Metal thicknesses

[15Michaeljoseph]

Hey guys, first question post in a bit... Taking this quarantine time to do some needed rust repairs on the 325iS. Does anyone happen to know what thickness steel I would need to do some patches on the rear frame rails? I have a small piece cut from a donor e30 and from what I can tell with my digital calipers it is 16GA. Can anyone confirm this? The metal seems thick enough, but 16GA just seems thin for a frame. Sent from my moto g(6) using Tapatalk

[Sunnyledge]

I have used 16 ga for a front frame rail repair as well as other structural patches. In the case of the front frame section there is a second inner reinforcing structure. I don’t think that is the case for the rear sections. The BMW factory repair manual references 1.8mm for some repairs in the collision section, which is slightly thicker than 16 ga. The 16 ga is fairly easy to form without elaborate tools.

[15Michaeljoseph]

I have used 16 ga for a front frame rail repair as well as other structural patches. In the case of the front frame section there is a second inner reinforcing structure. I don’t think that is the case for the rear sections. The BMW factory repair manual references 1.8mm for some repairs in the collision section, which is slightly thicker than 16 ga. The 16 ga is fairly easy to form without elaborate tools.

Excellent, I really appreciate the response, that's the affirmation I needed. Measuring the small piece of donor metal I have with a multimeter yielded results that led me to believe 16ga would be good, but since it is a structural component I wanted to double check; obvious problems if I go too thin, and possibility of stress cracks if I go too thick (area unable to "flex" with the rest of the car). Measurements varied slightly depending on where I was clamping the piece so I was getting a little paranoid. The repair seems simple enough, I'm very fortunate to have had the actual spring perch itself cut from a donor car. Hopefully the rot doesn't extend too far once I get it stripped to bare metal... :) Sent from my moto g(6) using Tapatalk

[15Michaeljoseph]

Just an update on this for posterity's sake: I patched the rear frame under the spring pads with 16ga steel, and went way overkill on the welds (3 passes) because I'm paranoid as hell about it. Then, I welded the rust-free donor car upper spring perches onto the fresh frame sections. Once the car is back on the road and has gone over a few bumps I'll update again ;) Sent from my moto g(6) using Tapatalk

[15Michaeljoseph]

Indeed drove the car for the first time since doing the rear end work... So far so good, no springs punching through my 16ga frame patches! Sent from my moto g(6) using Tapatalk