Suspension adjustments for good launch

[NY Twin Turbo]

I'm looking for advice on where I should start. I know testing and tuning is the only way to get it right. But still, there's got to be a good starting point.

Sounds crazy, but after all these years, the car has never been launched hard and I never messed with the suspension's adjustability. You never know. Some day, I may actually want the car to launch on more than 7 psi.

Anybody here have a similar set-up? I guess I just need a good starting point for average track conditions on an average day.

-3535 lb car.
-Metco adjustable uppers installed at stock length.
-Metco solid lowers with those instant center brackets welded on. Location of axle mounting point can be relocated up or down.
-HR Parts sway bar.
-Competition Engineering adjustable drag shocks. Front and rear.
-Mickey Thompson Drag Radial ET Street R's P325/50R-15
-Factory stock springs
-Air bags, just because I never bothered to take them out.


Pinion Angle?
Shocks?
Tire Air Pressure?
Air Bags PSI?
Lower Control Instant Center mounting location or not?
Pre-Load on the Sway Bar?

 

[marleyskater420]

Have you had the car scaled at all?

What does the car do when you launch it right now?

How does the suspension react upon launch and after launch? Does it hook up and then spin? Does it spin right out the hole? Does the car squat or does it raise up? Does it veer or pull to one side or the other?

Your best place to start is to just go launch the car and see what it does. Once we know how your car is reacting to your setup, then we can make suggestions. Until then, any suggestions are pointless without knowing how it reacts right now.

What could help though is to have the car scaled at full race weight (same amount of gas you will run at the track and with you in the seat). With that knowledge and with what you report back after you run it how it is now to get a baseline, we can give a lot better recommendations are where to start making adjustments.

First and foremost, go run the car and see what it does.

Have a friend film the car from about 10ft back behond the car, 10ft to the left (meaning if you are standing behind the car looking forward at the driver side taillights, you move 10ft to the left) and put the camera at ground level to where you can capture what both the front tires are doing and the rear tires and rear end of car. Make sure to be able to see both the front tires, rear tires, and the rear end of the car (to determine if it is squatting or rising) when you are filming.

If you can, load the video to youtube and post it here for us to look at.

Take baseline measurements of where all your adjustable pieces are currently at (like for your double adj. Rear UCAs, measure how many threads are exposed on eother side of the center tightening sleeve so you know exactly what the length of the arm is, etc etc) and write it down in a log book. This will be your reference guide for your car in the future at the track. Take notes of where all the suspension pieces are for your baseline, as well as how the car reacted to that setting and what happened during the run. This way you can have info for when you make changes, so you know exactly what changes you have done and how they have effected your car.

Hope this helps!

Also, I shot you a PM...

 

[The Granny]

If you haven't already I suggest reading a bunch.. it can help you make some fine tune adjustments at the track rather than make a hit, upload it, post it, and wait for some suggestions. That way you're not flying blind when you're out there.

An easy to follow and informative read: http://www.baselinesuspensions.com/info/Launching_A_Drag_Car.htm
One of my favorite articles: http://www.racingjunk.com/forums/showthread.php?17130-4-Link-Basics-Theory-amp-Help-Instructions - it can answer most of your 4 link questions.
Fine tuning shocks: https://www.cachassisworks.com/Attachments/Instructions/899-031-214.pdf

I just had got my car out of a chassis shop, I had work done by Madman over at http://lastorracecars.com/ and the guy is very knowledgeable about this kind of stuff. When I asked him about pre-load on a sway bar, (I have a TRZ bar but the same theory should apply for you), he said it's recommended to be neutral at all times. However, if you are constantly making hits and the car is launching and going immediately one way or another then some pre load would be necessary, however more than 1/4 of a turn is a huge adjustment for preload. So start with small turns and test.

Like Tyler said, posting videos from the right angle will help us make some suggestions for you. Another thing that could help is plotting your suspension set up and posting your results. Some of the measurements you'll need are here: http://www.baselinesuspensions.com/instant-center_general.php


Here's what wolfe racecraft recommends for pinion angle: https://www.wolferacecraft.com/pinionangle.aspx

edit: if you record with an iPhone use their slow motion feature and slow down the launch, that way you can analyze it better!

 

[marleyskater420]

If you haven't already I suggest reading a bunch.. it can help you make some fine tune adjustments at the track rather than make a hit, upload it, post it, and wait for some suggestions. That way you're not flying blind when you're out there.

