Launching ????

[BLOWNBY]

Here is the deal. A 3525(with me) 90 GT, 351 YSi supercharged with 20 psi and an AOD with 3.55's. I am running MT DR. Dynoed 670rwhp through my old TKO.

Front suspension:
PA k-member and coilover with 150# 14" springs, strange single adjustable struts and steeda sway bar.

Rear:
Eibach Drag launch springs and air bag at 32 psi, strange single adjustable shocks, mega bite Jr LCA's.

Tire: MT DR 275/60 15's at 12 psi.

I ran a best or 10.6's at 134 yet the 60' was in the 1.7x's. It should be closer to the 1.4's. How do I get this 60' better. I had some buudies watching and they said that I was pulling a front tire off the ground so the tires must be hooking a the start, yet the front would rise quickly and fall back down just as fast and as soon as that happens the rear tires would break loose.

Do I need to go to 175# springs? That would have the front end lift a little slower and come down softer correct?? Do ineed to tighten/loosen the shock or struts? Alos the front end sits low now with the 150# springs. Should I raise it with the coil over? Any ideas.

[93gt]

Have you considered getting some 15-9in wheels with some slicks? Im no expert, but I know how much my 60ft. improved when I added these on race day! I dont know what the capability of the DRs are, but I bet that would help! Are the DRs a rule in this class?

[David Schwarz]

From your description, what I can say is you're not getting appropriate weight transfer, and the tires are unloading shortly after you launch (but you already know this). Here are some thoughts I'll throw out - if nothing else, it will provoke someone else to jump in and correct me if I stray off course ;-)

1) First and foremost, what settings are you using on the shocks and struts? This information will help. The shocks should be mid-range to start. Set the struts full loose.

2) How much front end travel do you have? In other words, how many inches can you jack the front end up before the tires lift from the ground (measured to the center of the wheel well). My guess is that your car might be sitting too low in front. If I remember correctly, you need about 5" of travel - if you have more than that, you can raise the front which should help in the weight transfer department.

3) I would argue that you may want to use a lighter spring up front - perhaps 135# or even 125#. But this will depend on how much front end travel you have right now (I think). The last thing you want is coil bind when the car sits back down on launch

4) Do you know what the pinion angle is set at? The optimal setting will depend on the composition of the control arm bearings (solid versus synthetic).

Finally, does your car squat bad on the launch? This may also contribute to the unloading you are experiencing. I hope this helps some.

BTW - if you haven't read Kevin Slaby's "how to launch a drag car" over on the www.baselinesuspensions.com web site, then do that now.

[BLOWNBY]

Have you considered getting some 15-9in wheels with some slicks? Im no expert, but I know how much my 60ft. improved when I added these on race day! I dont know what the capability of the DRs are, but I bet that would help! Are the DRs a rule in this class?

Well, for True street you need a DOT approved tire. But in general I cannot fit a 28" slick in the rear with the Cobra ground effects. They grow to much and rub. I had a 27" Hoosier QTP and it rubbed a little on the ground effect. And a 26" slick will be too small for my rpm's and rev limiter. I may try the Hoosier QTP on this setup and see how it helps.

[BLOWNBY]

From your description, what I can say is you're not getting appropriate weight transfer, and the tires are unloading shortly after you launch (but you already know this). Here are some thoughts I'll throw out - if nothing else, it will provoke someone else to jump in and correct me if I stray off course ;-)

1) First and foremost, what settings are you using on the shocks and struts? This information will help. The shocks should be mid-range to start. Set the struts full loose.

2) How much front end travel do you have? In other words, how many inches can you jack the front end up before the tires lift from the ground (measured to the center of the wheel well). My guess is that your car might be sitting too low in front. If I remember correctly, you need about 5" of travel - if you have more than that, you can raise the front which should help in the weight transfer department.

3) I would argue that you may want to use a lighter spring up front - perhaps 135# or even 125#. But this will depend on how much front end travel you have right now (I think). The last thing you want is coil bind when the car sits back down on launch

4) Do you know what the pinion angle is set at? The optimal setting will depend on the composition of the control arm bearings (solid versus synthetic).

Finally, does your car squat bad on the launch? This may also contribute to the unloading you are experiencing. I hope this helps some.

