The rear end of this car is the entire reason for the months-long rebuild of my e30. One of the first upgrades I had planned on this BMW was a simple stainless steel brake line and racing brake fluid upgrade. The problem was, as soon as I took off the rear wheels I realized I had a rust bucket on my hands (see Tackling a Rusty e30). In fact, when I started to take the stock soft brake lines off, the hard lines were so brittle that they snapped. So, the e30 went up on jack stands and a total overhaul commenced.
The Black Flagged BMW E30 So Far
The front end got new control arms, new steering links, a power steering delete, a sandblasted and powdercoated subframe, a new sway bar, Powerflex LCA bushings, new lollipops/lower control arm brackets, rebuilt strut towers with new (to me) Eibach springs, stainless steel brake backing plates and brake ducting, new hubs and bearings, and new rotors, pads, stainless steel brake lines, and rebuilt stock calipers.
The rear is getting a similar treatment: Powerflex subframe, rear trailing arm, and differential bushings. Reinforced and powdercoated rear subframe and rear trailing arms. A refreshed and rebuilt differential. New axles. Eibach springs, new shocks, and a new sway bar. A new (stock) gas tank with new fuel lines and a new Bosch fuel filter. A new guibo and center bearing for the driveshaft. New wheel bearings. New hard brake lines, stainless steel brake lines, rotors, brake pads, and rebuilt calipers. And enough new nuts and bolts to hurt my “new parts fund” substantially.
Disassembly is easy. I kept everything in well labeled ziplock bags so I could remember where everything went. Once the underside of the car was disassembled, I cleaned it with some degreaser and warm soapy water, let it dry, and then painted the underside and wheel wells with some rust reformer and/or undercoating material. It’s worth noting that the body itself didn’t have any rust—i only treated it as a safety precaution and to make everything look new again.
Next I ran the new brake lines. I installed a hydraulic handbrake in this car (more on that later) so I tied the new brake lines into the handbrake at the center of the car. The lines were easy enough to bend with a small handheld tubing bender—I just used the old lines as a guide.
After the brake lines were in I freshened up the differential. The internal parts are in good shape so this was mostly cosmetic. An angle grinder and wire wheel took care of the old rust, then I primed and painted it with some Rustoleum. Instead of using a new paper gasket I used a blue liquid gasket material. New nuts and bolts, that Powerflex differential bushing, and a fresh fill of gear oil and this thing is off to the races.
Reinforcing the subframe and trailing arms weren’t too bad either. I sourced reinforcement plates and, after sandblasting, had a friend help me with the welding. Once everything was welded up I dropped it off at the powdercoater, and voila, good as new. Better than new, actually.
Putting new Powerflex bushings in the subframe is a piece of cake. The RTABs took a little more effort, but it worked out. New bushings all around—check.
After that, it was just a matter of putting everything back in place in the order it was removed, and tightening to spec. The main challenge of this job? Time and money. Everything takes time, and it seemed that as soon as I had something figured out, I would hit another roadblock. And usually that roadblock meant ordering a new part and waiting a few days. But every new part—every new nut, every new bolt—means one more thing that is rust free, safe, and solid.
As the last few parts go on and the last few adjustments are made, this little BMW e30 will be touching down on the ground for the first time since May.
Let’s hope everything works.