Inline 6 Fuel Mileage

[greg64]

Ya, that's the one. Seems like the way to do the job right, but I agree, it's expensive.

Sure would help when climbing steep grades with a load.

[cerial]

More gears= more choices.

I just got my 76 with a 292/465/4.56 14bolt. I have a Watson 3 speed with 1.52/1/.72 in the shed. The fact the truck already had buckets was a huge selling point.

The plan this summer is to stuff the Watson behind the sm465 then switch my other disk braked 4.56 14 bolt to 3.73 gears and bolt it in.

This will give me 12 speeds to play with.

It will give a rear axle ratio of 5.67, 3.73 or 2.68 for a variety of situations being able to shift from one ratio to the other for more torque or more speed. It will keep me around 2100rpm at 70 which should give mileage in the teens while being able to light up the tires with only the meager 275lbs reliably on 87 fuel.

They are the size of a sm420 while being built to handle major abuse. The units are out there for less then most of the other temperamental alternatives.

I would never put 2.68 gears alone in my little 76 because it would turn it into a dog. 70's Caddies with 2.94's and 500ftlbs big blocks had those gears and weighed about the same as our trucks with mileage in the teens would be lucky to pull 13 second quarters with a tailwind.
By being able to use the 5.67 or 3.73 gearing and shifting the sm465 accordingly it lets me get away with the fuel sipping 2.68 final ratio.

The result is up in the air at this point. It all sounds good on paper and I could be horribly wrong. But, 1.52*275lbs is 418lbs all under 50mph where the truck does most of it's work. I am pretty sure I can get a around 450lbs with a few modifications staying with cheap fuel and mileage in the teens by going with the Watson. Of course it does open the doors to bolt up a different engine or force some more air into the 292 later on if fuel mileage becomes less of a concern.

A aux transmission should be a option that is at least considered when trying to get better mileage.

[Oregoon]

Originally Posted by cerial

More gears= more choices.

A aux transmission should be a option that is at least considered when trying to get better mileage.

I learned to drive in the late 'eighties in ancient hay trucks--all of which featured auxilliary trannies. I've driven 5 and 4, 4 and 4, 5 and 2, etc... Two sticks are a blast! I miss them every day...

My '74 C15 with a Saginaw might benefit from an overdrive, but that's it unless I want to do some tranny swapping. Until the 3OTT linkage dies, I'll let it be.

Now, my other project...

I'm on the hunt for a Brown-Lipe medium duty over/under drive, like a 5831?

I think your Watson is the same thing, but branded differently?

I have a '70 IH Travelall with a divorced NP 205. If I added the Brownie, and a Granny 4-speed, I could probably pull the moon down in 4-lo, if I could just get a long enough tow-strap...

Only downer on the aux-trannies is weight and chassis-length. However, if yours is going in Edith, I don't see that mattering much!

In a perfect world, I'd build an early Chevy Panel (the long one!) with a 302-Jimmy, Dana 60s, piggy backed t-cases (205/203) an sm 465, and a Brown-Lipe over/under, and an automatic sandwich maker, the Victoria Secret girls, and a lifetime supply of gasoline and beer...

Until then, post photos of your auxilliary trans! Rare stuff...

[cerial]

It is a 5531A the "highway model". Here is some good reading on the topic.
http://forums.aths.org/Topic31310.aspx

Picture here it is without the shifter. I got it off of ebay from some guy in Texas who said it was rebuilt and ran for 3,000. I told him to give me everything (shifter, drive shafts,etc), and he did.

Here is a picture next to a 465.

I pulled the inspection cover to peek at the gears.

[greg64]

Wow, cerial, I like your style! I agree that having lots of gears would really help the 292. It has the rev range more like a diesel. I've thought about a gear vendors hung off the SM465, but they are so damn pricey. I've even looked at some of the medium duty trannys, but I'm not sure about the practicality.

Maybe the 6 speed autos are the way to go, but they ain't cheap either...

[Oregoon]

When my 3OTT goes bad, I'll likely address the lack of an OD. While a 5-speed swap seems like the easiest route, I'd love to find a Brown-Lipe, though it'd probably get used on my IH project.

My '74 has a low-mile 250, and is primarily used for transpo and yard-work. A T-5 would be ideal.

The Travelall will be the road-tripper and the trailer-hauler. Plus, anything one can do to squeeze anything approaching better fuel economy out of a Cornbinder is a good move!

Damn thing isn't even comparable to a Suburban!