Launch vidio

Speedy Goomba · Post by **Speedy Goomba** » Sun Feb 18, 2007 11:41 pm

I know there are places like TRZ that are making different shock mounts that allow you to use a typically coil over setup, which allows a much greater selection of springs.

the best setup is a factory, or factory based tubular setup, since the factory style springs are available up to 18" tall.

take an 18" tall spring, and compress it to about 9" and you have ALOT of stored energy:

I'll make a chart.

Lets say that your front end weighs for conversation 1800lbs.

with an 18" tall spring at 220lbs per inch
it will compress to 10"

at 10" it has roughly 1780lbs on it (based on the ratio of our control arms

as the front end starts to extend:

at 1" of extension it has 1560lbs of pressure on it

at 3" it has 1120lbs

at 5" it has 680lbs....then your front tire is yanked off the ground.

Now lets look at the typical spring for a Qa1 shock:

350lbs/in....they're going to compress 5" with 1780lbs of load on them

at 1" of travel they're putting 1430lbs of pressure back on the chassis

at 3" 730lbs

at 5" 30lbs

Bubstr · Post by **Bubstr** » Mon Feb 19, 2007 7:15 am

Possibly I have a skewd look at the front springs, but I look at it this way. First off Front springs and shocks don't create weight transfer to the rear, The diferental between the instant center and center of gravity height creates the force for weight transfer. Dragsters, Funny Cars and Altereds have been proving this for years. They sometimes have no spings at all. Now springs can store energy. They strore exactly the weight at rest put on each corner, no matter what spring rate. The difference in this case is how they give up that energy to assist weight transfer. A softer spring will give it's energy back at a slower but longer duration rate, and a stiffer spring will give back it's energy at a faster but shorter duration. Once all the weight is given up, there is no more to give. You have 100% on the rear. Any more rise in the front is just wasting Power to lift front, that could be used to go forward. I would prefer to get this weight transfer done as quickly as posible. Speed is the name of the game. After this first transfer, it's up to the instant center and center of gravity diferental to maintain it.

A byproduct of getting too high in the front is, sometimes when it settles it gains more sored energy than available from just front static weight. This extra weight comes from the rear, sometimes loosing some tracton when it sets back down.

One of the other advantages of haveing a stiffer spring, is you can get ride height lower in the front. the area under the car counts as frontal area. Frontal area can steal MPH, and with less air going under chassis, makes a more stable ride. Just ask any oldtimer that wheeled a 60s era high front Gasser. What do you guys think?

Speedy Goomba · Post by **Speedy Goomba** » Mon Feb 19, 2007 1:50 pm

With as much testing as i've done on my own ride, i'd say that yes the correct springs, shocks and bushings help significantly, i've tested each part inidividually.

The moment from ride height, to full extension is extremely significant to the wheelstand.

A small tire car must wheelstand to maintain traction.
Brian

Cobra · Post by **Cobra** » Mon Feb 19, 2007 2:30 pm

Bill,

While much good information has been given I would like to see you understand the science behind all this.

Please read Dave's book as it will give you the science.

Go to the forum below and read everything. Stock/Superstock racers perform magic with doorslammers.

http://www.classracer.com/cgi-bin/netboard/netboard.cgi

rallye bob · Post by **rallye bob** » Tue Feb 20, 2007 8:33 am

Cobra wrote:Bill,

While much good information has been given I would like to see you understand the science behind all this.

Please read Dave's book as it will give you the science.

Go to the forum below and read everything. Stock/Superstock racers perform magic with doorslammers.

http://www.classracer.com/cgi-bin/netboard/netboard.cgi

What page?

Speedy Goomba · Post by **Speedy Goomba** » Tue Feb 20, 2007 3:41 pm

I think you'll find the majority of the suspension information given on that site are from a handful of sources, myself, SSdiv 6, and a few other guys.

sc68z28 · Post by **sc68z28** » Tue Feb 20, 2007 7:07 pm

Cobra wrote: Please read Dave's book as it will give you the science.

Go to the forum below and read everything. Stock/Superstock racers perform magic with doorslammers.

http://www.classracer.com/cgi-bin/netboard/netboard.cgi

I'm hoping the book comes this week.
Thanks for the tip on Classracer, lots of good info there for clutch cars. ---Bill.

automotive breath · Post by **automotive breath** » Tue Feb 20, 2007 10:23 pm

Hi Bill,
You are getting good advice; I'll say more of the same maybe it will help out.

I have been working on my 3200 LB 67 to get it to hook and things are
coming together. I'm running a 11:1 compression 355 with a T350; 4500
stall/ 4.88 gear with 10.5 x 29.5 Drag ETs; the tires like 9.75 PSI. Best
times to date, 1.44 60ft 10.83 1/4 @ 123 MPH. Next step, advance the
cam 4 degrees and add .5 more compression to see if it will handle it.

As discussed the front suspension is extremely important. Assure zero
bind in the A arm bushings, as mentioned shocks with little resistance on
extension and drag race springs. I haven't received good feedback from
other racers running the QA1 set up in the front, I'm using moroso race
springs with 90/10 shocks, they work great.

Depending on front to rear weight distribution, tire condition and track
prep it sometimes becomes necessary to add weight to the rear of the car.

Endeavor to persevere and you'll have it flying!

