Thinking out loud about suspension design

[IZwack]

Dimple die that shiznit, Harold!

Wait, who's that :shifty_ey

Right, at ride height camber is zero, but for an offroad truck traveling at high speed, or even for rock crawling the wheel will be cycling throughout it's travel and the camber will be constantly changing forcing you to ride on the edges of the tire.

Agree -- same issue with the TTB though. But I guess its not as bad with the TTB since the TTB has longer "arms".

But taking a step back from the nitty gritty, the design would just be too complicated to implement. And because lives are at risk (highway speeds), a few of these would have to be made and put through some stress test under controlled/lab settings to find the weak points. Simulated computer modelling can reveal most of the stress points but real world situations are not always predictable and considered in simulations.

But on the other hand, getting back to the nitty gritty I think a good starting point for a prototype would be an IRS' center section -- not a solid/straight axle. Perhaps one that is either aluminum or steel (not cast iron) for ease of modification and welding. The "tabs" and protrusions from the center sectoin also makes it hard to cast since they leave plenty of "negative" space. However, redesigning the center section with casting in mind could make this a possility and drive production costs down.

 

[gijoecam]

Ditto... decent enough concept, but also, with a coilover (leaves wouldn't work for the afore-mentioned reasons), you need to stabilize it front-to-rear as well. Otherwise, you've be relying on that hinge to locate the wheel fore and aft.... not a pleasant thought. The forces on that 3-foot lever-arm would be massive!!

For all intents and purposes, that drawing is the existing IRS with a tube over it. However, that housing would have to be unbelievably massive to handle the acceleration and braking loads, in addition to the fore and aft suspension loads.

You'd be better off yanking the sub-frame and suspension mounting points out of an Expedition. That's got some decent enough potential by itself, with proven components, and plenty of articulation available. There was a site floating around where they yanked the IRS off a Navigator and grafted it onto the rear of an F-150.... huge waste of money, but cool in theory. Lots of performance tuning potential, for sure!

-Joe

 

[4x4xbrian.com]

#1 problem would be the wild changes in camber through the suspensions movement, this was the critical flaw with the ttb system. and that had much longer arms because the driver beam pivoted on the pass side, the shorter the beam the worse the problem. besides a similar design was built I believe on the corvair, which had a terrible defect in handling resulting in many lawsuits for gm because of uncontrolled roll-over. not benificial on an already top heavy truck. solid axle wins hands down.

http://www.corvaircorsa.com/handling03.html


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[410Fortune]

this is also the reason an IFS truck has upper and lower arms with a knuckle, so the camber can be maintained through the travel cycle.

This hinged solid axle = dangerous IMO, trying to re-invent the wheel here.

 

[Rick]

There was a site floating around where they yanked the IRS off a Navigator and grafted it onto the rear of an F-150....
-Joe

http://www.fstmotorsports.com/f150_irs.htm

 

[jester6]

Theres actually an old military truck w/ this exact design. We seen one in Flagstaff last winter. It looked pretty cool.

Im headin out the door, will have to do a search later & see if I can find the name of it.