Analize my Suspension Setup

[90mustangGT]

This is for a hardcore drag setup. Light car with a 347 and a manual tranny.

Front:
GMS Tubular K-member (moves wheels forward and engine back)
GMS Tubular A-arms
GMS Coil-Over with 12" 175-200lbs springs. (drag kit)
Lakewood 90/10 Struts
QA1 C/C plates
UPR bumpsteer kit
Weld Draglite 15x3.5" with 165R15 cheapo tires
No swaybar

Rear
HPM Megabite Jr. LCA's
HPM Megabite double adjustable UCA's
Moroso Drag springs
Lakewood 50/50's
Stock swaybar
Weld Draglite 15x8" with 26x10.50R15 M/T ET Streets

I have not tested this combo but I feel it will need more.
Here is what I am thinking of changing:

Swapping the front 12" 175-200lbs springs for 14" 110-130lbs springs. They are just a little firm and dont' have much travel.
Swapping the rear spring out for stock springs because the Moroso's make my car sit way high in the rear, about 3-4" of gap between the wheel and wheelwell. To level the chassis I will need to raise the front way high also, which would be way high, interfearing with the suspension geometery. However the stock springs arn't stiffer on the right side, so it will dip stage right which is never good. Maby an airbag, or probally a roll bar would be better.
Swapping the 26" ET Streets for 28" ET Drags, and keeping a set of Drag radials for street use. This will kill my gear ratio, so then I would need to change the gear as well. I will most likley use the ET Streets up.

How do you think the car would launch as is, and how do you think these changes, or just one of them, or your suggestions would help?

 

[ninety15.0]

what do u have for chassis bracing? i would look into that as well as some other things before changing springs again. do some research online and read about the physics of a well setup drag car and try to follow the same guidelines.

 

[90mustangGT]

Oh yeah, I have MM full lengths. But that is it. I'll probally be looking into a roll cage as well as torque box reinforcments upper and lower. I am also thinking of going with a coil over setup in the rear. I know a little about the physics or the drag car, not an expert by far. I know the idea is to get the weight to the rear but not to spend too much energy doing it.

 

[jackchan]

not sure what to tell you with your springs. I ran stock 79 4 cylinder springs in front of my drag car, with stock 90 LX 5.0 springs in rear with air bag.
the tires ET streets........are a little short, the 28 et drags will prolly hook way better.
I had a 8 point cage in my car and sub frames and everything was back welded on the rear control arms........i had a 128 60ft at best with the same tires that you are wanting to go to. I used southside uppers and lowers........but your contol arms should hook really well.
Jack

 

[bluevenom867]

Get a good anti roll bar.

Were runing a full Wolfe Racecraft rear suspension,and there anti roll bar is one very nice piece.

I know Comp. Engineering makes one for our cars and so does Steeda and a few other.

But its one of the most important parts as it can make you launch better and go down the track straight.

 

[90mustangGT]

Yeah, I definatly wanted to go 28's and ET Drags but I got the 26' ET Streets for $150 so I jumped on the deal because funds were low and since I had traded wheels the new wheels had some crappy regular cheapo tires that would have been dangerous.

I definatly want to get out of the hole hard. Maby a roll bar would do the trick, I think it is what's really missing in the suspension.

Well, I'm just trying to build the engine, but I like to plan, so I'll know what to do without bugging everyone last minute.

Thanks for the replies and keem em' comming.

 

[2000xp8]

If i'm not mistaken the rear wolfcraft sway bar (one that welds between the frame rails) isn't very street friendly.

As far as springs.
I'd use real springs all the way around, coil overs advertise spring rates for drag racing, But they lack strength.

I'd use a k member that can support the use real springs.
I believe the AJE k member has spring perches.
Then use the moroso trick springs, because they can be cut since the rates are the same throughout the spring. They are actually meant to be cut, it's not a risk.

http://www.ajeracing.com/mustang.htm
In the options list, they sell the perches.

This is all stuff used on my buddies drag radial car, that they can't keep on the ground. They actually had to tie off the front control arms with chains (which can be seen in the bfg ad) to shorten the distance the springs could launch the car.

 

[90mustangGT]

If i'm not mistaken the rear wolfcraft sway bar (one that welds between the frame rails) isn't very street friendly.

As far as springs.
I'd use real springs all the way around, coil overs advertise spring rates for drag racing, But they lack strength.

