Okay, my ongoing struggle is getting my car to hook. I know sticks are hard to launch, but I should be cutting better than 1.9's on slicks.

The rundown

T56, spec stage 3, Currie Ford 9 inch, new Trutrac posi, 4.11 gears, tubular lca (non-adjustable), comp 3 way (tried lowest and highest settings), Spohn LCA brackets on the bottom hole, Spohn TA -1 pinion angle, factory Iroc springs, factory rear sway with poly bushings, 26-9.5/16 Hoosier QTP's warmed up at all different temps and pressures from 25 down to 12. Lakewood 70/30's in the front.

Even worse my street tires which are Nitto Nt05 drag radials 285/40/18's.

Last time out to the track I ran the rears at a 50/50 setting, it would either spin when I launched at anything above 4500, or bog anything less.

It's the initial hit where I am having the problems. After about 10 feet it hooks and goes, not having any problems.

I have been talking to Spec, they told me it's best to dump the clutch to avoid burning it up. They tried to upsell me the stage 3+ which has additional material to allow for some slippage, and not put such a shock on the tires.

My other thought is that it is not squatting enough in the rear, and maybe I need some softer springs (like v6 springs)

Also I know 28's would have been better tire, and maybe that's my issue.

Any opinions are welcome!

Here's a video from the last time at the track.

 

Just curious as to what tire pressure are you running?

 

I started at 25 and then 15 then all the way down to 12psi on the QTP's. The Nt-05's I usually run about 30psi.

 

I would say 12-16lbs of pressure. How well is the track prepped and how much of a burn out do you do? At the .10 second mark you can see the front lift.

 

There really wasn't any track prep. We had the track for a few hours before they opened it up to the public so they just brushed it off a little at the beginning. The car racing me there was cutting 1.7's (auto) I think. Another 6 speed car was also cutting 1.7's with a similar set up that day.

 

You might be SOL if you don't want to change to a drag style spring and shock. I suck at the drag strip partially because I won't pull off my sway bar or get rid of my stiff springs. I run a RAM dual friction clutch and it doesn't hit the tiers so hard. Move the batt to the back if you haven't, that should be good for any type of driving.

 

Lower the air pressure, warm the tires, and maybe don't pop the clutch so hard with the RPM'S up. Do you have an adjustable shift light? You may have to launch at 4300 or find the sweet spot.

 

A Spec Stage 3 has over 800 ft/lb capacity. If you dump the clutch when you launch it, it's going to either draw that 800+ ft/lbs or break the tires loose. Spec's recommendation of upgrading your current setup to a Spec 3+ would only make your bog/spin even worse.

Here's what happens when the tires stay stuck- lets say your 383 is making 500ft/lbs on it's own (80 shot would add another 95 ft/lbs @ 4500rpm if you are spraying off the line). When you dump the Spec Stage 3 @ 4500 rpm, it's going to draw all 500 ft/lbs that the engine is making, plus another 300+ ft/lbs of energy from the rotating assy, which will cause the engine to lose a lot of rpm. That's what actually causes the bog.

If clutch capacity were reduced to 600 ft/lb it would only draw around 100 ft/lbs out of the rotating assy. There would be much less bog (600 ft/lbs is enough capacity to handle an 80 shot from 4500 off the line), and the reduction of capacity from over 800 ft/lbs down to 600 ft/lbs would also mean the tires would be much less likely to spin.

If you would like to stick with the clutch you have, but buffer it's harsh engagement to better match your engine's output, i can guide you in fab'ing a DIY version of my ClutchTamer. Should get you 1.65 60's on your existing tires without much trouble, also makes it easy to switch back and forth between NA and spray clutch settings without actually touching the clutch.

 

Thanks for the advice. I have read so many threads about success with the "rev to 6000 dump the clutch and hold on method" leading to good success. I have been afraid to slip the clutch this may be something to practice.

I have heated the tires up with some John Force style burnouts without much difference.

 

Interesting, basically what your saying is the problem is me, and you have a product to take the skill out of it.

I am going to try to learn to slip this thing on my own and see what I can do. Then maybe look into going that route. (probably after I burn this clutch up)

 

It does take a certain skill to launch a mismatched combination of parts with your foot, a different type of skill to identify a problem and put in place an effective solution.

 

I love a standard transmission but they are hard to launch in a fast car at the dragstrip.

 

Of course they said dumping the clutch is best, that puts the least strain on the clutch, the most on everything else and is the least likely to work. The only way to make dumping the clutch work is with a lot more/taller tire that will absorb the shock of dumping the clutch.

What is your 60' now? That video isn't really good enough to tell what is happening.

"Driving" it out of the hole (modulating the clutch so it grabs evenly and doesn't spin the tires too much) should get you in the 1.6 60, maybe 1.5 range (I've run a similar combination, making less power in a heavier 4th gen into the 1.6's on 275/40-17 Nitto NT555r's). You will likely run fastest either somewhat abusing the clutch or lightly hazing the tires off the line, both will require more work from your left foot to go fast then your right.

Without a better shot of the back tires on the launch, it's hard to recommend what else to change, but the fact is that you have more done to the car than you need to get it to launch into the 1.6's. My first 2 things i usually tell people is that you need boxed LCA's or better and a stronger panhard rod (this is really obvious in a stick car on the 1-2 shift but sometimes you see it on the launch, often it will flex and the car will jump sideways). The LCA brackets are likely a waste of time. Without taller tires/more sidewall the tires can't absorb the hit that they cause and typically just causes them to bounce around (the car I mentioned above run ran fastest with them in the stock holes or one down. Wouldn't work at all with them all the way down).

 

Good point on Spec's advice. I have twisted a driveshaft and busted my original 9 bolt over the years so I know the drivetrains taken hits. The t56 is also beat up pretty bad and going to get rebuilt here soon.

I forgot to mention I have a Lakewood adjustable panhard bar too.

Best 60 foot is a 1.9. When I pulled the clutch out last time it was about 50 percent worn so I am going to start slipping it more, and plan on having new pads put on it. (spec does it for $100)

I'll also try moving the lca up a bolt hole.

Here's a couple more videos, although they aren't any better.

https://youtu.be/ff_lJlp_Ty8

https://youtu.be/6kZGNPZluMQ

 

i think you kind of answered your own question. its time for taller and wider tires, especially with the gear your running. your asking a lot out of a 26" tall tire and only 8" of tread width. i also dont think a 16" wheel is doing you any favors?

 

Just a quick update, I went to the Texas Motorplex this weekend to get some 1/4 mile runs in. I ran the tires at 15psi, lcarb at the bottom hole and comp 3 ways at the softest setting.

First pass 2.0, as I slipped the clutch. The tires didn't break loose at all. Second pass tried to slip them a little less, same result 2.0 60 foot. The last run of the night I decided to go back to dumping it. Revved it to about 3500 and almost completely dumped it. It hooked like it has never hooked before. I was rewarded with a 1.8 60 foot time. I think with a few more runs dumping it at a higher rpm I will get down to the 1.6's I am shooting for.

Moral of the story, the tracks I was at before weren't prepped like this NHRA track and it made all the difference.