Subframe swap

[france320isco]

Hi,

I may have to weld my subframe 31112226017.
But: are e30 subframes interchangeable?
I'm considering to buy a new one but the 31112226017 is no longer available.

Thank you.

[ADA///M]

Hi,

I may have to weld my subframe 31112226017.
But: are e30 subframes interchangeable?
I'm considering to buy a new one but the 31112226017 is no longer available.

Thank you.

Yes, I believe all but IX models are interchangeable. Just have to add the reinforcements to get it to e30 m3 type.

[france320isco]

Yes, I believe all but IX models are interchangeable. Just have to add the reinforcements to get it to e30 m3 type.

Thank you.

So, setting aside IX, any E30 subframe needs to be reinforced before being installed in a 320is/M3?

[ADA///M]

Thank you.

So, setting aside IX, any E30 subframe needs to be reinforced before being installed in a 320is/M3?

to my knowledge, yes. I believe there's also some added reinforcements you can do as well while it's out of the car.

[christsay]

I would even say that finding a good straight non-M3 subframe is preferable as a starting point. IIRC the M3 subframe reinforcements are the gussets on the bottom of the subframe. These however do not address the tearing on the top side that can occur where the motor mount attaches. So to weld in the reinforcement plate you will need to cut out the gusset to weld the plate to the underside of the top surface and then weld a new gusset in.

[france320isco]

Thank you everybody.

I made a mistake. My car is not M3 but 320is. I thought the front subframe was the same but it is not (as pointed out).

The correct part for 320is is 31111130707 which is "ended" on realoem, but seems interchangeable with 31111126427 (316/318, ecc.) at least from:

https://www.realoem.com/bmw/enUS/par...707&series=E30

[christsay]

Interesting, my suspicion is that the 320is still has a S14 and more importantly uses the same motor mounts and arms so you would think that unless something is different with the subframe to body mount or the subframe to front wishbone mount that anything that works for a M3 should work for a 320is.

[france320isco]

Interesting, my suspicion is that the 320is still has a S14 and more importantly uses the same motor mounts and arms so you would think that unless something is different with the subframe to body mount or the subframe to front wishbone mount that anything that works for a M3 should work for a 320is.

I'll find out very soon...I bought a brand new 31111126427.

[christsay]

I'll find out very soon...I bought a brand new 31111126427.

Good luck and let us know what you find. Are you going to reinforce this before you install?

Here's some pictures of a US M3 subframe with ~170K miles. This was a street car that saw track time and the mount point was tearing so I replaced it with a reinforced subframe.

https://flic.kr/s/aHskqp8FQM

you can see the factory M3 reinforcement and the tearing on the top surface that the factory reinforcement does not help.

[france320isco]

Good luck and let us know what you find. Are you going to reinforce this before you install?

I Will let you know what I find.
The stock One has failed After 400,000+km and It was my fault.
8 years (~180,000km) ago I installed poly mounts, but one of them wasn't mating the subframe correctly. I decided to ignore It and the crack Is exactly were It didn't mate.
I'll be back to the stock mounts I don't think I'll reinforce anything. I have to understand why that poly mount couldn't match the subframe "surface to surface".

Here's some pictures of a US M3 subframe with ~170K miles. This was a street car that saw track time and the mount point was tearing so I replaced it with a reinforced subframe.

https://flic.kr/s/aHskqp8FQM

you can see the factory M3 reinforcement and the tearing on the top surface that the factory reinforcement does not help.

Thank you. It really looks like mine. But on Realoem It Is for M3 only.

[france320isco]

Last word.
After almost one month from the order local BMW told me that the subframe would have been available starting from jan '23.
And if it wasn't me asking for updates on my order they would have kept me floating around till the end of times.

So, I bought a used one on Schmiedmann, the part number is 31111130707 (320is) and it was like this https://www.schmiedmann.com/en/bmw-E...product=C47869
They specify what vehicles fit and what not.

The subframe fitted perfectly.