BTW - if you haven't read Kevin Slaby's "how to launch a drag car" over on the www.baselinesuspensions.com web site, then do that now.

1. Rear at 4 and front at 1.
2. I have no idea on front end travel. I will try to measure.
3. I believe I may need a heavier spring (175 vs 150) to control the front better as it settles. I have a 351 not a 302. Again I am not positive on this either? Plus the coils with the 150 nearly bind. (mean hit each other right??)
4. I have non adjustable control arms. However, my Mega Bite JR's are on the bottom setting. Someone mentioned try the top since maybe the bottom is biting really hard at first yet unloading thus breaking them lose as well. While the top setting doesn't plant is as hard?

All I know is with The Eibach drag launch kit last year and stock K-member, Lakewood 90/10 in front and 50/50 in rear and the TKO on slicks I could pull 1.40 60'.

Thanks

[93gt]

Good luck getting that sorted out! I have the same bumper. I almost think the 15-9 is about as wide as you can go without rubbing. (Your car is way too nice to beat the wheel wells up, or carve up) Maybe theres a better choice in a DOT tire out there for you. What about MT ET Streets? I run these on the street, but last year I ran them at the track. They have a pretty good selection of sizes. I called Harlow Racing and they hooked me up.

[regattacoupe]

1. Rear at 4 and front at 1.
2. I have no idea on front end travel. I will try to measure.
3. I believe I may need a heavier spring (175 vs 150) to control the front better as it settles. I have a 351 not a 302. Again I am not positive on this either? Plus the coils with the 150 nearly bind. (mean hit each other right??)
4. I have non adjustable control arms. However, my Mega Bite JR's are on the bottom setting. Someone mentioned try the top since maybe the bottom is biting really hard at first yet unloading thus breaking them lose as well. While the top setting doesn't plant is as hard?

All I know is with The Eibach drag launch kit last year and stock K-member, Lakewood 90/10 in front and 50/50 in rear and the TKO on slicks I could pull 1.40 60'.

Thanks

Yeah the unloading the left rear tire deal can be tough to work through. The 418 car doing the same thing but it's light enough to still go 1.58's on it's worst pass. I'd watch closely on the squat of the rear and I'd play around with the air bag pressure for sure. Maybe it just wants something different than the stick launch wanted.

Like the tranny though?

[David Schwarz]

All I know is with The Eibach drag launch kit last year and stock K-member, Lakewood 90/10 in front and 50/50 in rear and the TKO on slicks I could pull 1.40 60'.

Thanks

Do you still have the Lakewoods? If so, try switching back and see what happens. I'd be willing to bet that you have issues with your struts - either the wrong setting, or perhaps <horror> they're not functioning properly?? I did notice after my post that your car is on the portly side (no offense intended); if you're already getting coil bind, then I agree that a lighter spring would be the wrong direction to go. But I don't think a heavier spring will solve your problem either. The spring should be a source of stored energy that the strut controls (if I understand the concept correctly). I would think that a heavier spring would compress less, and thus have less stored energy to contribute on the launch.

But then again, maybe I'm just all turned around and leading you down the wrong path :weird:

[BLOWNBY]

Good luck getting that sorted out! I have the same bumper. I almost think the 15-9 is about as wide as you can go without rubbing. (Your car is way too nice to beat the wheel wells up, or carve up) Maybe theres a better choice in a DOT tire out there for you. What about MT ET Streets? I run these on the street, but last year I ran them at the track. They have a pretty good selection of sizes. I called Harlow Racing and they hooked me up.

The same reason I can't run a slick is true for the ET streets. They grow to much for the 28" to fit. While the 28" DR's don't grow or rather barely. I may try the 27" Hoosier QTP which are similiar to the ET Streets yet they make a 27". Which I had before.

[BLOWNBY]

Yeah the unloading the left rear tire deal can be tough to work through. The 418 car doing the same thing but it's light enough to still go 1.58's on it's worst pass. I'd watch closely on the squat of the rear and I'd play around with the air bag pressure for sure. Maybe it just wants something different than the stick launch wanted.

Like the tranny though?

