72 Lwb

[Outlaw72]

Hey Guys....

Jerry here....

1972 Cheyenne "Orange and White"
468 BBC
150 shot of dope
1 piece driveshaft
Rear disk brakes
4.11 w/ Auburn
TH350 w/3,000 stall
Tubular upper control arms
Chisolm drop
Centerline Telstars with 315/60 ET Streets out back
77 Corvette master cylinder

much more smaller items

The best I have run so far is 7.3X in the 1/8th. The last time out I broke the rearend on a REALLY bad wheelhop for what felt like a high 6 launch....anyway I am looking at shock relocators and some better trailing arms and shocks. Gotta get rid of that wheel hop. Hope you like..

[Outlaw72]

I need you guys to tell me how to make this turd hook at the track. Wanting to run some 6.50's on the hose. I'm getting ready to cut the rear wells out of it so I can stuff a bigger tire in there without narrowing the rear. I have some 200-250 shot pills that are screaming "Put me in!!!"

Right now it has chisolm lowering shocks all the way around and the shock mounts are stock. Stock trailing arms and chisolm lowerinf springs. I'm getting ready to dump some cash into a stronger rear and do not want to break it again due to wheel hop...

[djracer]

I have never heard of having wheel hop with trailing arms. It can be horrible with leaf springs.

I would do coilover shocks behind the rear axle and loose the stock shocks and springs. You may have to modify the bed floor to keep it that low in the rear.

One other thing you might try is a different spring in the front to help with weight transfer. You need something with more stored energy and a 90/10 front shock.

By the way I love the truck!

[bigjimzlll]

You probably had wheel hop DO to the broke rear end.
For hookin up...if it was easy everyone would be doing it..lol. Move as much weight to the rear. Battery, fuel cell. Lighten the front as much as possible. You say you have a 3000 stall, what does it stall to on the N20? Sometimes hitting the tires harder will help it hook. When I ran N20 I hooked better coming out of the hole with it. It would raise the stall to 6000 rpm instead of 5000.

IMO 3000 stall isn't much. The key to a stall converter is to keep it in the stall range(at peak torque) as long as possible. When the converter is on the "stall" it is multipling torque.
With my truck the stall is 6300 rpm and I shift at 7200 rpm. You can barely hear the 1-2 shift happen.
Track prep also has a lot to do with traction.

[Outlaw72]

djracer - Nice to see a truck in the 5's.....lets me feel warm and fuzzy that it can be done! Do you have any links to the suspension parts you speak of? Is there a kit that will allow me to mate coil overs to the rear of the truck? That would be ideal! I know the 90/10 - Trick Spring kit for the front but I cannot find anything that works. If you don't mind, can you point a fellow racer in the right direction.


bigjim - Everything happened so fast....I'm not sure what happened first. The rear or the hop.....On the pass prior to mine, some guy lost a rod on the track and oiled down the whole lane. 45 minutes and tons of fresh prep later...this happened. It has wheel hopped before in prep but it was minor and didn't really concern me at the time. I have just about everything to the rear I can get there....Battery, fuel cell, Bottle and Nitrous fuel cell, are all in the bed. I'm happy with the way the 3,000 stall performs but the hop happened when I hit it with 1,000 psi bottle pressure. The week prior to that the nitrous tune was a little different and so was the track prep. I was actually spinning ever so slightly out of the hole and things were good.

Thanks for your comments...

[Super73]

Outlaw,

Do you know the weight of your truck and individual axle weights?

Reason for asking is I'm running a 350lb 14" Hal spring in the front of mine. I had classic performance lowering springs in it before. Only 2 changes were moving the batterey to the rear and the spring change and my 60's on the street went from 2.3x to 2.0x.. I was using my G-tech Pro RR. I feel ok using these times because when I had it with me at the track, the 60's were dead on and the ET read .1 slower than what I went and 1mp slower than what I really went on every pass.

As far as hitting the tires harder, this is the very reason I am making and adjustable front mount for the rear LCA. This will change your instant center of gravity. With my truck, I have figured it to have 80% antisquat. 100% A/S means the rear of the truck will not squat, nor seperate under load. Anything bellow 100% will squat and anything above 100% will seperate.

As the rear seperates, it lifts the rear of the vehicle forcing the rear end itself down and planting the tires. But this can come at a disadvantage. If your front does not raise fast enough (IE spring / shock combo are off) that lifting of the rear will push the front end further down unloading the rear tires just the same.

In order to figure out A/S, you must first know where center of gravity is. You have to have a scale that will let you weight the truck a couple times. Remove your front shocks and put a steel rod in place of it so the spring can't compress. put the front end on and jack the rear up 10". You need the weights of both the truck on the ground and in the air. Then you need the weight of the whole truck. From there there is website I'd be happy to send you that you can input that data and get your A/S numbers.

[Outlaw72]

Thanks for the write up Super73!! I am not sure what it weighs but I will put it on 4 corner scales and a single scale to get those numbers. It still weighs quite a bit.

The lower control arm mounts you speak of......will that allow you to also manipulate the pinion angle?

I can remember in the past doing burnouts in the street and the truck would buck like a bronco.......I'm sure the 345/55 tires I had on it at the time didn't help that but now it does not buck like that with ET Street Radials. I can probably help things further if I disconnect that 1 ton front sway bar that is also in there. Looks like I need to start in the front and work on getting that to rise some on launch and go from there.

[Super73]

No problem..

Yes raising the front mount will affect pinion angle. From what I have figured on my shortbed, every 1" of movement upward changed the pinion angle up 1.1* So by raising the front mounting point, you would need to most likely readjust pinion angle the oposite direct.

[Outlaw72]

Some more pictures

[Outlaw72]

[Outlaw72]

Don't let anyone tell you the et street radials do not hook. It is starting to be argued that they hook better than than regular et streets..

