getting a leafspring car to hook?????

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dragrace5372 · #1 Post by **dragrace5372** » Mon Aug 29, 2005 9:50 am

looking for suggestions on getting a leaf spring car to hook consistently and go straight. car is a '72 Nova, BBC, dynoed at 800hp/674 ft. lbs., weighs 3440# (LF-886, RF-974, LR-880, RR-701) front suspension has min. 4-6 in. travel, 90/10 koni's front, rr shock aren't topping out, has multi-leaf springs, 29.5x10.5 tire, 4.56 gear, th400, 4500 stall, leaving (attempting) at 3000 rpm on 4 wheel line lock, installed caltrac bars, running in bottom hole with 1/4 turn pre-load on RH and 1 turn on LH. to get it to go fairly straight, ANY help would be greatly appreciated (for me and the tracks safety crew) Thanks!!!!!

#2 Post by **John_Heard** » Mon Aug 29, 2005 1:15 pm

Just some suggustions...

1. Taller rear gear will calm it down some, perhaps a 3.73, 3.90, 4.11. A 4.56 w/TH400 1st gear is a pretty deep starting line ratio.

2. Video tape your launches, they will be very helpful to see what is going on, hopefully in slow motion to help diagnose what exactly the car is doing at launch.

3. New tires... many times the tires are just shot, if these have some age or a lot of passes on them consider trying some new ones.

HTH,

John

jjrambo · #3 Post by **jjrambo** » Mon Aug 29, 2005 10:21 pm

get some of those single sided, leaf spring attachments, they attche to the front side of the leafs, and they restrict the the twisting action that you get with good tires.

i wish i could remember what the heck there called.

#4 Post by **John_Heard** » Tue Aug 30, 2005 9:06 am

dragrace5372 - Here's the kind of video you need to help tell what is going on...

632 Camaro Launch http://www.dragstuff.com/images/slowlaunch.wmv 1.6Mb Download

This video was slowed down with the free Microsoft "Windows Movie Maker" program. You can basically do the same thing with most home VCR's

Craig W. · #5 Post by **Craig W.** » Wed Aug 31, 2005 5:13 pm

What's your pinion angle? How about the rear shocks?

Like John said, the tires may be shot, even though they have plenty of dimple left. My car will hook better right now on 26x8.5s than my 29x9s. The 29s are just getting old and the sidewalls are starting to break down I believe.

dragrace5372 · #6 Post by **dragrace5372** » Thu Sep 01, 2005 2:21 pm

i am possibly thinking i might have more than one variable causing my problem. does anyone have a '68-'74 Nova that they have scaled on all 4 corners and not just front to back? just got car back 2 weeks ago from chassis shop to have suspension work done and while there had them verify rear axle is centered in car along with having it scaled and pinion angle set--which is at -3 degrees. the scaled weights to me seem way out of whack--the car has basically stock front suspension, has had a/c & heater and all unneccesary under dash removed, has lightweight bucket seats, no backseat, battery in trunk along with 8 gal. fuel cell and RF corner is 974# while LF is 879#. i have not added any ballast yet, but i can't see where all this weight is in the RF while the LR is 886# and the RR is only 701#. (all of the weights listed are w/driver) i've watched video a friend has of car and in slow motion on most runs it will lift the front tires and generally looks like it unloads the rear suspension and the front goes right down at the same time and the skating begins. i am going to try new slicks (was said to try radial design possibly) and leafsprings (Caltrac mono split-leaf) but i still would like to see some other weights from Novas too--how do you take out that much and where from the RF? sorry this is so long and Thanks for input!!!!!

Craig W. · #7 Post by **Craig W.** » Thu Sep 01, 2005 7:04 pm

Sounds like the front end is lifting too quickly. Try slowing down your front shocks by a 1/4 turn. That really helped mine (I have Koni SPA-1 shocks).

I haven't four cornered my car. Its got 52/48% front to rear at 3200 lbs with 70 lbs in the trunk. I suspect mine is a tad more equal side to side than yours since you have to add more preload to the passenger side than I do. I run a 1/2 turn more on the right. Best 60' times so far are 1.35 on 26x8.5" M/T slicks.

#8 Post by **John_Heard** » Thu Sep 01, 2005 7:38 pm

I've got a set of scales and have weighed mine once and it was much closer than that with driver, within 20-30lbs right to left. I can't say those are accurate weights because there were a few parts missing and tools laying on the car, etc. throwing it off a little so that's a ballpark on mine.

It sounds to me like something is bound up on your car, or there is a weak spring somewhere throwing that weight off. I'm not sure if you have access to the scales again. But consider putting jack stands under the frame of the car on the rear and remeasuring the front, then do that same at the front and remeasure the rear. Maybe you might see which end of the car is adding the cross weight. I would guess either something is bound up on the RF or LR corner, or maybe a spring stiffer on one of those corners perhaps. Or just the opposite, the LF or RR corner has a bad spring not holding up the weight it should. Seems like 100 lbs left to right is more than I would expect.

jones_performance · #9 Post by **jones_performance** » Mon Sep 19, 2005 8:47 pm

one word TRANSBRAKE!

we run a 3/16 gap in the caltracs and the top of the spring where it hits, adjusted with driver in car. works every time best 60 so far with a 560hp small blcok is a 1.32. t400 with a 5800 stall depending on track conditions we usually leave off the mat, if its slick we chip it down with the 2 step.

kevin · #10 Post by **kevin** » Tue Sep 20, 2005 2:59 pm

thanks for all the info.--just installed stock height Cal-Trac split mono leafs and new slicks yesterday and will find out this weekend how much better it works. i am pretty sure we found a few of the concerns i was having!!!!! we took the RH multi-leaf spring off and compared it to the Calvert spring and you can surely see a difference in the arch and when we started to take nuts loose on the LH side lower plate it was trying to push rearward as we were taking it apart as if the spring was bound. when we matched the old springs together, the arch was all together different between the two and the centering pins looked different too making it look like they were two totally different manufactures and spring rates all together. and it was also tight in the RH front perch which was causing a bind there also! so now the rear shackles actually are slightly tipped rearward instead of frontward when sitting which seems to mean the old springs were somewhat short on the rear half of the spring. whoever had this put together intitially had it pretty much all wrong, so i hope this will take care of alot of my rear suspension problem-the car sits pretty much level front to back (alot lower in the rear than it was) and should transfer weight alittle better with the rear down-but i would still like to get it re-scaled now to see if that takes care of some of the weird weight #'s i was having (with rear springs binding the way they were and being arched uneven and the one front perch binding) Thanks for the help!!!!!!!!!

#11 Post by **John_Heard** » Tue Sep 20, 2005 3:57 pm

Glad you found what it was Kevin, sure sounds like you made some improvements with the new springs.

getting a leafspring car to hook?????

getting a leafspring car to hook?????

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