[dave_letu]

I would like to get rid of the leaf spring suspension under my '67 firebird. The options I'm considering are: three-link, triangulated four-link, and truck-arm. I'd love to here your thoughts on which set-up would best fit the car. I drive the 435-hp car on a daily basis and like to take it to the strip every now and then as well as the occasional SCCA autocross event. The goal is to build something that will hook at the strip and hold me through the twisties all without breaking my back during everyday driving. Any thoughts?

Dave


oh ya....BillyShope, i think you might be able to help me out with this one. But you might just try to persuade into buying a jaguar instead...

[Deuce]

I believe the limiting factor to be the unit body construction of the car ... with a sub frame in the front. Without a full frame ... major changes cannot be done ... IMHO ...

[signbuilder]

Hot rod, or Car craft had an article in the last few months on a 67-68 camaro that some guys had put truck arms under. I believe they were "drifting" with it, but truck arms can be useful otherwise. I'll try to find the exact magazine to find out. It had pictures of the setup also. Not sure if if was back halved, or had subframe installed or what.

phil

[signbuilder]

It is a 69, in Hot Rod Feb '06. It looks like they did not add a rear subframe. The truck arms connect to a lateral crossmember just about exactly under the transmission yoke. I can't tell if/what they used to locate the panhard bar on the chassis side. In closer looks, the car has a roll-cage, but I still don't see any frame rails in the under car shots. Hope this helps.

Phill

[dave_letu]

yeah, the company who's truck-arm kit was used is www.hotrodstohell.net I see that they've had success with this type of suspension especially with drifting but how does it measure up when taken to the strip or road coarse? Does it help with anti-squat or equal tire loading during launch?

I'm not too worried about adding to the rear framing, but like mentioned earlier, i might not have enough room to put in a 4-link with the desired geometry. any ideas??

[Kim57]

I believe they use the truck-arm in NASCAR.
Kim

[solidaxel]

Do a search on a Cal-trac system for leaf springs.

[BillyShope]

Either the 3link or the triangulated 4link can be used effectively. Treat the triangulated 4link as if it were a 2005 Mustang 3link and use the appropriate modification at my blog:

http://home.earthlink.net/~whshope

[timothale]

I had a 31 chrysler roadster with the truck style arms. great for drag racing but squirlly on the street or on corners

[dave_letu]

Either the 3link or the triangulated 4link can be used effectively. Treat the triangulated 4link as if it were a 2005 Mustang 3link and use the appropriate modification at my blog:

BillyShope

Your program for the 2005 mustang three-link calculates for torque cancellation and zero-squat/rise. I'm was under the impressoin that a little bit of rise (anti-squat) is a good thing when it comes to drag-racing and exiting a corner. Anti-squat = more force on tires touching ground for more traction...??

Dave

[BillyShope]

Dave, it's true that, as the rear of the car is accelerating upward, the rear tire loads are increased. Unfortunately, that period lasts for only a short time and then the rear of the car is DEcelerated as it approaches its uppermost point, taking load off the rear tires. So, as the car bounces up and down, you have an oscillating load condition, which is anything but desirable.

[Triaged]

Have you thought about the Torque arm suspension from 3rd & 4th gen F-bodies?

So Bill...where would you need to put the torque arm for 100% anti-squat and equal loading

[BillyShope]

I wouldn't bother with the torque arm. Assuming the car squats in its stock configuration, the front mounting points for the lower arms would have to be raised until the instant center falls on the no squat/no rise line. (See page 657 of RCVD.)

Then to achieve equal rear tire loading, the rear mounting point of the right lower link would be lowered and the rear mounting point of the left lower link would be raised.

[dave_letu]

so, zero-squat or rise is the winner....

Triaged- The more I think about space issues the more I start thinking about torque-arms. I can't tell if it would be less complicated than a triang-4link to build since it needs a panhard bar or watt's linkage, but that's why i'm asking questions!

dave

[dave_letu]

BillyShope- You said to treat a triang-4link as a 3link in your blog program. Through user-provided dimensions it can calculate at what angle the upper link is mounted. However, with the upper link being vertically AND laterally angled, it seems the program would need another measurement to accurately calculate the vertical angle of the odd link. Without the correct angle, the instant center, and therefore amount of squat, cannot be accurately calculated. I'm hoping I missed something with your program, but...??

On a similar note, how does the additional link not affect the torque cancellation calculation? Won't the extra link, even though it's on the left side, still have some affect on torque cancellation? (If not that's great...but I guess I just want to learn how you derived your torque equations)