Spring help

Discussion in 'Race car chassis tech' started by Ian Fitzgerald, Jun 17, 2007.

  1. Just starting to put my chassis together for my '70 Gsx replica. Need
    a little advice for spring selection. The car will be all steel, although
    has been dipped and will run an absolute minimum of sound proofing, although
    complete interior inc. roll cage. Running all iron big block at this time approx.
    500hp, TH400, Good 10'' converter and built '72 10 bolt rear. Already have
    set of Hal/QA1 Stocker Star shox and a HR Parts rear anti-roll bar. I plan to index race and possibly bracket race the car, but it will also be driven on the street.
    I am a little new at the chassis set-up thing and expect you need some more information. If you feel I need a little guidance, please give it now
    before I waste money and time doing wrong.
    Thanks in advance,
     
  2. ralph sr.

    ralph sr. Well-Known Member

    im sure u could use a drag specific spring that would work on the street as well. but a better bet might be a good quality stock spring with a set of air bags for some amount of adjustability. theres tons of stuff on the net on how to properly set-up a rear suspension. good luck to u.:beer ralph sr.
     
  3. Thanks Ralph,
    That was my thoughts. Thinking about big block Chevy, Moroso springs
    for the front and stock replacement rear spring with air bags. Problem I'm
    havin' checking out A body rear spring applications there must be at least
    half a dozen, was wondering what you guys are using specifically. As I
    said I'm new to chassis set-up on these cars, but if you could give me
    a starting point I'd really appreciate it.
    Thanks again
     
  4. ralph sr.

    ralph sr. Well-Known Member

    for drag race primarily i would use a moroso trick rear spring. not intended for street use, but i think would work limited street use only. on the other hand, if ur mostly street driving use a moog replacement, or global west rear coil spring would work. summit racing carries the moog and jegs carries the global west. the moog replacement is the cheapest of the two. add airbags and adjust so that ur car leaves straight. usually the right side air bag will have the most air pressure in it. again there is tons of info on the net on how to set up a coil spring suspension. good luck and let me know how it all turns out.:TU: ralph sr.
     
  5. Hi Ralph,
    Wanted to avoid the Moroso rears as I'm using the HR parts rear anti-roll
    bar, as the moroso spring I believe has more rate to the right hand side.
    Think I'll check the rate of the stock ones I have and check free height,
    then speak to Global West. Although they do not quote a spring rate they do
    offer I think 3 different heights for 'A' body rear. - Don't ya just love these
    steep learning curves?!:TU:
     
  6. Jeff Kitchen

    Jeff Kitchen Well-Known Member

    I found out the hard way that using stiffer springs in the rear will kill the hook. I first used station wagon springs to raise the back end about 1/2" to keep it up off the tires. They wouldn't let the car transfer weight on launch. Now I use standard Skylark rear springs. I use Moroso 160's in the front.

    By the way, with an HR Parts bar in the rear (which I use also), you don't need the Moroso rear springs. Put the upper and lower arms in the stock location, use standard springs, and use QA-1 adjustable shocks. Shock adjustment is trial and error. Don't be afraid to use different settings side-to-side.

    Have fun.
     
  7. Thanks for the reply Jeff. I have admired your cars and work for a looongg
    time. Think we have actually met one or twice at the GS NATS. Love learning
    about these cars, you just never stop! Going to go with with what I have
    for now. My only regret is I did not find out about Del-Alum bushings 'till
    I'd already rebuilt my suspension. Will have to go with the Poly-graphite
    for now and just keep everything well lubricated and check for bind.
    Is there any particular replacement rear spring you can recommend as a
    starting point? I will also be using air bags.
    Thanks in advance,
     
  8. Jeff Kitchen

    Jeff Kitchen Well-Known Member

    I think the rear springs I have now are standard Skylark springs from Moog. If you have the HR parts anti-roll bar, you don't need air bags. They will just give you problems down the road trying to tune the suspension. Set the HR Parts bar according to their directions (carefully!!), and then use shock adjustments to tune it.

    Have fun.
     
  9. Thanks Jeff,
    I like this more and more. Keep things simple!!
    You mentioned that you use Morose 160 front springs is that 47160 242lbs/inch? Guess I'd better get this thing together and put it on the
    scales. Just one last point. Spring fatigue. I will also be using my car on the
    street. How much 'life' do these Moroso springs have before they become
    inconsitent and should be changed?



