Drag springs for our trucks?

[team39763]

I'm looking for some drag springs for my truck, but nobody makes any specifically for our trucks.  I was considering getting some made, but I don't know what dimensions to go with.  Anybody have any experience with this?  I had looked at the Moroso trick front springs for chevelles and novas but I don't know if they'll fit.  What about s-10 coilsprings?  I also have some 90/10 shocks on the way.  I'm looking to get max weight transfer.  I'm moving the battery to the bed and making my own aluminum front rollpan.  I'd appreciate any help or advice ya'll could give me.  Thanks.

[Pushrod]

4.3 V6 springs for a C10 might be the trick here. A bunch of GM a/g-body drag racers like to use the a/g-body V6 springs, even with a BBC. A bunch of mustang racers use 3.8 V6 springs in the front too. Its not serious aftermarket stuff but it works.

[team39763]

Do you know of any for sale?  I'm gonna check our local junkyard, but I don't think they distinguish between v6 and v8 springs.

[Pushrod]

http://www.racepages.com/products/?D=chevy+coil+springs&Ntt=chevy+coil+springs&Dx=mode+matchallpartial&Ntk=Main&Ntx=mode+matchallpartial&N=9408+4294966707+9869&Nty=1

[team39763]

Thanks for the link.

[Captkaos]

Just ran across this, but V6 and V8 springs are the same.  You really want a taller spring with a softer rate that will unload the front of the truck when you hook it up.  If you don't go taller, you could get shorter spring and If you aren't hooking, you probably need to work on that first.  BTW 90/10 shocks are a BEAR on the street...

I know Eibach makes Drag-lauch springs and Moroso makes some drag springs.  There was a post somewhere that a guy posted with info.  I will see if I can find it...

[Pushrod]

OOoooo, sorry about that! I was just lookin at that link again and noticed the springs were the same for all those models. I made the mistake of thinkin they had it setup for individual models. My apalogies. Thanks Chris for pointin that out.

[team39763]

OOoooo, sorry about that! I was just lookin at that link again and noticed the springs were the same for all those models. I made the mistake of thinkin they had it setup for individual models. My apalogies. Thanks Chris for pointin that out.

It's cool man.  I just ordered some Moroso springs, but I have a feeling I'll be sending them back.  I didn't get to weigh the front of my truck to see what the front end weight was.  All I know is my whole truck weighed 4000 with 450pounds worth of driver and passenger, so I'm guessing the truck by itself weighs around 3550.  I got rid of the front bumper and I'm moving the battery to the bed.  I'm considering putting in some summit racing seats(the plastic ones).  If I play my card right, maybe I can get my wife to buy me a fiberglass hood with her income tax money.

[VileZambonie]

I HATE the fiberglass hoods...make sure you check out some light weight steel hood options. they fit better and look better imo

[Captkaos]

Here is the post, it is from another forum, but I don't remember where, I just got the contents since there was good info and he had a spreadsheet...

Do you know the weight of the front end? If not, do you have a local scale that will allow you to get front / rear axle weights? This can be done at the track too if there is a scale. Weigh the truck, then just the rear of it. But it would be prefered if you were in it.

"Drag springs" are simply long springs with a low spring rate. The reason they are set up this way is to store energy. The more preload on the spring, the more stored energy you have. Then you can use the shock to tune the rate at which the front rises.

Spring rate is the amount of weight it take to compress a spring 1" So a 300lb spring that is 10" long, would be 8" long with 600lbs on it and 6” long with 1200lbs.

The trick is to compress the spring as far as possible with out inducing coil bind and leaving a little room for upward travel IE hitting a bump in the road.

You can determine coil bind simply. You can either call the spring MFG and ask them what compressed height is or, measure one coil with a caliper, count total coils and do a little math. Now I like to add a little wiggle room here and add one extra coil. IE if you have 12 coils, do the math like you have 13. ( 0.47” * 13 = 6.11 compressed height).

Control arms induce a leverage ratio. That can be figured out fairly easily by taking a measurement from the ball joint location to the LCA shaft that the arm swings on. Then take a measurement to the center of the spring location from the control arm shaft. Divide the spring number in to the LCA. This is what's known as leverage ratio.. (stock stuff on my 63... 9 / 17.25 = 1.91) I would assume this to be the same through the early 70’s but double check.

Now this is where things get a little tricky. You have a 14.5” 350lb spring with a compressed height of 7.3” and you need to now if this will work. It’s all going to depend on unsprung weight.

This is weight of:

Wheels
Tires
Brake assembly
Spindle
Bearings

1/2 of the following parts
Upper control arm
Lower control arm
All tie rod ends
Springs (but then divided again by leverage ratio)
Shocks (but then divided again by Shock ratio)
Sway bar end links

Take your total front axle weight and subtract the unsprung weight. Divide that by two. Multiply that by the leverage ratio. This is the weight the spring needs to support.

