Hey Guys,

I am trying to figure out the suspension on my car. If you watch the video you can see the car pull the front but set it right back down only to pull it again right away. I am not getting the consistent 60 ft numbers that Im looking for either.

In the video below, i made 3 runs (they are in slowmo for diag)

http://www.fast-ta.org/xvideos/2009/icediagmov.mov

The first was a motor run (transbrake,4500rpm,~500rwhp)
Second run was a 250 nitrous (transbrake, 4500, ~717rwhp)
Third was a progressed 100-250 (transbrake, 4500, ~600rwhp)

I just think that I need the car to carry the tires a bit more and not settle down so fast. I am using the stock springs in the back, the shocks are strange double adjustables. The front springs are qa1 shocks and springs. Pinion angle is currently at -2.5.

Im not a good one for understanding the dynamics of suspension components but i think i need some help.

 

It almost looks as if the re-end wants to squat to much, did you try to stiffin the rear? do you have lower control arm relocating brackets? What was your best 60'? Mine that day was a 1.51 on a 255 et street tire. Did you check pressure after each pass? I lowered mine to 17psi, next pass they were back to 20 after my run so i had to re-adj.

That day was a little cool also and you know gateways poor track prep.

 

The car may not look good, but if you have full adj fronts, i would try to raise the front of the car 1/4 to a 1/2 to help or just to try.

You need to go to a good track such a sikeston, to bad they are only 1/8, but when my buddy went there in his 6 speed, it was hooking and bogging on nitto tires at 5,000 launches. At gateway he always spins.

 

Generally speaking I run the Hoosier QTPs at about 11 cold. Im still on the stock rear springs and i do not have relocation brackets. I thought about replacing the rear springs but from a search here it looks like most people go with stock or v6 springs. The best 60 is 1.41 and that was motor. I havent really made a decent nitrous 60 yet.

Looking at the video the car seems to be squating most of the way down the track. Not sure how good of a thing that is or not.

 

I cannot view the video at work, unknown file. What I would say is def need to get a shock setting dialed in since your working with D/A shocks. LCA relocations do a world of diff.

I am not a fan of QTP's but they should work. I always vote for a a ET drag.

Does the car's body MUSH to the right at all?

I would say your shocks are not keep the front up the xfer the weight. If you get it reformated, let me know.

 

Springs are not going to make that much of a diff. To be honest there is not a GM part # out for v6 springs and until you have them tested, you dont know if its the same spring on a v8.

Whats the race weight of the car??

 

3450 with me in it. 3200 otherwise. The chassis is pretty stiff. I havent had much twist if any. 3.73 gears and a spool in a moser 12 bolt.

I converted the movies:

www.fast-ta.org/xvideos/2009/icediagmov.wmv
http://www.fast-ta.org/xvideos/2009/...r2009small.wmv (full speed)

 

MY buddy has the lower relocating brackets, and he said they work and made a difference, I do not have them on my car so I cannot say if i like them or not.

By relocating them its supposed to help pick the car up by giving the axle more leverage, I say try them, you can always take'em off.

 

What I can say is from my exp working with LSX Nitrous motors is at different power levels the suspension/tire requirements and settings are going to change. You have 3 different situations and when you went full bore on the 2nd run, that *** end kicked out bad indicating that your current settings are insufficent.

The other runs at a lesser power level seemed to be an issue of the nose bouncing which in my opinion is just messing with the shocks and taking note of the results/conditions (track and air)/ and settings.

What size QTP's??

Also in the end, when you want a off the line hit, going to a ET drag in my opinion is more important then a DOT slick. Also you may need a person lining you up in the goove, I find it hard to find it myself sometimes.

 

there are several things i think you need to do

1. have someone line you up in the "groove" going that fast at that power you need to be in the right spot not always easy to tell in the car

2. i would set the fronts at 3 and the rears at like 6 pass side and 5 driver side and go from there

3. figure out the suspension for each kind of run making 3 runs with different power levels is not gonna teach you anything

 

I can try the relocation brackets, but its still curious why the car wont pull and hold the front at this power level.

The QTPs are 28x11.5x15

The second run was really the first issue I had like that off the line. I usually do have someone line me up as well. Hard to see where your at and what part of the track is best. The car has a history of this type of launch.

Another possible piece of the puzzle is that the car is fairly light in the front. No bumpers, lightweight k-member, no accessories in the bay, alluminum LS2 block, no heater core or ac, no power steering. Has the stock hood. I run bogart wheels so those are light weight as well.

Ill admit it. After that second run, i was happy to go to the progressed 250 shot. I have a video from every run last year, (most of them on the same setup/shot) and they all show the little wheelie and then the immediate set down. Im curious because I know many fbodies that carry the wheels much smoother with alot less power.

 

where is your shocks set now front and rears?


it looks to me like you need to go stiffer all the way around, but hard to tell from those different videos

here is what we have JL Ws6 doing on a shitty track and he is the pewter ws6 no wheelie bars just win lights

http://quicktimeperformance.com/Media/EFI2008.wmv
and for the record we are not fans of big wheelies just win lights..hehe

 

Listen to Chef, he lines me up and I pick up wheels on his small *** 26" tall slicks of doom.....

https://ls1tech.com/forums/eastern-m...ay-new-pb.html

 

It looks to me like the car with the full hit (2nd run) just blew the tires off right away.. overpowering the tire/suspension setup.


The 3rd run it looks like it left decent, what shocks are the fronts, R series, double adjustable, single adjustable? If they are R series I would try loosening them one notch from where you have them, if they are double adjustables just try stiffening the compression up some more so the car will set down easier then it does.