[bigjimzlll]

The only problem with the radials seems to be if you lose traction they don't recover as fast (or at all) like the ET streets will.
Some of them 10.5 cars are going into the 6's with them......

[Outlaw72]

Here we have a competition called the texas true 10.5 ....

In the true street class, you were/are required to run the 28 11.50 ET Street tire only.....I have heard rumors that the tire will change to the radial ET street for this year. The truck did fairly well with them ..even on the street. I need a new set....and these are the 315's (30 inches tall) I want to try the 325's whcih are 28's and see if they work any better or worse.

[Super73]

I ordered the 315/60/15 MT Radial the other day. My current BFG 275/50/15 just don't work on the street. But they are wore out regardless. I'm hoping the new tire will help on the street and hook the bottle well at the track.

[Super73]

BTW, it looks like you have at least 100% antisquat.






See how the seperation is about the same. You can tell you are leaving as there is a wrinkle in the tire and your front end is moving.. You are transfering weight to the rear.

How much upward travel do you have in the front from ride height to where you start to take weight off the front tires? The more you have, the more weight transfer you are going to have.

Also, I know it might be hard to get the rear lower, but, if it were level with the front, under launch, you would end up with more weight on the rear tires. I see you have lowering springs in the rear, I'm assuming you do not have blocks there as well?

[Outlaw72]

That is one of the reasons for me trying the 325 ET Radials. They are 28" tall vs. the 315's that are 30" .... to lower the rear a bit.

I have some video of the truck launching on the bottle.....I will see if I can post it.

The front end doesn't come up much at all....

[Outlaw72]

Here...watch all three races.

Track Videos " title="Track Videos" target="_blank">Track Videos

[Super73]

The last one of the three gave me a little better angle / view.. If you can get the camera man up closer, not using the zoom as it make is more bouncy that would be great. That angle though is perfect..

What are you cutting for 60's?

Couple things I notice.

The front is coming up before the truck moves.. You want this as it's putting the weight on to the rear tires. But, you are right, it's not coming up real high. It seems like you either don't have enough stored energy do to the springs being too short, or you upward travel is maxed out. This could cause the front end to come back down and unload the rear tire.

Measure the height of the front fender lip at ride height. Then jack it up by the cross member and see how high it goes before taking the weight off the front tire.. Let us know what you come up with.

Also, do you still have the upper bump stop in place (tucks under the upper control arm). If so take it out.. Re-messure.

Disconnect the front shock. Re-messure.

The 2 large nuts on the upper control arm ends, back those off a touch and re-messure.




How close are you to the lower bump stop?

[Outlaw72]

Originally Posted by Super73

The last one of the three gave me a little better angle / view.. If you can get the camera man up closer, not using the zoom as it make is more bouncy that would be great. That angle though is perfect..

What are you cutting for 60's?

Couple things I notice.

The front is coming up before the truck moves.. You want this as it's putting the weight on to the rear tires. But, you are right, it's not coming up real high. It seems like you either don't have enough stored energy do to the springs being too short, or you upward travel is maxed out. This could cause the front end to come back down and unload the rear tire.

Measure the height of the front fender lip at ride height. Then jack it up by the cross member and see how high it goes before taking the weight off the front tire.. Let us know what you come up with.

Also, do you still have the upper bump stop in place (tucks under the upper control arm). If so take it out.. Re-messure.

Disconnect the front shock. Re-messure.

The 2 large nuts on the upper control arm ends, back those off a touch and re-messure.




How close are you to the lower bump stop?

That day it was cutting 1.63 60ft. and that is a best to date. If you listen close, you can tell it was spinning slightly. N/A it will cut a 1.7X ..... I got a 1.69 out of it one night on the motor. I'm having a hard time deciding on a 4.10 or a 4.56 gear since I just blew the rear up. I really liked the way it performed with the 4.10 and fear the 4.56 is too much.

It still has the factory bump stops I will take them out although one of them is worn to a nub. It also has a 1 ton sway bar on the front and chisolm lowering shocks. Tubular uppers are also in the front.

I will get some measurements on the front end as you mentiond when I get the rear back in it and sitting back on the ground. When I broke the rear end....the 60 would have been close to a 1.55 because it stuck hard and then had an extremely bad wheelhop. The videos you see above was on a conservative tune and only about 750-800 psi bottle pressure. When I broke the rear....I left on 1050 psi.

[Super73]

Next time out, take some whit shoe polish and draw a line on the rear tire being filmed. That will let us know where the tire is spining. What I mean by that is, is it spining right when you hit it or 5 feet out. They are 2 different problems.

[Outlaw72]

Originally Posted by Super73

Next time out, take some whit shoe polish and draw a line on the rear tire being filmed. That will let us know where the tire is spining. What I mean by that is, is it spining right when you hit it or 5 feet out. They are 2 different problems.

Without a doubt.....right when you hit it.

[hotrod 80]

i run a 150 kit and i run the bottle at 920-930 psi and go through the traps at about 900-890 psi. It's hard to make a truck hook with a street tire . There is a difference between a true slick and a et street . Track prep is also critical . The big track here in Houston only really preps for the nationals . The small one preps everytime like it's the nationals . I have 1.49 ed at the small track and on the same night , due to rain , blowed the tires off at the big track with no changes . Oh , this is in my luv , same transfer problems just on a smaller scale .

[Outlaw72]

Look what I found

http://www.bowtiebits.com/store/stor...ategory_ID=111

[57sailplane]

thats a nice kit but it puts the springs on the outside of the frame wer you may have issues when running a wide tire.

[Outlaw72]

Well...we can cross that one out...I found out that kit has been discontinued and is nowhere to be found anyway. I'm having a hard time determining the best way to get coil overs back there.