Multi link rear suspension tow rig.

[ericjon262]

Most heavy duty trucks run leaf springs, I've been thinking alot about my DMax suburban project, and how to go about making it ride better than a tank... In that particular project, I need to move the axle forward about 12" to get the wheelbase where it needs to be, I had been thinkin I would just make new front spring hangers and call it good, but I started thinking maybe making it a 4 link instead. FWIW, 1/2 ton GMR-800 suburbans came 4 linked, but the 3/4 tons did not.

From a tuning standpoint, a 4 link is much more tunable than a leaf spring setup, and opens the option for other spring types like airbags. Ideally, I want the truck to ride nice, but still be able to pull just about any trailer one would be crazy enough to pull with a GMT 800 truck. it's also worth mentioning that one of the leaf springs on the chassis is currently broken, so I would at a minimum need to replace the existing spring.

Thoughts?

[The Dark Side of Will]

Snag a GMT 800 Suburban rear frame half so you don't have to do any development?

[ericjon262]

Thought about it, Only the half tons got multi link suspensions, and the 2500 truck frame is significantly different than a suburban frame.

[pmbrunelle]

How much of trucks riding like tanks is because they need stiff (could be progressive) springs (regardless of type, leaf or coil) to accommodate heavy payloads, versus the type of axle location (leaf springs versus links)?

I suppose that with a leaf spring, you can tune it by rotating the spring in the pitch axis, so the axle moves back a bit with bumps.

[ericjon262]

That is a fair point, the Pig Rig doesn't have a terrible ride, and has 4 corner leaf springs.

I'm not dead set on 4 linking the chassis, more just considering options before I draw and build spring hangers. I've also considered what I have heard referred to as a "truck arm" suspension, similar to a ladder bar setup. It is as common on 67-72 Chevy trucks, and used coil springs instead of leaf springs.

I noticed some dodge trucks us a linked rear suspension, but I haven't seen or heard anything good or bad about them.

[The Dark Side of Will]

If you're just looking for a softer ride, install 1/2 ton leaf springs. If you still need to carry load, install helper air bags.

[ericjon262]

If you're just looking for a softer ride, install 1/2 ton leaf springs. If you still need to carry load, install helper air bags.

It's definitely on the list of considerations, a downside to multi link is that I don't think I would be able to convert to quad steer with it, that said, quad steer is more of a dream than a planned modification.

[The Dark Side of Will]

Then use two front frame halves for four wheel independent suspension AND Quadrasteer

[ericjon262]

Then use two front frame halves for four wheel independent suspension AND Quadrasteer

because that would be totally easy and quick...

I had been giving this a ton of thought, and I think I'll most likely end up moving the spring hangers, the solution is the simplest, and requires the least overall thought. I'm going to look into possibly changing the spring eye heights to improve ride quality, and I'll probably use 1/2 ton springs with helper bags.

[The Dark Side of Will]

I suppose that with a leaf spring, you can tune it by rotating the spring in the pitch axis, so the axle moves back a bit with bumps.

This requires adjusting the pinion angle on the axle, which is much less easy.

[ericjon262]

that kinda depends. there are off the shelf angle shims for setting pinion angle, as long as it's within a reasonable amount of misalignment.