Speedy Goomba wrote:A small tire car must wheelstand to maintain traction. Brian

Ed Wright · Post by **Ed Wright** » Wed Feb 21, 2007 11:16 am

I've not had any problems with QA1s, but Al Corda and a couple others have told me to throw them away and buy Afco and I would be faster. I try to keep the fronts ("R" series) set on zero (full soft extention), and keep the front end down with travel limiters. I run the rears (Also QA1) set on "5". I use 10.5 X 30" Hoosier radials, 4L60E trans, ATI 4400 converter, 4.30 gears. I just foot brake. I'm at 532 rwhp right now, gone a best of 9.95 @ 134 mph, 1.31 60'. Mine is an NA 383" LT1, weighs 3250 lbs. Some say they don't have to put much heat in radials, but mine won't hook without heat. Std bias tires have shown to be 2/10 & 2 mph slower than radials for me, and the newer stiff sidewall bias tires about half way between the two.
Here is a video of a 9.95 pass:

http://www.fastchip.com/Ed-995.mpg

CSH · Post by **CSH** » Sat Apr 07, 2007 6:55 am

Hello to you all,
Very good reading on this thread, just wondering what tyre presures on a 28 x 10.5 MT ET Drag on a 3600lb car would you guys run. I have seen a lot of rims nearly hit the ground with 10psi. I have a 71 camaro 406sbc,560hp@6750(conservative SF901 dyno),Caltracs on top hole,28 x 10.5 ET Drag,carrera front 90/10,rancho rears,moroso front trick springs,have 5.5in travel in front end,transbrake,5700 convertor,4.33 gears,TH350,wieght is 3600lbs, my best run is 10.66 @ 127.85 with a 60ft of 1.57. Only lifted the front left wheel once. I see on this forum you guys lifting the wheels high running slower times with a better 60ft. What am I not seeing in the set up of my car? Sorry to but in! You guys are a wealth of information!

Thanks Craig

sc68z28 · Post by **sc68z28** » Sat Apr 07, 2007 9:14 pm

CSH wrote:, just wondering what tyre presures on a 28 x 10.5 MT ET Drag on a 3600lb car would you guys run. I have seen a lot of rims nearly hit the ground with 10psi.
Thanks Craig

Hi Craig, I agree, when I tried 10.5 psi in mine I began to notice cupping type marks on the sidewall at the tread

Then later when reviewing the vidio, saw the LR rim going all the way down at launch.

I also found that more than about 13.5 psi, I was skating. So I've settled on 12 to 12.5
My car was over 3650# and has slowly been loosing weight, down to 3440# now. That has not really changed how much air I use.

Your set up sounds good, but I'm no expert. Hopefully some of the more seasoned racers here will chim in on your deal, I'll be listening as well.

It is frustrating running 10's at or near 130mph and our launch looks like this (see pic)

I have read Dave Morgans book, and can't wait to try some things. But first I've decided to put in a new clutch.

---Bill.

sc68z28 · Post by **sc68z28** » Sat Apr 07, 2007 9:24 pm

CSH wrote:Caltracs on top hole,28 x 10.5 ET Drag,carrera front 90/10,rancho rears,moroso front trick springs
Thanks Craig

Craig, what rear springs? and do you have at least an 8 pnt bar/cage attached to subframe connectors?

---Bill.

CSH · Post by **CSH** » Sun Apr 08, 2007 8:42 am

Hi Bill,
I dont have a cage or sub frame connectors and I knew it was going to be the problem but I spose I didn't want to accept it. I was hoping that there might have been something else that I was overlooking. I can now only run 11.00 or slower in our rules over here because I have not got a cage, but I still can work on the 1/2 track to see gains in performance. I have a business and do actually work on race cars for a living but, most cars I work with have more than 700hp and I was hoping mine would still be OK with out putting a cage in it because it is a weekend drive car with the family. I didn't really expect the car to soak up the initial hit so much. I spose when you have a dual perpose car you have to accept the comprimise of performance. I don't know what my rear spring rate is but I have noticed that the spring has bent behind the housing after running that time. What spring rate do you guys think is needed with leaf springs?
I also am no expert in suspension but can see a gain with your ladder bars up a hole. What angle is it on now and where does it end up when you go up one?How long are your ladder bars? What is you pinion angle? It would seem to me that your car is loosing 100hp or so somewhere.

Hope we all can get you sorted. -- Craig

sc68z28 · Post by **sc68z28** » Sun Apr 08, 2007 9:10 pm

CSH wrote: I don't know what my rear spring rate is but I have noticed that the spring has bent behind the housing after running that time. What spring rate do you guys think is needed with leaf springs?
I also am no expert in suspension but can see a gain with your ladder bars up a hole. What angle is it on now and where does it end up when you go up one?How long are your ladder bars? What is you pinion angle? It would seem to me that your car is loosing 100hp or so somewhere.
-- Craig

Mono, multi, or split monos, with or w/o pads? I found that when I was running the multis with pads they were allowing the housing to move, soaking up power.

My ladders are 33.5" center of housing to center front mount, and are 1.25" down in front (2nd to bottom hole out of 5). I'm thinking move it up one, I'll be in the middle hole and almost level (down 1/4'' in front).
The new clutch will be softer hitting, a little slip. So should I move the bars up now, or see what happens with the clutch first? You know the old rule, only make one change at a time.

Pinion angle is neg 1* from trans angle, and drive shaft is less than 2*
I used this method http://www.markwilliams.com/driveshafttech.aspx

The clutch will be from Rob Youngblood, It's his 7" dual disc.
http://www.advancedclutches.com/products.htm#Sportsman
---Bill.

John Wallace · Post by **John Wallace** » Sun Apr 08, 2007 9:31 pm

Your rear springs aren't floating at the rear end?