Over Drive

My favorite is the Mitchel with 26% ratio increase. 3.78-1 rear end ratio. If you just drive around town with your model A, then I wouldn't go to the expense and work of installing an overdrive. If you drive over the road, then I would consider getting an overdrive. Engine rpm's are reduced, making your Model A much more quiet. The expense is your call. If you have a friend with an overdrive, take a ride in his/her car and decide for yourself if it is worth it to you.
 
It depends on your use of the car---- do you drive long distance over 50mph?--- if the car won't go over 50 easily it may not have the power to use overdrive also
 
Yes on all the above, plus if you live in an area with hills its great to overdrive 2nd gear
going thru the twisty stuff.
Also add a high compression head at the same time, you will love your car.
 
Dodge said:
Yes on all the above, plus if you live in an area with hills its great to overdrive 2nd gear
going thru the twisty stuff.
Also add a high compression head at the same time, you will love your car.
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I agree with the HC head. A Higher compression gives you more grunt at the lower end of the rev range, just what you want with an O/D. All that is supposing the piggy bank can withstnd it.
As other have said, no need for an O/D if you only drive around town but if you tour, you'll wonder why you didn't do it sooner.
 
louieglen....are you asking about the 4-speed Ford F-150 truck trans from the 1980's and the 5 speed Chevy S-10 trans also?

fried okra
 
I believe Mitchell also makes a 36% but it is overkill for most. I just put a 26 in my CCPU for a daily driver on 65 mph highways. The other advantage is to be able to split the other gears, making it closer from 2nd to 3rd.
 
I don't feel qualified to say which is the best - I only have Mitchells in my cars. 2 with the conventional extra stick and 2 with cable shift. I think I prefer the cable but there's little in it.
 
I have had a 26% Mitchell for almost 14 years and love it. It is like adding a 4th gear that the a Model A never had. And the Mitchell is so easy to use I even use it regularly around town....anytime I hit 40-45 mph I shift into od. I have the heavier Town Sedan and would also recommend adding a HC head at the same time.....makes it easier to pull the od up slight grades, etc.
 
26% Mitchell with a 4.11 rear end ratio. Most A's are comfortable at around 2100 RPM cruising speed, with the above combo that's about 65 MPH. Too low RPM's is not good for the engine!
 
Jim Brierley said:
26% Mitchell with a 4.11 rear end ratio. Most A's are comfortable at around 2100 RPM cruising speed, with the above combo that's about 65 MPH. Too low RPM's is not good for the engine!
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That's true but high piston speeds in a long stroke motor like these is not good either. I don't like going over 50-55 mph with a 3.78 rear end and 26% O/D.
 
louieglen said:
No, I was wondering how many O.D's> were available for model A's, and which was the best. Thanks
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The transmissions listed in post #6 are both possibilities to install in a Model A.


They both have overdrives.


added: Each one has several different build codes and thus different ratio combinations depending on what modern cars they were installed in. Some builds work better with Model A.
 
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My favorite is the Volvo, which is the Laycock de Normanville as was used in the British sports cars of the 50's.One switch that is either in O/D or out. You do need to create a lockout so you Never Ever get into overdrive and reverse at the same time. They are a few hundred dollars less than the Mitchell and don't have square cut gears. Finding one is problematic, Rich Little around Bakersfield, CA has a few last I heard and he's wanting out of the business. Most popular is the Mitchell. They can make a 36% which would be good with a 4:11, or high rev engine. I have a 4:11 with 36% Borg Warner in my coupe and a 26% Mitchell, cable shift in 378 roadster. Both have Police heads and go rather well. I believe for me the 36% was better with a 3:78 as I don"t like to rev the stock babbitt high for very long. But I do have a spare engine built just for that bad day when and if I shake something loose With a new 5 main engine, I'm hoping comes out, I would love to do an overhead, 4:11 and 36% Laycock. Need good brakes for that.

Happy New Year and I hope you all had a Merry Christmas. Sorry I lost it on my last post, not good just before the Holidays. Won't do that again!
 
I do a lot of touring. Love the Mitchell. I have installed probably 10-12 units for others in recent years. One very special advantage with regard to the Mitchell is it requires NO MODIFICATION to the car. And, should you decide to sell your "A" and maybe acquire a different "A" you can easily remove your Mitchell, returning the car to original state and then install your Mitchell in your new "A".
 
I have a Borg/Warner 5 speed World Class transmission (based on transmission code) in my 1930 Model A Cabriolet with a 5.5 high compression head and a 3.78 rear end and I love it! The car cruises at 50-55 MPH in 5th gear with between 2000-2200 RPM: gas mileage on local rural roads and highways is 20+ MPG. I live in a hilly area in the lower Hudson Valley near the Catskills; hills are no problem but sometimes I shift into 4th with no loss of speed; engine temp stays at 160 except on long steep climbs it can go up to 170 but on long downhills drops to 150. A Model A friend of mine has a similar set-up with the same results. One advantage of the Borg/Warner over the Mitchell is one shift lever. Other members in our Hudson Valley club have Mitchells or an F150; they love them also. I don't think that you can go wrong with any of those set-ups and will really enjoy the results. Good luck and HAPPY MOTORING! Gary D
 
I should have added to my previous post that based on the casting# on the Borg/Warner that my transmission was out of either a 1988-92 Firebird or Camaro, or out of a 1993 Chevy S-10 V-6.
 
Anyone have any comparisons (or preferences) of the Ford F150 4 speed trans versus the 5 speed Chevy S-10 type transmissions?

Usage preferences, installation preferences, etc?

I also wonder which is more common and maybe how many total have been done with these transmissions.
 
The Laycock units are very, very nice, as are the T-5's like gary speaks of! Don't get an older B/W like was bolted directly to the trans, used by many car makes, they are slow shifting, tend to leak oil and suffered major damage from lack of oil.
 
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