Gary Z

A manual-transmission drag car will not launch effectively unless the clutch slips or the tires spin, or both. If there is no slip, the engine will bog. The attached charts show three similar quarter-mile runs that differ mostly at launch. The first chart shows wild wheelspin. The second chart shows a combination of mild wheelspin and some clutch slip. The third chart shows a dead hook launch while the clutch slips for approximately one second and then grabs. This data was recorded while I was looking for the optimal setting for my adjustable front shocks. No other changes were made to the car during this series of runs.

In all three charts, the blue trace shows engine speed (rpm) , the red trace shows rear wheel speed (mph), and the green trace shows throttle position (%)

Bryan @ Speed Inc.

iTrader: (19)

that's why T56rebuilds has a "slipper" clutch i take it. good info.

383ss

iTrader: (14)

pretty cool comparison. I've looked at my downloads with HPT the same way, but never directly compared them like that.

skifast87

sticky?

JDP

iTrader: (21)

thats what a lot of people dont understand about launching a 6 speed car, something has to give or the motor will bog

we dont have a convertor to slip for us, good info you posted, ill play with my tire pressure to adjust the spin/hook to try to get it to grip the most without bogging the motor when i eventually go to a slick

LSWaaa?

stick it

98TADRIVER

iTrader: (36)

yeah alot of newbies just rev it to 3k and dump it lol, they either spin or bog. it takes some finess and some patience but i found with my setup launching at 4500rpm on MT drag radials

from outside of car

Click here to see Video


Click here to see Video from inside the car
i had a weird suspension setup then, it wasnt wheel hop, it was the body bouncing a lil dont ask lol

on the street launching around 3200-3500rpm i slipped the clutch quickly, my buddy dumped it, and well u see the end result
Click here to see Video

shanev8

iTrader: (11)

so you think your a good 6 speed driver?
haha whats up ron

Gauge

iTrader: (3)

Slippage is key. This was one of my better runs at the time it was taken, and you can definitely hear the clutch slippage...

http://videos.streetfire.net/video/1...1e01420591.htm

camarokid94

iTrader: (2)

good comparo nice info. thanks for takin the time to put it to pics for some of us. i also look at my HP tuners log to check whats going on out back..

Beaflag VonRathburg

iTrader: (176)

I'm going to have to work on my launching. It's hard as **** with these 285/35/18s that are almost bald. I can't wait to get my mini tub and everything done. Get these 325/50/15s on there!

Bad Blu Formula

iTrader: (3)

So when your car pulls the wheels, your clutch is slipping also?

WS6TransAm01

iTrader: (13)

My car always spins a little off the line. Sometimes a lot. I try to get one or two full tire rotations when the car leaves, that seems to be perfect.

On a side note, No offense, but those shifts take you for ever. Each shift is almost a second, that is almost 2-3 seconds your car is NOT under power. Take your second run for instance; you can see the wheel spin in the MPH spike on the 1-2 shift, but you can also see that your MPH actually decreases between shifts. You are loosing 0.5 to 0.7 seconds in your 1/4 ET's on your shifting alone. I'm not trying to be a jerk, I just think that I have a bit of experience driving 6spds and am only trying to help.

For you're own sake, you should look at the same graph, but also turn on the line for Throttle Position, after the launch it should stay steady at 100% until you cross the line. It is obvious to me looking at that graph that you are letting off during those shifts.

I don't have the files, because it was not my data logger, but my shifts average from 0.10 to 0.15 seconds, with 100% throttle position across the board.

TeEnAgE pHeNoM

iTrader: (6)

Yea I always found that a 6-speed car launches the best when the tires turn over a few times at the beginning of the launch. The problem is it's hard to be consistent with the 6-speed cars. If you let out on the clutch just a little bit different it can make you spin or bog just that easy. Also if the track prep is real good you can just dump the clutch. I went to a track one time and I could drop the clutch @6500RPM on the kit and it would hook every time and cut 1.58 60's every time. Most of all the other tracks I had to launch around 4500-5500 and it would spin more than I would like but it cut consistent 1.60 to 1.65 60's. But I agree slipping the clutch is the best way to get one to hook especially on drag radials.

Gary Z

It may be possible to pull the wheels, bog the engine, and fall flat. My son can do this with his motorcycle . But if the engine doesn’t bog, which is almost always the case when a car pulls the wheels, then something is slipping. The point to appreciate is that slippage somewhere is a requirement for any good launch, whether you "see air" or not. My data suggests that better launches involve more clutch slip and less wheelspin. I should have mentioned that I do not deliberately slip my clutch – it just slips. Deliberately slipping the clutch can partially compensate for poor traction but I’ve worked on my setup instead. Effectively slipping the clutch is too difficult for me. If the tires "hook", the clutch will slip.

usd2sing

iTrader: (15)

good thread

dug

iTrader: (10)

lol, all you 6speed wizards are still in the 12's.

cool videos though.

Yeah, you need slip. Look for the Demonbird's 10second video

TeEnAgE pHeNoM

iTrader: (6)

I'm not still in the 12's!

WS6TransAm01

iTrader: (13)

You're right... my 10.41 @ 131.48 with a stock bottom end H/C NA on a stock T56 is still in the 12's

I don't need to see his video... I think I can manage on my own...

TeEnAgE pHeNoM

iTrader: (6)

Yea it looks to me like he is the one in the 12's! LOL!