Driver's side frame tube removal consequences????

[RM1SepEx]

Question:

What is the loss in stiffness/chassis rigidity if I remove that 1 inch tube that goes from the outside of the frame diagonally down at an angle to the center just in front of the driver's seat on my 818S frame?

My wife has to stretch to be 5'1" tall, I may remove that tube to allow the seat to slide forward several inches using the 3/4 tall seat sliders that I got from Cerullo... Just wondering how much it will effect the frame's stiffness. I have to believe that the scenario has been investigated.

[Jason Lavigne]

Hi Dan,

That is a common question. I'll start by saying that every tube we design into a chassis has a purpose, so by removing it, you're disabling the function that was intended with that tube. The short answer is that we don't recommend removing it.

To elaborate: That particular 3/4" tube adds rigidity to the car that would be noticed particularly when you're driving hard. The question is: Is the space gained more valuable to you than the rigidity lost? If so, you might consider removing it. I would just strongly recommend getting everything installed around it (shifter, pedals, column, and temporarily the seat) so that you can be really certain that you want it gone.

Also, like any chassis or suspension/steering geometry modification made before the car is finished, it's always best if you can have an opportunity to drive your car before you remove the tube/make the change, so that you have a better idea of what the impact was.

Hope that helps!

Jason @ FFR

[RM1SepEx]

Being an engineer myself I understand that fully, However I also can surmise that F5 has run models with and without that bar. I was hoping to get a number or something.

I've been married for 30 years and would like to keep it that way... that means my wife should be able to drive the car and adjust the seat position. It appears to me that MAJOR compromises were made when the seat area was so limited by that bar and the stock tank location. This is particularly true when attempting to use the stock seats. This kit is sold as a single donor vehicle yet those stock seats barely fit in that space with really NO room for adjustment!

So Jason... what I'm hoping for is that the torsional rigidity is reduced by x% from y to Z based on finite element analysis. I could then decide if removing that piece was a compromise that I was willing to make

[Jason Lavigne]

I'm definitely with you on wanting to make sure you both can comfortably drive the car. The tube was designed in from the beginning, and as far as quantifying the difference, I don't have any data on that to help with your decision. You could always consider re-installing if necessary, or maybe there's some other way to add gussets if you wanted to.

Jason

[mike forte]

Hi Dan,
Just as a thought you might want a seat insert with different foams that snap/clip into place. Many race cars have seat insert to enable different drivers with the same seat. It could be an easier fit that you just put behind the seat when you're driving.
Mike Forte

[RM1SepEx]

there is ZERO room behind a stock 05 WRX seat with me at 5'8" driving an 818