40 pick up trans, gears

[olfarmer]

Hello
Great site, been reading for years and been able to answer many questions about my 40 pick up. The past year I have re-built a 51 merc engine and is ready to install. The pick up has the original 4 speed with the lever to put it in reverse. I have been told it would make a better driver if I installed a three speed trans. The rear end gears are 4.10 and willl need to install different gears. It has been a long time since I drove it but did not like going over about 60 mph. What I am looking for is a good driver that could handle some interstate driving and short trips. Thanks for all the infromation and advice that is passed along to people like myself.
Mike

[Mac VP]

Your 4 speed trans is NON synchro and had the noisy straight cut gears. Its first gear is VERY low. High gear is 1:1 ratio like any 3 speed trans. If the vehicle is a half ton pickup, the regular 3 speed trans would be a nice swap and easy to do. High gear is also 1:1 ratio.

You can also change out the rear end ring & pinion gears to a higher set (ie 3.54:1) instead of your 4.11 set. That would give you a nicer cruising speed at comfortable rpm's on your motor.

[olfarmer]

thanks for the information and I will start looking for a 3 speed trans and a set of gears
MIke

[Barry WNY]

I would be looking for a complete reared, go through a matching unit and when ready swap it out. That way there is not so much pressure on the job. You have a few years there not much change car or truck. 3.78 are common I use it and am happy with it but I don't go over 55. A good used rear would cost about half a new ring & pinion, all the new goodies to go with it will cost the other half.

[olfarmer]

Thanks, I will look for another complete rear end go thru it and repalce as needed and change it out. What model and year of 3 speed transmisions that will work without any modifications and would be a good choice?
Mike

[Charlie ny]

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'olfarmer,
A late '39 to '41 trans is in my opinion the best because of the
improved syncro design. You must swap the clutch release shaft on
the '39 to the tang style that was introduced in '40. As you probably know
the '42 up truck transmissions were open drive so to keep things 'simple'
'41 back is the road to take, IMO.
90 % of these trans have the 16/28 tooth gear sets which are
more driveable than the 15/29 sets.
Mac VanPelt and others including me have these transmissions...
usually in stock...and/or parts.
Charlie ny

[Mart]

If it helps at all, I put a little video on Youtube demonstrating how to check an early Ford axle ratio.

Bear two things in mind: You turn the free hub or wheel twice, and the other hub stays still.

https://www.youtube.com/watch?v=bkvp3Fq21ZM

You can also hear my English Birmingham accent - think of Ozzy Osborne without so much slurring.

It might be, as it is a truck and may occasionally be expected to carry something that a 15/29 gaerset in the trans might be more suitable especially if used with a 3.54 rear end, and still worth considering with a 3.78.

Mart.

[rotorwrench]

The 15/29 works well with the 3.54:1 set for higher speeds and the 16/28 trans gears work well with the 3.78:1 rear gears for intermediate loading with fair speeds. If you are planning on driving with loads or pulling a trailer or what not, you may consider the more intermediate gearing of the 16/28 or 15/29 trans gears and the 3.78:1 rear gear. If you are going to run it for just light load cruising on relatively flat road surfaces then the higher speed set up would do the job for best economy. It will be set up more like a pasenger car than a truck but that's up to the owner to decide.

Kerby

[41panelmark]

Thought I would chime in on this. I have the later 41 transmission with a strong 41 motor and Merc crank. I went to the 3.54's and what a difference it made in cruising down the road without pushing the engine hard. You will be happy you did this.