Front single shock setups

[hispanicpanic]

So my question is mainly in particular to Formula Renault 2.0, but a lot of formula cars only have one shock up front for both wheels. I'm trying to understand how to tune these types of suspension setups. Are both front wheels tied together with an 'infinately stiff' sway bar? I just have no idea how the mechanical bits make up these types of suspensions and i need to understand more about them in order to set up my FR 2.0 in my sim.

[Vyssion]

If you'd like, I have written a guide all about tuning a car for simulations and games:
https://www.scribd.com/doc/305870890/Ra ... ning-Guide

As for how they are typically joined up, most suspension setups that I know are relatively independent of one another. They may be linked via an anti-roll bar, but aside from that type of mechanical connection, most of their influence on each other comes down to the vehicle dynamics and how the center of mass is moved about when one wheel hits something. I do know that in F1 cars, there is something which is called an "inertial damper" (or something like that) where as the pushrod is pushed upwards, a small weight is rotated around a threaded shaft very quickly, which causes it to move laterally away from the wheel. When the F1 car has passed the kerb, for example, the wants to return to its normal place, but first the weighted wheel needs to spin down the threaded shaft which takes time to do so. The overall effect is to simulate the vehicle being heavier than it actually is, thereby reducing the response time for impacts to the suspension system and giving you a smoother ride.

Of course, I may have remembered the actual process wrong, but these things do exist and are used for what I've said

[Greg Locock]

You are talking about inerters. They increase the response time. I doubt they are used on the OP's car. Other than those quibbles that was a very useful post, for some values of useful.

[Facts Only]

I believe what you are talking about is a 'monoshock' try googling that, plenty of info out there on the internet about how they work.

[hispanicpanic]

Googled monoshock and learned a few things but information is sparse. I can't find any info on the setup specific to the FR 2.0, so i have no idea how it deals with roll and how the front spring/damper play into it. I know how other setups do it, but i have no idea if the FR 2.0 is similar.

Still having trouble setting up my formula renault 2.0. I tend to run setups with very little rear swaybar but there's simply too much body roll, unloading the inside front tire on turn in. The only way to cure this is to increase roll resistance and it seems the only way to do that is to increase rear sway. Stiff rear sways make the platform super stable on turn in but corner exit is a total bear when applying power. Running Mid-ohio this week and all the hills kill me on a stiff swaybar. Cresting the hill under power and the thing just swaps ends instantly. I've tried increasing rear spring rate instead of increasing sway stiffness but it seems it doesn't contribute to roll stiffness as well as the swaybar.

[strad]

shouldn't he be looking at a stiffer spring rate rather than stiffer bars?

[rscsr]

To begin I don't think, that it is a problem if your are lifting a front wheel. It just means, that you are basically on the limit of rearwards balance for mid corner. Any decrease of rear anti roll bar would make no difference for the balance through mid corner.
I would just soften the rear pushing damper or harden the front pulling dampers.

Could you provide us with a telemetry file? And what kind of Sim do you use?

[silente]

Monoschock suspension system were pretty often used in Junior formulae till a few years ago.

Basically, they consist of a single damper/spring unit, which is responsible to control vertical movements and a slider that is responsible for roll controlling. Inside this slider, you normally find belleville springs (or cup springs, but they could also simply use normal coil springs if they want to, they use belleville springs only because they are very cheap and allow to change configuration (and hence stiffness) practically in infinite ways with a very low expense and relatively short operation time).

This slider moves horizontally and the springs resist his movements, creating an antiroll effect. The system is pretty "dirty", since while normal antiroll strategies use devices (like a T or a U antiroll bar) that, when you push one wheel up, would bring also the other wheel up, +/- the deformation of the antiroll device itself, this antiroll sliders practically do the opposite: if you remove the springs inside and you push one wheel up, the other wheel goes down, because when the slider slides inside its case, it brings the pushrod rodends with it.
Moreover, you don't really have a way to control roll damping at the front, beside the friction inside this slider.

http://www.race-cars.com/carsold/other/ ... 6952pe.htm

In any case, the first thing to understand would be if your simulation software has really modeled such a system or simply use a strategy where a single spring is used to control vertical movements (like in a third element with a t antiroll bar) and a "normal" antiroll bar (T or U) is used to control roll.
There were cars using such a scheme also in the "real world" like the old F.BMW.

[bigpat]

In addition to the post above, the 1996 Van Dieman Formula Fords used a monoshock front end will bellevile washers on the sides to control 'roll'. Bellevilles allow you to set up the roll stiffness differently for left and right hand corners if desired.

Monoshocks were used in F1, mostly late 80's to early 90's, most notably on the 1991 Jordan. Formula 3000's also used them, which is where my experience with them lies.

We used a conventional U or T shaped anti roll bar ( ARB), which normal longitudinal links to the suspension rocker. Between both ends of the ARB, we ran a 'bridge', r solid link between them. In the centre of this was a longitudinal link which mounted to the single spring/damper unit.

Roll stiffness was altered by roll bar size, and where the rocker links joined the bridge, the further towards the centre giving more roll resistance.

To achieve a rising rate on the monoshock, we placed a spacer between the bridge, and where the monoshock link picked up off it.

In general, you can't run much rear roll bar with a monoshock front end. You may also need a touch more rear spring rate, or try some anti squat geometry if available on the inboard wishbone pick-ups. With a monoshock you can also try some more castor angle to get some more work out of the inside front tyre. Just a suggestion.....

I believe in categories where platform stability is important, and particularly on medium to high downforce cars, its a simple solution, as it reduces the variables to control, which sometimes think is half the problem in engineering racecars.

Hope this helps,

Pat