2,260 Front weight
200 Unsprung weight
2060 is the sprung weight
1130 is each side
Multiplied by your leverage ratio 1.91 = 2,165

That would compress the spring a total of 6.18” making the spring 8.32” at ride height. Leaving .98” of travel before coil bind.

This is about where my truck is. I have about 2” of preload on the spring before the truck is lowered to ride height.

It’s a lot to figure out the right spring. But if you new the static weight of the front of your truck I could probably ball park a spring for you.



Here is a little spread sheet I threw together some time ago trying to figure out what will work for me.

http://73-ls1.com/63truck/weight_sheet_revision_2.xls

Some things that need to be know about this sheet..

1) Red Areas should be left alone..

2) This is currently set up for my trucks rear suspension. There might have to be some slight changes to the equations depending on your suspension set up (IE 3 link it won't compute the UCA for the rear properly). It takes the individual weights of the control arms and then doubles them in the final eqution showing unsprung weight. It should work however for a 4 bar, 4 link, truck arm, Ladder bar ect. It also uses a panhard bar in the equation so a ladder bar with a Z bar or a watts link set up might need the adjustments as well.

3) The front suspension equations are bases on a double A-arm suspension. So a strut set up might not work right or it might if you leave the UCA weight out.

4) If the drive shaft weight looks funny, ignore it. I divided it by 1/4 but it is multiplied by 2 in the final equation. So it does represent 50% of it's total weight.

5) "Max Control Arm Drop From Ride Height" is the amount the spindle would fall before maxing out suspension travel jacking up the front end (hope that made sense)..

6) All mesurements in the sheet are guesses right now. I have some weighing to do.

7) Axle centerline has to do with the truck arm suspension. The LCA goes past the rear axle center line so I tried to figure out the actual unspring weight by adding that in there. You'll more than likely put that to 0.

[team39763]

I HATE the fiberglass hoods...make sure you check out some light weight steel hood options. they fit better and look better imo

Why don't you like fiberglass hoods?  Is it possible to lighten mine up some without making it too flimsy?  How about if I took out as much bracing as I could and got rid of the hinges and latch and made it a pin on style then only used it for raceday? 
   Thanks for the info CaptKaos.

[choptop]

On the fiberglass hoods I agree with Vilezambonie, I hate fiberglass hoods. I have one from Harwood on my 3/4 ton and 1 from reflextions on my wifes 01. the fit and finish is second to none on the steel one and as far as weight savings, the guys I run with all agree. If the hood saves weight, then it looks like crap when running. The sides flexup, paint cracks due to the flexing, and your running a brick aerodynamically, what is a couple pounds different. If you get a hood that doesn't flex, (like the Harwood I got), then it really isn't lighter than the steel one. At least it doesn't seem to bee. Plus the metal is alot easier to smooth for paint. Big question is , is youor truck for racing or show. If racing only, go with light fiberglass models that pin on. If you want show, the steel is the only way to go. A full fiberglass tilt front end may be lighter and may be able to smooth up enough for a show rig, but I don't remember the name of the company that made them. If you remove the inner supports, your hood will distort severly.( been there , done that) Remove hinges, ok, but don't forget to install pins. There is alot of weight that can be removed from the front, but what to take off depends on what you are doing. Is it a daily driver, race only, do you need heater.a/c.It all matters

[VileZambonie]

I have a fiberglass cowl induction 73-80 hood upstairs in my garage. By the time we were done making that thing look good it weighed more than the steel hood and it still fit like a rotten piece of crap. Not only on my truck but several cars and other trucks over the years to no avail they just never look good (good from a far but far from good) Reflexxion makes an awesome hood for these trucks.

[team39763]

Ok, now I understand about the fiberglass hood....I'm dropping that idea.  I don't really need it to look good, just presentable.  I don't want to have the broke, crappy, farm truck that everybody points at when they see it.  It's going to be a race truck that makes occassional trips down the road for the raceday parties.  So, I shouldn't mess with the bracing on my hood?  Yeah, I was gonna take the hinges and springs out, but I need to think about it more because I hated lifting up that heavy ass hood.  I'm really just trying to get the truck as light as I can.  I don't plan to upgrade the motor any more at this point, so I wanna just get the truck lighter and make it hook good.
  Hopefully the moroso springs go in without too much trouble.  I'm planning to do it just like the tech article on here says. 

[choptop]

relocate the battery, ditch the bumper for a front roll pan, if you don't have the a/c hooked up, remove the a/c condensor, find a non a/c truck and swap out the a/c unit on the firewall with the heater core only version.Replace a-arm uppers and lowers with tubular unit, which will also drop the front end down a bit. Don't forget that weight is not the only thing to be concerned about, aerodynamics is as well. If you don't need the inner fenders ( dry area, only race, or drive on nice days, ditch them two. Are you running front runners or 20's on the front?? This makes alot of difference as well. I have seen many of these trucks in the ten's,  but it is hard to do with 20's and an a/c. Hope this is helpful.