frame shortening ????

[Menace]

So I'm in the driveway working on my cab and a neighbor came up and we started BS'ing. I told him my plans for moving my springs and differential forward and hacking off the excess frame. The frame is an 83 F150, drivetrain is a 460, C6 and Dana 60. He says that by cutting it down, I'm changing the center of gravity and with the torque I'll probably have bad wheel hop and never get any traction. I never considered that aspect of it. What do you guys think ?

 

[roddguy1]

Have you noticed all the custom made frames guys have built on this sight with all sorts of different weight bias. Stretched front ends, shortened rear ends, lowered to excess. You won't be having any adverse problems as long as you are carefull to keep things straight and properly aligned. BTW center of gravity is more a funtion of where the balance point of the vehicle is on a horizontal plain. ( roll center ) Meaning if you raise your frame, you raise your center of gravity and vise versa. Also the more wieght above the frame means a higher center of gravity. Notice that all those monster trucks position thier engines as close to the center of the truck and as low as posible in the chassie. There looking for the best posible center of gravity. Shortening your frame will have no adverse effect unless your trying to acheive a 50/50 balance front to back like the monster trucks. Think about it. If your bringing your rear closer to the front your actually helping to increase the weight bias to the rear. Which will help reduce wheel hop. However in a front engine vehicle your wieght bias will still be to the front. Remember all the funny cars of the 60's with the rear axels moved forward for better weight transfer which equaled better grip. There is obviously more to it than that as the suspensions where also designed to most effectively have the car rotate it's weight to the rear from a imagined center point, but I dont think your plan is to go racing anyway. Your friend may want to update his engineering degree.

If I may offer one suggestion though. Rather than go to the trouble of moving all the mounting points for the rear end and suspension forward why dont you just splice out the desired amount frame in the center and bring the rear section forward. To my mind that would be a lot less work and your not messing around with what the factory already did for you. Just a thought.

 

[Tripper]

So I'm in the driveway working on my cab and a neighbor came up and we started BS'ing. I told him my plans for moving my springs and differential forward and hacking off the excess frame. The frame is an 83 F150, drivetrain is a 460, C6 and Dana 60. He says that by cutting it down, I'm changing the center of gravity and with the torque I'll probably have bad wheel hop and never get any traction. I never considered that aspect of it. What do you guys think ?

I doubt havin' a shorter wheel base is gonna affect u're traction. If it's gonna break the tires loose... it's gonna break 'um loose either way.

If I may offer one suggestion though. Rather than go to the trouble of moving all the mounting points for the rear end and suspension forward why dont you just splice out the desired amount frame in the center and bring the rear section forward. To my mind that would be a lot less work and your not messing around with what the factory already did for you. Just a thought.

I agree... most people cut a section of the frame out right behind the cab to keep the rear suspension intact. There have been several articles in the truck mags showing how to do this. They typically go from long bed to short bed. Just saw this about 6 months ago in "Classic Trucks" I think.

BoB

 

[Sam_Fear]

Yep, you'll actually have more weight on the rear end initially. The wheel hop you might have is on the front end! The shorter your wheelbase, the easier to lift the front end. The way I see it, until you reach the point where you start to lose steering control at WOT, shorter is better.

 

[Menace]

Don't get me wrong guys, I've read build after build and haven't heard anyone talk of those issues. Just wanted to check out other's opinions. After all, the only stupid question is the one that's not asked. The frame I'm using is a extended cab short bed. After looking at it, I think along with Z-ing the frame I can move the rear spring supports forward to achieve the stance and proportion I'm looking for. I really only want enough room in the bed area for a keg fuel tank,battery and the radiator. So I'm thinking about a 3' bed. The F150's spring supports are on the outside of the frame. And hardly any kick-up compared to the S-10. So moving them forward along with z-ing should create the look I want. I just didn't want to create something undrivable. As far as lifting the front end, that's cool if it happens. Gotta have more than loud exhaust to **** my neighbors off !!! Wheelies down the street oughta do it.

 

[Dvapteam]

No degree here!

Menace. I'm doing just about the same thing...close at least. This is my first build and lets just say I have made a lot of mistakes but I just took it for its first test drive and no hop! Rodguy here is a good guy to take advice. I have been stuck on so many things and all his tips work out better then any one else....I think you'll be cool!