Rear Suspension, Exhaust, & 5-Speed

Running journal of three big projects on my 323:

• all bushings and mounts in the rear suspension
• full Supersprint exhaust, including headers
• Getrag 5-speed refresh and install (with driveshaft and shifter)

Getrag Reseal

April 10, 2022. I bought this 5-speed from a fellow E21 enthusiast in Rhode Island. It has unknown history so the smart thing to do is replace the input shaft, output shaft, and selector rod shaft seals. I wanted to replace the input shaft bearing too but that requires splitting the transmission cases and it’s more work than I want to put in right now. The seal job went really well but I obviously won’t know how successful until I drive it!

I took lots of pics: https://douging.smugmug.com/Cars/1980-E21-323i/Getrag-Seal-Replacement

Exhaust Removal

My current exhaust is all OEM stock exhaust but missing some key flanges. The front pipes were new when I did the E30 swap. The center resonator is rusted badly so this is good timing. The pipes between the resonator and mufflers are all custom and welded. No flanges! So the whole center + rear can’t come down until the rear subframe is lowered. Very annoying!!!

All of the exhaust manifold nuts came off without drama but I did find that using a 1/2” socket had a slightly tighter grip than a 13mm. I believe this is intentional on BMW’s part and seems very smart for a soft metal like copper.

E21 Gas Tank Removal

Gas tanks had to come down so I could inspect and paint the sheet metal over and around them. Removal is straightforward but the key is taking photos and marking the hoses on top. Some are for venting, the others are for feed and supply. The tank has a level sensor but the pump is external.

Actually dropping the tanks is easy. I drained the fuel using the crossover hose. I jammed a screwdriver into the end and let trickle out. I dropped them together with a 1×8 board across the bottom and my floor jack in the center.

Once removed I had a full view of the sheet metal. I’m pleased to see there is very little rust. No holes – just some serious surface rust that is absolutely treatable.

Prepping for Subframe Removal

The subframe is just two nuts but there is a lot more to work on before removing them – brake lines, parking brake, shocks, and driveshaft.

My first task was the brakes. I had planned to let the calipers just hang from the rear springs. But in typical Rust Belt fashion as soon as I put a wrench on the metal lines they split from the joint. I’ve NEVER had a BMW brake line come apart as intended. I have no better system – it just sucks. So now I need all new rubber hoses (they’re cracked), new metal lines on the arms, new metal crossover line, and an all new line all the way from the master cylinder to the rear junction. Sucks!

Next I worked on the driveshaft. It’s just four nuts from the shaft to the differential. I was not prepared for just how tight they are! The spec is only 53 ft-lbs. I got two nuts loose by hanging a wrench and smacking it with a mallet to ‘shock’ the nut loose. But this only worked on 2/4 nuts. There’s not much room for leverage. So then I worked on the front of the driveshaft and same issue! I eventually succeeded by jamming a wrench on the nut and using an electric impact gun. And that was with the trans in gear and parking brake on.

Onto the subframe itself. I wanted to loosen the outer mounts so it wasn’t so rigid coming off the studs. The 22mm nuts freed up with a little double-wrench action. The stupid 6mm Allen screws were seized on, however. A combination of rust, undercoating over the screws, and shallow Allen head equaled stripped bolts. I had to drill them out…

This sucker is finally free!

It fought me on several fronts. The worst was the 6mm Allen screws on the rocker panels. Nothing I did could make them budge and I had to drill each one out. One of the parking brake cable was stuck in the tube but came out with PB Blaster and pliers.

As mentioned above the exhaust was all one piece with no flanges. I could have cut the pipes but thought they would slide out once the subframe was out. It took some wrangling but they eventually did come free.

I separated the subframe from the diff and trailing arms and that all went smoothly. Next up is a lot of scrubbing, cleaning, rust treatment, and painting.

Now the real work can begin!