E36 M3 Front Suspension Overhaul Part II: Subframe Reinforcement and Solid Mounts

The second part of overhauling the front suspension included dropping the subframe to weld in reinforcements and replacement of the motor mounts. To remove the subframe I had to of course remove the steering rack first. After breaking free the tie rod ends from the spindle and loosening the universal joint on the steering shaft there are two more bolts holding the rack to the subframe.

Once the steering rack is out of the way, build an engine hoist out of wood or just put a block of wood on your jack and support the motor from underneath. The subframe is connected with 4 bolts. So like I had previously said in one of my posts I was getting some bothersome knocking noise in the front suspension of my car under hard breaking. After removing the subframe I discovered what this was.

So obviously that is not how it's supposed to look. As the subframe was being lowered both motor mounts fell to the ground. That's odd, I thought. What you see there is the bottom mounting stud of the stock motor mounts completely sheered off. So my motor was being held in by the top mounts and well, gravity. Here's the carnage.

Dear God...So THAT'S what that noise was. I was pretty happy to know that I found out what the issue was and also happy that I was lucky enough to avoid any major catastorphe.

Alright so subframe out ready to be welding. You can buy the reinforcements from VAC, AKG or Turner. They're all the same. The ones I got from AKG don't really fit so we had to grind them down anyway. It's just metal.

First things first prep the area to be welded. I used my buddies MIG welder, and generally MIG can go over more than TIG but just clean off the paint to make your life easier. Here's just some pictures of the non-prepped surface.

So as you can see the plates don't fit perfect right away. Grind them to fit flat. Here is the finished prepped surface ready for welding.

Prepped

Prepped Surface

Reinforcement Tab Installed

I guess now all you have to do is weld those guys in there!

Weld it up as best you can. There are areas that the torch just won't fit in. Once you feel good about the bottom piece put the top pice in place and, per the directions, tack down the edge closer to the center, weld it, then hammer it down to meet up with the outer lip.

And there you have it. Do the same for both sides. If you're going to run solid aluminum mounts I would say this is a necessary reinforcement to do. But even after seeing my stock motor mounts, I would feel more comfortable doing this with any mounts.

Here's the finished piece back on my workbench. I cleaned the shit out of the dirty ass subframe before painting it. I used self-etching primer on the raw metal to prevent rusting and bought a gloss black laquer from the same brand. It was from an automotive paint supply store so each can cost about $10. They spray really nice for a can though! Can't remember the brand but go to an automotive paint store and buy the professional paint in a spray can and it will be nice.

Here are the mounts I used from Turner. 

I masked off the "M3" on the subframe because I'm a dork.

Subframe ready to be installed

While I was under the car I also threw on solid aluminum tranny bushings from Turner. The process is bascially, remove the old ones, put in the new ones. Torque them down once they're loaded up. Not before. But with aluminum, I'm not sure if pre-load would change anything. They're already solid.

The front motor mounts torque to about 16-18ftlbs I believe. Like I said above, with poly or stock you let the engine load up the mounts before you torque them down. So that's about it for the reinforcements and mounts. Next up is some steering rack information.