911SC cross member.

[PeteKz]

Apparently, there are about 4 years of overlap in steel and aluminum.

[bighead]

Would it be worth swapping to a steel cross member to not have to worry about the aluminum cracking over time? Other than the weight, is the steel cross member inferior to the aluminum?
These cars are getting long in the tooth.

[Bill Verburg]

"73 RS was the first street car to get an aluminum crossmember.

Here are some pics of an al street and al RS

[mepstein]

Originally Posted by bighead

Would it be worth swapping to a steel cross member to not have to worry about the aluminum cracking over time? Other than the weight, is the steel cross member inferior to the aluminum?
These cars are getting long in the tooth.

Most of the time they crack due to an impact. I would suggest, if it’s not broke, don’t fix it. If it’s bent or broken, replace it with a new one. Replacing an aluminum one with steel will probably raise an eyebrow if you decide to sell.

[dannobee]

I don't think most of the cracked ones can be attributed to impacts. Remember, it also holds the steering rack. If you look at the cracked one in the link on post #13, that's pretty much how the ones that I've seen crack, but they will also crack where the height adjuster goes. And don't forget they also bend and will throw the front toe off. But hey, if it bends enough you won't need rack spacers to fix the bump steer.

It's been decades since I measured the difference, but it was something like 2 lbs difference between the factory steel one and the cast aluminum one. The steel one is surprisingly light. At the absolute lowest part of the car body.

To each their own.

Look at Tyson's post #12 here. He's pretty much seen the same thing that I have.

https://forums.pelicanparts.com/porsche-911-technical-forum/340596-alloy-vs-steel-crossmember.html