Outer Limits 4x4 Board

On my HJ47, the rear diff sits in front of the centerline of the tray by about 6 inches meaning that with a big load the load on the front axle gets less, not more. What methods are there out ther to shift the diff to the rear about 12" so that the front diff can carry more of the load?
I could grind off the rivets and move the front spring hanger but it is mounted where the chassis begins to rise up to arch over the diff. The rear hanger wont really be a problem to move.

Chassis extension.

Normally extend the chassis at the rear of the cab, before it rises up.

Shorten the tray? In the SWB models, the rear springs centre pin isnt in the centre of the spring. Extra wheel base can be gained by flipping the springs around. Not sure if the tray models are the same, I suspect not, but it might be worth checking..

How much weight are you carting?

How much weight are you carting?
Lots, well not really, but if the center of the weight is behind the rear axle, that means the front axle is taking less weight than normal wheras it should be taking a percentage of the extra weight in the tray. The other side of the rearward axle move is the 4wding capabilities, they can only get better with a rearward axle move.



Whats involved with the chassis lengthening??

The other thing too is shortening the tray is not an option , I have a camper canopy made to fit and thats cost too much to chop up and to lose room as well.

You could look at fitting a longer spring ,like f100 springs ,an just shifting rear shackle mounts back
This should move diff back by a couple of inches an at the same give you the extra flex achieved by using a longer spring

how much extra will I achieve using longer springs?

All depends on what springs you use. The distance from the front spring eye to the centre pin will dictate how far back you go. You need to decide how far back you would like to go and then research spring lengths to find the right spring. You will need to consider quite a few things in doing this.

* Spring has to be same width as what you are replacing to ensure it fits in your hangers and U bolt plates (unless you are prepared to modify/replace hangers/u bolt mounting plates).

* Spring eyes should be same diameter for ease of fitting to your hangers with existing pins (unless as above you are prepared to change).

* Rear spring hanger is going to have to be cut off and moved back to suit the length of spring you use and allow for correct shackle angle.

* Moving diff back any more than an inch or two is more than likely going to affect shock absorber mounting alignment, be prepared to modify this.

*You will probably need to add or remove leaves out of the pack to get the ride height and load carrying ratio right depending on what springs you go for.

* Tailshaft will need to be extended to match how far back your diff goes.

There is probably more for this list but thats just off the top of my head.

Brake lines need to be extended...

Basically look at anything connected to the diff and assume it may/will need to be moved/modified.

modifying the hangers and shocky mounts arent an issue, I was just curious how far I would get. I really want the axle behind the tray centerline by about 10" which at the moment means I would have to move the diff about 15-17"

how much do you carry?
does it seriously make a difference mate?
if its not breaking anything, and the truck is still stopping ok then leave it be.
didnt you say the rear diff is too far forward? wouldnt moving the diff back place more load on the front diff?
im no mechanical engineer here but i thought as you move the rear back more load would be transferred to the front diff?

DIRTY ROCK STAR wrote: im no mechanical engineer here but i thought as you move the rear back more load would be transferred to the front diff?

yes, thats what he wants.................

[quo
--------------------------------------------------------------------------------

how much do you carry?
does it seriously make a difference mate?
if its not breaking anything, and the truck is still stopping ok then leave it be.
didnt you say the rear diff is too far forward? wouldnt moving the diff back place more load on the front diff?
im no mechanical engineer here but i thought as you move the rear back more load would be transferred to the front diff?
te]
Dirty rock star, read the whole message, YES I want more weight on the front diff when loaded, YES it des make a difference, Yes I carry a lot at times , but not constantly, and YES I'm asking these questions because I want to change these things, not because I want it to "leave it be".
think also, how many times do you need to be hung up on the tow bar with your back wheels in the air, digging out the towbar to get the wheels back on the ground before you realize there might be a better way?[/quote]

15" is a long way back. Are you going to have enough length left in your chassis to have a hanger in the right place? Ideally the back half of the spring (centre bolt to rear eye) the same length or more than the front half.

sorry champ i thought you said you wanted less load on the front.

and i wouldnt know about the towball i dont have one. and have 90degree departure angle.
lengthening the chassis, or just movingthe diff and adjusting your bump stops to suit might get you there.
but there will be so many changes to be made...
tailshaft length -custom tailshaft, new brake lines, all the wiring to the rear lights will need changing.
you will have to get it engineered.