Weight behind rear axle

[matt s]

So as I am continue to work and redesign my rear tire carrier in my head I started to wonder about the effect on performance and handling from hanging all that weight behind the axle.

My current gate holds two 5gal cans and of course the 33'' tire and I have never noticed any issue.

In my planning I am considering upping the capacity to 4 cans, and I began to wonder if the extra 80 pounds (water in this case) was going to be an issue.

The gate will be built to handle the stress and that is not my concern, mostly wondering at what point there will be a noticeable impact on handling or other issues I should take into account.

Not that it matters much as this was really a general question, but this is for a 71 K5.

 

[bobcat charlie]

I've gone to a rear mounted winch bumper, M15000 winch, swing away tire carrier, and rack with 3 20L fuel cans specifically to get more weight to the rear. I try to shift as much of the weight as possible to the right rear to help traction. I don't see any downside to adding the weight to the rear, if you're going to add the weight anyway!

 

[AchillesBogart]

80 lbs shouldn't cause any noticeable problems, depending how far back it is. The problem with weight behind the rear axle is that it turns that axle into a fulcrum. If you move the weight far enough back you can lift the front end off the ground, 80 lbs would lift the front wheels off the ground, in this case 250 feet behind the rear wheel will lift the front off the ground (just basic lever calculation, no fancy variables) assuming a weight of 2000lbs on the front axle with a 10ft distance to the front of the rig. *Real world results will vary, use under adult supervision, preferably an adult that will let you try it; No refunds.

When you load up too much on the rear you can actually see the front wheels lift. If the back squats down and the front tires have no squat you are overloaded on the back and need to readjust. I learned to check that after 1 time, when your front wheels lose contact with the ground it is really scary.

 

[matt s]

80 lbs shouldn't cause any noticeable problems, depending how far back it is. The problem with weight behind the rear axle is that it turns that axle into a fulcrum. If you move the weight far enough back you can lift the front end off the ground, 80 lbs would lift the front wheels off the ground, in this case 250 feet behind the rear wheel will lift the front off the ground (just basic lever calculation, no fancy variables) assuming a weight of 2000lbs on the front axle with a 10ft distance to the front of the rig. *Real world results will vary, use under adult supervision, preferably an adult that will let you try it; No refunds.

When you load up too much on the rear you can actually see the front wheels lift. If the back squats down and the front tires have no squat you are overloaded on the back and need to readjust. I learned to check that after 1 time, when your front wheels lose contact with the ground it is really scary.

Yeah, its likely not a worry and I have driven trucks with the front wheels dangling, not fun.

The 80lbs is additional to what is already there, but still probably not likely to matter much. Your quick fulcrum calculations are pretty good! I think I am pretty safely within specs! Ha ha.

I just don't want to go off on a wild building spree only to find that the 80lbs mattered.

 

[ntsqd]

The added rear weight when at speed will increase the truck's tendency to want to go straight rather than turn. Noticeable? Probably. Worrisome? Probably not. It's not what you want in a sports car or race car, but since a K5 isn't exactly one of those.......

 

[bluejeep]

if you were into serious rock crawling and hill climbing it would make a difference and you would want to move as much weight into between the axles and low as possible. But that's rock crawling, not 'expedition'ing

:smiley_drive: