Hi,

https://albany.craigslist.org/pts/d/voorheesville-volvo-240-b21f-engine-and/7479406511.html

Is an M45 geared the same as an M46 without an overdrive ? What would be the proper rear axle ratio ?

Thanks, Peter

As originally sold, it depends on the model year, according to Volvo literature anyway.

But for your purposes, 1979 and 1980 are the same. Both M45 and M46 had the 3.91:1 rear axle and identical 1st thru 4th gear ratios.

They are, if you're interested, 3.71:1 1st gear, 2.16:1 2nd gear, 1.37:1 3rd gear, 1.00:1 4th gear and, if so equipped, 0.79:1 OD.


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'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD

Hi,

Yes, thanks to both posters. That was exactly what I was looking for.

Peter

The 4 speed M45 has the same 1-4 ratios as an M46. I just "retired" my 1980 245 w/M46 (sold the M46 already). The axle ratio is something in the 3.9 range--same for both M45 and M46. Later than the B21F equipped cars the axle ratio of M46 cars had a 3.31 -- much too "long" a ratio for the smaller B21. Volvo took a turn towards fuel economy with the B23 rather than performance as they did with the 140 models which had a 4.10 ratio for 4 speed cars---4.3 for 4-speed + OD. - Dave

There was a change for the 1981 model year. M46 stayed at 3.71:1 for first gear in gas engine models. M45 and M46 in diesel cars went to 4.03:1.

Thereafter first gear was 4.03:1 for M45/M46. M45 was not used after 1982, at least for the US market.

This is all according to Volvo literature which doesn't necessarily mean it is carved in stone. I say this because some may dispute my words. But it ain't me sayin' it. It's Volvo!


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'79 242, '84 DL 2 door, '80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD