Turning left, and right...

[BadgerTheFerret]

Who here not only does the straight line racing, but also takes their trucks to the autocross events and race tracks??

I have a 70 LWB, which isnt the "ideal" platform for turning corners, but oh well.

My plans are a 4/6 drop, and probably 18s all around. But I am open to suggestion.

Any pics or info will be greatly appreciated!

[LONGHAIR]

The front/rear weight ratio is the biggest killer. Anything you can do to shift weight toward the rear or lose it altogether will help. Huge sway bars will also help. That will stop body roll which in effect balances weight from side to side. You are probably going to need to up-grade the brakes too. Big wheels can add to the un-sprung weight, so keep them as light as possible. A heavy wheel/tire combination can have negative effects on steering and braking.

[BadgerTheFerret]

Originally Posted by LONGHAIR

The front/rear weight ratio is the biggest killer. Anything you can do to shift weight toward the rear or lose it altogether will help. Huge sway bars will also help. That will stop body roll which in effect balances weight from side to side. You are probably going to need to up-grade the brakes too. Big wheels can add to the un-sprung weight, so keep them as light as possible. A heavy wheel/tire combination can have negative effects on steering and braking.

Yeah, I plan on relocating the battery and fuel tank to the rear. I'll also run a roll pan and I was throwing around the idea of a rear mounted radiator. It would be tricky, but it can be done, and that would save/move quiet a bit of weight!

I'll also be running a serious 4 wheel disk setup, and big sway bars.

[SCOTI]

If your not keenly 'schooled' in suspension theory & the impacts of loading/un-loading & set-up of the suspension, a 'kit' from one source that's designed w/your goal in mind would help consideribly (ART's Street Challenge stuff or something similar). Then it's just a matter of tuning a system vs. a sum of various parts that may or may not want to work together.

Check out stock car products for all kinds of good stuff that can be adapted to these trucks if the kit approach is not for you. Another option (which also can shave some weight) is Porterbuilts C4 Dropmember. Better geometry & easy to adapt bigger brakes.

As mentioned weight control & distribution will yeild big benefits & the importance of sticky tires can't be stressed enough. No 'posing' if you're lookin' to run a decent number.

[Frizzle Fry]

Not the best videos (camera man didn't know how to use zoom and the audio gets out of sync)... Not the best driving either, but hey I didn't come in last

YouTube - ORPCA Autocross #1 05/18/07 - '69...

YouTube - ORPCA Autocross #1 05/18/07 - '69...

[BadgerTheFerret]

Originally Posted by SCOTI

If your not keenly 'schooled' in suspension theory & the impacts of loading/un-loading & set-up of the suspension, a 'kit' from one source that's designed w/your goal in mind would help consideribly (ART's Street Challenge stuff or something similar). Then it's just a matter of tuning a system vs. a sum of various parts that may or may not want to work together.

Check out stock car products for all kinds of good stuff that can be adapted to these trucks if the kit approach is not for you. Another option (which also can shave some weight) is Porterbuilts C4 Dropmember. Better geometry & easy to adapt bigger brakes.

As mentioned weight control & distribution will yeild big benefits & the importance of sticky tires can't be stressed enough. No 'posing' if you're lookin' to run a decent number.

I have a pretty healthy knowledge of suspension and the like. I modified the suspensions in my 88 T/A and 94 Z28 that I owned previously with pretty good results.

What I have seen so far is gmcpauls 4" disc brake conversion kit, cause I have the C/20, with 4 wheel drums, and that has to be fixed pronto!

I will have to check out the C4 dropmember you mentioned. Thanks!

Frizzle Fry - Awesome videos dude, that's exactly what I was talking about!! I already had inspiration, but those just reinforce it!

[SCOTI]

Any more info on what you currently have as well what the budget you're trying to accomplish the goal on? Knowing that will help us suggest the best options.

[SCOTI]

Mike.... Those video clips were cool. It's going to be a completely different beast next time it see the cones.

[BadgerTheFerret]

Originally Posted by SCOTI

Any more info on what you currently have as well what the budget you're trying to accomplish the goal on? Knowing that will help us suggest the best options.

It's a 1970 Chevy, C/20 long bed. I'm running a mild 350/TH350, 4.10 posi rear. I have a LS1/4L60E lined up, but I am also throwing around the idea of just building up the 350 for forced induction.

Well, it's going to be my daily driver at least for awhile, but having it down for awhile is no biggie either.

I'm in the Marine Corps and will be deploying here in about 4 months, so a nice chunk of the money I make from that will go towards the truck.

[66shortwide]

I'll be running C4 vette front and rear suspension, brake upgrades, and some serious roll bars on my 66. Hoping it handles and runs like all the videos that keep playing in my head. I'm all about the "pro-touring" theme.

[Tony@AirRideTech]

Frizzle.... thats cool brother!

[Frizzle Fry]

I had a 1.25" front bar and 4th gen camaro rear bar with poly ES bushings at that time. It was dropped about 4/5.5 and had KYB's all around. Front discs and 17" wheels. It was no G-Machine but it was a huge improvement over stock. Too darn long though...

