features Getrag M51, Volvo bellhousing adaptor, Concentric hydraulic release bearing setup
The famed Getrag M51 with 1:1 in 5th gear. The M51 has three sections.
Getrag M51 from a Volvo 260 with an aftermarket cast aluminium alloy bellhousing to suit a 4 cylinder B21/B23/B230 (available from SAM, Sweden)
Special fittment of a 'concentric hydraulic release bearing' shown here means no shift fork.
In other words, a compact internal 'slave cylinder assembly' fitted with a release bearing (bearing supplied by Titan Motorsport, UK)
are clearance for flywheel position sensors that are attached to the
Getrag M51 Sport - (1:1 on 5th) 5 speed syncromesh gearbox. Dogleg shift pattern (R-1)(2-3)(4-5). Gear set spur wheels nitride hardened to handle higher torque loads. Gearbox had an oil-cooler system with radiator and pump. GpA's were fitted with a special magnesium alloy bellhousing, and only 20-30 were made. Magnesium is an additional 40% lighter than aluminium. SAM in Sweden can still possibly supply an aluminium alloy adaptor.
GpA 240T Homologation ratio's : 1st - 2.328:1, 2nd - 1.675:1, 3rd - 1.353:1, 4th - 1.145:1, 5th - 1.000:1
[For standard M50 (4 speed) & M51 (5 speed) gearbox ratios, visit my Link to 'Gearbox Ratios compared' - covers Volvo / Getrag / Supra]
Automotive (SAM) in Sweden list a number of Getrag M51
parts and offer 'complete gearboxes'
Gearbox spare parts are found within this SAM Parts web page see Competition parts
1) Vaxellada tal 40 kpm (to my translator means gearbox handles approx torque 40 kpm or 400 Nm)
2) Vaxellada tal 50 kpm ("" "" gearbox handles approx torque 50 kpm or 500 Nm)
Volvo 260 V6 with Getrag -
The tough M51 and M50 are both made by Getrag and are both 1:1 in top gear. The M51 can be found in 1976 era V6 264's. The M51 dogleg shift 5-speed is the M50 4-speed box with an added centre housing section to accommodate the 5-speed gear train. It seems the M50 4-speed is probably the same gearbox as the '262' used in early BMW 528i, 1985 model 535 (262's have a detachable bellhousing). Input shaft spline can be different though to suit manufactures clutch choice. A '260' marking can be seen on Volvo Getrag boxes.
The bellhousing found on the
is not the same as a B21/B230, so a custom adaptor plate is
required. Also required is a Getrag splined clutch plate, custom
clutch shift fork, etc. Input shaft is coarse splined, and output end
has a 4 bolt flange. Getrag gearboxes are very heavy compared to say
a Volvo M45
4 cylinder bellhousing - If you have a Getrag 265 5 speed gearbox (with detachable bellhousing) and wish to adapt to a 4 cylinder B21/23/230 engine, then you need a machined adaptor to fit a Volvo bellhousing.
The Haynes Volvo 260 series repair
manual includes information on the M50/51. They have a complete
rebuild section with a little history and design information.
To quote from the Haynes manual: "When the 260 series was introduced in 1975, they featured a brand new range of gearboxes. These boxes were the M50, a four speed, fully synchronised box with constant mesh type gearing on all forward gears, and the M51, a five speed fully synchronised box with constant mesh type gearing on all gears, including reverse. Both boxes were similar in construction, being of light alloy with ribbing; the M50 being in two sections and the M51 in three.
In 1976 models, the M50 and M51
continued to be used in the fuel injected versions, while the
carburettor defined versions were fitted with the M45 or M46 gearbox
which had first been introduced and was being fitted to the 240
series as well. The M45 and M46 are both four speed, fully
synchronised gearboxes, but the M46 also has an overdrive unit
attached to it. For 1977 models, the M50 and M51 had already been
phased out. The only manual gearboxes fitted from then on were the
M45 or M46." End
For specific Getrag information visit Metric Mechanic
Getrag Specialist Mobimech - New gearboxes, spare parts, rebuilds
Link to Volvo GpA page
Link to Supra in Volvo 240 conversion article
Back to Quick Technical Index
Updated 5/2004 AH