I have LT's, CAI, tune. I am running street tires and getting low 1.9's. I am considering DR. I have the stock clutch. What are my chances of breakage? Thanks for the help Ranger.

Brian

 

Hi Bill,

It's not easy to be consistent in bracket racing with street tires in a manual-tranny traction-limited car. So going to DRs is advisable.

Assuming soft launches with minimal clutch slip and no power-shifting, I'd estimate 75-100 passes before the clutch needs replacement. Perhaps more. Just be sure to keep the clutch fluid pristine through observing the current swap protocol.

Ranger

 

Brian, if you avoid the driving error enumerated in post #1, you shouldn't break. Be sure to maintain the clutch fluid properly.

Ranger

 

Hey thanks Ranger.

Brian

 

Did you actually do all of your racing with powershifting? I've never done that yet to my car and don't want to. Also, you mentioned in tip #6 that poorly timed shifts are brutal on the tranny. I'm not sure what this entails...are you saying that only hitting the rev limiter is bad or all shifts that are not done at exactly the precise point into the redline? And why?

And last question is, when gunning it just for fun from a street light, I normally don't launch at all. I just get moving and then hammer into WOT and do a couple hard shifts from 1-2 and 2-3. Is there an optimal way to do this? (Since there are obviously no burnouts or extreme tire-heating during daily driving).

Thanks

Thanks

 

Also, what rpm with the DR's? Iam thinking starting at 4000.

 

I'm not a bracket racer. Just a guy that likes to find out what I can make the car run.

Before racing begins, I walk both lanes to the 660', checking conditions, determining an intended launch rpm, and verifying any obvious advantage to left or right lane. At the five tracks I ran a C5Z on, it was 3600-4200 on BFG DRs and 4600-5200 on ET Street Radials.

Once passes began, I tried to check with those making initial runs to gauge their impression of the quality of traction. Used those report to confirm or adjust my launch rpm for the first pass.

Assuming I executed a good, proper burnout, then the results of my first 60' and 330' would lead to tweaking the launch rpm and throttle squeeze. The normal increment of adjustment was 200-300. That process of adjustment occurred every pass. Better the traction, the faster I would squeeze the throttle after the clutch was out.

That's more than you asked but some points that merit occasional review. I'll be covering many subjects like this on my max acceleration DVD.

Ranger

 

I rarely powershift unless conditions a primo and will reward it. First time I ran 11.55 on DRs and a CAI, I powershifted all the gears because traction was fantastic that day. Still my only perfect pass ever. But I subsequently ran many more passes in the 11.5X and a bunch under 11.55 without powershifting the 1-2 and 2-3.

It's missed shifts that damage the tranny, usually shift forks and synchronizers. Misses occur from:

(1) poor coordination of the movement of clutch and shifter. That is a serious driver error, one that's easy to avoid through practice:
How to Improve Your Shifting

(2) poor clutch maintenance (nasty fluid) that yields incomplete disengagement of the clutch when the pedal in depressed. This phenomenom never happened to me because I keep my clutch fluid pristine. With that in mind, here are the seminal clutch fluid issue threads to review:

the fluid changing protocol in brief.

Clutch Pedal Woes--Fluid Impact

C6 Clutch Hydraulic Fluid--the Chevy Spec

Clutch Pedal Woes--Fluid Changing Kit

A Pictorial On How to Clean Out the Clutch Fluid Reservoir This is more of a production than I go through, but it's a good place to start.

In 500 C5Z passes I doubt I missed more than ten shifts, I've not missed any in 53 passes in the C6Z. And my trannies were and are perfect. That record comes from shifting drills and six years of the clutch fluid protocol.

Sorry for the detail. But they are important points for folks that care about these cars.

Finally, I don't run hard on the streets. Can't help you there. Trying to figure out how to deal with the subject of "street starts" on my DVD. I'd be happy to receive suggestions.

Ranger

 

When is your DVD coming out?

 

The plan is late summer.

Ranger

 

Any plans of coming out to Las Vegas? There are lots of Z owners in need of your help.

 

Thanks I just got done reading through the majority of that info and I'm on the way to Walmart to find some fluid (if they have it) and the syringe.

Another question I have on the shifting... did you use the stock C5Z shifter **** for all of your runs? I just switched to a B&M ripper shifter and I'm noticing that now my hand seems to be slipping off the **** quite a bit. I'm not sure if it's the lack of being use to the shorter shifter, or the fact that the shifter is faster now and my hand just isn't keeping up correctly...but I'm wondering if I should just get a better shifter **** altogether. I have a Hurst M6 shifter-**** in my 98Z28 right now that I might swap over to my C5Z. The majority of my hand slipping on the **** is from 2-3 (and I've been in the habit of using the palm method w/o fingers for quite some time now).

