Bar vs Spring

What are some considerations for making ARB change vs a spring rate change to adjust front to back roll stiffness?

Disclaimer: as it relates to a left turn only circle track car, with front ARB only and rear live axle. Please don’t judge me. 😜 I have a suspicion that most people here are road racers.

That doesn't narrow it down much, with different types and classes of vehicles, and 'oval' shapes, lengths and track surfaces ;-) I assume you're using some form of spool, but what about things like stagger?

As a rough guide, springs act on the wheel, ARBs force the wheels on the axle to work together. The trick, as you're aware of, is getting the balance right.

It is, as you said, not something most of us are familiar with, but with more information some suggestions may help point you in the direction of experimentation and testing.

Hello Gordon, tracks in the series we race vary widely in configurations. They can range from a few degrees of banking to 20 plus degrees, some have long straights, some hardly any straights, and corners can be paper clips or wide sweeps. For example, at one track the speed range slowest point to fastest point is 60 and 70 mph (i.e. minimal front to back load transfer), whereas another track it’s 70 and 120 mph.

We are finding what seems to be the sweet spot in balance is getting the RF shock travel in the 1 1/2” range, regardless of track configuration. Typically we use RF spring changes and / or front ARB changes to get the RF to the desired travel.

That being said, we can achieve the desired front roll stiffness with either a spring change or ARB change, but was curious if there are other factors to consider when tuning with a spring change versus ARB change? Or is the better way to think about it is that the RF spring and front ARB are basically two devices working together as one unit?

Circle trackers are most welcome here 😁

We're actually in the middle of production for a Suspension Fundamentals course at the moment which will help you answer these questions, slated for release in around a month which you might be interested in!

Ultimately, the springs and anti-roll bars are working in concert together, although in quite different ways. Each suspension spring is only affecting its own corner whereas the ARB is coupling both sides of the car together. One of the big downsides of using more ARB stiffness is that you are effectively reducing the level of independence on the front axle - this can be a problem on rougher track surfaces.

The advantage of tuning the balance with the ARB is you are de-coupled from how the front is behaving during braking (not sure how much/any of that you are doing!?) This means you can control the front ride height during braking more with springs, dampers and bump rubbers/springs while still having a de-coupled tool to tweak the balance.

Sounds good Tim, I’ll keep a lookout for that.