Cracked subframe - can i weld it?

[selespeed]

i recently found out i have a cracked subframe at one of the fastening points of the front subframe. right side. see photo. it looks bad. i have no idea how i got this. seems like a piece is missing and you can see the cracks seem to grow.

now, is it possible to weld this thing without taking out the subframe? this is a lot of work to take out.

anyone of you ever had this?

advice please.

thank you.

[colin86325]

Weld-in subframe reinforcements are available from many places.  Search s14.net for some ideas.

[DesktopDave]

I wouldn't recommend welding that part in-place. That's not as bad as it looks, there's a lot of metal there. I wonder if a front subframe impact sheared the flange vertically? It looks like the crack is propagating down the wend bead too, with a little rust helping it out.

In any case, I'd swap it out with a good used replacement. Front subframes are pretty common and cheap around here. You can't really tell how bad that damage is without removing the entire frame. With an engine support bar it's not really that bad to remove. You can do it in an afternoon.

Better you found out about this before it failed!

[selespeed]

I wouldn't recommend welding that part in-place. That's not as bad as it looks, there's a lot of metal there. I wonder if a front subframe impact sheared the flange vertically? It looks like the crack is propagating down the wend bead too, with a little rust helping it out.

In any case, I'd swap it out with a good used replacement. Front subframes are pretty common and cheap around here. You can't really tell how bad that damage is without removing the entire frame. With an engine support bar it's not really that bad to remove. You can do it in an afternoon.

Better you found out about this before it failed!

Yes. I agree it is better to swap out with a used one. but a good used one is not easy to find and often many in the yards are rusty. I have a small collision on the right side when the right front tire hit a road curb in 2014. i think this might be the cause of the missing sheared part. but as  you can see also the cracks propagating at the bottom helped by rusts.

i spoke with a mechanic and he too suggested to have it removed to weld to strengthen it. he argued there should be rubber bushes but i think this thing is anchored to the body by just 4 bolts. where are the bushes? are the 4 bolts have rubber inserts acting as bushes?

meanwhile, i also discovered a missing hex nut that is used to fasten the engine mounting (on the same side where cracks on subframe are found) - see picture. perhaps this loose mount contributes to the cracks of my exhaust header. even after welding the exhaust header for cracks it happened again in less than one year. i think engine starts vibration caused the exhaust header cracks.

[DesktopDave]

If you're in an area without many E36 around, welding is the only decent option. I've had good luck with frame and chassis welding over the years, I'd trust a reputable mechanic with mild steel welding like that subframe. I would suspect that a significant front wheel impact could cause damage like that, especially given the long lifespan of these cars. A few decades of metal fatigue and corrosion. BMW also tends to save a little weight on structural components compared with other manufacturers.

My E30 front subframe is solidly mounted to the chassis. No rubber except for the engine mounts. I'm 99% sure yours is the same way. The rear subframe is a completely different animal, rubber mounts all over. Perhaps that was what he was thinking about? We're pretty lucky with rust-free spare parts here in the USA. Shipping is expensive, but I've had luck with eBay salvage yards like Vines (in Georgia, USA?).

Hard to tell if that engine mount is compressed. They slowly collapse as they age, then the engine tilts a little from its original position. I wouldn't think that could cause exhaust cracking, but it's possible.