Gary Lewis Posted December 4, 2018 Share Posted December 4, 2018 Good observations, but I will add that the M5OD has a 5th gear ratio of only .80 so it’s not a very tall overdrive. The math on your gear spread is actually very similar to my set up except I don’t have overdrive, and I’m running taller tires. Yes, I forgot about the ZF having a little taller 5th gear. I guess the ZF has a lower low, and a higher high, right? I think the M5OD 5spd is a great trans for a light little half ton truck...but it has a bit of a bad reputation for being weak from what I read. Still, I've read lots of reports of guys putting hundreds of thousands of miles on them, trouble free, and Ford did sell a zillion of 'em. Beating on it in an offroad application...it likely doesn't stand up, and certainly not when compared to the ZF5. I guess the problem with gearing is that people have different needs, tastes, and requirements. All too often, people forget the impact tire OD has on overall gearing. Lots of guys would hate my truck geared the way it is, but I like it the way it just fine. Maybe something like a 3.25 diff would be an even better balance, but I was in a situation where I wanted to have my cake and eat it too! I wanted decent low end gearing, but I didn't want the thing to be screaming on the highway either. I HATED that 3spd. I've had an NP435 before, and I would take that all day long over the 3-on-the-tree 3spd. Again, like I said above, I think the only reason I'm getting away with my set-up is the small tires. If I suddenly switched to 31" tires, I think the truck would be geared way too tall. I agree with what you'se guys are saying. And, saying it another way, you have to start with the end in mind. If you have a light truck, like to cruise, and don't tow "heavy" then the M5OD might be a good choice. It shifts better than the bigger transmissions, and has a more usable gear ratio spread - for those conditions. On the other hand, if you are going to tow much, or need the creeper gear for off-roading or starting a load, the heavier transmission like the ZF is a better choice. But, you get fewer useful gears for daily driving and you get the big truck "feel" in shifting - meaning you shouldn't expect to speed shift. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 4, 2018 Share Posted December 4, 2018 I agree with what you'se guys are saying. And, saying it another way, you have to start with the end in mind. If you have a light truck, like to cruise, and don't tow "heavy" then the M5OD might be a good choice. It shifts better than the bigger transmissions, and has a more usable gear ratio spread - for those conditions. On the other hand, if you are going to tow much, or need the creeper gear for off-roading or starting a load, the heavier transmission like the ZF is a better choice. But, you get fewer useful gears for daily driving and you get the big truck "feel" in shifting - meaning you shouldn't expect to speed shift. I just had an interesting idea - a spreadsheet that allows you to find the engine RPM at a given vehicle speed given a bunch of variables, like tire diameter, axle ratio, transfer case ratios, and transmission ratios. And, it would have the transmission ratios already loaded. I know there are lots of calculators "out there", but I don't remember seeing one that already has the gear ratios loaded in for the transmissions we use in these trucks. It would be a way to let you see what a given setup would do. So, maybe at the top would be the various inputs, like tire diameter, test MPH, axle ratio, and transfer case. Then below would be a column for each transmission showing the RPM in each gear, including when in 4Low. What! There is! Driveline/Calculators. Link to comment Share on other sites More sharing options...
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