[Tydriver]

Originally Posted by preston

Go the suspension and chassis sub-forum and read every sticky post at the top by Ron Sutton.

I think this is very good advice, I will do this ASAP. I also placed a call to Speedway Engineering this afternoon and I am awaiting a return call from their tech guru. I am hopeful that they have some sort of calculator similar to a coil spring rate calculator, we'll see what they say..

Originally Posted by preston

Quick synopsis on sway bars - All sway bars are just a metal spring. Mass produced pre-bent swaybars are notoriously difficult to model ie determine their exact roll rate, so its experimentation or crap shoot or follow someone else's lead. The splined bars are easier to model and the manufacturers provide rate charts for various diameters and widths with the catch that each manufacturer has their own method of rating them. Speedway Mfg is the most prominent manufacturer of the splined swaybar so you can easily stick with them. Determine what width of bar will work including a 0-5" bend in the arms themselves (arm lenght also affects rate).

I agree, Speedway Engineering appears to be a pretty cool company from their website. I also see that there is a bunch of stuff on eBay too so there may be some more 'economical' choices available depending on my needs.

Originally Posted by preston

Now you have no idea what rate you want, but if you are going from nothign to something, you probably don't want to go to far, especially since more rear roll resistance can lead to too much oversteer. My ballpark recommendation is to determine as I mentioned above the width and attachment points that will work, then go to the speedway site and see what is available. I would recommend starting with a 1" diameter hollow bar and fairly thin wall. Thinner wall means less roll resistance. Try it for awhile, and then maybe experiment with something thicker (easy to swap in and out).

You are spot on about this, I have no idea what to order.. I am totally shooting in the dark here. That's why I am seeking advice !

I do have a couple of clarifications to offer however.. I do currently have a stock swaybar on the front, it measures 1 1/8th in diameter.

The rear of the GMT 800 Silverado trucks ('99-07) didn't have a swaybar from the factory on the 4x4 models (my truck). I am unsure yet if I will need/want one in the rear just yet.. I've upgraded other trucks and added swaybars to trucks that didnt have a rear bar with remarkable results. I will say, it was one of the best mods I did on my GMC Typhoon back in the day, but I never drove that truck competitively like I am this truck.

Originally Posted by preston

You can also drill multiple holes in the arms, and by shortening the arms (by moving to the shorter holes) you can get a sense of what a thicker wall roll bar will do and give yourself some finer adjustment. IOW build something, buy a fairly thin wall bar and start in the longest holes, adjust to the closer holes to see if it performs better. If it does, you might want to try moving up the wall thickness.

This is interesting, I hadn't considered wall thickness as a tuning tool, but that totally makes sense. I think I have 4 options for tuning at this point. 1) Wall Thickness of the bar. 2) Arm Length (not really an option as I have other suspension components to clear, cant get too crazy here). 3) Swaybar Diameter. 4) Hole Location in the Arm

Originally Posted by preston

For a rear swaybar I cannot imagine you would want to use anything larger in diameter than 1", but who knows I've never tuned a heavy AWD truck.

Yeah the AWD changes a lot of things vs. a conventional RWD setup. As a test I've done this a few times: I've run the same course, on the same day, only minutes apart in RWD; then again in AWD. It is amazing how much more stable the truck is exiting AND entering the corner. It's much more composed in AWD..

Interesting, the pre-bent aftermarket bars are 1 1/2" of 1 5/8" in diameter (I can't remember which).. The stock bar is just over an inch, but I believe it to be a hollow bar so I know the spring rate is pretty weak in comparison to the aftermarket bars or the splined bar option. I'll read up on the suggestion you made and hopefully between that and the call back tomorrow, hopefully I am more informed to make a decent purchase.

Originally Posted by YAMATHUMP

Very cool project, I have an 83c10 that I am starting on so it is cool to see someone else make a truck handle.

Thanks man, it's fun to play with my toy project again.. I need a tire sponsor though.. This pig can eat some rubber !! Another autocross this Sunday !!