What Is The Car Want - Setup

[awegrzyn]

Recently I learned how to do my own alignments. Sort of trivial if you ask me, so I got it.
I learned it on a Spec Miata, which is easy because everyone will tell you what the car wants.

But what about new formula cars where you do not know what to set the settings to? What would be a good base assumption?

My Car: Speads RM02
Weight: 900 with driver
Tires: DSR tires
Wheels: 10,8

Would something like this work for a beginner:

Front:
Zero Toe
Camber (static) - 3

Rear:
Zero Toe
Camber (static) - 2

Zero Rake
Cold Tire Pressure 15

[Evl]

I'd call your tire supplier. They should be able to tell you the hot pressures, which are what matter, and they should also be able to give you an idea of where to start on the camber.

[jcorsico]

For what it's worth, on my FE I run:

Front:
a bit of toe out (1-2mm per side)
1-1.5 degrees of camber

Rear
a bit of toe in (0.5 - 1 mm per side)
0.5 degrees of camber

~15 mm of rake

Tire pressure is driven by temperature distribution across the face of the tire.

Jon

[S Lathrop]

You have not mentioned the most critical measurements in a setup. Front and rear ride height. Regardless of rake, the car will handle very different with a 1" ride height or a 1.5 ride height.

Find someone locally who can step you through a formula car setup. It does not take any special tools but you really need a good system. And you need to do it accurately. I set and adjust ride height in 1 mm increments set weights within 5 #.

[brownslane]

Regardless of what base line settings you start with, you need to know what affect your tuning has. You need a good tire pressure gauge and a good pyrometer.

The pyrometer is an absolute necessity in determining what/how the tire is performing and will give you feedback when you make a change. Without it I would not bother testing.

Again the tire manufacturer will give you target temps that you aim for, will tell you what critical concerns there are and should suggest a reasonable spread of temps on the tire. For example, if the outsides of the front tires are running 40 degrees hotter than the inside, you need to understand that static toe and/or camber settings may need to be changed. Without the pyrometer you are just looking at round, black, sticky and hot things.

Keep notes on each and every change you make, be sure and change only one thing at a time, and then THINK about what you are doing and what the tire is telling you.

There is no such thing as running somebody else's setup and expecting good results. It doen't work that way. You need to set up your car to manage its tires specifically based on the car, the driver, the track, the temperature, etc....and this changes every day to a certain degree.

My three most valuable tuning tools are the pyrometer, a can of WD 40 for aero readings, and a good pressure gauge.

[JakeL]

Hard to give any specific answers with missing details.

On the Speads, My first piece of advice would be to call Rilltech Racing, they are probably more familiar with the Speads than anybody in the US. He may have other info on your car aside from just setup you'll find useful.

Barring that, with bias ply tires, you'll probably want camber more in the .5 to 1.0 range, ride heights probably in the 1-1.25f and 1.5-1.75 rear to have some rake.

Probably a hair of tie out in the front and a hair of toe-in in the rear.

But, do yourself a favor and call Richard to get a baseline, then follow Tom's and Steve's advice below - they know what they're talking about.

Jake

[JohnPaul]

weight: 900 with driver????

[RobLav]

I talked with Andre over the weekend at NHMS about a lot of F1000 stuff, and I think he is convinced to bring the car to the next event.

[Jasonrmbell]

900 with the driver?

[awegrzyn]

You have not mentioned the most critical measurements in a setup. Front and rear ride height. Regardless of rake, the car will handle very different with a 1" ride height or a 1.5 ride height.

I was not sure how to measure the ride height correctly on a formula car, but I met Robert last weekend and he explained me few things. At first I thought you measure the ride height from the bottom of the floor tray, but it did not make much sense to me as the floor can change independent of the chassis (especially at the rear).

Robert told me: measure from the chassis. Pick up my measurement points and be consistent. So as of now I have:

Front:
51 mm to the chassis (where the floor tray starts).
43 mm to the bottom of the floor tray (where the floor tray starts).

Rear:
56mm to the bottom of the floor tray before diffuser.
155mm to the chassis at the very end of my car (easy point to measure).

