aluminum subframes
 

watching some BMW plant operation, I noticed subframes are aluminum. I don't know how long this is been going on with new vehicles. Wonder how they fair in the rust belt states. Are they better than the steel ones?

... suspension members, hoods, fenders, doors, trunk lids... usually aluminum on a BMW. As with steel, corrosion resistance varies with how much money you're willing to spend. Marine-grade aluminum will hold up.

The bodies of BMW's are still steel, with some carbon fiber used in the really expensive ones (7 Series) and the electric ones.

One catch with aluminum is that it will eventually fail under fatigue. With steel, if you stay below ~50% of the yield stress a part will last forever. But, with aluminum if you cycle it it will eventually fail, regardless of how much below the yield stress the cycles are.

My 5 Series BMW has aluminum doors. Frau Putzer's X3 has aluminum front doors, but steel back doors. A 3 Series still has steel doors.

I've been asking for 3 Series loaners lately, sort of as extended test drives. The relatively heavy doors just don't feel right anymore.

It's almost impossible to spot weld aluminum. The aluminum body parts are riveted together.

W211/R230, W220, W203 had aluminum front, rear or both
subframes along with aluminum control arms throughout. It's been common on mercedes for the past 20 years.
https://bparts-eu.s3-eu-west-1.amazo...g8wOcziwSw.jpg

You're saying aluminum parts will always fail eventually? Please define eventually.

The front subframe on my E30 325i failed, not sure there's a rear subframe. Pretty sure it was aluminum. I got lucky and found a low miles convertible that had been rear ended hard at the boneyard for a replacement. Hard ass install. Lot of parts are connected to it. Somehow I got it in.

I discovered it one day, I was having some overheating, I popped the hood for a looksee, I noticed the fan wasn't spinning at idle which it normally would do, even with the clutch thing, spins slowly. Turns out the bottom of the fan was leaning on the shroud, halfway supporting the front of the engine, as the subframe was cracked. Hard to believe but true.

Unless you had a 325xi, your front subframe was stamped steel.

If you want to see subframe failure check out this mess.
https://youtu.be/M7Eh3bu-S48

Tesla's have megacastings:

https://www.teslarati.com/tesla-model-y-front-megacast-giga-texas-first-photo/

Whoa, that looks rough all right.

"... I assume that's important." :D

I can only imagine you're correct on the steel vs. alum. It's been over 10 years. Memory fails.

The subframes on early 107 cars failed and they were steel. I believe any metal can fail if over stressed.

It's been about the same for me. My m42 is still running to this day somewhere in mexico.

Metal fatigue is hard to get away from. Material fatigue in general. Painful thing for me in these old rigs is the way the small things break. Right now my '89 Chevy van is running great. Also, in short order the cruise control and windshield washer pump thing stopped working. Weird thing on the washer pump, I pulled the two wire jack off the motor and put my multimeter probes in it, was going to see if 12 volts went there when I gave the switch a turn. Funny thing, it read 12 volts w/o the switch (?!). Also my high beams don't work. Even the low beams go out when I hit the high beam switch. Gremlins, gremlins, they drive me nuts. I wonder how many cars land at the boneyard owing to unfindable gremlins.

Just to be sure I understand, you listed a long list of problems on your chevy not your mercedes....right?

I expect a lot more electrical/electronic issues to be the cause of end of life for many vehicles. Each year they add more and more it seems. I usually land up with a few issues in any even older car. Where even they can be a little complex to locate. Nobody seems to want a basic car anymore.

Build to sell is logical but is perhaps being overdone.

Oh, I can't take another heartache Though you say you're my friend I'm at my wits' end You say your love is bonafide But that don't coincide With the things that you do And when I ask you to be nice, you say You've gotta be cruel to be kind in the right measure Cruel to be kind, it's a very good sign Cruel to be kind means that I love you, baby (You've gotta be cruel) You've gotta be cruel to be kind

Well, yeah. This sentence here made that clear (not to be an ass, it's my default mode):

Meaning the engine the actual moving down the road is going on but all kinds of tiny details seemingly conspire against me.