Outer Limits 4x4 Board

Thanks Wilsby, yes the system you described on the trials vehicles does effectively do the same job as the tripod. I used that on the front suspension of my old 6x6. I chose the tripod on my current truck because I use a RangeRover axle housing with portals and wanted to retain the standard control arm mountings at the axle in case I decide to swap everything into a Rangey some day.
Further to the forced articulation. You may be able to run a driveshaft from the front axle''A'' frame pivot into a side gear of a diff carrier bolted to a crossmember, with another driveshaft running from the other side gear to the rear''A'' frame pivot point.
Bill.

This is getting interesting. Soo, by using a diff center to connect the front and rear tripods/torquetubes/whatever, there is no need to offset the front and rear pivot points to accomodate the gear-to-gear design you used previously? Symmetry is good. I like this.

On second thought, this does nothing to cope with the fore-and-aft forces on the axles. Suggestions?

I am not sure I know what you mean by fore and aft forces. I was thinking something like the ''A'' frame pivot bushes would be quite large and mounted on hollow spindles similar to LandRover hub spindles. the drive shafts to the diff side gears would pass through the hollow spindles and attach to some form of universally jointed driveflange on the ''A'' Frame. Heads beginning to hurt again. Anyone else care to workshop this idea?
Bill.

I guess I should have said that I envision the connection to the diff center from the A-fame being the only thing that keeps the axle in place longitudinally. The A-frame, or whatever we choose to call it has no bushing, it is connected via a uni to the diff center and maybe the spindles you mentioned. Low weight, simplicity and ground clearance are at a premium here.

Relative simplicity of the ''A'' frame principal is due to there being only one flexible bushing required when compared to the 6 or 8 bushings for other longditudal locating systemsl. Ground clearance would depend on where you mount the pivot bush crossmembers and should not be inferior to other systems. Unlike multilinks,The attachment of the ''A'' frame at the diffs can be above the level of the axle tubes.The weight penalty shouldn't be too high and would be largely sprung weight anyway and may go some way towards compensating for the increased unsprung weight of running portal axles. For what its worth, the trucks wheelbase from one side to the other doesn't alter much with roll or articulation with ''A'' frames compared to other systems as the axles remain perpendicular to the chassis.
Bill.

Bill, my point is zero bushings. Forced articulation thru the old diff center replaces them. Only problem axial loads need to be relieved from the diff center (which is really the gears for forced articualtion).

Wilsby, you would still need a flexible bushing to accomodate up and down movement of the axle. the old diff would only transmit torsional movement as in articulation. To simplify explanation imagine we bolt a Rangerover spindle and hub to the crossmember under the transmission. to the hub we attach the 2 arms of the ''A'' frame. This setup would provide positive for and aft axle location and permit the axle to roll in relation to the chassis, but would not permit the axle to rise and fall. So we must attach the 2 arms of the''A'' to a flexible bushing on the hub to permit this up and down movement. Both torsional and up and down movement could be accomodated with a large single rubber bush, but we want to transmit the torsional movement of the front axle ''A'' frame via the old diff to the rear axle ''A''frame, so it may be easier to use a hub with wheel bearings or plain cones for ''A'' frame attachment to chassis and a rubber bushing for up and down movement.
Bill.

I think I am beginning to understand your point Wilsby. you want to use a biggish universal joint as both the ''A''frame pivot and drive for the forced articulation. That should work in principal if you used a UJ from a large truck. the drive shafts could be supported on tapered bearings so there are no axial loads only torsional ones on the old diff carrier assembly.
Bill.

Exactly, sorry if I waffled along the way.

Hi All,

I have been following these topics with interest.

Wilsby, a picture is worth a thousand words, any chance of sketching your ideas and scanning and posting them?



Regards

Nigel

Thats ok Wilsby. Waffling is sometimes how ideas spring to mind and different notions can be workshopped.
bill.

No pics, no scetches, only exists in my head.

Turning the clock back 80 years or more, I'd be interested to know Ricks, Stu's or anyone elses opinions on how the old T model Fords suspension design stands up today as a competent allround off road system,
Centrally mounted to chassis transverse leaf springs front and rear for excellant articulation, positive axle location and tramp control due to torque tube drive at rear and ''A'' frame up front, and high roll centre seems to be the same qualities that are desirable in a 4WD today.
All the old T Model needed was a good set of dampers and a driving front axle, and even those were available as aftermarket options.

not sure if you have seen this thread off pirate but it has some interesting features along those lines
http://www.pirate4x4.com/forum/showthre ... ge=1&pp=25

that thread has very limited features

yes he's used the sideways style leaf spring setup like an old T model ford , but he's hardly come close to getting it sorted or mounted properly

so i would say theres no good features in there at all
just a pic of how the diff is mounted

there was a few comments thrown around about its mounting also

and the FWD motor/g'box configuration he's used has been done long ago and proven......by a friend here in sydney