Differential Usability

[Richard in Florida]

I have a nice tight 3.54:1 differential that I plan to sell. I had it in my '53 Victoria for a few months.

Do I remember correctly that such a differential will fit '49 through '54 Ford and Mercury passenger cars, and perhaps even '55 and '56?

Are there exceptions which should be noted?

[scooder]

The Merc used a Dana 41 and dana 44, both rear loader types, from 49- 51, don't know after that.
So this diff is no good for these.
Martin.

[Richard in Florida]

Originally Posted by scooder

The Merc used a Dana 41 and dana 44, both rear loader types, from 49- 51, don't know after that.
So this diff is no good for these.
Martin.

I found my old sheet of info on this, and you're right about those years. However, the '49-'55 Ford and the '52-'55 Mercury all used this type of differential.

[40cpe]

Richard, we know that you are searching for the best efficiency with your flathead/5-speed. Did you replace this differential for another ratio for better economy? What did you change to?

[Richard in Florida]

Originally Posted by 40cpe

Richard, we know that you are searching for the best efficiency with your flathead/5-speed. Did you replace this differential for another ratio for better economy? What did you change to?

Throughout all my experimenting and testing, looking for the optimum blend of performance and economy, I was using a 4.10 rear end. Through painstaking tuning of the Edelbrock 1404 four-barrel and my own magnetic trigger distributors firing an old analog MSD 6A I got the mileage up to about 22 mpg. That was on a measured course of 2/3 in-town and 1/3 interstate driving.

When I later anticipated some long trips, it seemed likely that putting in a 3.54 would result in REALLY good mileage. However, soon after I put it in, the long trips evaporated and I ended up just driving around locally with the 3.54.

Although the car drove quite well with the 3.54, even climbed the same "test hill" in 5th gear, the car wasn't as much FUN. The crisp neck-snapping acceleration just wasn't there. It was like driving my mother's '50 Buick.

So I put the 4.10 back in and the fun came back. This is how we learn, I guess. I never made any mileage runs with the 3.54, but I suspect the number would have been noticeably better. I'll never know.

[40cpe]

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Thanks for the feedback. Are you running .72 or .68 overdrive?

What are your RPMs with the 4.10 at 60 mph? 70 mph?

[wisbangman]

Very interesting... Everyone seems to want the low reving at 60 mph. We all know that Speedway makes a 3.54 and even now, a 3.25, and I have been thinking about them. I have heard about better milage, lower reving, more miles per gal. As well as higher miles per hour. But thank you for covering a part that we don't always think about, " More FUN " Thanks for another perspective !

[Richard in Florida]

Originally Posted by 40cpe

Thanks for the feedback. Are you running .72 or .68 overdrive?

What are your RPMs with the 4.10 at 60 mph? 70 mph?

My OD is .72.

With the 4.10, at 60 mph I turn about 2200 rpm in 5th, and at 70 mph I turn about 2600 rpm in 5th.

With the 3.54, at 60 mph I turned about 1900 rpm in 5th, and at 70 mph I turned about 2200 rpm in 5th.

[Richard in Florida]

Originally Posted by wisbangman

Everyone seems to want the low revving at 60 mph. I have heard about better mileage, lower revving, more miles per gal. As well as higher miles per hour. But thank you for covering a part that we don't always think about, " More FUN " Thanks for another perspective !

Guys much wiser than I teach that the characteristics of the cam (among other things) must be considered when thinking about cruising rpm. The venerable L100 doesn't begin to "come alive" until about 2200 rpm, so cruising at 1900 rpm might be false economy.

Perhaps the best lesson I've learned is that you can "work out" on paper how you want your engine and car to perform, but you must be prepared to have your theories blown to bits during actual road testing.

[Ol' Ron]

Richard is probably the most knowledgeable person I know, when it comes to tuning a flathead. While visiting me here in vermont he tuned the 294/L-100 with 3 Stromburges. Welre changing the rear to 3.73 from 4.10 as well. He trys most everything, just to make it better and to learn what doesn't as well.

[40cpe]

Originally Posted by Richard in Florida

My OD is .72.

With the 4.10, at 60 mph I turn about 2200 rpm in 5th, and at 70 mph I turn about 2600 rpm in 5th.

With the 3.54, at 60 mph I turned about 1900 rpm in 5th, and at 70 mph I turned about 2200 rpm in 5th.

You need to try something around a 3.73

Just joking, the 3.54 gears do seem a little high. Thanks for sharing your experiences.

[itsa52]

I think they used the Dana in some of the later wagons as well.

[Richard in Florida]

Originally Posted by itsa52

I think they used the Dana in some of the later wagons as well.

Yeah, the wagons and delivery vans used a completely different rear end.

[Richard in Florida]

Originally Posted by 40cpe

You need to try something around a 3.73. Just joking, the 3.54 gears do seem a little high. Thanks for sharing your experiences.

Actually, the 3.54 with my T5's 2.95 gear set was quite drivable. No laboring (pretty warm 276) or need for using lower gears more often... it just wasn't much fun.

When you've been used to punching it in 1st and having the front end look like it's gonna come off the ground (never actually does but it exercises the shocks pretty good!) you miss that. Punching it in 5th gear with the 4.10 is like punching it in 4th with the 3.54.

My "Frankenstein" Big Chevy magnetic trigger distributor and my Crane CDI/HEI ignition both add to the fun -- big time.