Information would be appreciated!!!'!!

[Bigt71g]

Hey guys, I'm definitely new to this, but I need as much help and knowledge as humanly possible. I've been trying to find out as much as I can on how to build my truck for autocross/road racing,but haven't had much luck, so here I am picking your brains. I understand the basics, since I've been a mechanic for over 20yrs. I get the basics and pretty much know what I want, but I'm having a helluva time finding the right parts, measurements, etc., etc..

Here's what I have. I have a 1995 C1500 standard cab,with a 4"/6" drop. I've been wondering if I should drop it more, also been trying to decide/find the best tubular a-arms for it. Have also been trying to figure out what's the widest rims I can run up front. I plan on running a 4 link rear, inside of the frame in order to run 18x12s. Still debating about running my 400 small block or opting for an ls.

Any help/info/ideas would be much appreciated.

[dirty rick]

I would run a 3 link with an adjustable watts link. A three link articulates well and is very simple to adjust.
This will give you the ability to easily adjust the rear roll center and it will turn the same both directions.
Combine this with a good set of double adjustable coil overs and you are set.

Look at what the truck guys on Ultimate Street Cars are using and the CAM guys for ideas.

I already have an IRS for my autocross project but I am going to switch to the above 3 link setup.

[Bigt71g]

I would run a 3 link with an adjustable watts link. A three link articulates well and is very simple to adjust.
This will give you the ability to easily adjust the rear roll center and it will turn the same both directions.
Combine this with a good set of double adjustable coil overs and you are set.

Look at what the truck guys on Ultimate Street Cars are using and the CAM guys for ideas.

I already have an IRS for my autocross project but I am going to switch to the above 3 link setup.

I was actually thinking about running a 4 link with a watts linkage to hold the rear diff centered. I'll definitely look up Ultimate Street Cars for their setups. That should cover the rear, what about the front??? Which tubular a-arms should I use, should I lower the truck more, widest rims up front, coilovers???

[RobNoLimit]

start here. Make it handle thread on the www.67-72chevytrucks.com Make it handle ( 1 2 3 4 5 ... Last Page)
My $.02 - While a Watts is accurate, and theoretically holds a perfect center, it is complicated and difficult to package. Also, can be difficult to adjust. On the back of a truck, with a terrible weight differential between 'sprung' and 'un-sprung' weight, A low roll center is a must to make it stick. Getting a RC in the 6" to 9" range is much more do-able with a long low panhard bar. Keep us posted.

[dirty rick]

Thanks Rob, I had not looked at it from that angle before.
I may have to change my approach again and do a panhard at first to find out where my rear RC is going to want to be. then see if a watts link is feasible.

And thanks for the link, some really good stuff there.



I read recently an article about the relationship of the KPI to caster angles, what are your thoughts?

[RobNoLimit]

As a basic rule, for short track (Auto-X) and road race set ups, I start with the idea that, Caster = KPI + 1. or, for the new generation, Caster = SAI + 1. So, if you have a 9 degree spindle, then base caster = 10*. Easy enough, BUT, large caster numbers can create a 'jacking' effect, where the IFS geometry 'loads' the inside tire more, and in doing so, 'lifts' the inside corner of the car, creating more body roll (lean angle) than a lower caster set up would do. So, next, you would look to low KPI spindles, BUT, this may sacrifice the scrub radius, unless you use a very deep offset wheel (like a new 'Vette). So, to get the track width, you need longer A-Arms, BUT, just lengthening the arms will create a slower camber gain curve during compression travel........... and so on, and so on. It's all a trade off.
For your info, the Hellboy uses 7* KPI spindle. Usually, I run around 9* caster. The increase in caster allows for a little less static camber, I run appx -1 1/2*. BUT, custom steering arms have given us VERY good Acreman numbers, set appx 2" ahead of the rear axle CL, this is a huge plus in my thought process towards good handling, and is something that most aftermarket suspension companies have missed. - or, not wanted to commit to a custom spindle design.

[Bigt71g]

Wow!!!!! So many things that I didn't know. I plan on removing the rear spare tire and installing a fuel cell, which should help with the weight distribution. I definitely need to do a helleva lot more research.