How good of a transmission is the M5OD-R2? I'm looking for a good transmission to put behind my 351W. I do not want a granny gear. I do a lot of freeway driving. I also like to run dunes and hills in the desert. The vehicle will probably be a F-100.

 

Make sure the shift forks are good, synchros and bearings etc good. Replace the rubber plugs that leak up top. Use the correct fluid (ATF iirc) and make sure there is enough oil in it.

If you hammer it with a 351w, you'll probably break it. If you drive it with some care, you will probably be OK.

Most of the problems with these that are listed here are low oil caused, and just plain high mile wear.

I do not recall a post where someone "broke" one of these, as in broken shaft, gears or case. That doesn't mean it doesn't happen....

 

I do hammer it so I had better find a different transmission. My next choice was the T-19A 4.02:1, 2.41:1, 1.41:1 and 1.00:1. The gas ZF-5 speed is gear spacing too wide I think. What would I need to adapt a close ratio ZF-5 speed to a 351W?

ZF S5-42 Close Ratio:
R: 3.79

1: 4.14
2: 2.37
3: 1.42
4: 1.00
5: 0.77

ZF S5-42 Wide Ratio:
R: 5.24
1: 5.72
2: 2.94
3: 1.61
4: 1.00
5: 0.76

 

The T19 would be cheaper I would think, if you can do without overdrive.

As for the ZF, as you know, the CR ZF is from behind a diesel, so you'd be looking at swapping the guts over to another case. You'd be into it for two transmissions.

As wide a ratio spread as the ZF has, I would think your 351w would have a broad enough powerband to pull just fine with those ratios.

A low reverse gear is your friend, as is the granny first.

Is this 2wd? You mention some off roading, so it can't be a total pavement hound.

 

This truck will see the a lot of desert but will also be driven on the highway. I am building this motor to have a really wide torque curve so I can run higher gears. If I could manage I would prefer to run a wide ratio 4 speed geared for 75 mph cruising in 4th gear.

 

75 mph with 32 inch tires and a 3.50 axle is going to get you 2756 rpm.

You can put in your tire size and other ratios here:

Novak Conversions - Gearing & Gearing Math for Jeeps

4 gears just isn't enough for everything it seems....

 

What sort of gas mileage would result from a F-100 with 32" tires running at 2756 rpm? This part always confused me. I always thought gas mileage was all in my foot.

In my F-150 I can go 75 mph down the road in 3rd gear 1.00:1 at 2,878. rpm in my just resting my foot on the gas pedal. I am gonna just have to take another road trip in "D" rather than "OD" and see how I like it. I know that I get 16 mpg on a long trip 50% mountians in "D" and the other 50% desert flat interstate in "OD". A shorter half-day trip through the mountians in "D" gives me about 13.5 mpg.

 

I would not look for this vehicle to be a gas mileage champ.

10-12 running 75 mph unloaded is my wag.

 

12 mpg at 75 mph with a T-19, thats what I would have expected from my C6. Ok then, I think I will just have to find a 5 speed to go behind my motor. What's stronger a M5OD or a T5?

 

Remember, that's my WAG, ymmv.

M5OD better bet than the T5.

There's always the NV4500 if you want to get a strong 5er and don't mind the extra cost.

High Impact - NV4500 5spd

BUT we're back to a granny first and ratios no better than the ZF.

Other options:

http://rsgear.com/performance/zf.asp

 

Just found this thread. I'm looking at installing a 351W and a 5 speed in my 67 F-100 4x4. This won't do much offroading, more of a daily driver. I was considering the ZF-5, but the cost and mods that have to be done may not be what I'm looking for. I'm thinking the M5OD may be the way to go.

 

I was searching for an overdrive. The T5 was apparently rated for 260-310 ft/lbs of torque. The M50D-R2 was a good choice. It has a rubber grommet that leaks but I am sure there is a fix for that. There is the ZF-5speed and the NV 4500 but I did not want truck gear ratios. They were a bit too heavy too. I would look into suping-up T5s and M50Ds. I ended up going AOD.

 

Damn, the salvage yard wants a ton for an M5OD, more than they want for a ZF-5! I may just try and find a donor truck whole, might be cheaper.

 

what is a ton of $$$$ for the m5od? and how might they be suped up?

 

they said $1050 for a used one. That's without the core charge. They quoted me 775 for the ZF-5, that's with core charge.