Find more about Anti-Roll Bars Part 2

Details of the operation of the anti-roll bar are presented in our blog post ” anti-Roll bars. A good thing or a bad thing?”

As stated in this article, there is much more to reducing anti-roll bars than simply Body Roll.

In this blog, I would like to focus on two very important properties of anti-roll bars in the frame structure for racing…Stiffness of the suspension in the roller and how you get more grip with stiffer springs and arches.

Roller suspension rigidity

The hoop increases the rigidity of the suspension in the roller, that is, in turns, the spring and hoop contribute to the rigidity of the suspension, as seen on the contact surface of the tire.

I’m going to quote an expert in driving dynamics here, so you don’t think I’m making it up:

Many of us have difficulties with this statement, especially when we know the concept of distribution of bearing rigidity. Our general understanding is that increasing the rigidity of the rollers in the front increases understeer in the stationary state and therefore the reaction of the vehicle is less. The car will be less agile.

What Greg is talking about is how the increased rigidity on the contact surface of the tires makes the weight transfer faster in the front, the car reacts faster, and the car turns harder at first.

Once the car has settled in the corner ,of course,” steady state balance ” – roller stiffness distribution, front roller stiffness vs rear roller stiffness-takes over.

My difficulty with the perceived improvement in mobility due to the installation of a larger front arch dates back more than twenty years.

In the 90s we operated a Pedders Suspension franchise in Batemans Bay. At that time, we changed the suspensions of road cars – fitting spare Springs, hoops and shock absorbers on popular models of the 70s-90s. When we finished with the mods for these cars, the improvement in the crispness of handling was immediately noticeable. I was back to test cars and customers were also very aware of the improvement.

In general, we would have attributed the improvement to a lot of things and so we had no difficulty with what was happening.

But when I started to improve my understanding of roller stiffness distribution, installing large diameter anti-roll bars on the RWD Kingswood/Commodore and Falcon cars and the resulting improvement got in the way a little bit. Cars should be more understeer and therefore less turn. I doubted the improvement and wondered if there was some sort of placebo effect here. I imagined?

Once we understand more about the rigidity of the rollers and the effect of the initial weight transfer on contact with the tire, it makes sense. With fast moving speeds in the linear gripping area of the tires, the additional reaction by faster lateral transfer of weight is the dominant element. If we approach the limit of the handle, if the car is actually a strong understeer, understeer will dominate.

How to get more grip with stiffer springs and anti-Roll Bars

At Racing car Technology, we found through testing that mechanical grip (and lap time) improved as spring stiffness increased to a point where gains balanced and some of the disadvantages could have a greater impact. For example, if they are too rigid, tire wear and overheating can be a problem. Power on and brakes can be affected on rougher sections of the circuit.

Optimizing suspension stiffness is usually the most important improvement we can get for the race car. For many of our customers, increased spring stiffness was the main factor in improving performance, sometimes by a few seconds per turn.

For racing cars, we recommend a driving stiffness of 150 cycles per minute (2.5 Htz). For production vehicles, this is 2-4 times stiffer than the standard spring mounted on the production vehicle. Less rigidity is recommended for historic cars and cars with limited lateral rigidity.

The next step is to recognize how rigid safety bars can help you get more grip.

In the old days, when I was driving the Ford Bowin P4A Formula (1973), I thought that if I reduced the overall stiffness of the roller (while maintaining the existing balance), I would find more grip and be faster. My cue for that thought was former owner and 1972 Championship winner Bob Skelton. It was rolling with less overall roller stiffness than I had done at ease.

This thought was wrong, as we know today. There is no theoretical limit to the rigidity of the rollers with which you can run. (The main reason Bob was faster than me was probably the softness. It was typical of the good runners of the day. Like Leo Geoghegan, he was a real impulsive driver who drove classic lines and maintained maximum speed in corners.)

Burying that thought for me was complicated by the writings of Carroll Smith. Even in 1998, in “Engineer in your Pocket”, he claimed that too anti-roll bar overall results in:
“The car will react very suddenly and have little feeling. The car tends to slip or skate instead of taking a set, especially in slow and medium speed turns. Car can flex on bumps.”

Due to my misunderstandings, I remained a supporter of less Anti-roll in the back for a RWD racing car until 2014. In 2012, for example, I remember that David Stone’s Mazda MX5 could run without a rear safety bar as long as the balance remained good. The thought revolves around the idea that the rear hoop tends to unload the inner rear wheel. (I hope we blew this idea into the “Anti-Roll Bars” for you. A good or bad thing ” – article.)

This is in stark contrast to our current recommendation in our training and consulting courses since 2015. all racing cars should have efficient front and rear roll bars with sufficient adjustment for mechanical balance to balance the car between too much under-bending and over-bending, which is just enough to require counter-steering. (The opposite direction creates a slower turnaround time than the desired optimal Balance.)

What changed everything for me is an article in the newsletter Chassis by Mark Ortiz. The bulletin, now in its 20th year of publication, is highly appreciated by many influential people in racing and handling racing cars. The article I read mentioned those who are in the running who still have a Problem with the anti-Roll Bars, especially in Australia.

Now I’ve never voted with Mark, but I’m a big fan of his work, especially the four-part series he did for the magazine Race car Engineering about dealing with race cars in 1998. But I had this feeling. Was it from me? Or is there at least one other person in Australia who has strayed in the same way?

I was stabbed in action. I immediately thought of Mygale space frame racing cars like the Formula Ford and F4 versions. These cars are very large anti-Roll Bars front and rear. If I could find out what is going on with these cars, I would be on my way to a better understanding.

In 2010 I was able to take a quick look at Cameron Walter’S Mygale FF numbers when he started in the Victorian state and at the national championships. With the numbers given to me for our WTW ™ weight transfer table, the massively rigid anti-Roll Bars made no sense to me. I think the rods must be hollow. But then we never had the opportunity to settle this as we did not make a consultation agreement.

Then in 2014, in response to what I read from Mark Ortiz, I looked through the question again. The stiffness figures of the springs and roller rods as well as the movement reports can be found publicly in the factory manual of the Mygale F4 car. So I could compile the data I needed for a pretty good crack to make the WTW. The analysis has proved beyond doubt that the Mygale is indeed super stiff .2 roll degrees per side G. actually no roll at all in the suspension.

The bird spiders were a revelation at their first competition in Australia in the early 2000s. in the following decades, they won the most Championships. The only car that can compete with them in the Ford formula is the Spectrum built in Australia.

The results of the analysis show that the demand for stiffness of the bearing is similar to a racing car in regular, while the rigidity of the rollers is much stiffer, and provides virtually no match suspension while the car is in the curve. According to old ways of thinking, manipulation should be bad. But experienced drivers or not, notice nothing unusual. I checked Videos of Mygales in Europe in full tilt on the wavebands in the race cars. Once again, nothing unfortunate. This is zero Compliance and instant adhesion to the outer tire and the lowest possible contact Patch variation to generate maximum Grip that makes cars so fast. However, most Teams and proprietary drivers do not seem to understand the basics of setting up Mygale, sometimes to their detriment. It would make no sense, for example, to try to remove the rear anti-Roll bar.