An easy to follow and informative read: http://www.baselinesuspensions.com/info/Launching_A_Drag_Car.htm
One of my favorite articles: http://www.racingjunk.com/forums/showthread.php?17130-4-Link-Basics-Theory-amp-Help-Instructions - it can answer most of your 4 link questions.
Fine tuning shocks: https://www.cachassisworks.com/Attachments/Instructions/899-031-214.pdf

I just had got my car out of a chassis shop, I had work done by Madman over at http://lastorracecars.com/ and the guy is very knowledgeable about this kind of stuff. When I asked him about pre-load on a sway bar, (I have a TRZ bar but the same theory should apply for you), he said it's recommended to be neutral at all times. However, if you are constantly making hits and the car is launching and going immediately one way or another then some pre load would be necessary, however more than 1/4 of a turn is a huge adjustment for preload. So start with small turns and test.

Like Tyler said, posting videos from the right angle will help us make some suggestions for you. Another thing that could help is plotting your suspension set up and posting your results. Some of the measurements you'll need are here: http://www.baselinesuspensions.com/instant-center_general.php


Here's what wolfe racecraft recommends for pinion angle: https://www.wolferacecraft.com/pinionangle.aspx

X2 on everything John said.

Those articles he listed are incredibly helpful and really break down the various parts of the suspension and walk you through what they each do, how they function, how they all tie together, and how to approach tuning your car's suspension.

Read, ask questions, educate yourself, and read some more. The more you can educate yourself, the more you can be confident in what changes to make when you are at the track and what adjustments to try.

 

[NY Twin Turbo]

Wow!

You guys are great!...........Maybe too much so.

I guess it helps a little if you guys know a little bit more about me. In other threads you may have noticed some of my previous posts mentioning that I'm not that good at drag racing! I consider myself a good driver with incredible feel for my Buick, but not so good with the formal form of drag racing. After botching a bunch of runs over the years, and the shock of using a transbrake for the first time, I pretty much decided I would have a trusted friend (name mentioned below in my signature) with an NHRA licence take her down the track. Now that I'm pretty sure this thing has the power to go into the 8's, there's no way I'm getting behind the wheel!

Constant suspension tuning takes a lot of runs and a lot of track visits. And I obviously built this thing and have owned it for 23 years so I'm not new to this process. But these opportunities don't come often for me. Maybe once a year or even 2 years.

I guess it's a little bit of dream, but I was hoping to set it up in advance somewhere within range. This way Brian can get a clean pass without the data log's TPS line looking like a rapid heartbeat.

With Brian's help and using all the information you gentleman have so graciously provided me with, from this point forward we would then make adjustments accordingly.

John, I plan to read through all that info. Thanks!

Tyler, I'll give you a call. Maybe this weekend.

 

[Mr.Spool]

I'm looking for advice on where I should start. I know testing and tuning is the only way to get it right. But still, there's got to be a good starting point.

Sounds crazy, but after all these years, the car has never been launched hard and I never messed with the suspension's adjustability. You never know. Some day, I may actually want the car to launch on more than 7 psi.

Anybody here have a similar set-up? I guess I just need a good starting point for average track conditions on an average day.

-3535 lb car.
-Metco adjustable uppers installed at stock length.
-Metco solid lowers with those instant center brackets welded on. Location of axle mounting point can be relocated up or down.
-HR Parts sway bar.
-Competition Engineering adjustable drag shocks. Front and rear.
-Mickey Thompson Drag Radial ET Street R's P325/50R-15
-Factory stock springs
-Air bags, just because I never bothered to take them out.


Pinion Angle?
Shocks?
Tire Air Pressure?
Air Bags PSI?
Lower Control Instant Center mounting location or not?
Pre-Load on the Sway Bar?

Depends on how you want the car to be setup meaning street or track.

 

[marleyskater420]

Wow!

You guys are great!...........Maybe too much so.

I guess it helps a little if you guys know a little bit more about me. In other threads you may have noticed some of my previous posts mentioning that I'm not that good at drag racing! I consider myself a good driver with incredible feel for my Buick, but not so good with the formal form of drag racing. After botching a bunch of runs over the years, and the shock of using a transbrake for the first time, I pretty much decided I would have a trusted friend (name mentioned below in my signature) with an NHRA licence take her down the track. Now that I'm pretty sure this thing has the power to go into the 8's, there's no way I'm getting behind the wheel!

Constant suspension tuning takes a lot of runs and a lot of track visits. And I obviously built this thing and have owned it for 23 years so I'm not new to this process. But these opportunities don't come often for me. Maybe once a year or even 2 years.

I guess it's a little bit of dream, but I was hoping to set it up in advance somewhere within range. This way Brian can get a clean pass without the data log's TPS line looking like a rapid heartbeat.

With Brian's help and using all the information you gentleman have so graciously provided me with, from this point forward we would then make adjustments accordingly.

John, I plan to read through all that info. Thanks!

Tyler, I'll give you a call. Maybe this weekend.