The shocks settings that chef listed are where my car usaully runs the best with a set of R series front shocks, qa1 315 lb springs (LT1 ones)

One other thing, not sure where your ride height is, but measure all 4 corners thru the center of the tire to see how high the fender gap is. The rake of the car changes the attitude alot I have found.

Qhen the qtp tires are shot, get a set of 28x10.5S et drags on the car, I am willing to bet that alone is going to have a large impact. I tried the qtp's a couple years ago.... they were o.k., but at the power level you are at it's questionable if they will be enough.

If you can, try ti pull a couple degrees in your tune from the bottom to say 4500 rpm, this should drop the transbrake rpm a hundred or so and bring it back by 4800 so it's really only changing the off the line power for a split second, shoudl help let teh tire grab.... that might help get it to leave too.

 

Ill check the settings on the shocks and measure the fender gap on the four corners when i get home this evening. I use the lightenfelter 2 step on the transbrake, so I could adjust that to whatever RPM might work. Basically holding the button activates the TB, sends 12v to disable the nitrous controller, and sends 12v to activate the 2step. The only issue with going with the drag tires is that I run the true street at the LSX shootout. Its probably worth trying here locally at a test and tune though. I also have installed travel limiters on the front, they are one the loosest setting at this point.

Oh and i agree. Im not a fan of big wheelies, but i just havent been able to get a good 60 out of a nitrous hole shot. If you figure I average 1.45 on my 60s on motor, I would think I would get alot out of even a 100 shot and certainly more on a 250.

Nice video

 

Just watch it when the car works like it should on a "2nd Run" type launch and putting it on the bumper. I have seen a car do it and was taping it the entire time. The driver was just the man and saved it!

 

Ok heres the update. On the QA1s in front they are at 3. The rear shocks are hard to tell. The big dial on the shocks was set 3 from the loosest point. (not sure if thats adjusting compression or extension). The smaller dials actually broke off because they hit the shock mounts on the moser 12 bolt....

Ride height (from center of wheel to fender)

Driver Front - 16.25 inches Passenger Front - 16.5 inches
Driver Rear - 16.50 inches Passenger Rear - 17 inches

(looks like i have some adjusting there )

Btw.. does have information on the settings for these strange shocks. There are no numbers or markings on either dial. (They are the S5070)\


Shocks in the front are QA1 (RC7855P)
Sprints in the front are QA1 300lb 15FB300
Rear Springs are stockers

Spohn Rear swaybar Pro-series

 

I actually want to put a set of 300 b springs in my car, it's getting alot lighter to the point that it may be needed.

Get the shocks fixed and reorientate the rears so that can't happen again... no point in a double adjustable if you can't use it.

I wonder how that happened too... I've never heard of it happening, but obviously it can. Wierd.

Measure from the ground to the fender, just run the tape so it's going thru the center of the wheel (use the center of the wheel to make sure the tape is strait up and down is what I meant, I probably wasn't clear sorry) I have my car at about 26.25 inchs in the front, the rear is 26.75 if I remember correctly, I'll have to inflate the rear tires and check

I have limiters at full loose on my car as well.. it's been a little bit of a struggle with them on the car, but without them on, the car goes on the bumper so that's a no go.

I was doing the same thing, 1.45 on motor and the nitrous it usually ses a 1/37 to 1.42 depending on the track. Don't get too caught up in the 60 foot, if you can get it consistantly un the 1.3x time I think you're doign o.k. 60 foot is very important I agree 100%, but if you focus too much on just that the car may not be doing the right thing 300 feet out (spinning out there, that type of thing)

Understood on the need for the DOT tire now. The only thing I can say to that... is if you have no choice but to run a DOT tire, sounds like over the winter you need to do a project, called an actual full tub not a minitu, notch the tunnel so you can lower the rear, build a set of relocation brackets so you can bring the rear up in the car about 3 inches and still have the right angle, open the wheel well's up some, and put the biggest DOT tire you can fit in the car.

If you could get a 31x14.5 DOT tire in there you'd probably be a TON better off. I don't know if there are any rules as far as max size, but if there's not and you are maintaining the car for that class I'd be setting it up with enough tire to dead hook every ounce of power you can make.

If you coudl hit it right out of the gate with all of it, and more then you're using it would go a ton faster and the big tire will do 2 other things, look bad ***, and be way more consistant when the track isn't there.

 

Just went out and remeasured. (rear tires 15psi)

DF - 27.5 PF - 28.0
DR - 29.50 PR - 30.0

I think the rule on the DOT tire is that the measured tread width can be no more than 10.5. The qtps i run are i think 10.0 or 10.5. I think i called Strange about the shocks hitting and it has been known to be an issue with some of the moser setups. Another thing I noticed in the rear is that the spohn swaybar is actually rubbing the sides of the shocks.

I would be happy with consistent 1.3s but I really want the overall better ET. Do you think I would gain anything from pinion angle? Its at -2.5 at this point. Chassis mount Tqarm if that matters.

Thanks

 

Sounds like that swaybar needs to go.. I run a wolfe one that mounts under the rear, and it works really well.

Maybe the shock mounts need to get refabbed/modded to clear... changint the swaybar definately sounds like it will help.

Your whole car is a bit higher up, that being said the car should want to transfer more weight.

I'd try to lower the back a little bit if you can, take the spring isolaters out and get the car move level, that should get some more weight on the back which will help.

If the tire width is limited.... what about the height? If you're willing to do the work, you can fit a 31 inch tire in these cars... full outlaw type tub has to be done, rear 1/4's will need to be trimmed and probably spread out a little.. but it will look nasty and probably hook better on the street then it does at the track now.

Something to think about.. when having to run a limited type tire, always exploit the rules as best you can.