hi,

We actually use non-inverted mono-tube shock design for our Group'4 kits, and find this to be strong enough for road and circuit use. Although unsprung weight is very important, I would not expect there to be any reduction when using an inverted mono-tube design.

Regards,
Wojtek.

PS. I have also answered your email with the same questions.

[Sp 01]

Wojtek,
I have Group 4's on my WRX. The question was more of a design Theory for "Inverted"struts. If the unsprung mass is similar for cars then why Invert?
What are the benefits of Inverted design. .
Please note I'm very happy with my G 4's and prefer to have a performance strut that doesn't require servicing

[Wojtek]

Hi,
I am pleased to hear that you are happy with your Group'4 kit.
I would think the answer to your original question of why use an inverted mono-tube design is strength and rigidity, which is required in racing applications where extreme loads are applied. As the shaft in an inverted mono-tube is not subjected to any radial loads, this is carried by the shock body, durability is improved as well. Having said that, there are more moving parts in an inverted design, so there is not much in it.
As for (unsprung) weight. In an inverted design with the car at normal ride height and the shock body compressed inside the housing, I would think that the unsprung (and sprung) weight would be actually greater then for a non-inverted design.

Regards,
Wojtek.