I could use some help trying to figure out how to get my car to have a better launch and improve my 60ft times. I have 675lbs of torque at the rear wheels and run a 4spd, so I don't know if this is how it will always be for a stick car or not. The rear suspension consists of the following. John's nine inch ford rear end, Posie's new woody/wagon springs with three leafs out 9 down to 6, cal-trac traction bars on the bottom hole or softer setting, summit racing three way adjustable shocks on the XS setting and 19lbs of pressure in the tires. I used to clamp the biggest three leafs on each spring front and rear of spring and launching at 3500 rpms would pull the tires of the ground most the time. I was told it was to stiff and I was getting the tires to hot or sticky. So I unclamped the springs and do a shorter burn out. In the attached video against the Bariccuda I have the springs unclamped and lauched at 3000 rpm. I seems as if the tires hooked up and are on the ground, compressed the slicks and that the body is moving up while suspension is moving down. I think that when the body is coming down it is flexxing the spring and causing the bouncing. In the video against the Vicki I have the springs clamped, shocks on XS setting, 19lbs of air in tires, and lauched at 3400rpm. Any ideas? video one: http://www.youtube.com/watch?v=VHLp692RBUc video two: http://www.youtube.com/watch?v=tGsQ-0j8J5Y
Landseaandair, Thanks for the reply. I have a friend with the same speedway spings in his 41 Willy's and he took two leafs out and said it leveled out the car and that it runs better. I was going to take two leafs out of the front springs this winter, but could you help me understand how it affects the back for future help with others who ask me about my car. Kevin
Just a hunch. Seen a lot of cars with Caltracs that worked great but mostly with IFS. Pretty much any car that sits high with no front end rise to soak up momentum seems to have a tendency to bounce in the rear with a hard launch. May have been standard fareback in the old days? Bit before my time.
X2 with post #2...Front suspension is too stiff..I can't tell you from this far away for sure but not only could the springs be too stiff but the shocks also..How much do the springs compress? Part of the problem could be in the rear springs, you started with 9 leafs, took 3 out and technically the spring "structure" is now off and is now not flexing/supporting the weight properly..I really think its in the front though, I can't write well enough to explain, pm me for phone # if you want..
frt too high and too stiff, rear section of the springs unclamped and the frt half stiff like the old mopar super stock springs and you should be able to bounce the car easily with out shocks and the shocks set at the softest setting that will control the springing i don't anything about cal- trac settings
Get rid of those junk rear shocks. Call us for some good Calvert 9 way adjustables and we'll help you with the rest of the set up.
How much travel do your shocks have before they top out from where the car sits loaded? It look as though they may be close to topping out. Leaf springs don't have the stored energy that a coil spring has and seem to not lift as fast in the front as coil sprung front suspensions. I'm running a transverse leaf spring set up on my car and the front end lift is minimal, it tops out the shock at about 2-1/2" higher than where it sits loaded and that's where it remains for the rest of the pass. I'm running an automatic with a 3800 stall converter, slapper bars, though. Take a look at some old gasser videos and I think you'll see that your suspension works a lot like they did. Nice car by the way what motor and trans are you running?
You've built a 60's era gasser.It looks to me it handles like a 60's gasser...badly.lol Not knowing anything about your motor,if you want better sixty foot times you'll need more RPM at launch,not less.The reason the front was high on Gassers was to transfer weight to the slicks of the day.Hard wall,not very sticky.When the soft wall slicks arrived,the front ends came way down
3 things stand out to me from the video. 1. You need rear shocks 2. front end is to high and stiff 3. you need to launch at a higher RPM or get a adjustable clutch or both Big reason 60 gassers didnt well and you have some of those traits, plus better tires and more power today compounds the problems
spikeshotrods, could be right that the shocks are topping out unloading the tires that would be the first thing to check
Not necessarily true... If a leaf spring is compressed as far as a coil, it has the same amount of stored energy. What typically happens with leaves (and I believe this is the case here) is the front spring pack is too stiff and the front isn't compressing at all. There is still too much wrap at the rear though. In the video, the left rear actually hops right off the ground on launch... Custom300, which 3 leaves did you remove? If you took long leaves out, the spring pack has less resistance to wrap-up. Anything that will locate the housing more firmly will help. If you want to maintain the old school look, I'd recommend hiding a top link up on the center of the housing. Just make sure you have a stout crossmember to mount it to.
I will try to answer as many of your questions as I can. I have 90/10 front shocks, removed the bottom 3 rear leafs leaving the longest 6 in car. The rear shocks are 3 inches longer than stock. I have 1 1/2 inches of travel in the front spings. Measured from bottom of frame to top of spring with front shocks out of car while tires where on ground and with it on jack stands and front suspension hanging in air. There was a 1 1/2 inch difference between the two. I thought about taking two leafs out of the front and putting 1 or 2 back in the rear. I also posted attached another video of the car launching @ 3500 rpms and has rear spings clamped. Exwestracer: I do have traction bars Posie's sold me a couple years ago that connected from the top of the axle tube out towards backing plate to a bracket on the frame by the front sping eye. Should I put it back in to help with wrap-up and if so will it affect how the cal-trac bars work? http://www.youtube.com/watch?v=1oow8ZOTbIU
weigh the car and get all four corners. this can be done affordably with 4 bathroom scales and lever arms to get the ratio in the right range if you dont know anyone with scales. rick
Thanks everyone for your input. I called Alex over at Moneymaker Racing and he helped me out alot. I just finished up removing two leafs out of the front springs, clamping the front half of the rear springs, and will be ordering Calvert 9 shocks for the rear Thursday. I will give this all a try next weekend and let you know how it goes. Kevin
Your changes sound good. Make a pass or 2 leaving at 3500 to see if there is any difference. Then try leaving at 4500-5000. When we had the clutch turbo in our car I left at 5000 and the car left hard with the front wheels high in the air. I think you need to leave at a higher RPM. The motor is bogging on the launch in your 2 videos. what kind of tires are you running? We run Mickey Thompson 29.5x10.5x15's and run 10.5 pounds of air in them. 19 seems high unless your running a radial.
cgaswillys, I am running Goodyear Eagle 29x9x15's they where they only ones I could fit due to section width. What is a clutch turbo?
Custom 300, if I'm understanding your Posies traction bars correctly, you would use them OR the Caltracs. The traction bars are basically a radius rod that should stop axle wrap altogether. It's kind of hard to explain compression on a leaf spring setup. I think the way you are measuring the front sag is not quite accurate. If you measure the spring with the axle hanging, the axle weight is pulling the spring down (stretching it). You really should measure the spring arch with the spring out of the car, then with the front end weight on it. If it's only moving 1 1/2" from the hanging position to full weight, I'm gonna say the front springs are way too stiff. You should be looking more in the 3-4" compression range...
exwestracer: Thanks for your help I am sticking with the cal-trac bars since moneymaker said my Posie's bars a similar to old Shelby bars on road race cars and don't to shit for drag racing. Kevin
Personally, i think you need to put travel markers on the shocks- looks to me like your doing the old mopar trick of pounding the tires down so hard, you're either bouncing the tire or more likely, topping out the shock's extension. if you have plenty of shock extension left, you might have to take some hit out of it with shock settings, or link geometry, because bouncing the tire aint getting it done for ya. -rick.
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