i know theres a ton of threads here about "how to i drag better" etc. but, i was wondering if theres any techniques that i should use for my Z. I've got an 81 z28 with a 4spd. hurst shifter and a 350hp 355. Its got the stock lmtd slp rear in right now but i've got a posi to put in at some point. Will the posi help alot? also my back tires are 295 50 r15's.

 

Posi and limited slip are two names for the same thing.

 

whoops, wasn't payin attention...meant to say that its sill got the stock rear end and i've got a posi to put on.

 

Posi both tires spin, limited slip only one tire spins(usually the right side) and the other sits there.

Posi will definately help your times, i don't no how much though.

 

"Positraction" is a name GM has used for years to describe the various types of "limited slip differentials" they have installed in their cars.

Positraction is to limited slip as Kleenex is to facial tissue.

Rich

 

Q-tip, Skidoo, Kleenex, Aspirin, Posi are some of many brand names that get used as a generic name.

GM calls it a Posi, Ford calls it a Traction Loc, I can't remember what Mopar called theirs.

If the GM diff uses clutches, it's a posi plain and simple. There's also something called a Gov Lock. The diff is an open diff but locks up when one wheel starts to spin, it has a toothed gear and latches which grab the teeth. That's the best description I can give. You can't manually tell if the diff is a Gov Lock or an open diff without driving it or taking the rear cover off to inspect it. Technically the Gov Lock can be considered a limited slip but a posi although it's a limited slip, is simply called a posi.

My car has a spool

 

thanks for your replies, but is there anything i should do differently with the older four speed technique wise off the line?

 

Posi will make a big improvement in your 60' times over an open differential, especially with a sticky set of tires and a good suspension setup.

Do you have any experience launching with another setup? What techniques are you familiar with, and what has worked for you in the past? That information should help us tell you how to adapt to the new setup.

 

i don't have any experience dragging, so i'm looking for basics i guess. My other car was just an import-93 accord, little bit of pep for a ricer but nothing to the Z.

 

Okay.

Launching any reasonably high-horsepower car at the dragstrip is a matter of experimenting and finding what works best. Every car is different.

I'm assuming you're running on street tires.

For your first launch, get staged and bring the revs up to 1500 or so, and when you see the last yellow light on the tree, let the clutch up smoothly and fairly quickly and get into the gas. This should get you a decent reaction time, but you'll want to experiment to minimize it.

After your run, look at your timeslip. On street tires, 1.9-2.0 is a pretty good 60' to shoot for.

As you make more runs, experiment with the RPM, the rate at which you let the clutch out, and the rate at which you put the gas pedal down, and work in whatever direction gets you better 60' times.

Most of all, have fun!

 

sweet, thanks for the help-i've got aftermarket tires on, i'm not sure how soft but the rears are definately pretty wide. i've got a cement pad at my house thats gotta be at least 100' long so i might try practicing on that before going to a track. only problem is its kida rough in some spots and not great for the tires.

 

A prepped drag strip is going to be pretty different than your clean concrete, rough or not. It's fine to practice, but you can probably expect to have a bit more traction at the strip.

Oh yeah, and don't do a burnout in the burnout box on street tires. If there's room to drive around it so that your tires stay dry, do that.

 

Agree, but a quick spin to clean them, which may require backing into the damp part of the apron is a good idea.

Rich