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Comment by JPKab | Hacker News Reader

I own a Tesla Model 3.

In the past I owned a GM vehicle which was damaged in a collision. The chassis had a few parts which were bent. The minute a chassis of any modern vehicle is bent in any way it is an automatic write-off in the insurance industry. This is exactly what I was told when my car was categorized as totaled.

It doesn't matter if the chassis is composed of many parts and can theoretically be repaired. It is such a huge undertaking to disassemble the vehicle to a level where you can repair the chassis that nobody in their right mind wants to deal with it or pay for it.

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And even if it was cost-effective to "unbend" the frame elements, they wouldn't be as strong as before because plastic deformation changes the crystal structure of the metal.

What is “plastic” deformation in the context of metal?

"Elastic" deformation means the material deforms under load and then returns to its original shape after the load is removed.

"Plastic" deformation means after the load is removed, the material does not return to its original shape.

A spring is the canonical example of elastic deformation; it returns to its original position when the load is removed. A dent in a car (or a bent frame) is an example of plastic deformation.

The hydrocarbon compound we know of as "plastic" got its name from this phenomenon (more precisely both the compound and the phenomenon got their names from a Greek origin word meaning "capable of being shaped or molded".)

https://en.wikipedia.org/wiki/Plasticity_(physics)

https://en.wikipedia.org/wiki/Plastic#Etymology

you do not straighten, you cut out and weld replacement pieces

> The minute a chassis of any modern vehicle is bent in any way it is an automatic write-off in the insurance industry.

This is true much more often than it was in the past, but it’s certainly not always the case.

I think it will be cool if they found a cost-effective way to make vehicles more modular like body on frame vehicles are, but without the tradeoffs.

There’s not enough detail about the process and materials here, but one of the issues with castings generally is that they sometimes fracture rather than bend.

Anyway, maybe this is a way to bring the cost of new vehicles down for more affordable models in the future.

Possible with the modular skateboard model:

https://mondaynote.com/evs-the-manufacturing-revolution-40a7...

This isn’t a given. It depends on what a repair entails. Often a steel chassis can simply be pulled back into shape.

An aluminum chassis is certainly more difficult. A friend of mine had a Lotus and the whole thing was written off for chassis damage that literally couldn’t be seen.

How was it known to be damaged if you couldn’t see it?

I believe lasers are used to check how various parts of the car align. Certain things out of alignment indicate a bent frame.

Could see chassis damage underneath. The body looked perfect.

Do any states that allow bent frame repair without a salvage title? It's been a while, but back when I was buying cars at wholesale auctions, it was a big deal when one slipped through with a bent frame without a salvage title. They reversed auctions all the time, including one truck we purchased.

If it's repaired and not totaled, it won't have a salvage title.

I have even "bought back" cars that my insurance wanted to write off (insurance paid me market value less their estimated salvage value) and there was no change in title.

I think the only time a title gets "branded" is if there is a change in ownership. So if the car is totaled/written off, and sold on to a salvage yard or salvage auction, and then repaired and sold again, it will have a "rebuilt" title.

Yes, Virginia does. Happened to my Jeep a few years back.

A steel frame can be pulled into shape. A steel unibody is another can of worms. It'll never be straight.

I had a WRX pulled back into shape.

Maybe we’re talking about different things? Maybe there’s some level of unibody damage that crosses the threshold? Because some damage to the unibody is pretty much guaranteed in any moderate accident. The whole vehicle essentially is the unibody.

Yes, bent unibodies can often be straightened by a body shop with the proper equipment. Of course serious damage where the body is really crushed or severely bent or broken might not be economical to repair.

And as a corollary, I knew someone who had his Porsche sandwiched in a sudden traffic stop and it needed about $90,000 of repairs, including the chassis being unwarped, as I understand it, and the insurance paid for the repairs because it was marginally (~10%) cheaper than replacing the car.

The comment you're responding to is making a distinction between the body and chassis. The Model Y has a cast chassis, but the blog article says it has "singular front and rear body castings".

Absolutely false. I had a new Jeep Wrangler get rear-ended (by a Smart Car of all things) with $13k+ in damage, including a bent frame, bent floor tub, and twisted roll cage, all of which was repaired.

Wrangler is body on frame.

The minute a chassis of any modern vehicle is bent in any way it is an automatic write-off

So…? The statement to which I responded didn’t make any distinction and is wrong regardless. Unibodies and body-on-frame can both be straightened. The former is more difficult, but doable in many accidents.

I’m guessing body on frame does not qualify as “modern”. What was the last passenger vehicle as opposed to truck built body on frame? The Crown Vic beloved of police departments?

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