How can I begin to unravel this^...... I sure hope we can address all of this without this thread turning into a worth-less flame-fest.... I'll give it a try...I know a few lucky people, myself included. Never plotted anything, no trick parts, no hop bars, lowered mounts, nothing but stock arms boxed and polyeurathane bushings, a single airbag in RR spring, CE/Summit 3 way shocks, and a OEM rear roll bar. Moroso Trick springs in front and worn out stock springs in the rear. My car was 3650 with me in it at the time and went 1.41 60' with my little 500hp 406 and a 150 shot.
Buddy of mine had a 72, 13:1 468, 200HP Big Shot plate, 3880lbs, full exhaust, etc, same suspension setup. 1.37 60', 9.66 @ 139mph.
All was 20+ years ago, and that was pretty common setup around here at the time. It wasn't perfect or pretty, but it got the job done. Ride height is a factor when it comes to making the stock location stuff work.
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I'd highly buying and reading Dave Morgans book, the Door Slammer Chassis. Lots of good information to be applied.
I will disagree with Billy's statement that pinion angle doesn't affect the hit, as would Dave Morgan and plenty of other racers. It is different for a leaf spring car vs a 4 link or ladder car.Door Slammers: The Chassis Book [Morgan, Dave] on Amazon.com. *FREE* shipping on qualifying offers. Door Slammers: The Chassis Bookwww.amazon.com
Billy, how fast has you car been with the 632 and chassis mods? What does the rest of your suspension setup look like? How does your suspension plot for IC? What does the front/rear percentage look like?
First, with all due respect sir, I'm sure you're a great engine builder, and I just want to say that I can appreciate that you're not chiming in here to sell people something, (just as I am not either) and that you just want to help out your fellow drag racers, (as I do). Let me say that there's no point in living in the past.....I mean...air bags you say???? That's why your car in the pic exhibited plenty of roll rotation. Airbags aren't as effective as using a rear anti-roll bar, (NOT an anti-sway bar like your pic shows, because the rear sway bars are much too thin to prevent roll rotation...AKA "body roll" during the launch). With air bags, in many cases in order to get the car to launch without roll rotation, the passenger side bag has to be pumped up enough to cause the car to sit in the staging lanes and on the starting line crooked and all hopped up higher on the passenger side.
Maybe that's all you had back then, but that is no longer the case today, so there's no point in doing that anymore. Especially when rear anti-roll bars are more effective, your car won't sit with the passenger side way up in the air, and even the bolt-in rear anti-roll bars are much more effective than air bags are, and can be had for $400 and all it takes is to drill four holes into the rear frame cross member of the car. Piece of cake. The whole install is easily accomplished within two hours even if it's being done without a lift in your driveway.
"ride height has a lot to do with making the stock suspension work" you say??? That's funny because I also mentioned ride height in post #41 in this thread, and I also explained in detail why that is the case, and exactly how lowering the car changes the instant center length. Did you know that? I guess you missed post #41 here. So perhaps if you read that, you might see that at least in some ways, your viewpoint and mine aren't as far apart as you originally thought.
Furthermore, by pre-loading the coil spring on one side of the car like that, (whether it's done with air bags or via other means)you can often cause a dangerous condition for cars that do long wheel stands, because the pre-loading of the springs differently from one side vs. the other can cause the whole car to pull to one side during the gear shifts. This becomes critical in the situation where the car wheel stands, and the driver needs to stay in the throttle and grab second gear to bring the front end down to earth in a controlled manner, instead of backing off the throttle which would cause lots of damage to the headers, trans pan, and oil pan. If the car pulls to one side during the 1-2 gear shift while the front tires are still off the ground, guess what??? The car can end up on it's door, or even go into a barrel roll down the track if the wheel stand was high enough during the gear shift. I've seen both of those things happen.
