Dana 60 gear ratio opinions

[averagef250]

The 61 front was ONLY used with the 3 speed auto tranny. They're passenger offset, same as a GM axle.

What are you trying to do?

3.54 gears with an overdrive are plenty adequate for even 31" tires. If you gear the rig too tall you'll get worse mileage than if you gear it for 1800-2000 @65.

The 89-93 dodges with the 727 auto and 3.07 axles were mostly fleet trucks. They tap out at 65 before the engine defuels. Not a very good design for a daily driver, but they make great, simple beater work trucks.

[ChrisB]

These early Cummins ran a 727 right? Is the D61 front similarly heavier than a D60 front, as the D61 rear is to a D60 rear? Or, is it just the wider pinion centerline to ring gear plane spread for the higher gears?

I want to spin slow empty cruising on the freeway. By slow I mean in the vicinity of 1500 rpm at 60. I hear you on the gearing too tall thing. I will be doing some testing with different freeway cruise speeds in my 72 diesel. I have seen very good mileage at 1900-2000 rpm and 65 mph. I want to see if 55 mph picks up mileage. Of course some of an increase would have to be attributed to lower aerodynamic drag.

Just about any diesel ought to be able to do better at lower than 1800-2000 rpm at a reasonable speed like 65 mph, if it is not undersized for the application and or has tendancy to need to much boost (is lugging) under that relatively light load.

Things I've heard that might cause lower efficiency at the lower rpm include later (suboptimal) injection timing. I understand my Isuzu has variable injection timing. I have a 3208 that does as well. I may be wrong, but I've hear the Cummins does not, at least in mechanical versions.

The vehicle would be a crew cab long bed dually, four wheel drive, that would be setup to be easily converted to run a single rear wheel for offroad trips, while not towing. It would probably run 32-33 inch tires. Off road it would run roughly 40 inch tires. The tall gearing and tall tires would be counteracted by deep tranfer case gearing.

[ChrisB]

Curious what you think?

I'm also in the market for a Dana 60 semi float with large Ford (9 inch ) housing ends. 3.73, 4.10, 3.54 respective gearing preference. I understand they sit under some half tons, maybe some 3/4 tons?

Is what I heard about the Cummins injection timing true? Seemed odd to me, thought it might be false.

[averagef250]

From what I understand the VE pump cummins have timing advance, but the P7100 motors are fixed.

[ChrisB]

From what I understand the VE pump cummins have timing advance, but the P7100 motors are fixed.

Thanks

Car-parts.com has turned up some 89-93 Dodges with the D61 front in a 3.07. They are also listing Dana 70 with a 3.07. In reading about Dana 70s, there's more variation in carriers than expected. I have yet to find a 3.07 gear in the aftermarket though. I guess there's just not enough interest in gears below 3.54. There are new Dana 80, Sterling and 14 bolt gears available that are lower (numerically) but not for the D70, D61.

Apparently the D70 HD has a larger pinion shaft and bearing, and uses the same carrier bearings as a D80. I even saw one description that said the 70HD uses a 11.25" ring gear....which I believe is mistaken, since tha's the D80 ring gear diameter. D70 also has large 4" axle tubes. IT has a 10K weight carrying capability wheras the other D70s are showing 7.5K. Seems like it should take a lot of abuse, but not sure if it'll take more than a Sterling or 14 bolt.

Let me know if your pal has any of these 3.07 gears or axle assemblies. I've been known to take long trips.

I am also in the market for the D60 semi float whith large Ford housing ends. Someone said they believe it may use the Timken Set 20 wheel bearings. I have a hot rod project for a large car that should be good for. Which years and trucks is it found in?

[HOWDY69]

Here is a handy little calculator.

http://www.richmondgear.com/streetcalculators.html

[averagef250]

I've seen the 60 semi float from 56 through 72 F-150's.

The 70HD is very hard to get parts for. They obviously do not use D80 size ring gears, 60/70 covers are the same size. 80 gears wouldn't fit under the cover.

I'll check on those gears.

[willowbilly3]

well with the 300 and a c6 and with the load you want to pull, i wouldnt go under a 3.50. the 3.73's would work fine.

The 3.73 seems to work perfect with a stock height F-250 tire on a stickshift so you might go with the 3.54 for the c6 to allow for the 200-300 rmp slippage those have at cruise.