    P.S. Guess I'd better start posting some pictures. Had the body back
    from dipping/coating is now at the body shop....That's if anyone would
    be interested in how a Limey puts one of these cars together.:3gears:
     
  10. Jeff Kitchen

    Jeff Kitchen Well-Known Member

    Everything's a compromise. The Moroso springs will die in about a year or so, unless you keep the car on jackstands most of the time. A stock spring will last alot longer, but the car won't hook as good on the track. You have to decide which is more important to you.
     
  11. Thanks again Jeff!
    I really don't mind the maintenance issue. In racing everything has a
    usefull life, just with suspension I didn't know what to expect. Think I'll
    have to sit down and come up with some usefull tests to check/measure
    both springs and shocks as I expect they will wear also.
    Incidentally, have you tried the 250 & 260LB Moroso front springs in
    your set-up? How much front travel do you have? and are you using standard
    or the taller spindles?
    Sorry to ask so much. Our racing season over here is quite short and want
    to get a good head start on the tune up.
    Thanks very much again:TU:
     
  12. Jeff Kitchen

    Jeff Kitchen Well-Known Member

    I run stock spindles and the 47160 springs (I think 242 lb?) Front travel will vary with nose weight vs. spring height. Get the front end as low as practical for your style driving. I think Tom Rix measured the optimum travel as around 4"? I run aluminum heads and a gutted hood, among other things, so my nose weight is likely less than yours. You may need the 47190's.

    Have fun.
     
  13. Thanks for your time and information Jeff.
    I'll measure everything as I put this car together, check free spring height
    and measure installed height, then work out the stored energy. Once together I'll put the car on the scales and then go play and keep plenty
    of records. I've got the 260lb front springs right now. I'll have to buy
    the 242 and 250 and see what works best with my combo. I'll be running
    the Micky T's also. So you've given me something to aim at 1.41 60ft.
    I found it interesting you mentioned that even with the HR rear bar I may have to stagger the shock settings for best launch.

    Going to check things out at the body shop again Thursday. Think I'll start
    posting a few pictures soon. So you guys can keep an eye on what I'm
    doing and point out things that aren't right......
     
  14. ralph sr.

    ralph sr. Well-Known Member

    ian, good luck with ur car and please post the pics when ur done.

    jeff, really good info, im learning alot from ur car. do u have any pics u can post? id like to see more. kind of makes me wish i was still racing.good luck:3gears: ralph sr.
     
  15. Jeff Kitchen

    Jeff Kitchen Well-Known Member

    Thanks for the compliments. It really doesn't look like much once you get up close. I built it to be a nice looking racecar ... not a fast showcar. I knew it would get scratched while I was working on it. I try not to, but things happen. Anyways, here ya go:
     

    Attached Files:

  16. gusszgs

    gusszgs Well-Known Member

    Jeff, very nice car indeed. Looks to leave nice and straight from gate.
    Question for ya, in your build you state your running stock suspension. I've read your running the H&R bar and QA-1's. What is stock? The control arms?
    I'm not trying to be a smart ass.:laugh: Would like to keep my suspension as stock as possible and try to get the thing to hook good. Thanks, Jim
     
  17. Jeff Kitchen

    Jeff Kitchen Well-Known Member

    That's a legitimate question. In the racing world, the term "stock suspension" refers to using the factory type (control arm, leaf spring, or torque arm) and using the stock mounting points for those types. If a car has ladder bars or a 4-link, it is no longer "stock suspension". One point of contention is whether the suspension must be stock for that car. For example, the new GM torque arm suspension works great, so some guys have taken that suspension and put it in an older car. It is "stock", just not for that car. Down here in the south, there are entire classes devoted to stock suspension. Most allow unlimited engine rules, as long as the suspension is stock. Some cars have come up with some wild interpretations of "stock"! BTW, these cars are running 7's in the 1/4 mi!

    You're right, there's not a factory piece on my rear suspension, but all the mounting points are maintained. I still have four control arms. I also added a bolt-on anti-roll bar.

    I would be hesitant to try and hook any real horsepower with totally stock parts and slicks. Look at Gessler's FAST car. He's running 10's but on stock tires. The car doesn't shock the suspension and dead hook like a slick car would. I'm pretty sure that's why he didn't do the Hot Rod magazine race last year. His car doesn't react well to slicks.

    I hope I answered your question. Have fun.
     
  18. gusszgs

    gusszgs Well-Known Member

    Yes.Thanks for the info Jeff. Jim
     
  19. Jeff, Thanks again for all the help. Still reckon, that is a nice racecar.
    Anyways, not gonna know any more 'till I get this thing put together.

    Ralph thanks for your kind wishes, I'm a long way off right now, but by the
    end of summer should be looking like a car again, stripes and all. Look for some pictures in the rides section.
    Later:TU:
     

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