Following this logic I'm going to assume that rake on a formula car is measured at the chassis as well. The only thing I'm not sure of right now is the floor tray and how it relates to the rake. Does the floor tray "go" with the rake or the floor stays always level.

900 with the driver?

- Yes. Car came from Canada. I have SCCA logbook for it, and it's weighted at 900 with the driver. I'm not sure what the rules were in Canada, as my car did not come with the anti-intrusion bars, even though the SCCA logbook has an annual tech of 2012.

[S Lathrop]

Ride height is a very critical measurement for any race car and especially formula cars. For an FB you are setting the basic balance of the car for mechanical grip, the amount and balance of down force at speed.

All the cars I have worked with specify the ride height relative to some points or surface on the chassis. In the case of a Citation it is the belly pan from the dash hoop to the roll bar. Again in the case of a Citation the front of the chassis is not on that plane but the bottom of the bell housing is.

When you look at aero data for a car, if it is available, you will see that the numbers are relative to ride height. In this case the ride height is to a reference plane.

The trick here is to figure out where that reference plane is and do all you measurements to that plane.

A quick way to set your ride height measuring system is to remove the diffuser/engine under tray and any skids covering the bottom of the chassis. Remove the springs and lower the chassis to the ground. Next find points on both sides of the chassis, at the front and rear. Measure from those points to the ground and you have your zero ride height or ride height reference plane.

A trick at this point is to make tools to measure ride height. I for one hate to crawl under a car to measure anything. Because the diffuser covers the bottom of the bell housing and skids cover the bottom of the chassis, we take our measurements from some point on the chassis. At the rear we use the top of the transmission. We bolt a small tab to the top surface that has a 1/8" hole in the tab. Directly below the tab is another hole through the under tray that allows us to drop a rod through both holes to the ground. We calculate the ride height at the rear with a ruler to the top of the rod. If you make the rod so that it is 6 inches above the tab when the car is on the ground, then you can use a 6" scale to read rear ride height directly.

At the front I build a stand to measure the ride height from the top of a front suspension pickup clevis. The stand is even with the top of the clevis when the car is on the ground. I then use scale or dial indicator to read ride directly.

You need to be measuring ride at 2 places at the one of the chassis to be sure the chassis is level, if that is what you want. I use a level on the chassis itself to check that. In the case of a Citation, the steering rack mounts and the top of the bell housing are uses to get a reference for level.

On the Dallara Indy Lights car there are 2 pads at the front of the tub for a level reference. The also are aligned with the front wheels. Standard practice there is to bolt a plate to the pads and measure ride height from the plate. At the rear on the bottom of the transmission there is a machined flat for measuring.

The Lola T97 Indy Lights car had a threaded boss on both sides of the front of the tub to bolt some type of measuring device. Frequently, people bolted dial indicators in those holes. On that car we used a bar bolted to the top of the transmission.

You don't need a million dollar alignment pad to do a good job. You can easily do a first class setup on a formula car with very simple tools and way less than $200 worth of equipment. A pair of good shipping scales will suffice for balancing the car. Lots of shimming material will do for an alignment pad. A long extruded aluminum bar (at least the width of the tires on you car) and a carpenter's level. A Tee square will serve for a camber gage very well. String and some heavy stands to hold the string taught are used to square the car and do bump steer if necessary.

FB cars are way too fast to not do a proper alignment job. What is acceptable for a SM might just hurt you in an FB.

[jcorsico]

Here's the fancy way to measure ride height. Basically put a bar across the top of the chassis, and then measure the distance between the top of the wheel and the bar. The closer the wheel is to the bar, the lower the car is sitting.

[awegrzyn]

Ride height is a very critical measurement for any race car and especially formula cars. For an FB you are setting the basic balance of the car for mechanical grip, the amount and balance of down force at speed.

Thanks for your reply. I really enjoyed it. It was very logical and complete. I have no follow up questions

Now I'm going to do what you suggested, and follow that up with pressure gauge and a pyrometer.

Guys, I know calling Richard would help, but I want to get there myself, so that I can learn it and apply the logic to any race car in the future.