Tire gripping launches ???

[lt4ever]

What kind of set up will I need for hard off the line launches that will practically eliminate tire spin? (I'm pushing 330 rwhp & 319 ft/lbs)

Currently, I have weld in BMR boxed style SFC, along with BMR, boxed style LCA and Goodyear drag radials on 16" rims.

I'm thinking of Koni DA's in the rear (considering this is a street car as well, I don't want to lower the car with a pro kit, b/c my headers are only 4" from the ground and I'd be afraid to bash my headers/ Y-pipe if I were running only 2.5" of ground clearance.) A Spohn adjustable torque arm with the pinion angle set around -2.5*. Wider 18" rear tires... something like 295-35-18 with a really good sticky/ drag radial tire. I'd like to shy away from getting a 12 bolt if I can get away with it. I also think 4-link suspension and mini-tub would be overkill. But I'm currently building a blown 383.

[mrr23]

don't need a 12 bolt. i'm still on 10 bolts in both cars. wider tires, yes. going up from 16" to 18" will result in less sidewall. you need a taller sidewall to absorb the shock from launching the car. as you can see, i run mid 11's on 245/50-16 nitto DRs as it is now. get the relocation brackets to help out more. also, remove the front sway bar. this way the front of the car will come up higher during the launch.

[TransAmMan]

well you could always cruise the streets on the 18's and get some drag lites with DRs.

Also if you want to lower your car. It really depends on what exhaust system you have. A lot of times it's actually the y-pipe that scraps not the headers. Theres a lot of people on here thats lowered with aftermarket exhaust and plus if you get those 18's you'll sit up a little higher then usual.

[lt4ever]

get the relocation brackets to help out more.

I thought LCA relocation brackets in conjunction with an adjustable pan hard bar where mostly for those with lowered ride heights to center the rear axle. Or am I mistaken?? Does LCA relo. brackets affect the pinion angle negatively? Would I need an adjustable torque arm at the same time to compensate for the pinion angle change? Do you prefer the bolt in kind or the weld in kind?

[lt4ever]

well you could always cruise the streets on the 18's and get some drag lites with DRs.

Also if you want to lower your car. It really depends on what exhaust system you have. A lot of times it's actually the y-pipe that scraps not the headers. Theres a lot of people on here thats lowered with aftermarket exhaust and plus if you get those 18's you'll sit up a little higher then usual.

Not sure if I want to go thru the fab work needed just to run 18" tires. Have you done it? I understand you have to cut out your bump stop and weld in a new one at a different location, roll the fender lip, bash the inner fender wall in places so that the tire won't rub, plus you have to use a spacer which places more stress on your lug bolts and would probably need to use ARP lug bolts. Plus, with a bigger tire it would take away from my 3.73 gears. OR are you saying just run around on 18", but at the track use 16" tires?? If so, just seems like a lot of work to run around on dubs.

[mrr23]

I thought LCA relocation brackets in conjunction with an adjustable pan hard bar where mostly for those with lowered ride heights to center the rear axle. Or am I mistaken?? Does LCA relo. brackets affect the pinion angle negatively? Would I need an adjustable torque arm at the same time to compensate for the pinion angle change? Do you prefer the bolt in kind or the weld in kind?

the recommendation is for lowered cars. you should buy them regardless. #1 the rear isn't centered from the factory. for instance, on my 86TA i used to have. the rear was offset to the left about 3/8". #2 even on a non-lowered car, the trailing arms are higher up from center pivot point of rotation. here's a pic of the wife's car. stock height no relocation brackets. you want the rear of the arm's mounting point to be lower than the front mounting point.



yes and no. relocation brackets do not affect pinion angle unless you were moving the arms way out of position. considering the arc the arms travel in. moving from the upward position to the lower position the same distance from center of arc will not change pinion angle. example: perpindicular from the ground is zero. if the arm is 1" up from that and you move 1" down from perpindicular, then you have not changed pinion angle. anymore than from original distance, then yes, pinion angle changes original 1" up from perpindicular and you go 2" down from perpindicular.

raising/lowering a car does as you are changing the height of the transmission in reference to the rear end yoke. now, you could get adjustable trailing arms and be able to change pinion angle that way. changing the length of the trailing arms changes the pinion angle.

weld in means less movement of the bracket as compared to bolt in. how much difference, i couldn't tell you. i used bolt in myself. no access to a welder.

[mrr23]

Not sure if I want to go thru the fab work needed just to run 18" tires. Have you done it? I understand you have to cut out your bump stop and weld in a new one at a different location, roll the fender lip, bash the inner fender wall in places so that the tire won't rub, plus you have to use a spacer which places more stress on your lug bolts and would probably need to use ARP lug bolts. Plus, with a bigger tire it would take away from my 3.73 gears. OR are you saying just run around on 18", but at the track use 16" tires?? If so, just seems like a lot of work to run around on dubs.

ok. lots of misconception on what you've heard. you don't have to do any of that if you get the proper offset wheels and tires. you can have 18" wheels and tires without them being taller(bigger). here's a quick chart to go by. all tires will still be 25.7" tall as original.

245/50-16 = 25.7"
245/45-17 = 25.7"
275/40-17 = 25.7"
315/35-17 = 25.7"
245/40-18 = 25.7"
275/35-18 = 25.6"
245/35-19 = 25.7"
285/30-19 = 25.7"
295/25-20 = 25.7"


what you do is shorten the sidewall of the tire to accomodate the larger diameter wheel. all will be same height, just in different widths. then, depending on the offset and width of the wheels you buy, will determine if you need to 'clearance' the inner fenderwell or not. then, depending on how much you lower the car, and offset/width of the wheel, will determine if it will hit the outer fenderlip.

[lt4ever]

Thank you! Great stuff!! I should print this page and save it.

[lt4ever]

also, remove the front sway bar. this way the front of the car will come up higher during the launch.

What's important about having the front end pick up? Or are you just mentioning that from a weight savings perspective?

[lt4ever]

you can have 18" wheels and tires without them being taller(bigger). here's a quick chart to go by. all tires will still be 25.7" tall as original.

Will I need to have the PCM reflashed to compensate for speedometer speed with any of those tire sizes?

[mrr23]

What's important about having the front end pick up? Or are you just mentioning that from a weight savings perspective?

weight transfer. the higher the front end, the more percentage of overall weight of the vehicle is towards the back. the more weight in the rear, the more weight over the rear tires, the harder it is for the tires to come loose.

[mrr23]

Will I need to have the PCM reflashed to compensate for speedometer speed with any of those tire sizes?

the speedo is based off of gear ratio and overall tire diameter. if you change either of those parameters, then the PCM needs to know that.

but, to answer your question, no. so long as the tire is the same overall diameter, then no need to reflash the PCM. computer does not care about rim diameter. only overall diameter.

[Jeff2002WS6]

weight transfer. the higher the front end, the more percentage of overall weight of the vehicle is towards the back. the more weight in the rear, the more weight over the rear tires, the harder it is for the tires to come loose.

Anybody ever try those quick disconnects that they run on jeeps for the end links? They use them to unhook the sway bar for wheelin then re-attach them for the street? Would the sway bar hanging lose at the end links interfere with anything?

[mrr23]

i have heard of some taking only the end links off. one guy had his sway bar rotate down and lock into the lower control arms. the car wouldn't come back down.