Correct Setup Procedure for US Atoms.

[nickpoore]

So, Bruce wrote a great article on Suspension & Setup in the club pages:
http://www.atomclub.com/account/index.c ... 6&page=105

The US Atoms were also criticized during Atomfest for their lack of correct setup.

What I'd like to do is start off with some basic settings, and see what everyone else things.
Please post additions / corrections, and I will make changes as necessary.

I pulled most of the data from Bruce's setup, however also use personal info for some settings.
Note that the Brammo manual (http://www.arielatom.com/pdf_manuals/Ar ... 070925.pdf) suggested very different settings on Page37, with a front ride height of 5.15". 


[align=center]  TRACK USE  [/TD][TD]  Ride height  [/TD][TD]  Total Toe  [/TD][TD]  Camber  [/TD][TD]  Springs [/TD][TD]  Bounce & Rebound  [/TD][TD]  Tire PSI [/TD][/TR]
[TR][TD]Front[/TD][TD]4.5"[/TD][TD]Out 0.3°[/TD][TD]-1.0°[/TD][TD]3.75"[/TD][TD]??[/TD][TD]14 PSI[/TD][/TR]
[TR][TD]Rear[/TD][TD]4.0"[/TD][TD]In 0.4°[/TD][TD]-1.5°[/TD][TD]3.15"[/TD][TD]??[/TD][TD]15 PSI[/TD][/TR]
[/TABLE][/align]

[Bruce Fielding]

I think the simple answer is, it depends...

It depends on what tyres you have.

It depends on how twitchy you're prepared for the car to be

It depends on how fast you can catch the car if it lets go

The race cars have had signifcantly more extreme settings than those posted.

The great thing about the Atom is that you can play with it until you get it just the way you like it.

[MadMaxedAtom]

^What Bruce said.  

I  like 1/16" toe in up front as it feels more stable to me.

[Mr.Woolery]

[quote="MadMaxedAtom"]
^What Bruce said.  

I  like 1/16" toe in up front as it feels more stable to me.
[/quote]

I like 1/16" toe out up front as it gives the car added turn-in response.

[MadMaxedAtom]

Other considerations are track temperatures(50 degrees or 100 degrees,makes a diff),track surface condition(open faced,medium and smooth),and the tracks general layout (lots of fast sweepers,maybe lots of switchbacks,etc...)

I actually carry my alignment equipment with me and make on site adjustments,if necessary.

I find adjusting at the track is good for a few seconds some days, and that is the difference between a podium finish and also ran.

[1965Cobra427]

I agree with Bruce that the "ideal" setup is different depending on the intended use of the car. Our AtomFest track setups were as follows:

Front camber -2 deg, rear camber -1 deg, front toe 1/16 out, rear toe 0 to 1/16 in. Ride heights varied from car to car. My older car is very low at 3-1/2" rear, 4-3/4" front. Most of the other cars were more like 4-1/2" rear, 5-1/4" front. We set corner weights to try and balance the front empty since a large number of the laps run included a passenger.

My short experience suggests that tire pressure is a big influence as well as tire compound, both being directly related to getting the handling as neutral as possible. These are easily sensed even by my uneducated butt. Too much dampening comes next for me and produces an uneasy, loose sensation. Rear and front toe, come next and are noticeable to me when they are out more than 1/2", especially in the rear. I could not personally sense a difference in corner weighting or ride height within the range that I have run. I'm sure that better drivers can feel much finer adjustments than I and could fine tune the car with enough laps.

In visiting with Joe and Tim during and after AtomFest, they both expressed that the car had more than a second per lap left in it with more time to adjust. These guys both ran laps that were three seconds quicker than my best, so I have lots of room to improve.

I find it interesting that the Brits run more negative camber in the rear than in the front. I understand their assertion that since the majority of the weight is back there, it follows that the chassis will load up more on that end and develop more camber change in hard cornering. I have yet to try that, but it seems like a good place to go next season.

[Mr.Woolery]

[quote="1965Cobra427"]
I find it interesting that the Brits run more negative camber in the rear than in the front. I understand their assertion that since the majority of the weight is back there, it follows that the chassis will load up more on that end and develop more camber change in hard cornering. I have yet to try that, but it seems like a good place to go next season.
[/quote]

As an intellectual exersize (haven't tried it yet, so can't say for sure), I would tend to agree with the Brits here.  Adding the majority of the camber to the rear would seem to pay off due to chassis loading.  Although more front camber may help heavier front weighted cars, I think the Atom sees more benefit from front toe-out settings.

..Oh, and MaxMaxedAtom just gained mucho macho points for doing his own alignment adjustments at the track. 

[Bruce Fielding]

[quote="1965Cobra427"]
Our AtomFest track setups were as follows...
[/quote]

The red car, however, was almost undriveable. Very twitchy and difficult to drive smoothly.

