My M46 OD is having trouble. I can no longer get the car
into reverse. It also does not downshift, when placed in
a lower gear, the RPM drops to idle without any engine
braking.

I talked to Duane Hoberg and he recommended replacing
OD unit. I have obtained a new transmission from a 1982
donor car, and almost finished installing it.

Now comes the problem. I did not think to check on the
size of the output flange. My car has the larger size
driveshaft, and the donor car has the smaller size.

For the OD image see the link below:
http://www.brickboard.com/FAQ/700-900/OverdriveExplodedDiagram1.htm

How do I remove the output flange (61) from the rear of the
transmission? There is a nut (64) that looks like it is
holding it in place. I have the new transmission in the
car, and turning the nut rotates the engine against its own
compression. I also need to remove the flange from the
old transmission that is off the car. I am stuck on this one.

Don,

Most times there is enough room to get a narrow pipe wrench ( I use an 8 inch pipe wrench with "extra" handle extension) on the portion of the flange that is next to the seal.

If not, a piece of angle iron with a 3/8 hole drilled in it to allow bolting it to the flange to allow you to rest the angle against the socket as you break the nut loose.

You would have to have two holes since the angle will not reverse and allow the same technique for installation.

Duane

Yeah, I've done this without special tools/jigs by having an assistant hold the flange with a pipe wrench while I loosen the nut with a breaker bar.

Don,

On the new tranny,remove the lower fly wheel cover (if it's in place already) exposing the teeth on the fly wheel ring gear. Jam the gear using a large flat blade screw driver in the teeth and place a socket and breaker bar on the out put flange nut to break it loose. The flange is on a splined shaft and will slide off ... you may have to tap the back side with a hammer to free it up.

On the old tranny, put it in gear and grasp the input shaft on the front with a large pipe wrench (you may need and assistant to hold this) while you use the socket and breaker bar to remove the out put flange nut.

An impact wrench,if you have access to one, really works well to remove these nuts without locking any thing down.

Hope this helps.

I would try to get an impact wrench because the above method puts excessive stress on the tranny internal components, and can damage the gears as well as thjew flywheel ring gear if the tranny is in the car.
If both of the trannys are out, you can either use an impact wrench on the nut while holding the flange with a big strap wrench, or as Volvo recommends, a flange holding tool that bolts into one of the driveshaft bolt holes and locks the flange against the OD housing. You can make one up with a steel plate and a big bolt welded to one side of the plate.
Removal can be done easily with the impact wrench, but torqueing of the nut during instal should be done with a torque wrench or adjustable torque setting for the impact wrench.
--
'89 245 Sportwagon, '04 V70 2.5T Sportwagon

I have arranged to borrow a air impact wrench, but I still
need to obtain the proper socket. I will let you know how
it goes.

Pete thanks for the tip about the strap wrench. I will try
that when I get the socket.

I will post and let you know afterwards how it went.

Donald E Booth
1984 245DL, B23F engine, M46 Transmission, 253000 miles