60 ft. article I wrote for another forum

[sparky2263]

You guys are welcome to do with it as you please.

60 ft. time-How and Why
How important is the 60 ft. time, what improvements help and how do I accomplish them?

In drag racing the 60 ft. time is THE most important to a fast ET! (reaction time is for racing another vehicle!)

For purposes of discussion I'm leaving the engine alone. We will assume it to stay at the same HP. There really is no single best mod to make as the problems vary depending on the vehicle in question. Discussion welcome!

First, just how important is 60' time? Improvements as little as .02 sec. can lower ET by a tenth! Why? Mass! We have to get that hulk of machinery moving! Sitting at a dead stop and accelerating at full throttle, think about it. It's the most challenging thing to do in a drag race. To me, this puts weight at the top of my list.

Weight-The old rule of thumb of 100 lbs of weight reduction shaving a tenth off ET is pretty accurate. But, the biggest gains due to weight reduction are in the 60' times. Not only that, but with less mass to get moving, less load is put on the tires reducing traction issues.
Another thing on weight, like that jacked up look in the back? Bad move, you just took a bunch of rear weight and put it on the front tires.
Okay, so you've gotten rid of all the weight you can stand (or afford if we're talking fiberglass!). Let's move what we can to the rear then. Ain't none of us that I know of can move TOO much weight to the rear. Easiest is the battery. Next would be all those big-*** amps and speakers I see so much of these days. Get 'em as far back as you can stand. For you guys with fuel tanks on the side think about installing a rear tank (not as hard or expensive as you'd think!). Us S guys can drop 30 lbs. up front easy by converting to a manual geabox. Next would be dynamically moving front weight to the rear. We'll discuss traction aids below.

Traction-Boy, how many of us haven't spun and watched the other guy scoot away!?! But, most of us drive our vehicles regularly and can't just drive around on race slicks waiting for the next red-light challenge. So lets address that.

Tires-See that treadwear rating on the side of your tire? If you bought 60k mile tires it's probably over 400. Not good. Too hard but not impossible to make hook. Hopefully you have them as wide as possible. Best bet is a drag radial but lots of us can't be shelling out $350-400 every 5-10k miles or so. So something in between is called for. Ask your tire dealer what you're expecting and see what they say. If they're goofy, you'll know.

Weight Transfer- Let's transfer some of that weight when we stomp the pedal. The more of that we can do the less we have to worry about tires.Herein lies the tradeoff zone. Cheapest and best way to transfer weight to the rear is front drag springs. I hear lots of whining when it comes to drag springs on the street. I run 'em. Makes high speed cornering interesting. But, hey, all the other sports only use 1 ball. DO NOT order just any drag spring from a parts catalog. Get it weighed and get the RIGHT springs. $20-$50 to weigh all 4 corners is CHEAP. Springs are under a $200 for our trucks. Unless you take corners as kamikaze as I do you'll be hard pressed to tell the difference. Drag shocks would add to the equation but things get REAL interesting on the interstate with both. Rear springs are okay but we're talking trucks and most of us have leafs so we'll skip that. Rear drag shocks will help it squat a little. If you find a set for you're application cheap enough, give 'em a try.

Cal-trac's, Slide-a-Link's, Traction Bar's, Slapper bar's, etc.- Take your pick. What you're gonna do is take the rotation of the axle, under load, and transfer that lifting force forward on the vehicles frame. That effectively puts more weight on the rear wheels. Tends to keep the dreaded "wheel hop" away also. On my high 12 blazer the $39 traction bars work great. BUT, they're modified to put the point of contact where I want it. If you've got the money for the bad-boy stuff, go for it. It does produce better results IF YOU HAVE THE POWER to use it.

Gear ratio- The lower the gear ratio (higher numerically) the lower the 60'. Period. How much can you stand? If you've got overdrive 3.50-4.20 should be your gear of choice

Posi-Traction- Need I say more? If you ain't got it, get it. I tend to stay away from the cone and clockspring posi's. The clutch, gear and locker types are the way to go. I'll do a separate write-up on the different types.