[MadMaxedAtom]

I don't like more than 1 degree of negative camber in the rear at all. At least not in my cars on the tracks I have tested at.

I have found the tire should sit as close to parallel to the surface as possible when loaded and be evenly loaded across its footprint, especially lightly loaded tires, for maximum acceleration and braking traction. The minimal (if any...) lateral traction advantage of tipping the tire in is more than offset by the loss of valuable straight line traction.

This is my own personal findings from over a few years of changing settings on the same car,same day,same layout,same tires etc.
Your results may vary...

I also like my rebound dampening tight and the springs on the stiff side.   When the traction Gods will allow it...

[rfmarz@frontiernet]

My "set-up" is I just leave it like it is and drive as hard as I can.

[MadMaxedAtom]

^That works too! ...and then you can use the excuse that your setup is off...

[1965Cobra427]

[quote="Bruce Fielding"]
[quote="1965Cobra427"]
Our AtomFest track setups were as follows...
[/quote]

The red car, however, was almost undriveable. Very twitchy and difficult to drive smoothly.
[/quote]

Curious about that, I downloaded the Traqmate data today and checked out the lap times. With a variety of drivers and passengers, the "best" laps of each recorded session ranged from 1:26.8 to 1:29.7 with a slew of 1:27's. This car was also running on A-048's that by the end of AtomFest were worn out (rears).

No excuses, just to quantify the car's behavior. This photo was taken on Saturday. It may be an optical illusion, but it does appear that the rears have positive camber under this loading and might benefit from a more negative static setting. Fronts look pretty good though.

[img width=800 height=576]http://i66.photobucket.com/albums/h269/ ... F-233a.jpg[/img]

[dingo]

Here's an embarrassingly simple set of questions. 

With the Brammo rod end adjustable arrangement.
What is the chalky white material that you can see when one backs off the outermost 15/16ths nut. That's the rod end lock nut.
A version of locktite?  Corrosion?

So MMA, don't jump on me here, it's not a turnbuckle.

There are several parts to this assembly. 

From outside in
Rod End,
silver 15/16ths lock nut
intermediate sleeve (black) with 1 inch nutface
1 inch lock nut to wishbone
wishbone

I had to loosen both lock nuts and ended up adjusting the toe in this case by turning the intermediate sleeve, then tightened back in sequence the inner LN and then the 15.16ths LN while keeping the rod end in correct orientation to the bolt passing through it into the upright \ hub by holding the nutface in a wrench.  With the fender on, and striaght wrenches, this is not as easy as it might be during assempbly.  I had to take the wheel off to easily get at the nuts.

Tell me, there's a better way?  Should I search for angled head wrenches?  I think once loosened a couple of shortie wrenches might come in handy.

How do others do this?  BTW, I turned that intermediate sleeve a full 360 deg and it's way too much. 
So I'm going back in to adjust.  Constructive input appreciated.

[MadMaxedAtom]

Mine has no chalky white stuff,but I would imagine it is an anti-seize compound as there is no reason to use Locktite on a system with jam nuts in place.

My jam nuts are 9/16" so no problem getting a wrench in there.

A full 360 turn on the adjuster sleeve (aka-turnbuckle) is going to move your toe in or out about 3/16" with 15" rims (and 23" dia. tires)

You should not have to move it that much (a full turn)unless something is bent or you are setting up from scratch.

Oh...I just realized you are adjusting the camber.My mistake. 

Yea,it is difficult to get the large wrenches in there to loosen the jams.
I take off the wheel,loosen the jams,reinstall the wheel,take a measurement,adjust accordingly,remove wheel tighten jams,reinstall wheel and final test setting.

One flat on the adjuster screw is about 1/4 degree of change.  Hope this helps  

[dingo]

Thanks MMA.  I KNEW turnbuckle would come into play.

So, can you confirm though as I did not visulaize it.

I AM right in adjusting the intermediate sleeve?

The brain got paralyzed when I thought, that by turning the intermediate sleeve, I am
screwing it into the wishbones but simultaneously out of the rod end.
With a net zero change.  In this case, I was fiddling both with toe and camber.
I agree with what's written above, more upright (i.e. modest -ve camber) does assist straight line braking.

I started this exercise as I could tell that there was no toe in and I've seen some cars come from the factory with toe out and wanted to correct that (if present) and to understand why Eric was faster than me at the last outing.  

As I was in there, I figured I'd get the right tools and an understanding of what's all required.
So I think I will seek out some angle headed wrenches and shorties.  If I could fabricate a shim to slap on the wheel lugs onto which I could attach my straight guide, then that would save the wheel on \ off ballet. It's a fiddle in a crowded garage.

Back to the original main question. The adjustment is in the intermediate sleeve?