I had my car dropped a little on all four corners using the stock bolts. The drop is maybe an inch to inch and a half. My question is, could this be detremental to better 60ft times at the drag strip. Maye adversly affecting the weight transfer by keeping the car flatter? Want to know your input.

 

I don't believe so. I ran my old '02 car many times with the stock height and lowered fully on the bolts. My best 60ft ever in the car came after it was lowered; 1.51 60ft with about 400rwhp. I can't imagine it would have pulled any lower with the stock height config. C5/C6s hook very well regardless. Most of the variance of good versus bad launches comes from technique, tire selection, gearing, and track prep.

 

My best 60' time on my 03 C5Z was 1.58 (with 380rwhp), AFTER it was lowered about an inch on stock bolts....
Ron

 

Some of the best drag strip launches (low 1.5 to high 1.3 sixty foots) I've seen were from cars lowered (at least lowered in the rear)...those were on C5s/C5 Z06s of course but I would think that the results would be similar among the C6s.

 

If I could pull a 1.3 I'd be in the 10's...lol.

 

Power and time spent in chassis movement do not contribute to forward progress.

 

I think what you guys are talking about is anti-squat. Anti-squat is the rear suspension's reaction to the torque imparted to the wheels during acceleration and is different from weight transfer done by the long "ladder bars" of drag cars.

Here's a diagram to calculate anti-squat in a given rear suspension:


The red lines are the upper and lower trailing arms, if you extend those lines forward (the blue lines), they will intersect. The vertical green line (through the white circle) is the center of the front axle and the horizontal line (through the white circle with the cross) is at the height of the center of gravity. The orange line drawn from the bottom of the rear tire through the intersection of the green lines (we'll call that point A) is the 0% anti-squat line. Anything below that line and the rear suspension will multiply the torque reaction while anything above the line will reduce the torque reaction or provide anti-squat. The light tan line drawn from the bottom of the rear tire through the intersection of the blue lines and continuing on to intersect the vertical green line (we'll call that point B) gives the amount of anti-squat by the following calculation: (B-A)/A*100= C where C is anti-squat in %.

C2 and C3 Corvettes with the single trailing arm have no anti-squat capability and depend solely on the spring to counter the torque reaction on acceleration. If you've ever sat in a C2/3 and put it in gear or goosed the throttle (in an automatic), you've felt the rear end drop when the spring absorbed the torque. The big blocks have stiffer springs because of their higher torque and as a result, the ride suffered.

The C4s incorporated anti-squat geometry which allowed lower spring rates and a more comfortable ride. But because of the trailing arm arrangement, as you lower the car or as it squats on acceleration, it changes the angle of the arms in the direction which causes a reduction in anti-squat. Anti-squat is desired from a road racing perspective so the chassis doesn't get upset (suspension movements are minimized) when loaded or unloaded by the engine. Weight transfer is desired from a drag racing perspective...they are two different things.

The C5/6 Corvettes went to a double wishbone rear suspension. It still has anti-squat but you use the line drawn through the pivot points of the upper and lower control arms to establish the red lines in the drawing above. A couple of advantages to this arrangement are: 1) as you lower the car, anti-squat increases (the center of gravity, point A decreases while point B remains the same distance above A), 2) as the rear squats on acceleration, anti-squat increases (the intersection of the two blue lines is higher). As you noted in your post, the cars with only the rear suspension lowered leave even harder because lowering only the rear changes the angle of the red lines even more to raise the intersection point while the CG stays close to the same...this combination gives the most anti-squat, maybe those guys know a thing or two about how to set up a chassis. As the guy above said, suspension motion is wasted motion.

With the stiffer chassis of the C5/6 and the increased anti-squat, spring rates are reduced for a better ride and each wheel is allowed to react to bumps instead of the chassis "reacting" to it. Go to an autocross and you'll see the difference between the C2/3/4/5/6 (I'm talking stock to stock). The C2/3s are wallowing all over the place with the front and rear suspension jacking up/down on acceleration/braking and bumps upsetting the chassis. The C4s don't wallow and you don't get much jacking of the suspension, but bumps will upset the chassis. Now watch the C5/6s, no wallowing, not much jacking, and you'll see the wheels go over the bumps without upsetting the chassis (unless they're big bumps)...very refined.

 

i lowered the back after i got headers and dyno tune. and then went 1.7s on stock runflats 12.0s all day long.

 

WOW! ME TOO! How do you pull those 60Fts? Gorilla Glue on the tires!

 

750rwhp and Mickey Thompson drag radials.
Mike R's ('Stealth99C5') Cartek/STS designed rear mounted turbo C5 hardtop cut a 1.36 sixty foot on the stock suspension.
Even 'Robz' cut a 1.41 (even a 1.40 maybe?) with his Cartek heads and cam C5 Z06 on ET Streets (bias ply) as well.

 

I'm lowered all the way with cut bushings, and get 1.6's pretty regularly, 1.7's all the time. Sits pretty low but Squats pretty well. Still can't pull the wheels though with my stock cam!