Torque Converter- Will do more than all the above put together to lower your 60' time. BUT, if you don't have your traction issues fixed the converter is GUARANTEED to make it worse! A 2500 stall converter will normally reduce 60' times .2-.4 over a stock converter. I run around 3000 on my converter but I kept my lock-up functioning and don't suffer fuel mileage problems.

This article was brought to you by Sparky2263.

[riverhorse59]

[QUOTE]Originally posted by sparky2263
[B]You guys are welcome to do with it as you please

Posi-Traction- Need I say more? If you ain't got it, get it. I tend to stay away from the cone and clockspring posi's. The clutch, gear and locker types are the way to go. I'll do a separate write-up on the different types:

I enjoyed your article, I will try to keep it and review it further.

I have 3 posi units set up for my car . 373---411---456

I remember back in the 60s a relative had a 427 Fairlane Gt with a 4 speed ,headers and a 456 open rear. He would not sacrafice the horsepower that a posi used up. He was explaining the old for every action there's a like and equal reaction deal to me and he would offset the weight transfer caused by the torque of the driveline with air bags in the rear springs . He could get both tires spinning exactly the same by preloading the springs with the air bags.It must have worked will because back in 1966 --12 seconds flat 112 MPH was fast and he won his class most of the time. Have You ever heard of this??

[sparky2263]

Thanks. I was gonna do the posi write-up but never did.

I think with the traction available back when what you are saying held some truth. I'd heard old guys say "don't need no posi" but never put much into it. Who knows?

With tires and track conditions today I'd say posi is a must for drag racing.

[riverhorse59]

I think the same thing would still apply today, but I would certainly want a good strong 9 inch,Dana or at least a 8-3/4 chrysler rear. What I am using wouldn't last 5 minutes

[vara4]

Very good, But here's some questions? What about removing the front sway bar to help weight transfer to the back wheels.
Or what about moving the rearend a couple of inches forward?
Do you think the drop spindales for the front ends will hurt your weight transfer to the back wheels? Now my power band for my cam is from 3200 to 6300 rpm's, wear should my torque converter come in at? A little higher / lower or right where the power band on the cam comes in on a 2500 pound car. One last question, is there a way of telling what gear will work best for your set up. This is what I mean! I want my car to be winding out of the last gear in my rpm range at the end of 1/8 mile trac I run.


Thanks
~ Vegas ~

[sparky2263]

Okay, I'm no chassis "expert" but all my rides have dead-on 60' times so I'll answer best I can. I don't know if you're leaf or coil suspension so I'll address it in general terms.

Front sway bar-for drag racing it is removed or disconnected. This allows the front end to "work" and transfer weight to the rear. A travel limiter is sometimes used on the left front as a way to make the car launch straight. The 2 G-body cars I have set up use 'em. BUT, a rear sway bar can accomplish the same thing.

Rear sway bar (since I brought it up). One of the most handy tools in getting the car to launch straight. A direct means of providing pre-load is accomplished with an adjustable rear sway bar. Cheap for what they do, $250 or so.

As far as wheelbase, the longer the wheelbase the more predictable and softer the car launches. The shorter the wheelbase the more fun though . More a function of front/rear weight % though. Moving the rear-end forward will increase rear weight % but there's better ways.

Drop spindles, all things being equal, will lower the instant center which can be taken care of in the rear. Spring and shock selection in the front will do much more for weight transfer than spindle height.

The best rule of thumb for converter selection is to have a stall speed equal to peak torque rpm's. At least for your first converter ) I use JW because they give you 1 free re-stall within 90 days.

As far as best gear, if you're gearing for the 1/8 mile, it's gonna be a pretty big number! Tire size and growth %, peak hp and converter efficiency will determine gear selection. Any knowledgeable dyno operator will be able to determine best gear selection with the dyno results. Thank God we have one of the best dyno op's in the business here in Gainesville. I have LOTS of gearsets from before they were here .

Holla back if I can help further.

[vara4]

Good answers thanks for the tips.


~ Vegas ~