Drag Racing Discussions > Front Engine Dragsters

How to properly launch a FED?

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Mister_Fitz:
Thanks for all the good and helpful answers!

I had a small impact with the track wall about a year ago, very narrow track. Then I built a chassis jig and straightened the chassis. After the repairs the wheelbase and the cross measurement of the wheelbase differed around 2mm, that's around 1/16". So I think that the chassis is as square as it can get.

I'm currently running about 1/4" - 1/2" of toe in. I know it is a bit much, but I thought I rather have to much then to little, the car would be more stable at high speed? Are there any down sides except the increased roll resistance?

I will try to get hold of some shoe polish to paint on the wheelie bar wheel. It is a very good idea.
How do I tell if the wheelie bar wheel is steering the car, or if the car is steering to the right for some other reason and the wheelie bar just follows?

I do not think that I'm steering the car to the right by mistake. I don't shift to 2nd until about 100-150 m out, so during the launch and the following seconds both hands are on the steering wheel.

I was just in my garage and I measured the roll out of the tires and I noticed that the left tire have changed allot since before the race previous weekend!
The tires are brand new and this weekend I put one burnout and one pass in them, both the pass and the burn out were actually quite gentle...
I have measured the roll out of the tires during 1-2 weeks in the garage, tires mounted to the rims, and they were within 1/8".
Now how ever has one of the tires expanded and the roll out differs a little more than 1"!! How is that even possible??
I have completely deflated the big tire and put about 21 PSI in the small one. I will try to inflate the small one even more and put it out in the sun for a while. Is it possible to get them back with in 1/8" again? Have some one heard of anything like this?
I do not think this sudden tire expansion completely explains the launch problem. Last 2-3 seasons I have had the same problem with my old set of tires.

My Race master tires have arrows on then so they are direction sensitive. Is it possible to swap them anyway? Or will the tires be damaged?

dreracecar:
1/8" is nothing,  air pressure set at the last moment before you bring the car up into the fireup zone is the best. Direct sun on one tire will raise presssure on that one tire and not the other. Goodyear tires are only directional for the first strong hit to set the tire-after that they can be switched--dont know about M&H. Raise the bar and add more weight to the front and try again, if it does not turn its the bar

gregm784:
I try and have someone video each run. After the video, i make sure they video the wheelie bar mark on the ground.  Pick a goofy color of chalk or shoe polish, so you know what mark is yours.

Tire speed is easy, start dropping tire pressure in 1/2# increments.  It'll eventually give you tire speed.  If i dead hook my tires on my 200" car, it'll drive the car in a random direction.

BK:
I had similar problem with my car. I ended up steering the car with the wheelie bar. When I had two wheels I would set the left wheel about an inch lower than the right. It would stop the left side letting more weight transfer to the right.  With the single wheel I would have the wheel 11/2 to 2 inches off to the left. I also ran a 1/4Lb more air on the right. Mine would dead hook and then unload the tires on the bar. To take some hit out I put a pneumatic cylinder with a needle valve on the throttle. Slowed the 60 foot a little but the car was deadly consistent. I was running Super Pro brackets so ET didn't mater that much.

Lorbiecki:
1.) Is the car lifting the front end and then making a move? If so, look at wheelie bar alignment. We had a bar that was bent and it actually drove the car to the side.

2.) If it is not on the bar and going to the side, then all the above will effect it.

3.) Look at your driving techniques. I have seen people that actually turn the wheel without knowing it on the launch. Sounds weird, but sometimes when accelerating, the drive may use the steering wheel to support the hand and it will rotate unintentionally.

4.) Try to get the car to slightly spin the tire.

5.) I have been up to one PSI different between the two tires. Don't be afraid to do it!

Good luck...

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