TL;DR
- The E36 325i’s M50 used a Getrag S5D 250G five-speed (Bentley). The same Getrag family was fitted behind four-cylinder engines, while the M52 328i and the M3 used ZF five-speeds.
- BMW’s M20, M40, M42, M43, M50 and M52 share the gearbox bolt pattern, so a four-cylinder car’s gearbox physically bolts to the M50.
- The driveshaft’s front section depends on the gearbox: Getrag and ZF are not interchangeable at the flex disc.
- Identify a gearbox by its label, not by casting numbers: Bentley warns that forged casting numbers are not reliable for identification.
Which E36 used which gearbox (Bentley)
| Model | Years | Engine | Manual gearbox |
|---|---|---|---|
| 318i / is / iC | 1992–1995 | M42 | Getrag S5D 200G or S5D 250G |
| 318i / is / iC | 1996–1998 | M44 | Getrag S5D 250G |
| 323is / iC | 1998 | M52 | Getrag S5D 250G |
| 325i / is / iC | 1992–1995 | M50 | Getrag S5D 250G |
| 328i / is / iC | 1996–1998 | M52 | ZF S5D 320Z |
| M3 | 1995 | S50US | ZF S5D 310Z |
| M3 | 1996–1998 | S52US | ZF S5D 320Z |
This table covers US-market cars. Bentley notes that the Getrag S5D 200G was dropped from production in September 1992 and is interchangeable with the S5D 250G. European cars such as the 316i with the M43 aren’t in the table: check the label on your gearbox to see what your car has.
Gear ratios (Bentley)
| Gear | Getrag S5D 200G / 250G | ZF S5D 310Z / 320Z |
|---|---|---|
| 1st | 4.23 | 4.20 |
| 2nd | 2.52 | 2.49 |
| 3rd | 1.66 | 1.66 |
| 4th | 1.22 | 1.24 |
| 5th | 1.00 | 1.00 |
| Reverse | 4.04 | 3.89 |
The ratios are almost identical. The real differences are the make, which decides the driveshaft and the linkage, and the gearbox’s condition.
| Getrag | ZF | |
|---|---|---|
| Oil capacity | 1.0 L | 1.2 L |
| Drain and fill plugs | 50 Nm | 50 Nm |
The correct oil type is printed on a label on the gearbox.
Options for an M43 → M50 swap
Keep the car’s own gearbox
Because the bolt pattern is shared, the four-cylinder car’s gearbox bolts to the M50. An owner who put an M50 into an OBD1 318is reports the car’s Getrag gearbox works fine, with the six-cylinder shift linkage. What to consider:
- It’s the simplest and cheapest route.
- Its condition matters more than its type: a tired gearbox behind nearly double the torque won’t improve.
- If the clutch slips with the M50’s torque, the fix is a six-cylinder flywheel and clutch, as owners recommend for the swap anyway.
Use the donor’s gearbox
An M50 from a 325i normally comes with a Getrag S5D 250G: the box BMW paired with the engine. Swapping it in at the same time keeps the original six-cylinder combination of gearbox, clutch and linkage.
Driveshaft
On a four-cylinder to M50 swap with a Getrag gearbox, owners report:
- the rear section of the four-cylinder driveshaft can stay;
- the front section is too long and must be replaced with a front section for a Getrag gearbox;
- a ZF front section won’t bolt to the Getrag flex disc.
So the front section always has to match the gearbox make. Fit a new flex disc and centre bearing while it’s out. Flex disc bolts are tightened by size and grade: M10 8.8 at 48 Nm, M10 10.9 at 64 Nm, M12 8.8 at 81 Nm, M12 10.9 at 100 Nm (Bentley).
Mounts and crossmember
- Gearbox support crossmember to body (Bentley): M8 22–24 Nm, M10 42 Nm.
- On a four-cylinder to M50 swap, the four-cylinder crossmember is reported to fit, mounted to a different set of holes in the body.
- Fit new gearbox mounts while it’s out: old rubber transmits vibration and lets the gear lever move.
Summary
For our 316i swap, the plan is to identify the car’s gearbox from its label first. If it is a Getrag in good condition, keep it with the six-cylinder linkage, a matching Getrag driveshaft front section and a six-cylinder clutch and flywheel. If it’s tired or a different make, a donor Getrag S5D 250G from a 325i is the factory pairing for the M50.