I'd use a k member that can support the use real springs.
I believe the AJE k member has spring perches.
Then use the moroso trick springs, because they can be cut since the rates are the same throughout the spring. They are actually meant to be cut, it's not a risk.

http://www.ajeracing.com/mustang.htm
In the options list, they sell the perches.

This is all stuff used on my buddies drag radial car, that they can't keep on the ground. They actually had to tie off the front control arms with chains (which can be seen in the bfg ad) to shorten the distance the springs could launch the car.

I don't quite understand the advantage of what you call "real springs". How do coil overs' lack strength? The reason they are usually in a lighter rate is thier location gives them more mechanical advantage. Your buddy's drag car doesn't sound too well set up. Maby some people want a car that throws the front end up in the air and drives all over the track but that isn't my idea of racing.

I have been told by mant sources that the ideal setup is the rear stays flat and level, doens't dip or rise very much, none at all if possible, the front rises up and the left front is just barley off the ground while the right front is just barley touching if not just barly off the ground because any more lift and that's just wasted energy going up instead of forward, and the car drives perfectly straight because all energy should be focused to the end of the track, not towards the wall where it will have to be redirected back forward which will loose energy.

 

[2000xp8]

Not well setup lol, he held the world record for street tires (in a mustang), for quite some time, at 7.98, and was the bfg ad car for 4 months in 22 magazines.
Also has been on many MM&FF covers, including a wheel stand on drag radials, that lifted all 4 onto the bumper.
Coil overs suck, many people switch back to standard springs, because there is no advantage to using them, other than height adjustability, but if you lower the car too much, you change the spring rate anyway. They are pathetic little springs, and if you drive on the street they will loose strength very quickly.
Even the magazines have done articles on how 60ft times have worsened with coil overs on a drag car.

 

[90mustangGT]

Maby i was wrong there but then agian, I'm not saying a conventional spring setup is bad, and I know that it's true the springs do wear out faster than the conventional type but I don't think they are a disadvantage. Yes, people's 60's have been hurt by coil over converisons if the coilover wasn't set up right, but set up right I am sure they would be equal.

 

[2000xp8]

Look i'm not telling you what to do. Just saying what i'd do. I see a whole lot a 8,9,10,11 second cars daily, most of which are street cars. IMO coil overs are a novelty item. You just can't compare them to an eibach drag spring or the moroso's.
And to top it off, they ride horrible.

K members are also tough on the street, how much street driving is the car going to see?

Not trying to be pushy, just giving you advice on things i see very often.

 

[jackchan]

2000xp8,

whatever, you do NOT know big daddy!

however I did meet him in Bradenton in 00' (i think my math is correct). The year he hit that bridge and buckled all his front end up under the car.

 

[90mustangGT]

Look i'm not telling you what to do. Just saying what i'd do. I see a whole lot a 8,9,10,11 second cars daily, most of which are street cars. IMO coil overs are a novelty item. You just can't compare them to an eibach drag spring or the moroso's.
And to top it off, they ride horrible.

K members are also tough on the street, how much street driving is the car going to see?

Not trying to be pushy, just giving you advice on things i see very often.

Hey, I apreciate it really. I asked for advise, and you gave me yours. I have a set of Moroso's in the rear but also have the front one's too. Personally for me, the coil overs made my car ride better, as well as launch better. My buddy runs the Moroso's on the front of his camaro and they work great. If properly setup, they should do the same thing. My car won't see a lot of street driving, but some. I have the GMS unit which is really a road race k-member. I was going to get rid of it but many people taked me out of it saying that it was worth it to keep the heavy duty units. I have heard a few bad things about some of the K-members breaking. I saw it happen at the track once, the car came up off the ground durring launch and when it came down it tilted sideways and then sparks flew, hand had to be dragged off and I know the The K-member holds the engine, front suspension, and Chassis togeather, I dont' want to be shady on that. I think that would be like not putting in SFC because they added weight.

I just dont' want to do all that converting when I have seen sevaral setups with coil overs launch really hard, the hardest I have seen.

I guess a taller tire in a full slick and a rollbar would be my best bet?

 

[bluevenom867]

If i'm not mistaken the rear wolfcraft sway bar (one that welds between the frame rails) isn't very street friendly.

They all weld in between the frame rails,thats why they work.If they made one that bolts in the stock location and actualy gives you the traction and straightness like the Wofle Racecraft or similar,then all the racers would buy it.

Its not so bad on the street either,if you plan on runing serious at the drag strip,than you need one.