Setting/Pushing your engine back

[BajaBronco13]

Has anyone pushed their engine back (a few inches) to balance out the weight of your vehicle? Not sure if this is class 3 legal. Not sure if I would even attempt it on my vehicle but I'm curious if it's worth the hassle and what kind of benefits were gained by it?

CP

[Blanco]

Has anyone pushed their engine back (a few inches) to balance out the weight of your vehicle? Not sure if this is class 3 legal. Not sure if I would even attempt it on my vehicle but I'm curious if it's worth the hassle and what kind of benefits were gained by it?

Engine must be located in the stock mounting location as delivered from the manufactuerer +/- 1 inch.
This will be measured from the centerline of the front spindle to the back of the block. engine height must remain stock +/- 1 inch as measured at the centerline of the crank.

So I dont see much movement allowed within Class specs. http://thewebwheeler.com/forums/images/smilies/shrug.gif

[RelentlessPursuitRacing]

Has anyone pushed their engine back (a few inches) to balance out the weight of your vehicle? Not sure if this is class 3 legal. Not sure if I would even attempt it on my vehicle but I'm curious if it's worth the hassle and what kind of benefits were gained by it?

CP

1 inch is the max. You wouldnt want to go to far back anyways with the short wheel base. Just makes your rear driveline that much shorter.

[BajaBronco13]

Anyone see the benefit of that one inch back? I don't but what the hell do I know.

CP

[RelentlessPursuitRacing]

Anyone see the benefit of that one inch back? I don't but what the hell do I know.

CP

CP, You just have to ask yourself 1 question......have you you ever said to yourself....."Boy, if I only had 1 more inch!". :D

[BajaBronco13]

On a daily basis.......uh what the.... LOL.

Thanks Jerry, always a builder, lol.

[3amigo]

I decided to move the body and motor back the inch that is allowed on the trooper I'm building. Its been a lot of work, but I figured I might as well do what I can within the rules. Will it make a performance difference? Probably not.

[straightaxle]

To start to see any difference in weight balance, you would have to move it 10 inches. An inch will not make a noticeable difference.

[BajaBronco13]

To start to see any difference in weight balance, you would have to move it 10 inches. An inch will not make a noticeable difference.

Hey Moss,

How did you come up with 10 inches? Not doubting you, just curious how you came to that measurement.

CP

[straightaxle]

For an example, if you assume the total truck weighs 5000 pounds, 105" wheelbase, starts with a 50/50 weight distribution and the engine/trans/tcase weigh 800 pounds. Taking the sum of the moments around the front axle, if you move the engine back 1", you get a weight percentage change of 0.15%, if you move it back 10", you get a change of 1.5%. Even at 10", you aren't getting much of change, it was just a random number I threw out there. Take something heavy and move from the front to the back (like the battery), you see a much larger change. 65 pound battery from the front axle to 120 inches behind the front axle is a 1.5% change, the SAME as going to all the trouble of moving that engine back 10 inches! Now if you REALLY want to see some radical changes, if you start with a 2500# total weight and move that 800# drivetrain, or only have a 36" wheelbase, etc., etc.

[151FAB]

Very well said ST8AXL, great point about the battery.

[fj40]

Hanging the spare tires as far back as possible, fuel cell and extra parts, will give your truck the balance your looking for.

[BajaBronco13]

Hanging the spare tires as far back as possible, fuel cell and extra parts, will give your truck the balance your looking for.

That's definitely the game plan for the spares. I'm not sure about the fuel tank, it maybe better to have that more centered on the vehicle (behind the front seats), since that weight changes with more or less fuel. That will effect the handling of the vehicle.

What do you guys think about moving the front wheels forward 2 inches? Has anyone done this? Steering won't be an issues since I'm having a double swing set steering system made.

CP

[3amigo]

I think that the rules state that the front spindle location must be within an inch of the stock relation to the body, so 2 inches would be outside of the rules.

[Yikes]

It would also mean making a custom crossmember, which is a modification of the frame.

[Stephen]

Moss is right, I did some of the same calculations on my K5 and moving the axle 7" forward didn't change the percentages more than a couple percent. In the real world I could feel it but other ride height changes happened at the same time. All of this is of course not class 3 legal.

Moving objects in front of the front axle to the back makes a HUGE difference as illustrated by the battery and it's even more pronounced as you get farther in front. It would probably be scary how bad it is to mount lights on the bumper. With most of the motor being behind the front axle, it has to move a LOT to make a difference. In our build (still not active, darn it) I'm planning on the 1" leeway making up for measuring variations and maybe some minor clearance problems but there's no practical performance to be gained.