Thread: first time out 9.89@144

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Okay, I am going thru this slowly in my mind......the front is not "limited"but even when you jack it up, it only drops 2.5". Which compound rubber are you running and what is the springrate "and" the Caltracs rated at? You have good stuff under there. It appears the tune is not right and I wish you could shock the tires harder but if the rubber ain't there, it ain't happenin'. Could you spend some time with this car this week and find bar angles to determine instant center. Find a way to get the travel you need for your preffered front lift to help the rear. I am not going to go into squat and anti-squat at the rear yet because it seems it's not loading it up yet. If you could scale it for corner weight, great, if not don't worry about it now. Everything you mentioned for components can work and are very adjustable, don't give up and start back to basics. Tire compound is a good thing to know. Sometimes using your tracks to back up into works great and sometimes backing up into the previous run's tracks makes the thing hook super well. Depending on the compound of your tires.

i just jacked up my car and the front drops 5.75ish. we have the same car and setup can't figure out why his only drops 2.5" i even put my foot on the spindle to try to push it down on his no luck!!!! i have 28" front tires and he has 26" could that be anything??? thats about all i can find different between the two. thanks denny and nitro shawn for your input even after i was a dick to you guys...

Tire size won't be a factor on launch for your condition. I am curious as to why the thing has a self "limiting" condition. I still am concerned of the lazy 60footer. That tells me there is a rear supension problem yet. I would worry about the front travel first and go to the rear when fixed. Then further progress will be easier.

What is your pinion angle?

If the car in the pic is the one you are trying to get to launch, first thing I would do is get the back end down!!! I don't think an instant center plot would even register with the rear that high static!!! How much rear end drop are you getting? Besides the Cal Tracs, what is the rest of the rear suspension??? Also what tires are you running and what pressure are you running in them? 60' time is slow, are you sure the converter has flashed when you launch? Maybe just some converter slippage killing the 60' time....

Read all the posts in this thread---Did I miss something??? Usually a reason when the car gets out, then the tires break loose...

Originally Posted by DennyW

Usually a reason when the car gets out, then the tires break loose...


What ???

Dave is talking about the chassis "un-loading".

that's why I asked if he could get better info for our inquest and help...a lot of unknowns and no magic pill

erik the pinoin is set at 4deg nose down at the ground. i can't get the rear any lower with out hitting the wheel wells. there stock other then cutting the inner a moving it in 3" so the tire would fit side to side. nitro the rear is a mopar 8 3/4 with a 3.91 gear back brace 35 spline axle spool disc brakes. the leaf springs are mono leaf with the spring rate from the chart. the front weight is 1750 and rear is 1520 with out driver. strange two way adjustables in back. i did the trick were you put a plastic ty strap around the shock to see how far it travels and it didn't even move. the car doesn't go up or down on launch. DAVE drag radials set at 15psi we went to 14-13 with know differents in 60 foots. the convertor is a neal chance 9" custom made for us. it hits around 4500 alittle tight but this is a nos combo that should run 9.0 on motor and 8.30-40ish with a 300-400hp kit.

Didn't mean to confuse ya Denny, old chassis guy stuff. After the car launches, the tires break loose... Could be many reasons for this... My first thought would be the chassis is for some reason unloading the tires,,,,,could be due to chassis flex, lack of movement on the rear at launch then when the front end settles down the tires get loose... Anyway, is this car on coilovers or leaf springs in the back????

Hmmm... Leaf spring rear....Could be the springs are wrapping up at launch, the car hooks good, then when you get out aways the springs unwrap and the rear of the car lifts, which will unhook the rear end.... Only way I've ever got leafs to work worth a poop is with a set of housing floaters and 30"-32" ladder bars.... and that was with a mono leaf....Are yours multi or mono leaf, and what bushings do you have in them??? I think Moroso used to see some Del-alum bushings for Nova's and Camaro's, they worked ok IF you added a grease zerk to the spring eyes to keep them from binding....

dave this is the same setup that i run in my car and it runs 8.30 and the 60fts are the hi 1.2s. my head starting to hurt lol. i tried to adjust the rear shocks all over the place. the rear would go up 2-3" in some setting and it would drop 2-3" with the shocks set up lighter on compression.

Originally Posted by DennyW

Didn't really confuse me, I didn't understand the term you used, I guess. That was one of the things we were talking about, shifting the weight, and keeping a load on while getting past his spin spot.

((i did the trick were you put a plastic ty strap around the shock to see how far it travels and it didn't even move. the car doesn't go up or down on launch.)) That tells me he's not transfering enough load weight to the rear. The power over powers the load ratio.

Yup, and the usual reason for no rear end travel is the suspension is bound up someplace, or the shocks on the rear are completely wrong.... Good weight transfer that "stays" well out past the 60' timers, preferably all the way till just prior to the upshift is essential for keeping the tires planted. The science of a leaf spring sez it won't do that without housing floaters and ladder bars....a multi-leaf spring IMO only compounds the problem, hard enough to keep a mono leaf car planted, let alone the results of all those leafs in a multi leaf fighting against each other....

dave we pulled the shocks off at the track and pushed down on the back of the car and it moves smooth no binding. that's what i thought first but it all moves very easy and smooth. the shocks are fine i put them on my car to see if that was the cause and my car went and ran the same 60ft it always does. the spring wrap up isn't very much i have one round of preload on the drivers side and a half in the pass side.

I'm thinking there should be some squat in the rear at launch But i don't know much about leaf spring set-ups.

Maybe too much rear spring?
shock settings wrong front or back?
Add weight in the trunk? (not a preferred method but might help)

Just throwing out idea.

Don't know much about cal-tracks either but can they be adjusted to affect I/C?