Tom400CFI

I just got back from another night at our crappy strip. I managed to get in 4 T&T runs tonight, by lying about the number of runs I'd made to the staging lanes manager.

I've got two problems;
1. I can NOT get this car to 60' in less than 2.1x. Most of the time, it's 2.2x, and sometimes as bad at 2.3x Just terrible. I used to nail 1.8x's in my Trans Am all the time, on BFG R1 KDW's. I know that the run flats are harder to work with, but I swear, it feels like they're on grease compared to what I'm used to. There's just NO traction at all. I'm running 24-26 PSI, and tonight I was launching from 1000 to 1100 RPM. Roll off the clutch nice and smooth over about 1 full second, and be to 3/4 throttle by the time the clutch is out. WOT at any time in first gear resulted in wheel spin.

2. Wheel hop during burn outs. I can't believe that I didn't pop my diff tonight. The harder I tried to do a burn out, the more wheel hop I got. ANd I got a LOT!. SO much, something was "thumping" under the car; sounded sort of like the trans was hitting the floor pan. WICKED ANNOYING! The F-bods NEVER did this. Ever. No way could I even think about doing a proper brake stand and really cranking on the tires. Car just won't do it.

I don't know what to do (with my driving). I can't do a good burn out b/c of wheel hop, and I can't lay down a decent 60' to save myself. Grrr. My first pass tonight in 100* heat and a DA of 7600' was a lousy 13.3 and that was on a 2.3 sixty...so once again, 12.9x's were possible....if I could get any traction.

'06 Quicksilver Z06

The C6 is not a drag racer. And if you continue like you are going, its just a matter of time before you bust something and end up on a flatbed.

Put it on a road course, thats what it's built for. Its independant rear suspension, and rear mounted transmission mated to the differential is not a drag racing setup.

Ranger

Tom400CFI,

Your rear psi is correct.

Please watch the the burnout phase of this video



(1) I am very careful with the water; and keep the fronts dry.
(2) Placement of the rears in the water. You want a sheen of water on part of the tread.
(3) Placement of the damp rears at rest just before I spin them. You must not start in the heavy VHT area.
(4) You must use the brake to hold the car in position while the tires are spinning.

In the vid i'M on DRs. Spin stock tires to first smoke.

More burnout details are at the link in my signature.

Is it correct that you got wheel hop only during the burnout attempt? If so, the procedure above will cure it.

Ranger

cbrf4i1

ranger, i would like to get your opinion on lots of my runs, still has my emt tires. my local track doesn't really prepare the track on street drag night. to avoid any wheel hop i always end up leaving the line at idle (600 rpm) with smooth clutch release and smooth throttle application. by the time i hit 2000rpm, clutch has been long out, w 100% throttle with no wheel or spin. car will continue to pull without wheel hop / spin until 4800 ish rpm..then here comes the hop......most times there are lots of wheel hop too on the 1-2 shift, no i don't power shift. what do you think?

tom, sorry for the hi jack.

Ranger

What psi are the rear tires set to? And areyou checking/adjusting the rear psi before each pass?

As for spinning at 4800, I suggest concentrating on keeping your tires in the racing groove throughout the pass. That's where traction is best. Around the torque peak if your tires drift outside the groove, they can start spinning.

I would also suggest reviewing your treatment of the water box. If water get into the wheel wells, it will later drip onto the rear tires.

Ranger

cbrf4i1

i start at 30 psi, if it spins / hops, i lower 1 psi per run until 26psi. i avoid the water completely since i am leaving the line at idle,

Ranger

I'd suggest starting those F1SC tires at 25-26 psi and readjust it to that setting before every pass. The psi will tend to creep up and become uneven side-to-side. The lower psi will help cushion the shock to the drive line and reduce the tendency to hop.

With the consistently lower rear psi, should not hop on the 1-2, if it does, you'll need to squeeze the throttle more post-shift rather than an immediate one-piece motion to the floor. That squeezing will help. Doesn't take much, but some.

Even on my 10.85 stock pass, I was 100% off the throttle during the shifts. How fast you get back to the floor is governed by traction. At your track, the feedback the surface is giving you is "slower squeeze post-shift."

An alternative approach is heating the rear tires via a burnout to first smoke. Then using a higher launch rpm as part of the 3-element launch routine you're already using. Details are here: Burnout Without a Line Lock

Heated tires will dramatically reduce the likelihood of wheel hop.

