Transmission Replacement (Getrag 250)
Summary
Replace failing transmission.
Start Date: July 18, 2012
Odometer: 309000km
Total cost: $481
After replacing my failed M50 engine, I tested the car on a short test track. After about an hour total track time, the gearshift became extremely loose, causing difficulties shifting into gear. The transmission also started leaking a fair amount of fluid. The failing transmission was the original 1991 318is Getrag 240, and was near expiry likely due to age and the high demand placed on it by the track and the M50 engine.
I decided to replace the transmission with the Getrag 250, salvaged from the same car as the M50 engine I had recently installed in my car. An E36 ZF 310 or 320 transmission would also have fit, and is preferred because it is heavier duty, but I was working against a deadline, and didn't have time to source the part or research installation.
Parts
Getrag Part Numbers
Getrag and BMW each have their own part numbering system for Getrag transmissions. BMW, in fact, has two numbers: the official part number, and the serial number cast physically onto the side of the transmission. I could not find a definitive reference that translates either a BMW casted number or a Getrag part number to a matching common name such as "Getrag 250". Hence, I ended up sourcing my Getrag 250 based on the VIN on a matching M50 engine, knowing that a 1992 325is would have been originally equipped with a Getrag 250. For those looking to identify a Getrag 250 without the benefit of a VIN, here are two part number sets from confirmed Getrag 250 transmissions:
Getrag Number: 220.0.0 225.96
BMW CastingNumber: 12222239
Getrag Number: 220.0.0 225.94
BMW Casting Number: 12219349
Journal
On an E30 with an M50 engine, the Getrag 250 transmission is a direct fit, and bolts correctly onto the existing transmission crossmember. There is, however, very little room to access the bolts on the top of the transmission, particularly on the top side of the engine starter motor. Once the transmission is off its mount, jacking up the front of the motor slightly can help pivot the transmission down for easier access to the top bolts. The Getrag 250 also requires a matching clutch slave cylinder (the clutch slave cylinder from the Getrag 240 does not fit on the Getrag 250).
Once I had the transmission running, I quickly discovered that the car's current differential (a 4.10 LSD) was completely unusable for the track due to the low 5th gear red-line speed of around 150km/h. If you are mounting a Getrag 250 in an E30, be sure to investigate a matching differential. I settled on a 3.23 LSD from a 2000 M Roadster.
Part number on the Getrag 250
Cleaning the Getrag 250
Old Getrag 240 Removed