I mean that's cool. You'll be the Jackie Knox of the Grand National world... hehe

With Brian driving the car I'm sure he will have some great intuition as to what changes to make.

Here is Chassisworks' basic instruction manual for their shocks. This might give you some idea of where to start with the shock adjustments. https://www.cachassisworks.com/Attachments/Instructions/899-031-214.pdf

The biggest thing you can do right now, is obtain the shock dyno sheet on the shocks you are using. This will tell you what the range of adjustment is, how fast it moves, and what the available adjustments are.

Shoot me a call anytime man. If I'm awake, I answer. If I'm dead, or just sleeping, I won't answer.

 

[turbo2nr]

These cars launch really well right out of the box.

Exotic parts not necessary in my opinion.

Build 12psi of boost and let her rip! You'll get some 1.4s in 60' easy.

Only if you have a problem, then you start scratching head and open thy wallet.

 

[Nick Micale]

My opinion is to remove the relocation/instant center brackets and install a HR Parts rear anti-roll bar.

Having installed a couple dozen of these on GN's in the 10's, 9's and a couple 8 sec. ones we easily see 1.30/1.40 short times on many street/strip builds.

 

[marleyskater420]

My opinion is to remove the relocation/instant center brackets and install a HR Parts rear anti-roll bar.

Having installed a couple dozen of these on GN's in the 10's, 9's and a couple 8 sec. ones we easily see 1.30/1.40 short times on many street/strip builds.

I believe in his original post he said that he has a HR bar and the lower relocation brackets welded in.

 

[murphster]

Drag Radials need to be dead hooked on the launch and don't recover well. Like mentioned, a video will tell you if you're spinning on the hook or its unloading after the hit and spinning then. Two different things that need different adjustments.

For the dead hook, ideally you need the rear as stiff as possible with solid bushings in every arm and a welded in anti roll bar. Of course, people go fast with a lot less but the more deflection you have could cause it nit to hook. Another thing that helps the dead hook is a double adj rear shock with loose extention to plant the tires and tight compression to keep it planted.

The video will help see whats going on with the geometry. A good instant center with give minimal squat in the rear and keep the front end rise within reason. If the front end has too little travel it could be bouncing back down quick and unloading the rear. Or if it comes up too quick and then unloads the front shock extension may need to be tightened.

You also need the tune real good on the launch and making sure the power is coming in quick because that can limit a good 60ft even if everything else is good. Knowing at what rpm to launch at on your converter take trial and error and going over the logs.

At your power level, 1.4s should be easy and 1.3s not too hard with just a decent suspension setup.

 

[NY Twin Turbo]

My opinion is to remove the relocation/instant center brackets and install a HR Parts rear anti-roll bar.

Having installed a couple dozen of these on GN's in the 10's, 9's and a couple 8 sec. ones we easily see 1.30/1.40 short times on many street/strip builds.

I believe in his original post he said that he has a HR bar and the lower relocation brackets welded in.

Yes this is correct.

I have an HR bar.

Back a few years ago, I had a Wolfe bar. But I kept snapping the rod-ends. Then I upgraded to the QA-1 heavy duty rod-ends. Then I snapped the leaver arm off the pivot bar!

Remember, I drive this thing in the NY City suburban areas. And I drive it a lot. It just couldn't handle the stress of all our uneven road surfaces. We finally cut out the frame sleeves and removed it. Then we installed the HR bar with axle tube brackets welded on at the maximum spread. The rear feels just as tight but with just enough give to prevent breakage.

The Instant center brackets on the Metco lower control arms are welded on and will allow me to chose between the stock and lower mounting hole on the the axle bracket. So I don't necessarily need to use them even though they are there. It just gives me the option.

I do count on Jack and Brian's expertise quiet a lot. But whenever we get to the track, First we will make a conservative pass for a good data log. Then Brian will say "lets turn it up!" Then he will blow the tires away. By that point we are out of time or are worried we will get tossed for running too fast. I think our best 60 is somewhere around mid 1.50's. In street trim and off the street, the run he made at Cecil (in my signature) was launched from less than 3 psi. He still went 116 MPH in the eighth.

I guess I know what I need to do. I'm not really complaining, but it is quite difficult owning a multi purpose car like this. Car shows, racing, and driving. All while having so little spare time and money. That is why I am trying to minimize the trial and error.

 

[dynoman]

Do what Marley said about a good video or two . Seeing whats really happening during the launch in slo-mo can tell you where to start adjusting . I'm in the same boat , plenty of power , crappy 60' . I'm going to have lots of launch video taken next time I go to the track .
To bad you didn't go to Piedmont ( TB Nats. ) this year , that would have been the perfect place to " practice " and make adjustments with all the help in the Turbo Buick world at your disposal . Good Luck , Sam