Ranger

jsk96z28

With a Z51 package its not a 1/4 mile car thats for sure. Bad spring rates, bad trans gearing, brakes that are for show not to stop. But to say the C6 is only for the road course??? Tell that to ranger....

yell03

Welcome to the FUN world of trying to get a C6 manual tranny car out of the hole on stock rubber.

Automatics are easy to get 1.9s in.

My best in my manual tranny C6 was a 2.02 and another 2.05.
All my other launches were 2.1s and 2.2s.

Howard

Ranger

If we avoid driver error that provokes wheel hop and ravaging the clutch with big-slip launches, then the C6, like other Corvettes, acquits itself well at the drag strip and other racing venues. Great cruisers and road cars too. And a fine DD.

These cars are stout and fast...and respond well to good driving techniques.

Ranger

Tom400CFI

Thanks Ranger. I can't view the vid at work so I'll look at it tonight. Upon reading your text, however, I think the root of my problem might be that I'm not wetting the tires. I have avoided for two reasons:
1. I don't know how to get the rear tires wet w/o getting the fronts wet, and
2. I was afraid that I'd get water in the tread, and w/my short 2-3 second burn outs, not shed ALL the water and end up w/more water on the tread surface, from seeping out of the tread grooves.

At this track they won't let you drive around the water box, and back up. So how do you get only the rear tires wet?

As for "Brake holding the car" aka Brake stand, the car won't do it. It either bogs out quick, or wheel hops. Water would DEFINITLEY help this, however, on my F-bods, I also used to avoid the water entirely, they I'd put the shifter in 2nd gear, bring it up to about 2k, jam the gas jump off the clutch, and hit the brake. Then I could sit there all day if I felt like it, 4000 RPM, 2nd gear, not moving an inch. I'm definiltey familiar w/the "brake stand"....it just feels like this car will break trying to do it.

LAST night, I didn't get any significant wheel hop at the launch; a little on one pass. The bad wheel hop was all occuring while I was trying to warm/clean the tires. However, in past nights, I have gotten som pretty bad hop during the launch. To the point where I'm "spending" concentration on thinking about if I should push in the clutch to prevent breakage or wait to see if it stops.

NORTY

Is it possible to have tire shake with the EMTs? I'm thinking no because of sidewall stiffness. Anyone ever had it on their C6?

Tom400CFI

The Corvette is "for" whatever I want it to be for. And drag racing is PART of what I want it to be for. All Corvettes have always done well at the strip, and the currnet model should be no different, IMO.

Thanks for a post which doesn't address the original question at all though.

Ranger

I did about 450 burnouts in my C5Z without any harm. 78 now in the C6Z without harm. Your FBody approach is what I recommend and describe in my signature-linked procedure.

I drove a C6 M6 coupe for the first time last weekend. Did a burnout for the owner's amusement; did wet the rears first, and it survived unscathed.

I hate lane set-ups and rules that preclude backing into the water. I'd suggest talking with the lane master about your situation.

Ranger

Ranger

tire shake to drag race cars with big tires is the same thing we call wheel hop. Because of their power levels, they make more smoke when it occurs.

Ranger

Tom400CFI

I'll ask the jack (mean LANE) master about backing up but like you've read in this thread, this track is really tough to deal with.
http://forums.corvetteforum.com/show....php?t=1729964
I'll even ask nicely too.

'06 Quicksilver Z06

Good luck. Hope you don't bust anything expensive, attempting to hone your launch technique.

Tom400CFI

Me too. But if I do, it's still under warranty.

RANGER, can you post or PM me a format of your excel spread sheets that you use to break down your times? I searched but couldn't find any.

'06 Quicksilver Z06

Not if you bust it on the strip. Your warranty does not apply if you are racing on a drag strip. Check your warranty with regard to "racing or other competition.

So while you are beating on it and getting wheel hop, do know that if you should crack open your differential case attempting the perfect burnout and launch, and trying to "get the car to 60' in less than 2.1x" that your warranty does not apply and a C6 differential and perhaps even a transmission should it go down with the carnage, is not cheap.

I'd quit while I was ahead. Yell03 trashed his transmission attempting to flog what he thought were "acceptable" drag strip times out of his last manual C6.

not08crmanymore

"DA 7600' "??Does that mean 7600 FT above sea level?If so,what's the corrected time of the run if you were at normal level??If it's mid 12's corrected,you're right on,time wise.