BMW E61 Turbo Replacement - Engine Subframe Powdercoating, Steering Rack Rebuild

In order to pull the engine out of the front of the car with the transmission, the subframe needs to be dropped in order to allow the oil pan to pass over the steering rack. With the subframe on the floor, it was pretty easy to clean it up and check the condition of the subframe and steering rack.

Here's the subframe. Carbon steel construction, with one engine mount, 2 heat shields and steering rack attached.

The engine subframe on the BMW E61 is fabricated from carbon steel, painted or powdercoated black in the factory. My car is 9 years from the date of manufacture, and has been operated in Toronto and Montreal its entire life, subject to Canadian winters and road salt. What's interesting is that there is virtually no rust anywhere on the steel and aluminum body components. Most of the underbody structural and suspension components are made from aluminum - like the rear suspension frame, and the front suspension arms. There are a few components which sufferred from corrosion - the subframe, some of the aluminum heat shields, particularly at attachment points to the body, and one driveshaft tunnel brace also made of steel which I decided to replace.

The subframe was the one component of the car showing the most significant rust damage

Once I had a look of the extent of the paint bubbling and corrosion on the subframe, I decided that I didn't want to invest the time to try to clean it up and treat the corrosion myself - I had lots of other things requiring attention, like getting the new turbos, head gasket, oil pan gasket, etc on the engine and get the engine / transmission ready to replace in the car. So I decided to strip the subframe, remove the steering rack, and take the subframe to a local powdercoating shop to have it sandblasted and coated.

In preparation for sending out the steering rack - I measured the tie rod locations precisely for setup on reinstallation.

I found a local powdercoating shop that normally does industrial work, and the owner was a bit of a car guy and accepted to do my subframe for $150 - which was a great deal in terms of how much time it saved me from cleaning this up myself.

Subframe back from Powdercoat - beautiful.

He did a great job of sandblasting out all the rust, you can see in the powdercoat finish some of the pitting in the steel which was now overcoated, this should help keep the car on the road for another 10 years. He also protected all the studs and weldnuts from powdercoat - I didn't have any threading or tapping to do - which also saved time.

You can see some of the rust pitting in this photo - right hand motor mount area.

And some of the pitting here.

For the steering rack and axle half shafts / CV joints - I took them all to Axle Automotive (Capital Dominion Radiator) on Gladstone Avenue in Ottawa for rebuild. The rear axle half shafts were both spraying grease, and the fronts were fine but I had them repacked with new boots as a preventative measure anyway. They stripped down the steering gear, cleaned it, replaced the rod seals and boots, and the steering gear seals. I had the option of having the rack painted black - I opted to keep it natural aluminum. It turned out really nice - and now with the car on the road I can report that the steering feel is excellent - rack is performing like new. The price for the rebuild was very good - better than I could find at any shop in the Montreal area.

Front axle half shafts and steering rack - back from rebuild with all new boots. 

The aluminum body of the steering gear shows some oxidation - purely cosmetic and something I can live with. 

One thing to note is that all the bolts holding the subframe to the car front frame are torque to yield type fasteners that need to be replaced when loosened or removed. I did purchase new fasteners for the subframe.

Subframe prepped with heat shields, steering rack, left hand motor mount and power steering lines ready for the motor.

Sources and Links

I hope you found this post useful. Feel free to ask questions in the comments section below. I answer all questions. If you're interested, you can help support this site by using the following links to Amazon.com in the United States. Turbo parts were supplied by Turner Motorsports. Other parts were supplied by Pelican, BMW Park Avenue in Brossard, and eEuroparts. Capital Radiator in Ottawa did the steering rack rebuild.