245 - Changing M45 box for M46 with overdrive

It is posibele to change de gear box M45 for one M 46 with overdrive?

It fix in my 245 from 1976?



  • Yes.

    But you will need to change the front section of the propeller shaft.

    You will also need to add a relay and electrical wiring to operate the overdrive solenoid.

  • There is an M46 240 on the VCoV website at the moment that could be a donor car.

  • Shipping to Portugal however could be a bit on the expensive side. 😉

    OP may find one closer at http://forumvolvo.com/forum/ but the site doesn't have as much traffic as here.

  • Ex850RSnoopy @Ex850R Somewhere Over the Rainbow. Melbourne.

    Maybe try UK and the car wrecker , those thst pull apart cars for parts.

    Get on a forum in uk and ask.

  • The gearbox is this one

  • carnut222Greg S @carnut222 Daylesford VIC

    OK, you're sending us photos of a bellhousing...so hard to say what's going on. What engine do you have? The photos you've sent appear to be for a V6 engine as the bellhousing looks totally different than a B21 bellhousing - the starter is on the wrong side - so if you have a 4-cylinder B21, that bellhousing will not fit your car. Send some pics of the transmission please. You may be able to just use your existing M45 bellhousing. The other thing to consider is the input shaft splines changed in about 1979 to a finer spline, so depending on what year the transmission is from, you may need a different clutch disk as your 1976 would definitely have the coarse spline on the transmission input shaft.

  • carnut222Greg S @carnut222 Daylesford VIC

    Note also depending on what engine that M46 transmission was originally used on, you may have to swap over your M45 gear shift linkage. If the M46 was originally on a V6 engine the gear shift linkage will be way too long for the B21. Again, you should be able to use the parts from your existing M45 and bolt them onto the M46 transmission.

  • edited July 2020

    Part number 1208136 is listed in the 240 parts catalog as an M46 gearbox (240-260 series 1979-1984, Group 43, page 899 of the Swedish - German edition).

    It looks to be the part number for a D24 engine car.

    To use it behind a B21/B23/B230 engine, there is a sleeve which goes into the bell housing that needs to be changed, and perhaps a few other changes. Fortunately, the input shaft of the gearbox appears to be the same across D24, B21, and B27 engines.

    However, a close examination of the part manual is recommended.

  • carnut222Greg S @carnut222 Daylesford VIC

    The bellhousing itself needs to be changed to one that will match his engine...presumably he can use the one off his M45.

  • Hi, I'm back again...

    The subject is the same, the change of a M45 for a M46 with overdrive in my 245 from 1976, with engine B21A.

    I have a new possibility, i attached photos, and i would like to have your opinion, if possible. 😶

    I know that I'm in Europe but this forum it's the best I saw.

  • carnut222Greg S @carnut222 Daylesford VIC

    That's an M46 but the bellhousing has the starter motor on the RH side, so it is NOT for a B21/23/230...it must be for a B27/B28 V6? Or a D24? Whatever, it is not for a OHC 4-cylinder.

  • That's a D24 bellhousing.

  • Would it be possible to use the bellhousing from your existing M45 on your M46?

  • I can use, I have another M45 gear box and I can experimente

  • if I can change the bellhousing, the gearbox gets compatible with my B21A?

  • As long as all items bolt up together, yes

    try it and find out

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