Offset diffs. Where have all the real 4x4 engineers gone?

[Guy]

Arent the centred rear diffs more a product of the transfercase's ??
As most Transfercases are now chain drives using planetary gears for reduction, combined with realitively long life, ease of engineering and low NVH levels, I would imagine that they would sap less power and therefor fuel it makes sense to use a cheaper non offset rear diff ..

I could be wrong though ...

[bj on roids]

Bill, I am racking my brain trying to think of the benefits of the setup you describe. I like the custom Dana 60 front, very creative. I picture you as a bit of a crazy scientist looking dude, very back to the future. But on with my story. The inner dual serves what purpose?

Additional tyre wear!
Additional and increased bearing loads, decreased bearing and axle life.
Heavier axle, heavier tyre assembly!
More unsprung weight.
Harder to stop.
Harder on brakes.
Uses more fuel.

Then I think about the front axle:
Larger scrub radius.
Harder to turn
Harder on steering components.
LESS turning circle.

It is understandable that no-one wanted to go near it, it sounds very unsafe on the road. I cannot think of any offroad advantages that would outweigh all these other disadvantages! Perhaps you can enlighten me.


DISCLAIMER:
If a suzuki wanker posts a picture of that orange thing with 8 tyres, I will knock his block off, its useless.

[antt]

come get me bj i'll be in the guild bar tomorrow after my test

[daddylonglegs]

Bj, most of the disdvantages you listed do apply. with the following exceptins. No1 Increases bearing loadings. Because I made up the axle assemblies I built them wide enought so that the auxillary wheels were inboard , not outboard of the original wheels, meaning that the overall width of the vehicle was the same whether it was on singles or duals, so the scrub radius did not change either.
Because the tyres on the auxilary wheels were slightly smaller in diameter than the outside wheels, they did not touch the ground on hard firm surfaces, so normal ground pressure was maintained. The extra floatation afforded by the extra wheels only came into play on softish ground that caused the outer wheels to sink a little, so there were not the usual traction disadvantages associated with dual wheeled vehicles on firm slippery surfaces such as wet grassy slopes etc.
The twin wheeltrack dimensions of 39" and 62 inches gave the truck stability, yet allowed it to traverse severely rutted tracks, whether they were made by Suzuki LJ50's, Ford F250's or large wheeled tractors. It was virtually impossible to get hung up.
Of course there were trade offs, but not as much as you imagine, and none of the disadvantages involved bad handling,compromised steering
control, or braking performance. Accelleration was a little slower due to inertia and fuel consumption in stop start traffic conditions was slightly higher, but there was negligable difference on long runs. Because the extra tyres didn't touch the road under normal conditions there was no additional cost due to tyre wear. All vehicles are a compromise one way or another , but for my purpose/ interest ,the advantages outweghed the disadvantages.
When I originally thought up the concept, after measuring up the chassis frames of various 4x4's, I came to the conclusion that there was only 2 vehicles that I could use as a basis for this conversion. CJ6 Jeep or series landrover. I chose Rover because I already had them and the narrow chassis which allowed the very narrow inner wheel track.
I hope this enlightens you a little BJ.
Regards Bill.

[modman]

bill would it be fair to say your c.o.g. with the duels was low.
i remember you tried to lay it gently on its side but it wouldn't tip
with a 12.5 swamper and 7.5 inner tyre you had a tread with of 20"
no wonder you never sank into the ruts, you would never of fitted
be good if you could get those pics scanned and put on the thread, maybe you could get some pics of the 6x6 with belly wheels as well(i like to stir up trouble!)
david

[MKPatrolGuy]

you could get some pics of the 6x6 with belly wheels as well(i like to stir up trouble!)
david

I think I remember reading an article on this ages ago, was a Short wheel base rig, yes?

[bj on roids]

come get me bj i'll be in the guild bar tomorrow after my test

i was there!!

10am!! it was closed, so off to the casino,

ill be in the city tonight after the wallabies flog england!

that orange thing is so Grimace

[daddylonglegs]

My apprentice asked me years ago if i had any photos of the 6x6. I said no because photos are not really my thing., and I tend to move from one project to the next without looking back too often. Next day he came in with a whole bunch of photos that he'd downloaded off the net. We don't communicate anymore so I have no idea whose or what website he got them from.
Bill.

[daddylonglegs]

Dave, If you are talking about the 6x6 landRover, the answer is yes, there was a story in one of the 4x4 mags in the mid 1980's. But the 4wd has not been written up.It's a bit too "old school" and utilitarian to be of much interest these days.
Bill.

[MKPatrolGuy]

Dave, If you are talking about the 6x6 landRover, the answer is yes, there was a story in one of the 4x4 mags in the mid 1980's. But the 4wd has not been written up.It's a bit too "old school" and utilitarian to be of much interest these days.
Bill.

Yeah it was the 6x6...

[Rainbow Warrior]

Does centre pumkin mean Patrol rear axles are the same length left & right, so I only need one spare?

[modman]

i allways thought that the patrol diff centre was exactly central,
but chezzy has shown me 2 different axles, i believe there is 30mm difference.
david

[XterraGuy]

Weird, a "centered" rear axle that is still asymmetrical? What possible reason could there be for that? Only case I know of is the Nissan viscous R200 (IRS) LSD where one of the stub shafts is longer than the other because the internals of the LSD are asymmetrical.