i keep reading take out the spare and jack to reduce some weight. but i gotta ask does it really make a diffrence? or is one of MANY things to take out for those guy stripping out there car, and jack and spare alone dont do anything.
sry if this is a stupid question but i dont wanna take out something that can help me and that sence of security for nothing.
thankz

My spare tire, jack and jacking tools weigh 38.5 Ibs, so if your not die hard racer going for the best time you can get, taking out the spare and tools would do little for performance, it might actually hurt it because the extra weight in the back helps for traction.

My car is faster with a full tank of gas. I ran a 12.4 at 117 with tools and a full tank of gas in the back end for ballast. Before that, I ran a string of 13.0s 113ish with 1/4 tank. I honestly think the extra weight helped- my 60s went from 2.2 to 1.9-2.0.

I think the weight it in the right place to aid traction

Taking the stuff out is just one of those "every little thing helps" kinda things. I believe about 100 pounds is about 1/10 of a second in a quarter mile which is something like 1 carlegnth so for a daily driver leave them in.

removing the spare and jack and racing with a 1/3 tank of gas has dropped my E/T a tenth over a full tank + spare intact. i rely on my driving skills to get a good launch, not excess weight. to date my best 60ft has been a 1.75, so i dont think the reduced weight has hurt my short times

everything, and i mean everything counts, as long as you just wanna keep knocking the tenths, or even hundreths off, every little bit helps, just keep that in mind.

weight reduction is your friend. though it may not seem like much now, if in the future you take anything else out it will be worth it. As far as traction if you want the weight over the tires i suggest putting the battery back there.



chris

But how would you explain the 4mph jump in trap speed.

Always make several runs and average the number when your testing a theory. Yes, weight in the rear can help. riding with a passenger can help as well (depending on the car). But usually, reducing weight is beneficial. I'd like to get my car down to about 3000 pounds (almost there). That much of a weight loss is multiplicative (if that's even a word?).

Depends on the situation. Think of it this way----->you have a car you just finished building. You get her to the track and run 12.01, 12.01, 12.01...etc. I'd be pulling anything that I could out of the car to save weight, and dip to the high 11's. Of course you would have to be careful not to take it from the rear, so not to hurt your 60ft times, but see my point?

I agree that less weight in a race car is better- you don't see John Force adding wight to his car. However, I do belive that weight in the right place can be a 'band-aid' for poor suspension/tires. I didn't mention it, but my suspension was completely stock (except for lowering springs) and I was running BFG drag radials. I actually felt that my 1.9 60s were decent for a lowered stock suspension on radials with a manual trans. I will admit, I'm certainly not a skilled drag racer, but I do believe it takes a little suspension work to pull a 1.75 60ft. If you did that 1.75 on stock suspension and radials I must say I'm impressed (especially if it was a manual trans). Just my 2˘

100% factory stock suspention, right down to the shocks that came with the car when new. keep in mind im running a Corvette... they have a much better rear suspention setup for drag racing than whats offered on the factory fbody.

the car is an auto, with 3.07 gears, DRs, and a 2500 stall converter. in a TPI Vette that adds up to mid - low 1.7 sec short times

Um, I've run a 1.76 in my 6 speed 4th gen with a completely stock suspension and factory GSC's on it. I've run a 1.71 in it by swapping the panhard rod for a stiffer one (not sure it did anything off the line but it is necessary to go straight on the 1-2 shift in a manual car) and air bags in the rear springs.

FWIW, the 'vette rear suspension is AWFULL for drag racing. There is no effective way to engineer antisquat into an IRS, where on a drag launch the torque arm in an f-body suspension acts almost like a ladder bar (actually more like a traction bar because it transmits the force forward rather then up) and can result in significant anti squat to the rear suspension which actually pushes the rear suspension down into the pavement resulting in more traction.

Take a look at a well setup f-body at the dragstrip and you'll see that the back end of the car at least stays level with the ground on the launch, it may even rise as weight transfers to the rear (the suspension basically turns some of the torque in to downward force pressing the tires against the pavement harder, resulting in more traction). An extreme example is the suspension used on the GNX which was essentially a very short torque arm and the rear of the car actually rose when you hit the gas. In contrast as the weight transfers to the rear of a vette since there is no antisquat in the IRS the back end actually swats down as the suspension pretty much compresses under the additional load and gives up traction.

everyone always says that IRS sucks for drag racing, but i have to disagree. people must be watching the IRS Cobras and Supras and the like and make the assumtion that ALL IRS setups blow on the dragstrip. keep in mind the Corvette has had IRS for over 40 years now... thats plenty of time for the engineers to get it right.

ive witnessed numerous C5s and C4s cutting 1.5 sec short times or better on completely stock suspention setups. alls they need is a higher stall (for the auto cars) and a set of sticky tires. no factory stock fbody suspention will come close to that

It's not a question of design or refinement. It's strictly a question of geometry and what's possible with one or the other. F-bodies can run 1.4's with sticky tires and a stock suspension and can pretty much work well into really insane ranges with stock geometry with stronger parts. Assuming similar strength parts (well, with respect to "they're strong enough to not break or deflect excessively for the load, the design of the 'vette suspsension requires them to be more serious for the same power level), the same tires on a car with similar weight distribution you will always be able to leave harder with the f-body's TA rear suspension then the 'vette's IRS (or any IRS that I know of). Period.

The real question is does it make a difference? Not really. With decent tires both could hold for a 60' where the question is more a matter of finding more power then traction for most of the people in this discussion. The corvette IRS becomes illegal at the track well before you couldn't find tires that would allow it to work well enough…

1.4 and 1.5 60fts? I am very displeased now with my 1.9 thanks to you guys. I guess I need to practice some more.

What you can run depends a lot on the power you're making and how it's being applied to the ground. For example, my stockish L98 formula just doen't make enough power to run faster then 1.8's. On street radials and driving it off the line the best I've managed is a string of 1.86's. Switching to some DR's (275 50 15's) that once I warmed them would hook no matter what I did (I mean, unless I was in water and holding the brakes the car wouldn't spin the tires) I couldn't get the car to run better then 1.89 no matter what I did (well, I suspect that if I shifted the lever from N into gear at the rpm that I wanted I could get it to go faster, once…). Switching to a 2800-3400stall converter (or a manual tranny) would probably move that into the low 1.7 range or possibly a 1.6, but at that point I'd have to start making more power to get out of the hole faster.