third members

[foghorn]

I'm looking for a bolt on change for the 3rd member to get better gas milage. I was hoping for maybe around 3:23 or better. I really want to go closer to a 2:50 or so. Thought maybe a big LTD,merc or maybe a towncar might be my options but looking for info or feedback on this issue. I'm thinking i have what looks like a dodge dana 44 style housing. Thats just to give you a close idea to what i have i need to crawl under it and find out for sure


thanks
steve a T.G.D.

[FORDification]

Dana rearends don't really have a 'third-member', per se...it's a bolted-in carrier, and it's not an easy task to switch gears in them. And AFAIK the Dana rearends weren't available with anything higher than a 3.07:1 ratio anyway, but most you'll find are in the 3.54:1 ratio.

If I were you, I'd get my hands on a 9" Ford rearend from a different half-ton truck, allowing you to easily swap the removeable third member with one with lower gears. (Most half-ton trucks have a 9" Ford rearend anyway.) Swapping in a complete 9" rearend would be a whole lot easier than messing with the Dana differential gears IMO.

If you decide to do this, keep in mind that Ford trucks up through '72-ish had 28-spline axles and the '73-ish and up (there's not a definitely changeover date) used 31-spline axles. The '73-up truck rearends are wider as well, so you can't use the third members from those trucks, since the longer 31-spline axles won't fit into the narrower housing. And because the frame widths on the 2WD trucks was wider on the '73-up trucks, the spring perches were moved farther outboard to accomodate that, although if you wanted to relocate the two spring perches on those, it'll bolt right in otherwise.

These trucks didn't come with anything higher than a 3.00:1 ratio (my '67 F100 6-cyl/3-spd. truck came with these gears), so to get down into the 2's you're going to need to go to a passenger car. Most cars with a 9" had 28-spline axles, except for some of the larger ones (like the Galaxie), which did come with 31-spline versions.

So that's my advice, for what it's worth. Swap in a '67-'72 9" rearend, and if the gear ratio that currently installed isn't high enough, hit the salvage yards and just get a 28-spline third member from a passenger car with the ratio you want.

However, should you decide to keep the Dana 44 and swap the gearsets, keep in mind that Dana 44s have two different carriers:

- 3.92 & Up Carrier
- 3.73 & Down Carrier

...so depending on what your current ratio is, you might also be looking at getting a different carrier.

Hope this helps.

[foghorn]

thanks keith that is some very good info to go on. I did crawl under my truck and pull the tag and the thing reads top line WDM-W OAD
next line reads 3.50 9 301A. I know the 3.50 is the gear ratio. But the rest is jumbo to me

steve a T.G.D.

[FORDification]

Well, something's not right. That's the tag for a 9" Ford rearend, non-locking, 28-spline, used in these trucks from '63-'71. So either you DO have a 9" Ford rearend, or somebody's swapped that tag onto your Dana. Is there a removeable rear cover, or does it have a third member that pops out from the front?

[rjewkes]

Also 3.00 where decent mileag in my 72 as i got 10-12 mpg intown and 13-16 Highway except the last trip i took with her and the engine was draggin'.

[foghorn]

The chunk comes out from the front and it has a smaller section that comes off around the yoke area. Sure wish i had a way to post pics right now. I need to get the soft ware from my father in law so i can use his camera to post pics.

[FORDification]

You've got a 9" Ford rearend. Well, that's very good news! These rearends are known as the 'Poor Man's Quick-change', a reference to the very expensive Halibrand Quick-change rearend. Changing gears is as simply as popping out the pumpkin with one gearset and popping in a different one. All you need to do is find a 28-spline car piece with the ratio in it you'd be happy with, and since these are a dime a dozen in the salvage yards (at least in the yards with older vehicles) that shouldn't be a problem.

Here are a couple links with good info on these rearends:

http://www.kevinstang.com/Ninecase.htm
http://dfwmotorsport.com/Fairlane/9inchrearends.htm

[GT-Racer]

great info Keith. That first article is some good reading for the less knowledgable 9 inch owner.

Like me.

[pat67shorty]

2.50-3.00 gears are common in non performance torinos/montegos/ect.

If you weren't in oklahoma, my buddy had 2.50s in his torino and would trade for the 3.50s in a heart beat.

[rjewkes]

For a mild mix of milaeg and performance why not a 3.25? I have one setting under an old trailer. If you wantyed to come to joplin(not sure if that is too far from bixby or not perhaps we could swap the Rear ends out?

[foghorn]

i'll keep it in mind but i'm gonna look and see what i can find first. But i do appreciate the offer very much and no it isnt to far just a couple of hours drive. Bixby is just south of tulsa. Bixby,Jenks and Broken Arrow city limits all border Bixby. In fact this weekend i am going to the Grove area and pick up my styrofoam for my boat floation in the floor area. Just wish i could take off during the week to go look for this chunk.



steve

[willowbilly3]

Just putting in taller gears may not be the answer. If you go too tall, your engine will be running too slow and you will be pushing harder on the gas at every small incline. I wouldn't go taller than the 3.00 unless you are running some short tires or something. Maybe 2.50s if you plan on running 28" tall tires.

[foghorn]

I plan on running the stock size of tires. They might be a little bit bigger than stock according to the wheels i get. I will be looking for the flare side chrome wheels when i get ready to buy wheels. They are 15" rims and i was planing on some where around 235/70/r/15. I kinda am old fashion in a way and still like the 60 series tires. But they just are not as wide as they used to be.
steve