Rear Subframe Reinforcement?

[Funkmasta]

We are rebuilding the 335, and our first issue was the rear subframe. The old one tore in half.
[img]

I did a search and couldnt find any info on methods others have used to reinforce their subframes. Any insight?

Surely SOMEONE has done this before... ?

If not, I supposed I will post how ours turns out.

thanks in advance

[redhatpat]

I haven't had to do this, but....

It looks like you could just weld on some big washers over the holes and that should be enough to strengthen those areas.

[Funkmasta]

I am almost tempted to re-plate the entire top

[Funkmasta]

New subframe has been sent out, will be done tomorrow!

[backtrail69]

I hope I don't have those problems with my turbo car. That thing has got some balls..

[Van Westervelt]

That looks more like it wasnt tightened down fully.

[e304me]

yeah and washers werent used

[Funkmasta]

yeah and washers werent used

They were initially... All the rash attempts to re-secure the diff with the new bolts didnt work anyway.

Curt, the two drivers side bolts were backed out, leaving the two passenger side bolts bent, and starting the tear on the upper portion.

Not quite sure how it all happened @ 5k miles after the swap.

[e304me]

first off get a new subframe. then buy some of that long steel plate at home depot or something. its like 1/8 x 1.5 inch x 3feet. then for the top cut a piece that will fit across to the two bolt holes. then cut holes for the bolts and if they are small enough you wont need a washer. I wouldnt think you would need to do anything for the bottom. and probably not even anything for the top if you use washers and loctite

[iflytii]

That looks more like it wasnt tightened down fully.

Ditto. Looks like the bolts backed off and caused the problem.

[86espowa]

i am building a nice, super super rear subframe.

using the existing subframe as a template, i am going to cut a piece if steel, and weld it onto the top of the part of the subframe that is broken in your pics, and drill the same size holes as before.

that should step up strength, and ensure it wont rip, regardless of how much power you have!

[Funkmasta]

Ditto. Looks like the bolts backed off and caused the problem.

Winnar. strange that it happened after 5k miles... oh well. Glad it didnt happen in Redding on the way to Bimmerfest. ;)

[Funkmasta]

BTW, my subframe reinforcement should be done in about an hour...

[iflytii]

Winnar. strange that it happened after 5k miles... oh well. Glad it didnt happen in Redding on the way to Bimmerfest. ;)

Mine kept backing out on me until I finally doused them in loc-tite. Trashed 1 subframe in the process. Haven't had any issue since.

[Funkmasta]

Mine kept backing out on me until I finally doused them in loc-tite. Trashed 1 subframe in the process. Haven't had any issue since.

You better believe that the new bolts will be drowned in loctite!!!

pics to come