Drag Racing Discussions > Front Engine Dragsters

How fast with short wheelbase?

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Dolmetsch:
OK. Now we are getting somewhere.
When I am in good traction and if I run my tires too low my car will pull the wheels on launch so the tail or bottom of the cage smacks the ground.  Of course the first instinct would be some sort of wheelie bar but that tends to hurt traction a bit since it has to to some extent unload the tires the amount of pressure the wheelie bar/s are taking. The alternative is to make the chassis longer without increasing weight. In my case since the car is a bit overbuilt (1 5/8" mild steel .120" min DOM ) that is possible. However That is not what I wanted so I elected to run the tires no less then 9 psi which deals with the problem for me nicely.
Many of the early Altered and such handled badly because of the high center of gravity and a lack of understanding of Automotive suspension design.  Many very short road cars will do over a buck fifty and handle like a dream. It is not the wheelbase that is the problem. Or lets put it this way , It is entirely possible and practical to make a short wheelbase car , even a rail handle well. Air does not much enter into it if it is a open tube frame car (no body frward of the motor) Some of things done to rails of front suspension would make even a good sports car squirrely if it was set up that way.  They are all done with good intentions but sometimes excessive is excessive. Extreme caster angles , no ackerman , fast ratio steering arms and zero toe sometimes take the suspension or alignment into extreme areas where it is probably not wise to be. I know not everyone will agree but it is part  my trade by profession so you will excuse me if I hope.  Sometimes things are just done that way because the other guy did it that way.  Not a good enuf reason I think. The two fellows who also drove my car  are used to longer cars. One drove a successful RED (225 inch) for years. (I supplied his engines. Actually I am happy to be able to say ENGINE) The other runs a 160 inch FED with a injected BBChevy currently. Both offered the comment without any asking on my part. They were surprised.  If you check the ride along video you will see that even in the traps there is not any sign of ill handling. It is rock solid straight.  I have see lots of video if those 90 to 120 inch cars running straight and strong back in the day. I have also seen some bad ones but generally altereds not rails as I recall.  Bottom line is does the front axle know or care how close it is to the rear? Probably not would be my opinion. It cares about its alignment.
Don

Pipe Dreams:
   Just one more thought to throw into the mix. In a front engine dragster we set behind the rear wheels, so the drivers weight also needs needs to be added to the equation.
   When we weighed my car on a set of four corner electric  scales the weight on the front wheels was  10 pounds lighter after I had gotten into the car.

GlennLever:
The whole premise of the question was the only difference between the two vehicles was the wheel base.

rooman:
If overall weight is the same and the motor is in the same place the long wheelbase car will have less static weight on the front wheels because they are further from the engine mass which is usually the biggest chunk of weight in the car. Think about a big kid and a little one on a teeter-toter (see-saw). The little kid needs to be further away from the pivot point to counteract the big kid's weight.
As Pipe Dreams commented, he added his weight to the car but the front end got lighter due to the fact that his body mass was pretty much all behind the rear axle centerline. 
 Taking an extreme example, if the front wheels were moved back to a point in line with the front crank pulley the static weight on them would be higher than on the rear wheels even if you clipped the frame off and made the car lighter overall. It is all about where the center of mass is related to the contact patches.

Roo

GlennLever:
If the total weight of the vehicle does not change and the weight distribution on the rear wheels does not change how can the weight of the front wheels change?

See below?

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