TORQUE or BODY ROLL

[LivermoreDave]

Hello all, LivermoreDave here from KY, I'm a newbie. From the posts I've read, it seems there are a few posters that may have an idea how to correct a problem I'm experiencing with a '78 Fairmont.

A few specs:
An engine that may be producing near 550 to 575 HP.
JPT C4 w/brake
5.14:1 final drive
29X11.5X15 slicks
C/E adjustable coil overs 150# springs
UPR upper & lower bars
Strange adjustable struts w/UPR coil over spring kit
Total car weight w/driver 2850#
Corner weights: RF 766, RR 617, LR 587, LF 878
Six point roll bar, attachment points are, torque boxes, behind the front seats and half the distance between the axle and the rear of the frame.


I have installed "limiters" on the front, and tried about every adjustment possible, front and rear! I've "strung" the car, tracking is straight, housing is square to the frame.
The car rolls almost to easy, drives like a Lincoln (after the launch)! The car at times will sit in the water box decent, at times it acts as if the left rear is doing more work than the right.
Now, here's the problem. During launch, the car steers to the right almost every time, pretty violent and within the first 100 feet before the engine runs through the power band and lets the front tires become a factor in steering the car. Now when I say steering to the right, I mean steer from "torque" or "body roll", which ever you wish to call it. The car reminds me of a drill bit, it is twisting from the rear to the front!
My first questions are, does this car have enough bar (bracing)?
I have a "anti-roll" bar kit here at the shop, and considering installing it if it will eliminate this problem. I too am thinking of adding a "hoop" and "down bars" along with a "dash bar". Then running a bar on each side out to the strut towers. Is the "un-equal" length of the UPR bars aggravating the problem? Is the location of the UPR bars mounting points causing change in geometry during launch? I understand ladder bars are the best to prevent "body roll" and I will install a set if necessary, I would like to make work what I have! Any ideas? Thanks Dave.

[wsp1925]

Dave,
I have seen many things that cause this in racing.Most of the time it all comes back to the structuring of the firewall.It only affects the car on launch.If you read a chassis book such as Dave Morgan's ,it will give you a good insight on what I am talking about.This is only my opinion and may not solve your problem.....good luck

[decals]

The car is pictured on this page:

http://www.windyhollowdragway.com/gallery50606.htm

it is the green Fairmont with "Joker" on the side. The pictures shown were taken leaving the line, the body twist gets worse than this. The front end was tied on the drivers side, that is why the left front is higher than the right front. I have seen the car leave, the whole left side (front and back) raises (or twists) about 3 inches higher than the right. It runs in the 6.50 range going crooked, so it makes pretty good power. I have seen Mustangs go faster than this with a "basically" stock rear end, isn't the Fairmont the same?


Donnie Hagan

[LivermoreDave]

Thanks for the reply guys. I was hoping to have the Dave Morgan publication here today but it didn't happen. How ever I've saved an article of Dave Morgan's and read it over, and just speaking in general terms he mentioned the "un-equal length" bars can contribute to the "roll" issue. If you don't mind, what is your thinking with the firewall? The car's firewall is original. Are we thinking along the same lines of structural bracing?
Donnie has a couple of good pictures on the www.windyhollowdragway,com picture gallery.
I'm sure someone has experienced this problem as I. I'm open for ideas! Thanks Dave.

[KEVINS]

Install the antiroll bar before making any major mods. This will get rid of the body roll during launches which can also steer the car and set it up with 0 preload at first. Make sure the 6pt is attached good and extends as far forward as possible to help keep the body from flexing. If you can tie it into the firewall all the better since the firewall is a criticle structure point.

ks

[wsp1925]

Like i said earlier .I was just bouncing the firewall thing of my head.The upper torque limiter will maybe cure it but ,but is it a bandaid or a cure?.We ran a B/SM ford fairmont in NHRA comp elim. for 10 years and never needed a anti roll bar, but that might be your answer.The other thing that could be hindering you could be the structure of the roll bnar and how it is tide into the chassis.I am only giving you my point of view!!!! does not mean I am right....good luck

[LivermoreDave]

Well guys, it seems my brother (car owner) has beat me to the punch! He left with the car Wednesday night, and didn't return until I had left for work. Tried calling him, no answer! I suppose he was tired of waiting on me to make a decision on the next wrench we would throw at it. Anyway, Friday I unlocked the trailer and nosed around. My suspicions were correct, he had taken the car to a local chassis guy and they put a "anti-roll" bar in it. It sure looks different than the C/E unit I have at the shop! I too noticed they had taken some preload out of the right rear. Another thing I noticed, you guys have mentioned, and the article I read of Dave Morgan's mentioned to set the "anti-roll" bar up with NO preload at first, this bar seems to have preload in it! Oh well I'm not a chassis man as Donnie can attest, so I will keep posted the results. Thank all you guys, and you too "Duck" for the assistance. Dave....Oh, by the way. wsp1925, Don Bowles of NHRA Super Modified fame lives about 20 miles from me! Thought you may know him?

[LivermoreDave]

Good day gentlemen, wish your holiday is going well. I mentioned I would report on the "Torque or Body Roll" issues my brother and I have encountered with his 1978 Fairmont. First, I must thank everyone for being generous with their ideas.

The car made it to the track Saturday night and performed almost flawless. With the "anti-roll bar" set at neutral the first pass went well. If I may explain well, wells definition to me before Saturday night was simply not taking the paint off the guardrail! With only small adjustments to the "anti-roll bar", to make the car sit straight in the "water box", the night was a blessing in disguise! I was a bit skeptical about the correction the "anti-roll bar" may offer, but it did the trick. The front limiters were removed, rear shock setting were now where they should be, not one to one extreme and the other the opposite extreme! Now maybe we can concentrate on other areas of the updated car and get it to move forward with less resistance. My brother told me Sunday here at the shop, after such effort was needed to get the car off the line (before "anti-roll"), it now was boring to drive! I said that's good, good working cars are usually not fun to drive! I always relate to Donnie's car, several years ago when he and I done a lot of racing together at many locations, we were doing this and that, causing much inconsistency. When we made the car easier to drive so the driver could concentrate on the job at hand (diving the lines) the car became faster, quicker and boring to drive!

I do have a question. I have been associated with fast cars in the past, although most were complete chassis cars and some "back-half", this roll issue was never a problem. Is the current production location(s) of suspension attachment points part of the problem or the cars construction (production cars) not adequate for drag racing?

Thanks again to all, and thanks to the NMRA site for allowing me to post.

Dave.

[KEVINS]

Is the current production location(s) of suspension attachment points part of the problem or the cars construction (production cars) not adequate for drag racing?

Thanks again to all, and thanks to the NMRA site for allowing me to post.
Dave.
Excellent results!
What a lot of racers didn't realize is that the attachment points for the control arms were not designed for drag racing so, Yes, this is a part of the reason for cars not handling well. Another thing is that a lot of back half cars use ladder bars b/c they are easier to construct and these cars don't have body roll b/c the way ladder bars work. Back half cars also have more tire sidewall and this can also help absorb some of the body roll but a 4-link car will still have body roll w/o an antiroll bar but can be tuned to help prevent it.

Good Job!
ks