00fxd

Which way should the pre-load be for a front control arm spreader bar? Push or pull?
Thanks,
Frank

Solofast

Preload to pull...

63Corvette

I'm not sure what you are asking. If you are putting a "spreader bar" between the front suspension towers (A-arm suspension pickup points on the frame) then they should spread or prevent the two frame points from coming closer together due to suspension loads (g-force tending to force the front mounting points closer together). If it's something else, then I misunderstood.

00fxd

Not sure what I am asking? Is my terminology wrong somehow? VanSteel etc calls it a spreader bar - you may call it something else. Control arm, A arm ...

I just ran across this doc.
https://www.vansteel.com/PDFs/Spread...structions.pdf

"Once the bar is installed, you can pre-load it slightly outwards. Installation of this kit
usually gives the car a tighter “feel” when driving."

Thanks fella's,
Frank

63Corvette

"Once the bar is installed, you can pre-load it slightly outwards."

Well then this seems to answer the question you asked

00fxd

It does and you did too,
Thanks again...
Frank

Solofast

Since we are in the autocross and road racing forum here I was assuming that you were looking for the best performance from the bar.

If you preload it in compression (spreading the towers) as you turn the car the outboard tower (the one with the highest load) will flex to spread more under cornering loads and you will lose camber. The "slop) in the Heim joints will then take up and the bar will be effective.

If you preload it in tension it will be effective immediately and loads will be transferred to the opposite side of the car with out regard to slop in the joints.

I can't think of any reason why you would want to preload it in compression since the bar is really trying to work in tension.

00fxd

I don't autocross too much, just "spirited" mountain driving. So that would be my focus.
Regards, Frank