Quote:
Originally Posted by focusedontheprize
Very cool setup. Interested to see the finished product from just this work.
Question:
I am just started to get my toes into Chassis Engineering. In the future, I would like to put something underneath my '49 that is autocross worthy. I have miles to go (in the learning section) before I even do. However, when I see guys who run a more "complex" suspension setup, I see a large amount of them reusing the stock frame (boxing and bracing).
Is the frame really that structurally sound than just boxing and bracing it will allow you to run it hard?
Reason I ask, I never pictured these frames to be setup (dimensions and geometry) for running this as an autocross setup even with the bracing and boxing. Seems I was wrong, but I am wondering what I missed.
Thanks.
|
It's an interesting balance. A race car chassis is tuned through the suspension. That lessens the variability and helps consistent feedback. A street car has compliance in the chassis for comfort and cost. The older trucks are designed for ultimate compliance. Riveted frames are great for driving all over a farm pasture and not developing stress cracks. I wanted to use some of the frame for my build but realized early the original cross bracing and C-channel wasn't going to cut it. The size of the beam itself isn't bad (roughly 6X3" in some areas). So the issue becomes how its boxed and what system is used for torsional rigidity. I used a series of cross members and triangulated that all together. I also solid mounted the engine and cab. The cab has a rigid subfloor that helps stiffness. Now, this is never going to be as stiff and caged vehicle or anything that has a frame further away from the axis of torsion (like a good unibody or monocoque), but pretty good none the less.
The wheelbase is 116" I believe. This makes a terrible auto-X vehicle. Mixed with the width and vision perspective and you have a cone eater. I wanted to take my truck to a solo event for giggles but haven't got there yet. Any chassis can be tuned if you put the time and effort in. My opinion:
1. Ditch the front suspension
2. 4-link a rear end
3. Box the frame from the front coil mounts to the rear coilover mounts
4. Add extra bracing at transmission mount and 4-link mount
5. Get everything reasonably low (engine and suspension) to control polar moments. *don't exceed the suspension's optimal position because you'l get all types of bump induced crap*