hello all,

i am looking to put replace the trans in my 1987 245 DL (M47 trans).
i have located an M46, but its out of a 79 240...
is any M46 just an M46 or are there differences in the trans model depending on year?
the junk yard i found the 79 M46 at says it is not a direct fit for my car, but i am not relying on their opinion.

anyone out there know???

much appreciated

This is turning into a project, isn't it? But if you want to go with the M46 you will need to change out the driveshaft.

Maybe the center carrier bushing too. Someone help me out here.


--
'80 DL 2 door, '89 DL Wagon

the drive shaft on the M47 has a Guibo where it attaches to the tranny output shaft.

The M46 attaches to a U-Joint up front.

The set up is the same as how your driveshaft connects to the rear-end

You will need a driveshaft, and of course a U-joint.

The M46 came with 2 different drive shaft sizes and that means the flanges on the Trans and the rear end are different sizes too.
You may end up having to have the correct flange/U-joint welded on the drive shaft for your car.
I think most cars after 84 or so only had the larger size drive-line assembly.
And the most 4 cylinder cars before 80 had the smaller drive-line and I remember.
Just do some measuring before making up your mind.

Gary

It will fit. There's no problem there.

First gear will be a little higher in the '79 gearbox than in the later M46. I can't remember exactly when they made the switch but by '84 first gear ratio was 4.03:1. The '79 1st gear will be 3.71:1 so it might be a little slower getting away from a full stop. If that makes a difference you might want to shop around a bit more. What is your '87's rear axle ratio?

Electrics are a little different but I assume you will just stay with what you already have. Use your '87 shift knob and push button and wire it up the same way as before and you're good.

Edit: Oops...I just noticed you are replacing an M47. Obviously no electrics on that. Get the wiring and shift knob with the switch if you buy this trans. I much prefer the later push button setup with relay. Your '87 won't have the OD indicator light in the instrument cluster. You may be able to add that but you would want to grab the green 'OD' gel out of the old cluster. I would have to consult the wiring diagram before I fully commit to this idea.

'79 will have a cast iron case. I'm thinking your '87 case is aluminum.

Drain and fill plugs may also be a little different. The older ones take a 17mm hex key to remove/install.

The '79 throwout bearing carrier will attach to the bell housing in a different manner.


--
'80 DL 2 door, '89 DL Wagon

You should determine what model the M46 came from. It is possible it could have come from a 260 series (V6) in which case the bellhousing, shift extension, and input shaft are different than a 240 M46. The V6 version has a 10 tooth spline for the clutch--the 4cyl version has more, finer splines.
As for gearing - the '79 M46 has a 3.91 rear and a 3.71 1st gear -- overall ratio 14.5:1 (with a motor 200cc less capacity than the B230).
The M47 equipped car has a 3.31 rear and a 4.03 1st -- overall 13.3:1 . With the earlier trans installed you will have an overall 12.2:1. You can expect it to be slower off the line as bulletproof has suggested--but it will be a more flexible 1st gear. I think the other gears are close for each tranny--including a .80 overdrive ratio the M46 and 5th gear in the M47.
What flywheel does the M47 use--a '79 would have had a flat flywheel - is yours flat--or stepped?
You'll have to use the earlier shifter with the built in overdrive switch -- that switch in a '79 will be a slide on/off switch with no relay involved--just the direct to the 4th gear only lock-out and solenoid wiring. Dave

Good point about the shaft splines, Dave. Didn't even think about that.


--
'80 DL 2 door, '89 DL Wagon