So my Dad and I were discussing ways that you could make a rear wheel drive car front wheels lift off of the ground when it launches. My Mom actually posed the question. I answered by installing springs in the front that do NOT provide much down force. His response was to put weight in the back of the car. To me this sounds absolutely ridiculous though.

 

WTF do springs have to do w/ down force? your answer makes absolutely no sence, if I was your dad, there wouldn't be a disagreement, I would have beat you w/ a stick for such an absurd answer.... lol

 

800 foot pounds of torque, stripped to the floorpans, sticky meats out back and a torque converter or clutch that can transfer the power without ripping the transmission out of the car.

Oh, and putting weight in the back would also make it easier seeing as lifting the wheels is all about weight transfer and, if the back is already heavilly weighted, it will be much easier. Look into the "Little Red Wagon" wheelstander from back in the day. Or the "Hemi Under Glass" for that matter.

Your dad should punish you for your impudence and make you read a book to compensate for your lack of knowledge .

 

you were completely off w/ your theory on the springs; they have nothing to do w/ downforce. your dad was on the right track, but mere jacking won't get the front wheels off the ground. tires play the biggest role imo.

increasing the ride height at the rear increases the load at the rear...increasing the load at the rear decreases the load at the front...decreasing the load at the front means less weight transfer is needed during acceleration to lift the front tires...

weight transfer is determined by a lot of factors, including center of gravity height, wheelbase, and the tire's coefficient of friction (these are the 3 factors that i think are fundementally the most important; there are a lot more though). higher CG height, shorter wheelbase, and larger coefficient of friction (assuming acceleration is traction-limited, which seems to be a drag racer's achilles heel) yield more weight transfer.

in order to lift the front tires, weight transfer must be greater than or equal to the static load at the front tires. in very simple terms, if the load at the front tires is 1200 lbs and the front tires are lifted off the ground, then weight transfer from front to rear would be 1200 lbs.

ack...cutting to the chase, read a book because the subject can get extremely complicated. my recommendations would be:

How To Make Your Car Handle by Fred Puhn...just because you thought there was some sort of relationship between downforce and springs. this book is a good starting point...ask your dad to buy it for you or something.

Fundementals Of Vehicle Dynamics by Thomas Gillespie...what i currently have my nose stuck in...if you haven't taken a physics course and a math course higher than trig, don't even bother; this book get's REALLY ANALYTICAL!!

EDIT: forgot about torque...i'm a suspension guy so i brain fart most info relating to engines. read a book

 

I've got to agree with SilverCIVIC96 about punching your ears. (LOL)

I think the punishment should be that you read from front to back one of the books that slateraptor quoted.

Wes

 

And by the way, I have to hand it to your Mom to have the moxie to ask the question!!

Wes

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Supra &raquo;</TD></TR><TR><TD CLASS="quote">installing springs in the front that do NOT provide much down force</TD></TR></TABLE>

you should rephrase yourself to say "installing shocks in the front that do NOT provide much damping"

that way you would be somewhat correct...less damping will help transfer weight.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slateraptor &raquo;</TD></TR><TR><TD CLASS="quote">increasing the ride height at the rear increases the load at the rear...increasing the load at the rear decreases the load at the front...decreasing the load at the front means less weight transfer is needed during acceleration to lift the front tires...
</TD></TR></TABLE>

i agree with what you said, but increasing the ride height doesn't change the actual weight at that tire, you can only change weight dynamically (acceleration), or from moving the weight physically like your dad said.

 

just put 1000 lbs in the trunk and call it a day

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cyphear &raquo;</TD></TR><TR><TD CLASS="quote">i agree with what you said, but increasing the ride height doesn't change the actual weight at that tire, you can only change weight dynamically (acceleration), or from moving the weight physically like your dad said.</TD></TR></TABLE>

touche...

 

torque is the key but i think you were looking for installing a set of 50/50 shocks in the rear and 90/10 in the front

the valving in the shock in the front uses 10 % of its dampening on the up stroke and 90 % an the down stroke which lets the front of the car unload and shift the weight to the rear then you need the tourqe to continue this mnovement to pull the front tires off the ground, old domestic trick to transfer the weight to the rear tires for dragracing

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SilverCIVIC96 &raquo;</TD></TR><TR><TD CLASS="quote">WTF do springs have to do w/ down force? your answer makes absolutely no sence, if I was your dad, there wouldn't be a disagreement, I would have beat you w/ a stick for such an absurd answer.... lol</TD></TR></TABLE>
and i would beat you for being ignorant.
less shock absorbtion means better chance the front will come up...lol. simple physics man.