Spring and swaybar conversion.

Dentspeed · Post by **Dentspeed** » Sun Oct 22, 2006 10:21 am

Hey all suspension gurus. Is there any way to compare the amout of roll resistance when looking at different spring rates and swaybars?

What I mean is for every mm of bar diameter, what would be the change in spring rate. Branden Burkhart was running 10K/560lb. springs on the front, but used that huge Strano bar, I think it is 31mm. I would rather go up on spring rate and keep my 24mm bar. Any help?

TedV · Post by **TedV** » Sun Oct 22, 2006 8:07 pm

you would need to measure all the dimensions of the bar and do some math to figure it out. unless you can call the bar manufacture and get the equivalent lbs/inch rate. Or tie down one end of the bar and measure force to deflect it. Lots of variables that effect roll bar stiffness, length of the bar in torsion, how far the end links are from the cross torsion part of the bar, what steel it’s made from. The more bends the more pain it is to figure. Easiest is to call Strano and ask. How stiff can you go on your springs before you can’t stand it? The more stiff the springs, the slower it will be on bumpy courses.

MARKP · Post by **MARKP** » Sun Oct 22, 2006 8:29 pm

What he said. Generally speaking, I like more spring and less bar.

TedV · Post by **TedV** » Sun Oct 22, 2006 9:10 pm

MARKP wrote:What he said. Generally speaking, I like more spring and less bar.

me too, but depends on the car too

Dentspeed · Post by **Dentspeed** » Sun Oct 22, 2006 9:39 pm

Now my brain is hurting.

gbwrx · Post by **gbwrx** » Mon Oct 23, 2006 7:05 pm

FYI-FWIW---This doesn't help your question as you had already said you didn't want a bigger bar. But, I am pretty sure that Strano bar is 32 mm. I definately wouldn't get it due to how many posts that I have seen about it breaking control arms. Not saying that it would happen but I thought about it quite a bit before I got my front sway bar and I ended up with the Whiteline 27-29mm.

Miata 37 · Post by **Miata 37** » Mon Oct 23, 2006 7:46 pm

I have a spreadsheet that someone made (with WAY more suspension knowledge than me) that talks about things like "roll couple," spring rates and bar sizes. All of the pre-loaded info is for Miatas, but all you need to enter to make it fit your application are the rates and bar thicknesses. If you would like it, just let me know.

TedV · Post by **TedV** » Mon Oct 23, 2006 8:20 pm

the spreadsheet would only work if the suspension and sway bars are exactly the same between an STi and a Miata. You could use it to get an idea how different changes effect things on a Miata tho... maybe..

Steve-o · Post by **Steve-o** » Mon Oct 23, 2006 9:06 pm

Sounds like a fun toy to have anyway.

steverife · Post by **steverife** » Mon Oct 23, 2006 10:06 pm

Autocross isn't about thinking, autocross is about mindlessly copying the fast guy.

Strano bar breaks control arms?!?!?!?! How much does an STi control arm cost?

kinada423 · Post by **kinada423** » Mon Oct 23, 2006 10:51 pm

http://www.vividracing.com/catalog/prod ... ucts_id/53

The myth is answered.