TIA,
~Desert

 

I've alway run the stock shifter on my Corvettes.

You might try wearing a sports glove on your right hand.

I went that route in the summer of 2001 when my hand came off the shifter on the 2-3 and hit the dash. After examining gloves of every description and trying a few, I've settled on a Nike Receiver/running back glove (model # GF0030). Hard to find this time of year. But a Nike or UnderArmour batting gloves are similar in effect. The slight padding and positive control give good grip with the fingers on the 1-2 and 3-4 and firm confidence on the 2-3.

Ranger

 

Hi Zosixin. I'm pretty much saturated by the DVD production effort. Once it goes to distribution, I hope to make some stops at a few track rentals around the country and meet with owners seeking max acceleration. So when the time comes, let me know if the Vegas owners want to host a rental and make some passes in Corvettes. I suspect they'd shed some tenths in an afternoon.

Ranger

 

Thanks for the replies, Ranger. This is a little bit off topic but since it's still related to drag racing I'll ask the question:

Out here in SE Arizona the only track I have available to race at is Southwest International Raceway at 4000' elevation. Right now the weather is great for racing at about 60deg F or so. And the only fuel option I have is 91 octane (not sure if they have other stuff at the track yet). Not sure of the air density but the climate around Tucson is extremely dry this time of year.

So given these conditions, what % ET loss do you predict compared to your 11.81 run in your '02 C5Z (if you ran that car here in AZ)? And, what type of fuel did you run there for that 11.81 ...did you make any runs using 91 octane?


Just asking so I can know what to shoot for (even though my car isn't bone stock anymore lol)
Thanks
~Desert

 

Hi Desert.

The NHRA publishes correction factors for ET and Trap Speed for tracks at various elevations around the country. You can use that chart to compute a goal for your car in comparison to cars running on tracks at lower elevation.

NHRA Elevation Correction Factors

NHRA altitude correction factors--Original Source

Just remember that the adjustment is made based on elevation alone, not weather.

NHRA cites the Tucson race facility as 3000'; it's the location of some Lucas Oil Div 7 events. You would use the chart for Stock & Super Stock.

In Maryland the fuel is 93 octane. That's what I use. I tried a few gallons of 104 Sunoco at the track once, when I was nearly out of gas amid passes. I promptly lost about a tenth on the higher octane fuel. MIR is at 80' elevation.

Ranger

 

What you found out there is that the higher octane fuel will actually cause a performance loss unless the vehicle is modified enough to need it and tuned specifically for it. I had a fuel sponsor (Power Mist) and the equipment setup to run that absolutely had to have it. In contrast, the stock equipment suffered a noted power loss when running anything other than high test pump gas.

 

I saw this on the C5Z launching thread:

Considering street tires (I run 18" BFG KDs) that aren't heated and a lack of water there, what RPM range and PSI do you recommend I practice with for this technique? I'd like to do some of this to practice but I certainly don't want to risk any breakage. I normally run 27psi in the rear and 35 in the front for street driving.

Sort of goes back to my stoplight question I guess

 

Ranger,
I believe you have used this term but I dont understand it. I have a M6. Do you only do it between 3-4 ? Let me know.
Thanks
Dave

 

For max acceleration, the motor should be shifted at an ideal rpm. On a stock or near-stock LS6, that point is right before the rev limiter, 6600.

How far in advance you need to start the shift is governed by (1) your leg speed in getting the clutch in before smacking the limiter and (2) which gear you're in. 1st revs faster than 2d. And 3d revs slower than 2d. So each gear requires a different lead.

Like shooting a moving deer. Different lead of the target depending on whether the deer is running, trotting, or walking.

So the ideal shift point is 6500, let's say, to give a slight cushion.

If 6500 is my target and I accidently shift at 6200, then I short shifted. That hurts acceleration and during a pass, is considered a driver error. I know that because on my record 10.85 pass, I short-shifted the 2-3 by 300 rpm, costing me .06-.08.

If a C5Z driver were to short-shift the 1-2, 2-3 and 3-4 at 6000 instead hitting perfect shift points near 6500, then he'd lose more than half a second in the quarter-mile. That's 5.5 car lengths, a large distance in a streetfire video, for example.

Ranger