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1941 Auto Transmission

Started by James Bartlett, June 05, 2007, 11:07:41 AM

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James Bartlett

I'm looking at a '41 Caddy with original automatic transmission, and was wondering how well these transmissions performed. Can they be rebuilt? Are parts available? If you had the choice between a manual and auto transmission, which would you prefer? Thanks for your help. I can be e-mailed at jbartlett1@houston.rr.com


Doug Houston

After March 1, 1941, Hydra-Matic was available on Cadillac. It was pretty successful, having had some campaigning. Of the four '41 Cadillacs I have, three have Hydra-Matic on them. I have replaced the original transmissions with post war transmissions, and the cars are a joy to drive.

Now, on the original transmissions. If you can find a reliable shop who is interested in maintaining the transmission, you can enjoy it to the fullest. there is a guy in this arera (SE Michigan) who has a '41 60 Special with the original Hydra-Matic in it, and it works beautifully. It's even reasonably quiet too. Many of those early transmissions screamed like a tortured cat, and some did not. His shop has had luck wit finding parts when he needed them, but there will be a day, when he will be face to face with reality, and  the transmission will no longer be maintainable. Parts for post war transmissions are still around, but they never were abundant for the 41-42 cars, because of the short model year usage. Almost none of the parts in the early boxes carried over after the war.

If you like the car, go ahead and buy it. If the transmission isn't performing perfectly, have the valve body removed and have the valve plug bores cleaned in it, so the valves slide smoothly in their bores.  Should there be other issues with it, the best route is a postwar transmission replacement. The later transmissions bolt in place of the old ones exactly. In order to do this, you'll need everything from the flywheel to the U-join t yoke from a 46-48 Cadillac. Re-use the two control levers.

And whatever you might do; don't just stick a "working" transmission in ther car. Have it rebuilt with new seals. If you think you're saving expense by doing this, just wait for the bill to re-remove it, and do the job right!

Rusty Shepherd CLC 6397

Quote from: James Bartlett on June 05, 2007, 11:07:41 AM
I'm looking at a '41 Caddy with original automatic transmission, and was wondering how well these transmissions performed. Can they be rebuilt? Are parts available? If you had the choice between a manual and auto transmission, which would you prefer? Thanks for your help. I can be e-mailed at jbartlett1@houston.rr.com


One thing you'll need to know about early Hydramatics is that after starting the car in Neutral (there is no Park position), you must pause in Hi (apparently the designers couldn't come up with the word Drive for the primary operating position) or Lo and wait for the transmission to engage it before shifting to R. Failure to do this will result in clashing gears and premature transmission failure. In post-war cars, a change to the valve body forced you to make this pause and in about '51 an internal change eliminated the clash and the need to pause. Also, you'll find that pre-'56 Hydramatics shifted much more abruptly than modern transmissions do (particularly the 2-3 shift).  If you've ever driven an automatic Mercedes from the 60's, 70's, or 80's, they shift much the same way.

Doug Houston

The other half of what Rusty said above is: On all H-M transmissions before 1951, THE REAR WHEELS MUST BE TOTALLY OUT OF MOTION when you drop the selector into reverse. Even with the postwar trannys, when the reverse blocker opens in the valve body, you can still do some damage if you drop into reverse  with the wheels rolling.  Now, another item: with the engine not running, reverse locks the drive shaft. That was the "park" brake on the early H-M transmissions. Best to use the parking brake too, though.

The 1951 and later models had a cone clutch reverse, and you can yank the selector into reverse as soon as the engine fires. I have one on one of my '41s.