Rivian's Body on Frame Architecture overview - on Sandy Munro

[KeithPleas]

What I found odd about the body on frame were the beads of sealant between them. First of all, the beads were not at all consistent with some large gaps. But what I really found curious was how the beads were squeezed out at the fastenings but completely proud and intact at other points. Makes me think that either the mating surfaces were a) not flat and/or b) rather easily deformed.

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[Floridavid]

Less efficient how? I've been seeing numbers which indicate that the Lightning actually weighs LESS than an R1T. If true, the Lightning is actually more efficient in the use of materials while also being physically larger.

Weight is only a piece of the equation for efficiency. RIvian has designed their truck for extreme off road loads and has shown to be overbuilt in each of the Monroe videos. Their structural architecture maximizes the load share of the body/bed unibody, frame and suspension attachments.

If the Lightning is built like traditional pickups, then the bed is isolator mounted and not a significant contributor to the torsional and bending strength of the truck. The bed and cab are essentially payload and the frame is designed to be the primary structure. There are many advantages to this, but strength to weight ration is not one.

David

 

[thrill]

Less efficient how? I've been seeing numbers which indicate that the Lightning actually weighs LESS than an R1T. If true, the Lightning is actually more efficient in the use of materials while also being physically larger.

That would only be accurate if the Ford had the same rigidity, same effectiveness in a crash, and same NVH,. Otherwise, the vehicles have been built with different material requirements for different target results.

 

[R_1_T]

Weight is only a piece of the equation for efficiency. RIvian has designed their truck for extreme off road loads and has shown to be overbuilt in each of the Monroe videos. Their structural architecture maximizes the load share of the body/bed unibody, frame and suspension attachments.

Yeah - I've watched the videos. Overbuilt from the Monroe guy's perspective, but built as required by Rivian's internal requirements. The Monroe guys have a built in bias from working at legacy manufacturers and suppliers. At every stage of the tear down, you've heard comments along the line of "we've never seen that done before". No shit guys - there's never been a vehicle quite like this...

Every vehicle has a set of KPI's they've targeted as a vehicle team. There are trade-offs made. Different priorities ultimately lead to different solutions (designs/materials/etc), but this doesn't mean that one is better than the other in absolute terms. Rivian's design choice has resulted in more noise being transferred into the cabin - both suspension/road and powertrain. The Lightning is quieter. Those observations have been consistently noted by reviewers and members of this forum who've driven both, so don't shoot the messenger.

A bit of history - Jeep actually did something similar with the Comanche pickup which also incorporated elements of frame and unitized body construction. Jeep's design isolated the bed from the rest of the vehicle structure. Clearly not the same, but the concept of combining them has been done in production previously. Jeep's goal was to minimize investment by utilizing as much of the XJ Cherokee's structure forward of the B-pillar as possible. A fully boxed subframe was added to support everything rearward. I owned one - it was a great little truck that I racked up over 100,000 miles on.

 

[Arky]

Weight is only a piece of the equation for efficiency. RIvian has designed their truck for extreme off road loads and has shown to be overbuilt in each of the Monroe videos. Their structural architecture maximizes the load share of the body/bed unibody, frame and suspension attachments.

Part of the reason the most burly off roaders don't use a unibody is because under the kind of loads you can get twisted up on a mountain trail can cause your doors and windows to go out of alignment if you stress the body for strength. With the weight of the Rivian and the glass roof that would be my main concern, they had to build it stiff as a rock because *any* flex is going to be a nightmare. That's probably a lot of the reason behind the weight, because it doesn't seem to flex too much when people have shown it at odd angles and terrain.

Decoupling it means all those odd loads are handled in the frame itself which is designed to be able to flex a bit without damage when towing, crawling, etc.

 

[rushidesai]

I just watched this video and was really concerned for two reasons:

1. Does this over-engineering make it hard for Rivian to control cost? They cannot keep spending $220K to build these vehicles. Sure they can improve process with scale but at the end of the day are they going to be limited due to the fundamental design?

2. Do 100 fasteners and manual welding make these vehicles less reliable over the long term? How will they hold up to age and what does it mean for residual value in 8-10 years.

 

[Dark-Fx]

They cannot keep spending $220K to build these vehicles. Sure they can improve process with scale but at the end of the day are they going to be limited due to the fundamental design?

This is misunderstanding capital costs. They spent $220k for every 1 vehicle they build. That doesn't mean each vehicle cost that much to produce.

 

[crashmtb]

I just watched this video and was really concerned for two reasons:

1. Does this over-engineering make it hard for Rivian to control cost? They cannot keep spending $220K to build these vehicles. Sure they can improve process with scale but at the end of the day are they going to be limited due to the fundamental design?

2. Do 100 fasteners and manual welding make these vehicles less reliable over the long term? How will they hold up to age and what does it mean for residual value in 8-10 years.

Keep in mind these videos are made by a consulting firm with an impetus to sell you on the necessity of their services, all the while totally ignoring any context for the design decisions taken in the vehicle they’re taking apart.

 

[rushidesai]

This is misunderstanding capital costs.

Do they break down cost of revenue from capital expenditure? I thought the 220K was calculated on gross loss (i.e. before capex).

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