10.5W - 31 &Ladder bars, how much horsepower can you hook???

[cudabin]

Need some advice on what to expect with a new combination i will be trying in Spring.

We have a 2,750# 67 notchback cuda w/ driver, ready to race with a new 540ci Alum race motor that dyno'd 900HP. Best ET with the old iron 470ci motor on Gas was 9.56 at 143mph with a 1.32 60 foot at 2,900#s

Suspension:
34" double adjustable ladder bars with Strange double adjustable coilovers and 110# hypercoils.

Front suspension is stock with tubular control arms (heim joints on uppers) and adjustable strut rods, with 3 way adjustable shocks set at 90/10 and MP drag race tosion bars. Have adjustable front travel limiters

Tire is a 10.5W - 31 MT Drag (new set) with 9 psi on a 12" rim.

Rear Shocks are set 3 clicks from full soft on both comp and ext.

We scaled the car at 2,900#s:

LF= 859 RF= 796

LR= 633 RR= 623

Total #'s = 2,911

It would hook good and carry the front end for 50 feet if launched on the transbrake around 3,400 rpm but would spin if we went to 4,000 rpm or more...

On a "very well prepped track" we ran a 1.30 60 foot launcing at 4,400 rpm, but at SIR our home track the traction is not good.

We are now 140#'s lighter on the front end w/ a 540ci Indy Aluminum block and Terminator Alcohol injection which will make 900hp.

What should i do to the suspension to get it to hook with the increased power and less front weight???

Ideas please.

Cheers,

Arnie

[race9899]

You might want to stiffen the rear shock extension a bit, but I would try it just the way it is otherwise

[cudabin]

Come on guys, it's winter hear and I need some advice to keep my mind off all the snow...

Thoughts and comments???

Arnie

[Craig W.]

A 31x10.5W is more than enough tire to handle 900hp at that weight.

Some front shocks with more adjustment would be a good addition if the existing setup proves troublesome.

[Hitchcock]

How much power did the old motor make? If it's close I would just go!

[tigwelder]

I like to increase the shock button setting on a tranny brake car,I would set the rear shocks at 6 and belive it or not, I stagger the setting, meaning I would set the left shock at 5 and the right shock at 6. the higher setting will keep the tires planted and help it from unloading and moving the weight back to the front causing a loss in traction. also was the car scaled with the drivers weight in it? if so I would adjust the right ladder bar to have more proload(weight) this can be done while on the scales, 1 flat of preload may move 50 lbs from left to right. I like to have more weight on the right rear than on the left rear. make sure you are planting the right rear not the left, and easy way to check is to jack up the car about 2 inches from the rear end, and see which tire is closer to the ground. if they apear to be even distance from the ground then there is no preload, if the right is a bit closer to the ground (maybe 1/2 in or so ) then you have right preload. this will determin the direction the car goes while on the rear tires. you need a touch of right preload usually to compensate the rotation of the ring and pinion (torque). also check pinion angle, too little will unload chassis, to much will cause cool wheelstands. spring weight might need to be looked at as well as ladder bar front hole location. this should keep you busy till the snow melts. good luck,

[Bruce69Camaro]

Ok, first I want to say that sounds like a fun ride.

I'm learning more and more each day about suspensions, so my question is, if your putting out more HP then the first motor, wouldn't you want to step up a little on the rear springs to say, maybe 130lbs to make up for the extra HP being thrown back on the rear?

Also if you really need to, buy some snow tires and go out and play instead of waiting...
Sorry....

Bruce

[tigwelder]

the spring rate is more dependant on the total weight of the car, and how much weight you have on the rear portion of the car. if you go with a stiffer spring rating you run the risk of being to stiff and unloading ( bouncing ) the weight back forward. with a lighter spring rating and more rebound (button) action you tend to let compresion happen with spring and the rebound holds the car down on the tires. too quik of a hit on the tires forces the energy back to the front of the car, exspecially with the higher tranny brake launch. I'm thinking snowmobile for winter fun.

[Bruce69Camaro]

That makes sense, that's for explaining.

Bruce

[cudabin]

Thanks for the input guys!

So I guess i will increase the compression setting and give an extra click firm on the right shock to fight the tendency for the right tire to lift up.

I will also rescale the car with the new lighter motor in it an try a 1/2 of flat of preload just to see how much weight it throws to the right rear.

I know that on a sticky track we got a 1.29 and 1.30 sixty foot and it pulled slightly right on those launches, so preload should help.

Any other thoughts or ideas???

Arnie

[tigwelder]

do you remember if the car tends to get loose (wiggles) just a bit during gear changes? I always have my drivers pay attention to shift points, this will tell the chassis tuner if the car is needing a stiffer rear shock button setting. since you are limited on the front settings without coilovers up there. also since the car did tend to drive to the right on some of the runs, it would indicate that you need the right preload adjustment. check the burnout and see if it hops straight up on the tires and sits still during the burnout. if it doesn't then you need some more chassis tuning.

[cudabin]

Car goes straight downtrack and does not feel loose when shifting... Has 5.5 degreees positive caster and i can dial in more with the tubular UCA's on heim joints.

Only pulled right when it dead hooks. If i run a 1.34 - 60 foot w/ a 3,200 rpm launch it goes pretty straight.

I have adjustable snubbers to limit front travel for wheelie control if needed.

Cheers,

Arnie

[cudabin]

Just bought some Strange double adjustable front shocks...

Where should i start with the setting for extension and compression???

Cheers,

Arnie

[wikd69]

Thanks for the input guys!

So I guess i will increase the compression setting and give an extra click firm on the right shock to fight the tendency for the right tire to lift up.

I will also rescale the car with the new lighter motor in it an try a 1/2 of flat of preload just to see how much weight it throws to the right rear.

I know that on a sticky track we got a 1.29 and 1.30 sixty foot and it pulled slightly right on those launches, so preload should help.

Any other thoughts or ideas???

Arnie

woo hoo !!!! I love that wheels up shot !!! Beautiful :)

[Moparious Maximus]

How do you like that tire?

Im looking to try a different tire this year and that one is right in my size range.