Model A Auto Transmission
- Thread starter Tveditr
- Start date
Charlie Stephens
Well-known member
Several people have done an automatic transmission for the same reason you have. Search the archives for "automatic transmission" Use advanced search so you can restrict your search to Model A's. Put your location in your profile there may be someone close to you.
Charlie Stephens
Charlie Stephens
Y-Blockhead
Well-known member
Check with Bendtsen's. They list an adapter for the Model A to Chevy Automatic transmissions.
https://cdn.shopify.com/s/files/1/0021/2415/2950/files/FO1001101.pdf?v=1592251539
There is also a kit or plans to use the small 904 Torqflite trans.
But I have a concern: If your Dad doesn't have the leg strength to push in the clutch, will he be able to push the brake hard enough to make a panic stop? Or the arm strength to quickly steer around an obstacle? Or if he no longer has the foot/hand coordination to shift gears, does he have the cognitive ability to drive at all?
I don't mean to throw rocks, but these are situations that I think we all must face at some point.
/
Gene F
Well-known member
NHUSA has a point to consider. Besides, someone in the family can take him for a drive in it.
I'd like to add something, before you undertake this project. The rule-of-thumb on automatic transmissions. We will look at the Chevy transmissions... A THM350 takes 35 HP to drive. A THM400 take 50 HP to drive the unit. Something to think about.
Tveditr, I don't mean to be dictatorial, or negative. Hope you understand that every once in a while I have undertaken collector car projects, and after done I have said to my self "had I known, I may have done this differently. Not trying to decide for you. In my mindd it's always nice to have options.
I'd like to add something, before you undertake this project. The rule-of-thumb on automatic transmissions. We will look at the Chevy transmissions... A THM350 takes 35 HP to drive. A THM400 take 50 HP to drive the unit. Something to think about.
Tveditr, I don't mean to be dictatorial, or negative. Hope you understand that every once in a while I have undertaken collector car projects, and after done I have said to my self "had I known, I may have done this differently. Not trying to decide for you. In my mindd it's always nice to have options.
SteveB31
Well-known member
I installed a Chrysler 904 automatic in a 1931 coupe 20 years ago, and it ran and drove wonderfully even with 3.54 gears, so to those that think it takes 35hp to run an automatic transmission, you are very incorrect in your statement. The car was fast, shifted up and down just like to was supposed to. A joy to drive.
Slowmotoring
Member
A perfectly good model a is only perfectly good when the owner is perfectly happy with it. If that means putting a automatic transmission in it, and he can otherwise drive it safely, then perfect! Put the automatic in the car and a smile on his face! I dont have a clue on how to adapt a automatic transmission to the original model a engine but i hope you find a way for your father to enjoy his car for as long as possible. After all the model a isnt a rare car, hence the reason why they are probably one of the least expensive classic cars to buy and repair. Dont get me wrong. Some model a’s are rare since some models didnt have high production numbers and some are true survivors in spectacular condition but these cars are typically trailer queens not being driven anyway. So for the most part the model a isnt rare. Do what you need to do to enjoy the car and enjoy it!
Doug Linden
Senior Member
I believe that John LaVoy's "Model A Times" magazine is going to feature this type of conversion in upcoming issues.
Jack Shaft
BANNED
I've been involved with a few conversions, I learned one thing. In my opinion removing the torque tube and going open driveshaft with a model a ford is a mistake. others might cite me for this opinion, and that's fine, fire away.. I worked on one that the rear axle torque rolled 45 degrees.. radius rods hanging from the axle flange bolts. The only thing that kept it together was the spring shackles. The actual lash up is straight forward, and you can design a transmission to work with the A's torque range..
Might I ask where you got this information? I have heard similar claims, but have never seen nor heard of any actual tests to back up such statements! Such a "rule-of-thumb" is just another baseless urban legend.
Some power is needed to run the front pump, but nowhere near 35 or 50. And why should a THM 400 require more horsepower than a THM350? Both run the same operating pressures, both have the same number of gears, and the same torque converters.
Last edited:
Jack Shaft
BANNED
That's an extremely high loss rate.. the transfer of power from mechanical to fluid and back to mechanical (torque converter) does require power as well as the transmission pump as cited above.. but not 50 hp..what it does do is limit the way the driver controls the engine torque, and that's what makes a model a fun to drive,,
Off topic but:
Just a quick reference. If you want/need to run an open driveshaft, you will want to check out:
http://www.modela5conv.com/advertisements.html
See their third link kit to handle the "wrap up" torque from the rear end. You could probably come up with something similar on your own.
Just a quick reference. If you want/need to run an open driveshaft, you will want to check out:
http://www.modela5conv.com/advertisements.html
See their third link kit to handle the "wrap up" torque from the rear end. You could probably come up with something similar on your own.
Jim Brierley
Well-known member
Art Moore is a paraplegic and has installed a Chrysler 904 in 2 of his A's. The conversion has to be done correctly, but is a very worthwhile project for any handicapped or older person. Art races his speedster at hill climbs, etc., and does very well with it. He first ran one with a stock B engine, it also performed well, so horsepower in not a major concern, and raising the HP on these engines is very easy to do, and not expensive either. If my dad wanted to drive his A, I wouldn't hesitate to put an automatic in one for him. There easy ways to adapt Chevy and Ford transmissions too.
Gene F
Well-known member
Saturday mornings they used to play car how too segments 1/2 hr each on "Speed channel". They were rebuilding a THM350. A automatice does have some parasetic drag, so they are not as efficent as a stick.
51504bat
Well-known member
You are entitled to your opinion but it is after all HIS car. The 3 speed trans in my 8ba powered '39 p/u came from a guy who has an absolutely gorgeous '39 convertible. Problem was his leg could handle the clutch anymore. He swapped out the stick for a c-4 and once again he is back to driving his car. And I got a cherry big fork 3 speed trans for a fair price. A win win all the way around.
Y-Blockhead
Well-known member
The Ford C-4 has the least parasitic drag of most automatics. I have a C-4 in my '55 Ranchwagon with a Gear Vendors gear splitter behind it. I think it would be fantastic to have a setup like this in a Model A for a driver who could no longer use the clutch.You would have to convert to an open driveshaft also.
Alaska Mike
Member
I would not deny the old fellow his opportunity to continue to drive his car, if all it took was an automatic transmission. You can always change it back.... The memories made are worth more than any model A.
I don't mean to throw rocks, but these are situations that I think we all must face at some point.
very good point. In his last years my father developed neuropathy in his legs. He accidentally hit the gas peddle over the brake and ran his car into a brick building.
thank God nobody was in front of him.... he gave up driving shortly thereafter.
very good point. In his last years my father developed neuropathy in his legs. He accidentally hit the gas peddle over the brake and ran his car into a brick building.
thank God nobody was in front of him.... he gave up driving shortly thereafter.
Jack Shaft
BANNED
Oh my somebody said it...its HIS car...in America personal property rights are paramount, I spent a little time in my life defending that freedom, where a man can do as he wishes with his belongings. I try to explain that to the purists, that they sound like Nazis when they try to impart that altering a model a ford is blasphemy on others. Do as you wish with your car, defend that freedom with your life if necessary, others have.