[SCOTI]

Originally Posted by Frizzle Fry

Too darn long though...

Yep.... and that can't be changed. Or can it ?

[Frizzle Fry]

Originally Posted by SCOTI

Yep.... and that can't be changed. Or can it ?

Impossible...

On subject; a C4 or C5 (when it comes out) dropmember with IRS would be the ticket.

[oldspowered67C10]

Truthfully, the stock suspension parts can be made to work pretty well. As said before, mounting the engine/trans as low and far back in the frame as possible would help alot also. But you really need to do something about the frame though. The stock frame simply doesnt have nearly enough torsional rigidity to do anything seroius with. All the best suspension stuff in the world wont help much if the frame wont let it do its job properly.

[BadgerTheFerret]

Originally Posted by oldspowered67C10

Truthfully, the stock suspension parts can be made to work pretty well. As said before, mounting the engine/trans as low and far back in the frame as possible would help alot also. But you really need to do something about the frame though. The stock frame simply doesnt have nearly enough torsional rigidity to do anything seroius with. All the best suspension stuff in the world wont help much if the frame wont let it do its job properly.

True. I'm thinking a couple forms of frame bracing would be very necessary.

Is there any difference in the frame rigidity of a 1/2 ton and 3/4 ton?

[leftcoast66]

Originally Posted by BadgerTheFerret

True. I'm thinking a couple forms of frame bracing would be very necessary.

Is there any difference in the frame rigidity of a 1/2 ton and 3/4 ton?

If anything I'd think that the c20 would have a stiffer frame to deal w/ more weight being put on it.

[BadgerTheFerret]

Originally Posted by leftcoast66

If anything I'd think that the c20 would have a stiffer frame to deal w/ more weight being put on it.

Yeah, exactly. So, more weight, but the stiffness would pay off in the long run. I hope.

[SCOTI]

Originally Posted by BadgerTheFerret

Yeah, exactly. So, more weight, but the stiffness would pay off in the long run. I hope.

More weight works well toward high speed stability (Bonneville) but I don't think it would benefit the corner-carver. More rigidity/less mass would be the hot ticket so add more cross-members or torsional frame bracing to the lightest possible frame.

I'm doing C4 front end w/ShockWaves (dbl adjustable) up front. The rear will utilize either a modified version of the truck arm suspension w/a Watts link or a parrallel 4-bar (depending on space limitations). My goal is to bring the springs out as far as possible on the rear end within my wheel back-spacing limitations & add as many additional c.members as possible to increase torsional strength.

Alum a-arms, spindles, brake pieces, radiator, heads, water pump, & relocating the batt to under the bed will help off-set my weight gain up front (BBC/4l80e). But the BBC torque curve will help scoot the portly truck along nicely w/o having to be excessive (and still be old school w/those big ole valve covers).

[Frizzle Fry]

The 67-72 3/4 ton frames use the same rails as the 1/2 ton. They do have additional triagulated braces in front of the TA/carrier crossmember. Maybe more, but those for sure. Those won't add much for torsional rigidity.

An old-school trick is to weld the existing cross-members to the side-rails. That alone increases torsional rigidity over the factory rivets.

A step beond that is to box the rails and add one of these (pic courtesy of Progressive Automotive) :

[oldspowered67C10]

When I boxed mine I did a experiment to see what it would really do. I put the frame on jack stands under the lower control arm cross shafts in the front and under the shock crossmember in the rear.

Before the boxing when I put a jack under the right rear of the frame I was able to jack up the right rear over 10 inches before the frame came off the left rear jack stand and I ran out of travel on the jack before the right front of the frame came off the jack stand.

After the frame boxing, welding in the crossmembers and some other light bracing I was only able to jack up the right rear about 2 inches before the left rear came off the jack stand and around 4 inches before the right front came off. While not as good as a full cage, hopefully it will help somewhat. I also own a real sports car and I dont expect my truck to ever handle like it does but Im hoping it will be at least as good as new pickup(which really arent too bad considering).

[SCOTI]

Originally Posted by oldspowered67C10

After the frame boxing, welding in the crossmembers and some other light bracing I was only able to jack up the right rear about 2 inches before the left rear came off the jack stand and around 4 inches before the right front came off. While not as good as a full cage, hopefully it will help somewhat. I also own a real sports car and I dont expect my truck to ever handle like it does but Im hoping it will be at least as good as new pickup(which really arent too bad considering).

That's also a key thought to keep in mind.....

[BadgerTheFerret]

Originally Posted by SCOTI

That's also a key thought to keep in mind.....

Haha, true. I don't expect my truck to handle like a Lotus or something, but that's not gonna stop me.

[SCOTI]

Originally Posted by BadgerTheFerret

Haha, true. I don't expect my truck to handle like a Lotus or something, but that's not gonna stop me.

There's always the guy who swaps in Vette suspension parts into his truck & then complains that it doesn't handle like a Vette.

[BadgerTheFerret]

Originally Posted by SCOTI

There's always the guy who swaps in Vette suspension parts into his truck & then complains that it doesn't handle like a Vette.

Hmm, so, Lambo parts won't make it handle like a Lambo?