If the launch needs to be managed or controlled with the suspension, then it should be done with varied shock settings from one side of the car to the other using double adjustable shocks, instead of pre-loading the coil springs differently from the passenger side vs. the drivers side. Taking care of that with double adjustable shock settings instead, will never cause the car to pull to one side during the 1-2 gear shift, nor during any gear shift. This is important information not only from a technical viewpoint, but also for safety reasons. It sure isn't pretty when a door slammer drag car ends up on it's side.
Second, you say that leaf sprung cars are different than cars with 4 link rear suspension? That's funny because that's exactly the SAME thing that I said. Sounds like you're just looking for an argument. May I suggest that you re-read my post sir?
Third, so you "highly" recommend Dave Morgan's book, eh? Well so do I. So much so that I attended Dave Morgan's 8 hour seminar. And it helped me out so much that I attended it a second time two years later. It's actually amusing that on one hand you call into question and even attempt to debate with me on the points I've made, and then you turn around and "highly" recommend Dave Morgan's book, because it just so happens that most of the things I've shared here in this thread were things that I first learned from Dave Morgan. OOOOOPS!!!!!
In both Dave Morgan's seminar classes that I attended several years ago, one of the attendees who paid an extra $80 to the basic $80 fee, brought his drag car to the class, and Dave had it put on the lift for all of us to stand under and look at during one point of the seminar, and we all discussed with Dave what weak points there were on the car in question, and Dave shared with us and with the owner of the car what could be done for improvement. BTW, for a third $80 Dave also would go to the drag strip with you, and watch your car when it launched, so that he can give you more advice for your car.
In the second Dave Morgan seminar I attended, another racer brought his car, and Dave had it put on the lift and he showed us how to find the true center of gravity. I have had other street/strip cars besides my Chevelle. I'm just not one of the guys who list everything in my post signature. I don't want to turn this thread into a childish mine vs. yours contest. This is supposed to be for peoples' education, not a DI_ _ wagging contest. So I sure hope that we can avoid that, and I also hope that it's not the very thing that you're meaning to turn this whole thread into. I say that because I'm mindful of what Tom the moderator already warned us about in this thread when he made it into a sticky.
BTW, Dave showed us a whole lot more in his seminars than his book gets into. Here's just one very small example: Do you know a very simple method to gauge if any part of your chassis is flexing during a drag strip run down the 1320? Here's a hint: it can be done with a piece of dental floss. Another thing he shared with us at the class/seminar was various brands of drag shocks that he had cut in half to display the internal differences, and how the internals worked and how they would make differences at the track. One of the shocks he had was the AFCO "BNC" drag shock, (Big Nose compression) and we learned how it was different than the rest and what advantage it could offer to the drag racer.
Also lots of drag racers will talk about their best run(s) and what their cars turn. But then when you bring your car to meet them at the track, you often find that their ET's and short times that they previously claimed actually only happen about 2 to 4 times out of every ten runs. If you did things the hard way 20 years ago, and your car ran pretty good in half the runs you made, then I say BRAVO to you sir. But today there is no point in doing things the hard and primitive way. (like using air bags). Because some of those out-dated methods don't work as well. And they often don't result in consistency with a number of drag cars.
You touted Dave Morgan's book, (as do I) but here are two things you're overlooking:
#1. Dave Morgan's book has an entire chapter that stresses the importance of INSTANT CENTER LOCATION of drag cars, and he even displays a chart in that same book which displays various instant center lengths. So what good would any of that be if the reader/end-user doesn't find out where the IC length is on his own drag car and how to change it if/when it's waaaay too far off to be effective??? Sure he can just wing it and try bazillion different things and maybe get lucky after 200 or 300 runs down the 1320. But why go through that if the same can be done in 10, 20, or 30 runs??? I will ask you the same thing I ask the wrong-wheel-drive car drivers at the drag strip: why do it the hard way???
#2. The rear suspension software that I use to find instant center location was developed with the help of none other than DAVE MORGAN himself, and it mentions his name right in the program which can be seen by all of us who use this particular suspension software. OOOOPS!!!! And it also has Dave's recommendations included.