• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

240 auto->manual swap on early 240, need new speedo cable?

digital.aaron

digital.aaron

S powered
Joined
Feb 10, 2012
Location
turnin up the volume to 11 on the dial
Hi everybody. I'm getting ready to swap an M46 into the 76 245 in place of the AW70 that's in there now. I have the early dash with mechanical speedo. Will I need a new speedo cable, or will my existing one plug into the M46?

I assume if I reuse the old one I should get a new tranny-side seal, correct?
 
I dunno about autos, but there are different colour coded gears for the M46 speedo connection, that correspond to different rear end ratios, maybe something to think about too.
 
Early cars the clusters vary in # for each axle.

81+ mostly speedo gear varies.

76 has a aw70 4 speed auto swapped in or 3 speed bw55?? or would those be bw35 like a 75? I confess I'm not a 76 automagic connoisseur. Early automagic cars are kinda rare and have always been a pita to dig into the trans with limited used parts and interchange for those mint condition old lady early automatic amazon/140/240. Some could be fixed and read about with parts from a dodge dart.

If 3 speed auto, it will be quite the conversion both electrically and mechanically to have come out right.

Speedo gauge, gear and cable will all need to match up to read and work right and good luck finding a totally fictional early speedo/odo and cable. Went thru rebuilding one for a nice original 78 245. What a pita. Guy was patient while I found a lasting mostly original solution.

I've seen clusters r0920, r,0980, and r1000something in earlies...last one I had to check all the rear ends when diving for cluster parts. Horrible.
 
Last edited:
1976-81 240's have Bw/Aw55 stock. B21. Here in North America, only the B18, B20, and B30 had the Bw35. Maybe some B16's in the 122's. Those get swapped to M40/41 trannies.

Speedo should be a r0,960. With a 3.91 rear axle, use the black speedo gear. Same gear as what's used in a 1983-85 non-turbo 240 with the 3.31. But, it will match up for a 3.91, since the worm gear on the OD unit is different between the 1976-82 M46 (and 1981-85 Turbo M46) and the 1983-85 non-turbo M46. My 245Ti has a 3.91 axle. With the speedo gear from an '84 non-turbo M46, my speedo reads correctly. M46 in my car came from an '82 non-turbo 240.

Early speedo ratios are:

r0,585 (245 with 185R14 and metric speedo)
r0,605 (242/244, plus GLT/Turbo 245 with metric speedo)
r0,960 (1975-85 245 with 185R14, imperial speedo)
r0,980 (1975-85 242/244, plus 245GLT or 245T with imperial speedo)
r0,990 (1973-75 164E)
W1.03 (1973-74 140)

Speedo gear color:

Black - 3.91 and 3.31
Red - 3.73
Blue - 3.54

I've seen some that were yellow, but not sure what ratio they were for, and they might've been for a 140 or an 1800.

The speedo cable needed is the one for a M46. The M45 cables are too short, and the auto cable just barely reaches. At the moment, M46 speedo cables seem to be only made by Scam-Tech.

-J
 
Most 78 and earlier ive seen have an angle drive off the od unit.
Later don't seem to.

I've seen lots of different numbers on the 75-78 cars. Early wagons with 4.10 got 1,xxx something is all I remember.

I want to forget the 75-80 cars as much as possible. I don't miss them.

Cable interchanges between 3 and 4 speed automatic? It most certainly is different on 81-82 3 speed and 83+ 4 speed. Same between 4 speed and early cluster 3 speed?

Soo many applications and variations. I did note the 3 speedo gears and that most 81+ cars the speedo is the same (well, sedan and wagon like late cars), gears at trans end vary. 80 and older...lots of variations...huge pain.
 
Last edited:
945ti said:
Most 78 and earlier ive seen have an angle drive off the od unit.
Later don't seem to.

I've seen lots of different numbers on the 75-78 cars. Early wagons with 4.10 got 1,xxx something is all I remember.

I want to forget the 75-80 cars as much as possible. I don't miss them.

Cable interchanges between 3 and 4 speed automatic? It most certainly is different on 81-82 3 speed and 83+ 4 speed. Same between 4 speed and early cluster 3 speed?

Soo many applications and variations. I did note the 3 speedo gears and that most 81+ cars the speedo is the same (well, sedan and wagon like late cars), gears at trans end vary. 80 and older...lots of variations...huge pain.
Click to expand...

Yes, early wagons did get the W1.03 ratio with the 4.10 and 4.30 gears.

Re: the speedo cable, maybe some cars had M45 cables with the Aw55. I do know that the '80 264GL B21 car that I helped put an Aw70 into didn't need a new speedo cable. Fit fine.

Speedo ratio mainly changes with tire size. Cars with larger tires typically got the lower ratio. Hence the K9800 ratio on later wagons with the 185SR14 tires, and K10042 on later sedans with the 185/70R14 tires.

-J
 
You must log in or register to reply here.
Back
Top