JJ

I suspect my IROC is around 350-375hp. The car has the stock 87 suspension in place w/3.45s. I finished it close to winter so never made it to the track, on the gtech it would run consistently 7-8 mph faster than my 96mph (track timed) formula and would hit 5.5 sec from 0-60 on firehawk sz50s with obvious traction problems. I have spohn sfc in the garage and am going to buy spohn LCA/brackets and adj. torque arm, poly bushings. Probably bilsteins on the corners with the new springs. What kind of improvement would one expect from the complete suspension, maybe .5 in the quarter??, I'd like to hit low 13 and 105 with this car and will probably buy a set of drag radials in the spring as well.

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87 IROC, 350/5 speed. gmpp 350, vortec heads w/some work, XE268, 1.5rr's, 650dp, rpm intake, MSD ing., ect.
89 formula, L98.

ede

if you don't have traction you're wasting time, with good traction you can easily cut .5 off your ets. it's hard to guess at what kind of return you'll get out of a change.

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ICON Motorsports
1st & 3rd

Zee

It depends on what you do with those springs and shocks.

IMHO if street/stip is your concern I would without a doubt get something adjustible like a Koni so you can loosen them up at the strip. Any stiff lowering springs will certainly slow you down in the 1/4. Also, I would disconnect the front bar at the strip and add an air bag from Air Lift in the right rear. 40 or so PSI in the front tires and about 25 PSI in the rear with street radials depending on size. Don't forget to ice down the intake.

I think the LCA you have mentioned, stock springs and all of the above should net you that .5 you are looking for.

paul_huryk

There is no need to do anything to the front suspension, just the rear.

The "oldschool" way of getting traction is to make the front end rise quickly to add extra weight onto the rear wheels, thereby increasing bite in a straight line. This was the best way to add traction in the '60s and '70s, but now with all the suspension parts available, why go oldschool? BTW, oldschool makes your car handle worse than a school bus.

What you need to do is get a few parts for your car:

Rear control arms (adjustable if possible)
Rear control arm relocation brackets
Aftermarket torque arm
Panhard rod (not really needed, optional)

The mentioned parts will give you a lot of bite off the line, maybe enough to run 1.7s 60' times on street tires (if everything is set right). If you still have a traction problem, then invest in a set of drag radials, they always help.

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Paul Huryk, billionare in training.
Monkey Guy Racing
Almost part of the moderately infamous NJ in-your-face all goomba crew

Do it right the first time.

Paul's home page

1985 IROC LG4 POS Best: 15.20s at 92.1mph
1984 Camaro 350 LG4 Best: 12.21s at 121.7mph

The smart person pays for something today so that more is received tomorrow.
The ignorant person gets something today and hopes to have enough money to pay for it tomorrow.

Zee

Well, call me old school then.

Just a question, on your site you recommend quite a few "old school" and widely accepted means of removing weight from FRONT of the car. To what end is this FRONT end weight removal if not for altering the weight distribution of the car? Is that not the same relative effect as the "old school" method of adding weight to the rear of the car? Just for the record I am not an advocate of adding any weight for the purposes of traction.

Also, to what end is all of the torque arm and LCA work you recommend? Planting the rear tires? Is this not another way of doing the same thing as maximizing the pressure on the rear wheels? Seems like it would be just simpler to allow the weight to transfer.

I'm sorry but when a street car hooks, weight transfers to the rear and the front goes light. Most anything slowing down or restricting this process will slow you down on the strip.

I guess in the new school things like front engined dragsters will make a return and those old school pro stock cars will move their engines two feet further forward and start driving from the front seat. Batteries will move to the front to eliminate all of that extra wiring.

Who knew all those old farts needed to do was to change the geometry of the rear control arms and stiffin' things up a bit to hook up?

If the question were "how do I maintain the great handling of my 3rd gen AND improve my 60 foot time" you and I might be in greater agreement.

[This message has been edited by Zee (edited January 07, 2001).]

AlkyIROC

Adding weight can be an advantage but you have to know where to put it. When running a car in stock eliminator, you must keep the car no less than the shipping weight. What the drivers will do is lighten the car up as much as possible then add weight to where it will do the most good.

If you can. weigh the car on each axle. A good weight is 50/50 front and rear reguardless of the total weight. When my car had the small block in it and was stripped down for racing I weighed it with me in it since the car doesn't go down the track by itself. Total weight came to 3045. It worked out to 1800 on the front and 1200 on the rear. If I could move 300 pounds or add 600 to the rear it would balance out. Adding that much weight is out of the question so now it's "how to move or lose weight off the front."

Improving the f-body suspension may gain that .5 second but the real gain is in consistancy. Every suspension component that flexes and twists is lost energy. If you eliminate all this lost energy then there's more to transfer to the ground. The downside is that you eliminate a smooth and quiet ride.

I doubt anyone using this forum races in a heads up class including myself so we're all classified as bracket racers. The key to winning a bracket race is to cut a good light and have a vehicle that runs consistant. It's nice to have a fast car but a consistant 16 second 4 cylinder powered f-body can still beat a 14 second V8 that can't make 2 passes with the same ET.

Road course handling is another thing to consider. My car couldn't handle turns the same way other cars can. It all depends on how the suspension is set up.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car
383 stroker (carbed) with double hump cast iron heads and pump gas
454 Big Block almost ready for the 2001 racing season

Best results before the 383 blew up
Best ET on a time slip: 11.857 altitude corrected to 11.163
Best MPH on a time slip: 117.87 altitude corrected to 126.10
Altitude corrected rear wheel HP based on power to weight ratio: 476.5
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

paul_huryk

Zee,

Maybe I didn't make sense in my statement, but what I said is true in terms of making better traction from the rear end.

On my web page, I mentioned removing weight from the front end, not taking it and repositioning it somewhere else, my battery is still in the stock location, until it goes into the back seat. You do alter the distribution when weight is removed off the front end, but you also reduce the total weight, which is almost as important.

My idea is to plant the rear tires without making the car a handling nightmare, why make a good handling car (stock) into a minivan with dead shocks? With the good aftermarket parts available you can have traction in a straight line and handling. No matter how much weight transfer you have, it cannot overcome ****ty stick suspension parts (torque arm and RCAs). Easier (and cheaper) doesn't mean better for third gen suspension.

All the best hooking cars I ever saw-at the track or on the street, all had one thing in common: hardly any front end rise and a lot of rear end rise. You may ask why, but the answer is simple: the harder the rear pushes against the ground, the more it rises, exception being cars with independent rears (they squat instead).

I thought the reason for the rear engined dragsters was for safety: no engine and trans exploding in your face, plus the lessened possibility of a wheelie flip-over with the long wheelbase.

BTW, I took weight off the rear of my car without affecting the straight-line traction, still runs 2.0 without an aftermarket torque arm, should run 1.8 with it. I run street radials, not slicks or drag radials.

If the bean counters at GM made some decent decisions with the third gen suspension way back when, we wouldn't be talking about this today. If I remember correctly, these were the old farts that said cheaper is better. If they would have made the rear suspension like Spohn or Global West does, old farts would have to eat their words.

My 3 cents.



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Paul Huryk, billionare in training.
Monkey Guy Racing
Almost part of the moderately infamous NJ in-your-face all goomba crew

Do it right the first time.

Paul's home page

1985 IROC LG4 POS Best: 15.20s at 92.1mph
1984 Camaro 350 LG4 Best: 12.21s at 121.7mph

The smart person pays for something today so that more is received tomorrow.
The ignorant person gets something today and hopes to have enough money to pay for it tomorrow.