Lowest workable rear end ratio with 1950 Merc

[Sixseven]

What is a reasonable rear end gear ratio for the 1950 Mercury 110 hp engine?

The engine is in the station wagon which is geared at something like 4.4/1. I see that possible gear sets can be installed from the low 3's up to my current set. My tires are 28.9-inches in diameter, with a range of rear end gear ratios of 3.0 to 3.8/1 my engine rpm at 65 mph would be:

3.0: 2300
3.2: 2400
3.4: 2600
3.6: 2700
3.8: 2900

I just chose easy gear ratios so actual available ratios may differ. In the evaluation I wonder is the engine can still power through any of these gear ratios. May be that I just want to avoid highways altogether. My current gear ratio calculatres that I am turning about 3400 rpm at 65 mph. I've also contemplated installing an overdrive transmission. That option is not dead, but I'm still working on locating one with all the controls.

Mission: drive to shows, cruise stay relatively local but within a 200-300 mile range, not kill the engine in doing so.

[tubman]

My '51 Ford with a basically stock '51 Merc engine (it has reworked Edmunds heads, a Mallory dual point, and a 2GC on a bored out Merc manifold) cruises comfortably between 2300 and 2700 RPM and pulls 3.55 gears easily at those revs. A wagon is heavier than a coupe and I would wager you have less power, so I can't tell you anything definite. I think the important thing here would be to keep the revs under 2700 the majority of the time.

[Sixseven]

Thanks Denny, currently I need to keep it at around 50 mph for that rpm. Appreciate it. I did get hold of Charlie, he has no transmissions but may be able to lead me in that direction. I'm making sure I cover both a rear end ratio change or the OD route. Thanks again.

[Ron_r1959]

I talked to a " V8fordman," that was his name on here last spring that had a couple overdrives on a skid out east, he didn't know much about them but he would sell them. You might try to locate him on here.

[rotorwrench]

If it's a 1950 then verify whether it is a Dana 41 or the later 44. The carrier is smaller on the Dana 41. A lot of stuff is available for the Dana 44 but a person generally stays with the 19 spline rear axles. In 1951, the Merc-O-Matic was available so there are some tall gears for those. The overdrive trans models generally used a 3.9:1 gear set in either the 41 or 44 axles. The 41 just has the smaller diameter carrier with a slightly smaller ring & pinion ratio.

[38 coupe]

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The rear cover is shaped differently on Dana 41 vs Dana 44. 1950 should have a Dana 41, but you should verify first if you still want to re-gear your axle. I have not seen a Dana 41 gear set with higher speed than 3.54 (link to one vendor for those gears here). However, since you have a heavy wagon I would go with the overdrive transmission route instead of re-gearing the rear axle. You don't have to have all the factory controls, you must have a working solenoid and you can turn it on and off yourself.
I have friends with a 1950 Mercury sedan that is stock other than a +.060 bore and dual exhausts. That car has a 4.27 rear axle ratio and owns the highway in overdrive, it is a great setup.


edit: I found a web page that shows the difference in shape between Dana 41 and Dana 44 rear covers. Scroll down in this link: https://ck5.com/forums/resources/axl...tion-chart.10/

[jeepguy1948]

An overdrive should be very high on your list if you want to accomplish your goals. If you had an overdrive you could keep the rear gears that you have and the ability to “split gears” is priceless in a heavy car. If you want to skip the od then I would say 3.78 is probably as high as you want to go (for one thing your clutch is going to suffer with a heavy car, people think about top end, they forget about stop and go). They are expensive and there is a long wait but Steve Mitchell at Mitchell Manufacturing is who you need to talk to. Just my $.02

[Kens 36]

Unless I am missing something, the Mitchell is not appropriate for a 1950 Mercury.

I have the standard rear end ratio of 3:90 in my 1951 Mercury and added an overdrive. Works perfectly and is a pleasure to drive.

Ken

[pistonbroke]

I would just install the stock Overdrive and end all your problems . It will drop out of over drive when needed and back in when ready. The stock over drive rear end gears are what you have already, are you sure your wagon didn't have OD originally? Tim

[Sixseven]

I'm keeping the rear end for now and want to thank everyone for their advice and for searching their stock for used OD transmissions. I gave Mac Van Pelt a call and he assembled a completely rebuilt OD trans for my car, complete with new controls. I may get around to a 3.9 rear end but for now I'm going to see how the OD works for me. Here's a pic of me, my new transmission and Mac Van Pelt at his shop.

[Don T]

1950 Meteor, stock 239, 3.88 gears, 27" tire diameter, stock overdrive. Most of our travels to shows here are 1-3 hour drives at 65-70 mph. It is quiet, easy on gas, and it takes a big hill to ever have to use the kick-down. I am not sure I would keep it if it did not have the overdrive.