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These suspension systems always intrigued me. Supposedly created as a hybrid of solid axle and IFS, they were mostly seen on the front of late 80s, early 90s trucks and SUVs. Is this the rotary engine of suspensions (a neat gimmick but overall not entirely effective?)

Also, has there ever been a car outfitted with suspension like this?




 

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My understanding of twin I-beam suspension is that it can sustain a direct artillery blast without damage, but it's hard on the outside edges of the tires.

Also, for what it's worth, it contributed to the Explorer rollovers because it requires the engine being mounted higher up in the engine bay. This raised the center of gravity and roll center.
 

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Ford pickups had them for decades and decades. (I didn't know the new Econoline still had them, though!)

Yes, they wear tires when the suspension gets old, yes it's a pain in the ass to change the bushings, but they're tough as nails and those bushings are cheap. It's like extra-long swing axles in it's handling, though. (This is not a good thing, but it's fine for a 40 year old truck.)
 

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they were mostly seen on the front of late 80s, early 90s trucks and SUVs.



Is this the rotary engine of suspensions (a neat gimmick but overall not entirely effective?)

Late 80s?! No. They were around looong before that. Ford introduced the twin I-beam front suspension in 1965. They used it from 65-97 in pickups, and longer in vans and chassis-cabs.


As for it being a 'gimmick', I'd have to say no; Ford used the same basic design for over 30 years in their trucks, and over 40 years in their vans. The early I-beam systems used really heavy duty, forged steel beams and radius arms, making them pretty bulletproof. One of the upsides to the design was that it used only 4 bushings in the whole front suspension, and required very little maintenance (just grease the kingpins and steering parts once in a while). The downside was that once the bushings started to wear, the truck would fall out of alignment and eat front tires rapidly. The design also changed camber over bumps over a large range, making handling interesting in some situations.


The design had its negatives, but overall it was very rugged and simple. The best trucks were the 65-79 F-series and E-series, with the forged steel beams and radius arms. In the 80s Ford switched to stamped steel radius arms, and I-beams with ball joints in them instead of kingpins. This later design isn't as rugged, and seems to wear out faster and eat tires, more so than the early trucks.


 

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WTF is that
That is a Ford Twin Traction Beam front end on a 4x4. It is just the driven version of the Twin I Beam. That one has had the shocks and springs removed so it is drooping further than it would in normal use.

These were used in Explorers, Rangers, and Bronco IIs. Despite the goofy looks they work pretty well off road and offer more suspension travel than a double wishbone IFS setup. Caster angles do change as the suspension moves through it's travel but when they are stock the changes are minimal.

Here is a good FAQ on the TTB (driven version)
http://www.greatlakes4x4.com/showthread.php?t=9287
 

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Volvo 850 has a similar design for the rear suspension.
That's interesting. I hadn't realized there was much similarity there.

That looks like a cross between I-Beam and semi-trailing arm suspension. One other key difference is that the radius arm of the Ford suspension is a leading arm. When the bushing is gone, it pushes the wheel back pretty far and it rattles around pretty good. Another key difference is the fact that it's the rear suspension on the Volvo. That's enough differentiation that it's say that it's an interesting footnote, but little more than that. :beer:

I thought that twin I-Beams came out before '65, though. Were they all straight axles before that?
 
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