.....and I noticed something that seemed kinda strange to me. Tell me if this is "normal".

I have, along with my other mods, a Yank SS3200 stall converter installed. When I launch at full throttle, the RPM's do not come close to 3200, until the spinning wheels TAKE it there and beyond.

If I keep the spin under control by feathering the throttle for 40 or 50 feet and then go WOT, the rpms STILL won't flash to 3200, staying around 2400/2500 and increasing as the vette accelerates.

So I try launching (just for the helluva it) in 2nd gear and the rpms "flash" to around 2300/2400 rpm and gradually climb up, grunting and groaning all the way, never reaching 3200 even when I finally backed off the throttle at about 45mph.

The ONLY time I saw the tach jump to 3200 (actually it went to 4 grand instantly), was when I was loafing along at 25 mph and floored it. THEN it took off like a raped ape and about slung the vette completely out of control.

Next, I tried power braking it while in 3rd gear and while holding the brake pedal down and rapping up the "R's", the tach hadn't even gotten to 2400 before the whole drive train began "shuddering". Not wheelspin...not like the tranny or TC was necessarily slipping, but "shuddering", violent vibrations, after which I shut it down immediately.

Try to imagine how the engine would "shake and shudder" with two spark plug wires pulled off. That's the "feeling" I was getting.

Please, someone tell me what the hell is going on here? All this was done in "Competitive Mode".

I was always under the impression that a 3200 TC would flash to 3200 whenever going to WOT, or even moderate throttle. Am I mistaken about this?

Is it "possible" one of the dyno techs I've been to "forgot" to unlock the TC after the dyno runs?

 

Traction Control Off ?!?!

 

Yes, I stated "all this was done in Competitive Mode". I would assume that means traction control was off.

It would SEEM to me that the TC does not unlock until AFTER the transmission shifts out of low gear..... or I am IN another gear and the tranny downshifts to low, or at least a lower gear when I go WOT.

Does that sound reasonable and is that even possible?

 

Trust me, you'd know if the TC was locked. As someone mentioned above, make sure you have your traction control set to Competition Mode. Besides, unless specifically programmed, it doesn't lock in 1st or 2nd.

In Comp Mode, you can power break and heat up the tires. If you are not worried about getting your brakes hot, try it. On my car, if I don't power brake and get a good burn out, I will spin through the top of first, all through the 1-2 shift and the first half of 2nd. If I get the tires nice an hot, I can launch and it will stick all the way through 1st and 2nd.

This worked well with run flats too, believe it or not. I dropped the pressure down to 20, got them nice and hot, and they hooked up fairly well. Nowhere near as good as my T1Rs, but far better than people give them credit for.

Also, I am not putting out gobs of horsepower either...about 390 to the rear with a stock converter. So take that into consideration.

 

When you power car with brake on there is a built in limiter triggered by extended brake travel switch. Just a possibility.

 

Sounds like wheel hop.

 

this is correct. The factory program will not lock the TC in 1st or 2nd gear.

 

Sounds to me like the convertor is trying to lock up and release. That gives the shuddering effect. I wouldn't try that too much.

 

I went to the Yank website and did some reading. Seems that (most) of what I am experiencing, is perfectly normal. Except for the 'shuddering'. I'm gonna have to look into that a bit further.

So I guess I'm ok to hit the strip Saturday. I'm kinda interested in seeing just what this baby will actually do in the quarter. Those 'gears' and run-flats are either gonna make it or break it, in ET and MPH.

So far, it seems that hitting the throttle part thottle off the line gives the best launch, while once in motion, going to full throttle rapidly, but not all at once, gives the best acceleration with the least amount of wheelspin.

Hopefully, if the track is well-prepped, I may be able to just "punch it" and go. We'll see.

Thanks to all that responded. I guess I was just pressing the panic-button a bit too soon. Still, it's always good to check first.

Wish me luck. Think I gotta chance at low 12's?

 

if it's any help; I can't powerbrake any more than 1300 - 1400 rpm with my stock converter. The further I push the accelerator - the RPM"S won't climb above 1400 - but my brakes won't keep me stopped.

 

I am not the pro drag racer, or any drag racer for that matter. But I am telling ya, a good burnout does make a big difference, even with the run flats.

 

Mine doesn't really like being power braked either. I've started just taking it to 1000 and mash it on takeoff. Seems to yield the best results. I'm thinking maybe something to do with the computer not liking much fuel when the car is sitting still?

 

Ya know, that could be something to look into. I've noticed on about every dyno run I had, that initially, just at the tech romps on it, the A/F is very high and then drops down to more acceptable levels.

Probably because the injectors flood the intake manifold with fuel a fraction of a second before the incoming air clears the MAF, causing the computer to back off a bit on the fuel.

I wouldn't think though, that in the fraction of a second for all that to take place, that it would make all that much difference in acceleration.

 

Mine does the same thing. So does my buddy's (Scoundrl on here). I think that's normal.

 

Wheel hop is a very bad shudder and very bad for your driveline.

 

Yup! That's what it was, too.....the rear wheels trying to overcome the brakes and they were "jerking" in rapid succession.

I won't be doing that anytime soon in the near future. So much for doing a "burnout" in the staging area. I'll just go up there 'dry' and take my chances.

 

Get a line lock installed. It will allow you to lock the front brakes and leave the rear free to spin. I had one installed when I had the Head/Cam package done. It makes burnouts easier and they aren't very expensive at all.

 

I've always got the most flash out of my converter by bringing the rpm up between 1200-1400 rpm while waiting for the last yellow. On the last yellow I hit full throttle then release the brake. Sort of like side stepping a clutch. Guaranteed to get you best 60 ft. times. Are your tires up to the task.

 

in your specific case, it may have something to do with the first gen active handling (assuming your 2000 has AH).

There were complaints about it still being a little-bit intrusive when powerbraking (even when in the Competitive Driving mode). And that was one of the changes made in the second gen AH software; starting 2001.

I have no AH or TC interference while powerbraking in the Comp mode. More power than the brakes are capable of holding back

 

I do something similar, and my best 2 runs were like this:



factory tires, stock TC, 3.42 ratio, Z06 mufflers, Predator tune, Z06 airlid, K&N OEM -type- filter, gutted pupcats.