Volvo M90
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M90 is the model designation for a Volvo gearbox that is found in Volvo 940/960 models from 1994-on. The 940 and 960 are one of the last true rear wheel driven Volvo's.
The gearbox is made by Getrag in Sweden and it is of a 3-axle design, deriving from the volvo M56 gearbox of the front wheel driven 850 series. It is rumored that the the gears between these gearboxes can be swapped.
The gearbox comes in 3 different flavors. There is a version for the cast iron 4 cylinder engines of the 940 (redblocks), the all aluminium 6 cylinder of the 960 (Whiteblocks) and the version for the Audi 6 cylinder diesel engine (D24TIC). The differences are the bellhousing bolt pattern and the output shaft flange (3-bolt flange for guibo on the redblocks/Diesel and 4 bolt flange on whiteblock engine transmissions).
The variant for the 6 cylinder Volvo engine will fit on all 4/5/6 all aluminum volvo N/RN-series engines.
The clutch is hydraulically operated by a master/slave cylinder setup with a normal clutch fork + throw out bearing. The flywheels used with these gearboxes are duall mass versions (petrol engines) to eliminate the noise that 3-axle (3-shift) gearboxes can make in neutral, and a regular (single mass) flywheels for the Diesel engine.
All gears, including the reverse gear, are synchronized.
A M90 transmission mounted to a Redblock Volvo engine.
The M90 gearbox is available with different gear ratio's.
| Gear | M90H1 | M90H2 | M90L1 | M90L2 |
|---|---|---|---|---|
| 1 | 3.54:1 | 3.54:1 | 3.91:1 | 3.91:1 |
| 2 | 2.05:1 | 2.05:1 | 2.20:1 | 2.20:1 |
| 3 | 1.38:1 | 1.38:1 | 1.38:1 | 1.38:1 |
| 4 | 1.00:1 | 1.00:1 | 1.00:1 | 1.00:1 |
| 5 | 0.81:1 | 0.70:1 | 0.81:1 | 0.70:1 |
This gearbox is the strongest manual transmission that Volvo fitted to their RWD cars. The L versions are stronger than the H versions.
The later versions are better, Volvo redesigned the 3rd gear synchro in 1997 to eleminate the possible failure of the synchro due to bad gear engagement under heavy loads. It is possible to modify the synchro of the older M90 gearboxes to eleminate the problem. [1] [2] [3]
