The Conversion(AW71 to M46)

The Conversion

    A transmission swap in a volvo is very starightforward.
    The Volvo's used the M46 from the 70's right up until the late 80's. Any four cylinder Volvo has a transmission that can be adapted to your four cylinder Volvo.
 

What I had:
    M46 transmission and shifter
    1982 DL clutch assembly
    1982 DL clutch cable

What I needed:
    700 shifter assembly
    Rear drive flange
    OD relay
    Clutch pedal and brake assembly.
    Flywheel and pilot bearing
    Rear mounting bracket and mount
    Drive shaft front section
    Centre bearing

The Short story:
    1. Remove the AW71. Since there was no gear lever left, I didn't have to worry about the interior.
    2. Remove the torque converter (bolted on to the driveplate) and driveplate, but keep the bolts.
    3. Install the pilot bearing (new) and then the flywheel. Since I don't have a crankshaft position sensor, I did not worry about how the flywheel was positioned.Then install the clutch. Change the rear seal before you mount the flywheel, if you want.

    4. Change the output flange and the rear seal on the transmission. The output flange is different between the 700's and 200's. They are also different between manual and automatic transmissions.
    5. Change the shifter assembly. The actual stick is OK but the rod and shifter cage must be changed between 700's and 200's
    6. Install the transmission, then the transmission cross-member and mount.
    7. Change the front half of the driveshaft to one from a 700 with M46 (change the carrier bearing too)
    8. Bolt the driveshaft on to the transmission flange with locktite!
    9. If you are installing a hydraulic clutch, it should be bolt-in. If, however, you are using a mechanical clutch, it is necessary to weld a @1.5" lever on to the clutch pedal  with a hole drilled to allow for the cable attachment. The pedal assembly is one with the brake pedal, so both must be changed.
    10. Wire up the OD. This is explained below on this page.
    11. Install the stick, turn the key, drive the car.

Notes on Transmissions:

    The M46 has a complicated overdrive unit and I would suggest making a wiring harness for it. The old one would probably be rotten. The only difference between the 700 and 200 transmissions are the shifter assembly and the output flange. Also note that the 200's have a cable actuated clutch rather than the hydraulic (as do the 700's). The brake pedal assembly can be easily removed and replaced with the clutch and brake pedal assembly. A hole in the firewall is there for the cable.

Notes on flywheels:

    Volvo has a few different flywheels. I would sugest taking the flywheel from the car where you took the transmission. Otherwise you may need a different clutch and clutch release fork assembly. If your engine has a crankshaft position sensor, you will need the right flywheel for your engine.

Notes on OD:

    The Overdrive unit on the M46 is a hydraulically engaged, electrically activated gearbox. When the OD solenoid is activated, the OD engages. In order for the OD to only operate in fourth gear and to automatically disingage, a relay is required that is linked to the gear selection and to the OD switch. The following diagrams are from the Volvo dealer:

         OD relay p.1
         OD relay p.2
 

The Long Story:

    The first sign that things would not go too smoothly was when I took off the old AW71 bell housing and found a driveplate. What? No flywheel?! Picked up a flywheel. Then I got an output flange the same size as my drive shaft flange. I took the torque converter and driveplate off my engine and put on the flywheel and clutch. Perfect fit! Next was the transmission. I had made a wiring harness and installed the 700 shifter assembly. That was heavy, it took me the whole day just to get it into position. When I did get it on and bolted the bell housing the the engine, I had the transmission supported by a jack. Next was the mounting bracket. Since I hadn't heard otherwise, I expected the old mount to fit, nope! Another to-buy item! In the mean time I tried to mate the drive shaft to the new transmission and realized it was half an inch too long! After seeking advice, I was told that I should take the front section of the drive shaft from an M46 700. Those have the triangular flanges as well, so I traded mine in! The drive shaft cost me way too much (250$) but I had no choice. It needed a new centre bearing and rubber, so I had that pressed on and I threw it all on to my Volvo. Perfect fit!
    I bought a pedal assembly and realized that the 700's had hydraulic clutches so I had a 1.5" piece welded on to the clutch pedal for the cable (for which there was already a hole in the firewall!).

    After a new distributor cap and injector seals (for the fun of it) I started the car. Pressed the clutch, shifted into first and slowly let off the clutch while watching the drive shaft (I still had the gaping hole). First gear worked, in to second, then third, the fourth. IT WORKS! Mind you I couldn't hear myself think during the trials because my exhaust snapped off at the catalytic converter during the accident.
 
 

    In the end, the whole job cost me around $1000, that's less than a good used AW71 around here. But! I still have my Volvo!








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