Sway Bars on an RCR

[John Lowe]

'Ello all

As shipped my RCR40 comes with 550lb springs front and rear with dual adjustable QA1 dampers and a front sway bar dia of 1" and rear of 3/4". I have followed Deans set up for ride hight, camber and caster at the front and plan to do so at the rear. Sway bar lever arm length and distance from suspension pivot to link attachment is the same both front and rear. (A one inch bar is about 2.6 times stiffer than a 3/4" bar given equal lengths)

As I understand it increasing roll resistance at the front using a sway bar will increase understeer whilst increasing at the rear reduces understeer/promotes oversteer. Does anyone have any practical data on the effect of sway bars on an RCR40 and what has worked for them? Clearly my aim is to be as neutral as possible for a mix of track and road use. As a start point I am ignoring the effect of changing damper compression and rebound settings in the equation, I can only think through one variable at a time!

Best

John

 

[Tim Kay]

John, I'll be watching the response here. I am addressing similar settings albeit on a Tornado.

I purchased a set of front and rear QA1 DDR3955 (frt) and DDR5855 (RR) with 500# and 350# springs respectively. For the street I lowered the spring rate to 350# and 275# respectively.

Beware, something that really played with my mind at first was the double adjustable shocks had an effect on the ride height if set too stiff. I backed off the adjustment all the way, set the ride height then adjusted the dampening.

Keep posted here on your spring rate, I am curious what rate you end up with.

 

[Dean Lampe]

Well here are some suggestion that have helped me with my car. I would go to a 350 to 375 spring in the rear. That will give you a wheel rate between 270lbs and 300lbs. That is a good street/track setting. My sway bars are 32 inches long. The front is solid one inch and the back is 1 inch hollow with .090 side wall thickness. The rear arm is 10.5 inches from bar center to mounting point. The front is 3 inches to a 40 deg. bend then 8 to the mounting point for 11 inches total. On the shocks I would start at 20 clicks out and work your way in. On the back I am at 19 clicks out on rebound and 14 on compression. The front is 15 out both rebound and compression. I think this will be pretty individual but that seems to be a really good general setup for me and the car given how I drive. Don't get to lost in the math. It is great for initial setup but trust your tire temps and your rear end. Let me know if I can help.

Dean

 

[John Lowe]

Dean

Many thanks for the advice. My lever arms are shorter than yours, 8ins front and rear, the fronts having about a 15degree bend approx 2.5" from the bar. The bars are 37". I need to figure out the maths to see how this would compare with your set up and will pm you to get your views on what I find. In the meantime do you have the name of a good anti sway bar supplier?

Best regards

John:thumbsup:

 

[EGLITOM]

John

i created this file for calculation of sway bars, feel free to use it

just change the yellow highlighted fields to your desired values

TOM

 

[Fran Hall RCR]

John,

You only need to play with spring rates...not the bars.
Keep in mind that you cannot have a single set up that performs 100% on road and track ...they are two different animals...you do have the parts in hand to have the best of both worlds though...

375-400lb springs front and rear with the bars set at zero preload will give you the opportunity to turn a knob or two and have compliant street ride and track performance when needed...

This is a starting point depending upon how serious you plan on getting on the track and car handling preference is a very personal thing...

 

[John Lowe]

Tom, many thanks.

Fran, good stuff, so much to learn so little time:laugh:. Do I get the softer springs direct from you?

Have developed a great (well I think it is!) solution for mounting the rears, I will post some pics soon. As ever delighted with the level of RCR engineering, had a Tornado owner over on the weekend, he went a wonderous shade of green......

Best

John

 

[Jack]

Fran, shame on you for posting on turkey day! You are supposed to be enjoying FAMILY time!

Jack..

 

[Dean Lampe]

Tom, that is a great calculator. Here is what I found mine to be. I have adjustment holes in the arms drilled on 1 inch spacing.

View attachment SUSPENSIONCALCULATIONS(1).xls