Installing the Lower Cross
Brace on Your BMW
Wayne R. Dempsey

Difficulty Level: 4
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

[click to enlarge]

     Many E36 owners upgrade their chassis with the factory crossbrace that mounts underneath the engine. This crossbrace was installed as stock equipment on all convertibles and the 1995 LTW, a lightweight version of the M3. The convertibles received this bar to stiffen up the chassis since their chassis are naturally less stiff than coupes or sedans because they have no roof. Installing the crossbrace on a standard E36 coupe or sedan serves a dual purpose: The crossbrace stiffens up the chassis and also protects the engine sump from road hazards.
 

     Installing a crossbrace is quite easy; the only difficult part is installing the inserts that attach the crossbrace to the front axle support bar. M3 cars manufactured after October 1994 already have these inserts installed. For all other cars, the holes are predrilled in the front axle support bar, but you will need to install the inserts.

     The inserts corresponding to the crossbrace are called “blind rivet nuts,” or “nutserts.” The nutserts are installed into the front axle support bar and compressed against the sheet metal so they don’t turn. They support loads from the attachment bolts.

     First, jack up the front of the car and support it on jack stands (see our article on jacking up your BMW). Identify the four holes in the front axle support bar and remove any dirt or debris that may have gathered in them. Test-fit the nutserts into the holes. If they don’t fit, chase the holes with a 7/16-inch or 11-millimeter drill.

     Now, install the four nutserts into the holes. Use the procedure outlined in Photo 3. Check to make sure the nutserts are installed tightly and do not rotate in their bores. If they do rotate, pop out the insert and try again with a new one.

     With the inserts installed, remove the support bar that runs just behind the rear of the engine sump. The crossbrace replaces this bar. Bolt in the new crossbrace and apply blue Loctite Threadlocker on the threads of the bolts as you install them. Tighten the larger rear bolts to 70 N-m (51.5 ft-lbs) and the smaller ones that mate with the nutserts to 27 N-m (19.9 ft-lbs).

     There’s been some talk in BMW circles about the benefits of welding the crossbrace in place. This is not a good idea, as it would require you to cut out the crossbrace if you needed to drop the oil pan to replace a seal or your rod bearings.

     If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.