Independent Suspension vs Solid Rear Axle??

[CrazyOldMan]

The issue for manufacturers is that there is a ton of data showing that the average person in these segments (the two biggest in the US) doesn't take their vehicle off-road. Or if they do, it is fireroads and light-obstacle kinds of stuff that isn't too stressful or dangerous/damaging - especially when you need that vehicle as a daily driver. So it gets difficult to justify the crappy ride of a solid front axle in a half-ton truck for the 2% of the market that want it, versus the rest of the market that wants their truck to ride and handle well. We are building a capable, rugged truck, and it will be able to take you to 95% of the places most people would want to go. Beyond that, you might have to add a lift kit and some mods for specialized use. I've been to Moab numerous times, and any vehicle with decent approach and departure angles and locking diffs can do most things out there. Heck, we took a first-generation Touareg in and out of Micky's Hot Tub. Guys with $30k in mods on their Jeeps were just shaking their heads.

We have some deep off-road enthusiasts employed at Scout with some serious rigs. We have had major aftermarket companies out to our engineering and design office in Michigan. The vehicle itself is body-on-frame and can handle a lift kit. The bumpers are designed to be removable. Front and rear locking diffs are available, and a front sway bar disconnect. We expect some robust aftermarket support down the road. I know some of you would love a solid front axle, but the tradeoff in ride and handling was too much.

Can I also say “BRAVO” on the bumper design? This is a big issue with the GX 550. Being able to swap for aftermarket without cutting is important - clearly you guys have thought that out. Just making consistently smart choices. Really, really impressed.

 

[chucchinchilla]

there is a ton of data showing that the average person in these segments (the two biggest in the US) doesn't take their vehicle off-road. Or if they do, it is fireroads and light-obstacle kinds of stuff that isn't too stressful or dangerous/damaging - especially when you need that vehicle as a daily driver.

 

[CrazyOldMan]

Strong (possibly overkill) tie rods and some heavy duty half shafts with good shaft/joint angles and you can prevent most issues. I agree though, IFS is inherently weaker and a locker highlights that more. The “POP” is indeed common but when well designed from the factory, it’s less and less of an issues these days. Lifts change your half shaft angles and put more stress on those joints, bigger tires and lower gearing puts more stress on everything. That’s the common cause of the pops.

The minor tradeoffs of IFS are worth it for most vehicles these days.

To prove your point - there are a number of failed front drive shafts (at the boot) on the Grenadier when lifted. Failures aren’t on the wheel hub assembly, but the front of the drive shaft where the boot gets pinched with a tighter angle. So it’s not as vulnerable in the same way - but it’s another point of vulnerability and a good example of what happens when you mess with geometry.

 

[R1TVT]

Strong (possibly overkill) tie rods and some heavy duty half shafts with good shaft/joint angles and you can prevent most issues. I agree though, IFS is inherently weaker and a locker highlights that more.

I would say this is where Rivian has had to invest time & spend more $$$ in their services centers - addressing issues with the joints and half-shafts wearing prematurely or creaking and creating gremlins. Why? There is a great amount of travel and ride height adjustment (with air) that can be the cause of additional stress at the joints. Creating the balance between driveability, performance, cost and comfort is tricky with these modern suspension designs. It is certainly better to bust a tie-rod or replace a worn shaft, than to take out an entire drive unit (or something much more costly). I'm guessing Scout understands all of this when it comes down to the final production design of the entire suspension system given the expertise of the staff that Jamie has pointed to.

 

[CRobin]

Can you explain how a solid axle leads to better articulation? That seems counterintuitive, given that it seems like there would be fewer constraints on an independent system. I understand the fulcrum bit, that makes more sense to me but I’m confused by the articulation thing.

I was going to ask the same thing. But I love all these answers so far! Thank you ALL for explaining!

 

[CRobin]

You also get into discussions about which part should be the weak link. Do you want to break expensive and difficult-to-repair stuff? Or cheaper/easier to repair items?

To your earlier point, the set up is indeed IFS and a rear solid axle with coil springs? Or leaf springs?

 

[CRobin]

I would say this is where Rivian has had to invest time & spend more $$$ in their services centers - addressing issues with the joints and half-shafts wearing prematurely or creaking and creating gremlins. Why? There is a great amount of travel and ride height adjustment (with air) that can be the cause of additional stress at the joints. Creating the balance between driveability, performance, cost and comfort is tricky with these modern suspension designs. It is certainly better to bust a tie-rod or replace a worn shaft, than to take out an entire drive unit (or something much more costly). I'm guessing Scout understands all of this when it comes down to the final production design of the entire suspension system given the expertise of the staff that Jamie has pointed to.

Right! and makes you wonder why Rivian stayed with the most expensive way to set up with Air suspension???? Out here you can't even see a Rivian less than $107,000. and that is the for one of the lowest trims. SMH. I am sure the other suspension options are far cheaper than an expensive air suspension set up no???

 

[R1TVT]

Right! and makes you wonder why Rivian stayed with the most expensive way to set up with Air suspension

All trade-offs...

Ride Comfort / Durability
On-Road / Off-Road
Height Adjustments / Static height
Camp Mode Levelling / Piling up rocks under one wheel

Etc,. etc, etc,

I think the main reason why they stuck with it is because on road ride quality is really good with air AND you can take advantage of the side-country stuff like levelling for camping. Because it is very difficult to mod a Rivian and they are pricey, there are better rock-crawlers with solid axles to go roll boulders with.

 

[socalscout]

Solid axles and multi link suspension for the win.

IFS is for minivans and sedans