So far I like it. When I hit 9's I'll LOVE it.:blob:

[BLOWNBY]

Do you still have the Lakewoods? If so, try switching back and see what happens. I'd be willing to bet that you have issues with your struts - either the wrong setting, or perhaps <horror> they're not functioning properly?? I did notice after my post that your car is on the portly side (no offense intended); if you're already getting coil bind, then I agree that a lighter spring would be the wrong direction to go. But I don't think a heavier spring will solve your problem either. The spring should be a source of stored energy that the strut controls (if I understand the concept correctly). I would think that a heavier spring would compress less, and thus have less stored energy to contribute on the launch.

But then again, maybe I'm just all turned around and leading you down the wrong path :weird:

The Lakewoods are gone. I believe your logic on the struts is correct. My thought though on the 175# spring is that I really don't need the etxtra stored energy since I already have enough power to pull the front tire. While the heavier spring would prevent it from rising so fast. Plus by it being stiffer will allow it to fall back slower and keep the pressure on the rear longer and smother as opposed to immediate loading and unloading.

Fortunatly I have a buddy that has some 175# that he has on a Jackstand car and he wants to go to 150#. So he said I can swap with him to see if this helps and he then will take mine. I have a buddy actually three now that run drag radial (suspension gurus) I will have have watch maybee and give me some clarification in my thoughts as well. But I guess a quick 5 minute flop of springs can't hurt to try.

[BLOWNBY]

Well I managed to add about an inch or so of travel to the front end and I will take the sway bar off and see what happens. Hopefully this helps. And try to adjust the shock and strut settings from there. If no major improvement I will then move my rear control arm to the softer bite setting. It is on the kill mode and see what that does.

[BLOWNBY]

It appears that I have about 5 3/4" travel in the front end. Is this good or bad??

[David Schwarz]

It appears that I have about 5 3/4" travel in the front end. Is this good or bad??

All of my knowledge comes from Kevin Slaby, who sold me my UCA kit (Baselinesuspensions.com). Buy his UCA kit and he'll give you un-ending tech support that is far and above anything I have received from any other vendor I've dealt with (with the exception of Mike, from Mike's Transmission). According to Kevin, 5" should be sufficient. So I would stick with the springs you have and work through some of the other issues you may have...

For instance, I could have sworn I read somewhere that you still have the front sway bar installed. I'm guessing this is a street car as well? I'll absolve myself from any legal liability by not advising you on what to do with the sway bar; but I will tell you that I don't have a sway bar on mine, and there was a time when I drove it carefully on the street. I just had to be carefull not to make sharp/sudden turns.

You do have me confused on the Megabite Jr.'s. My MM LCAs have an adjustable spring perch for ride height. Is that what you're talking about? Rear ride height becomes key when trying to nail down the optimal instant center for your car. I know that there are some LCAs out there that are double adjustable (like the Granatelli's), but I have no knwledge of how adjusting the length of the LCA effects traction off the line.

Check back with me in one year's time, and I'll be able to give you a real schooling on suspension. I'm going to have to figure out how to get a stock suspension hatchback down the 1/4 in 8.5s using a 28 x 12.5 ET Street (that's basically a 10.5" slick). I know that I'll be learning a lot about suspension during that time.

[BLOWNBY]

For instance, I could have sworn I read somewhere that you still have the front sway bar installed. I'm guessing this is a street car as well? I'll absolve myself from any legal liability by not advising you on what to do with the sway bar; but I will tell you that I don't have a sway bar on mine, and there was a time when I drove it carefully on the street. I just had to be carefull not to make sharp/sudden turns.

You do have me confused on the Megabite Jr.'s. My MM LCAs have an adjustable spring perch for ride height. Is that what you're talking about? Rear ride height becomes key when trying to nail down the optimal instant center for your car. I know that there are some LCAs out there that are double adjustable (like the Granatelli's), but I have no knwledge of how adjusting the length of the LCA effects traction off the line.

Yes I had the sway bar on there. The car sees about 4,000 miles per summer. I took it off and drove it around some. I barley noticed it not being on there. I hope this helps at the track. On my Meja Bite Jr's: Yes there are two mounting holes. The bottom one on which I am currently at, plant the tires harder than the setting above it. It does also affect ride height. But there is spacer in there that can be removed as well. The main reason for them is how hard the plant the tires. The top one may help by not plantiung as hard nort unloading as fast. ?????? I am going to start with the changes I have thus far and then go from here. I don't want to make to many changes yet.