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41 transmission replacement

Started by Rod Dahlgren #19496, September 29, 2009, 09:43:02 PM

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Rod Dahlgren #19496

I know this has been asked before but since I cant remember what time to stop work to eat anymore, I need to be retrained on this one.... What do I need to do to bolt up a 46 to 53 automatic trans to the 41 engine?

I did not specify what year trans... Yes I know they are the same but different.... Yes, I can look at them and think about it myself.... Just want some extra input here.
Did You Drive Your Cadillac Today?

Doug Houston

I always squawk about replacing prewar transmissions with later ones, as everyone here knows. So, out with the soap box, and here we go!

I have H-M postwar transmissions on three of my '41 Cadillacs, and one on my '41 Oldsmobile. The selector quadrant matches on all of them through 1951. Though you can put a dual range transmission on one, as well. I'd recommend staying before 1953, though. They may work strangely with a later model.

One of our guys locally, has a '41 with a '54 transmission in it. It does all sorts of strange things. While it may not be the transmission's fault, he has an attraction to incompetent transmission shops,  and an allergy to sound advice.

You'll need the transmission, of course, the 46-48 bell housing, fluid coupling from 46-48, and flywheel from the same cars. If your crankshaft has studs on it for the flywheel, they unbolt, so that you will be able to use the screws from the H-M flywheel.

Keep the selector lever and the TV valve lever from the '41, and re-use them on the new trans.

All postwar transmissions have the slip joint with the front U-joint, so have that joint yoke on hand. If the '41 is one that originally had a slip joint in the drive shaft, just forget about it, and use the original drive shaft.

The front pump was changed from 1949 and later. It protruded past the transmission face, and there isn't a relief in the flywheel housing to clear it. If you have one of those transmissions, you'll have to have a 4 inch diameter counterbore; 1/4 inch deep, machined in the bell housing to give the needed relief. That's the only modification necessary for the transmission update.

Once in the car, with engine running, be sure to do an external band adjustment in the transmission. It can make the difference between perfect and lousy performance.

Two of my '41's have '49 transmissions in them. and the third has a '51 in it; all from Cadillacs. because of differences in Hydra-Matics in other cars, best to stay with a Cadillac transmission. I'm totally delighted with the way all of them perform.
38-6019S
38-9039
39-9057B
41-6227D
41-6019SF
41-6229D
41-6267D
56-6267
70-DeV Conv
41-Chev 41-1167
41 Olds 41-3929

Steve Passmore

What was wrong with the 41 transmission?? I only ask as your a strong advocate of originality.
Steve

Present
1937 60 convertible coupe
1941 62 convertible coupe
1941 62 coupe

Previous
1936 70 Sport coupe
1937 85 series V12 sedan
1938 60 coupe
1938 50 coupe
1939 60S
1940 62 coupe
1941 62 convertible coupe x2
1941 61 coupe
1941 61 sedan x2
1941 62 sedan x2
1947 62 sedan
1959 62 coupe

Doug Houston

If it's me you're asking, this is what I know:

1. The front pumps on most (not all) of them are noisy, to varying degrees. They vary from unbearable to tolerable.

2. Shifts are positive, but soft.

3. There is no detent in the transmission. It's in the selector head, and is rarely sharp enough to hold the selector lever in place.

4. Reverse is far trickier than in the 46-50 transmissions. There is nothing to prevent you from doing a lot of damage if you don't do it properly.

5. Replacement parts for these are harder to come by if, for no other reason, because fewer units were made.

6. From all I've seen, maintenance is needed more frequently than on later models, though this may be solely my impression.

7. Clutch pistons were 6 small ones, that could not close the clutch plates. tightly enough. Mainline pressure needed to be higher.

All of the above things were designed out of the transmissions after the war, or during it.  All of them were incorporated in the post war units.

One of our fine comrades nearby has a 41 60S sunroof model, with an original  H-M trans. in it. It's about as quiet as I've ever seen, right from 1941. He's had it out of the car a couple of times, I understand, and it does have a torus cover leak, from his description. I feel as he does, that since it's original, and has about 100K on it, don't change it. He knows that, if he ever hes to have it worked on again, and that parts are no longer there, I have a '47 trans.  in my stash that he can have. I even doubt that he'd consent to use it! I have four of the postwar transmissions in my cars, and none of them leak a drop. I rebuilt them myself.

If you wish to have the car perfectly original, and have the transmission working properly, no one could ever fault that.

If you are going to drive the car, especially on a tour, and you have a breakdown along the way, you have a chance of finding a shop that could service a postwar transmission. If you have the original one in the car, you're going to play H--l finding a parts source for it, or someone to fix it.
38-6019S
38-9039
39-9057B
41-6227D
41-6019SF
41-6229D
41-6267D
56-6267
70-DeV Conv
41-Chev 41-1167
41 Olds 41-3929

Rod Dahlgren #19496

OK, Some help so far... Thanks! I too, respect originality. But this car is not a show car, just would like it to be a respectable driver. The FORMER owner had taken apart the trans a couple times trying to fix it and gave up and put the car up for sale.. I bought it.. I have a KNOWN good 52 and 49 trans... So since the externally are very similar and far superior to the 41 tans... Easiest way to go so I can get the car back on the road is to put one of these in the car. Yes, the 41 trans. will go back in the garage for safe keeping.
Did You Drive Your Cadillac Today?

Doug Houston

One more remark. Well, two. The '49 transmission would be the best choice to use in the car. The '52 is a dual range, and will work well in the car, but it has the two "drive" positions on the selector, and doesn't exactly match the column quadrant.

Second. If you're going to install any "known good" transmission in a car, without at least checking the condition of the seals and the control valve body, you're courting lots of grief. I'd like to have a nickel for every "good" transmission that was put in a car as it came out of the previous one; then had to come right back out, and be rebuilt. Standard shift yes; automatic, no.

I've never seen or heard of a used automatic transmission going straight into another car, and either working right, or at all. 

It's your baby.
38-6019S
38-9039
39-9057B
41-6227D
41-6019SF
41-6229D
41-6267D
56-6267
70-DeV Conv
41-Chev 41-1167
41 Olds 41-3929

Rod Dahlgren #19496

Well Heck, Now I gotta clear up a couple things... The TWO USED transmissions I have came out of great running cars that the owners decide to Hot Rod. Not me, I did not do it.. But I DID drive BOTH cars prior to the tear down. So, yes, they are GOOD used transmissions..

I would LIKE to be a purist when dealing with collector cars.. But a rebuild of the old hydro could cost a customer as much as the car is worth. So to be realistic and try to save one more car from a Hot Rod conversion, I bought this car and will get it back up and running with a transmission I already own because I SAVED the parts from from guys that had already taken one more original out of the pool.

Of COURSE I replace the external seals... But there is no point in opening up a good clean working hydro..........

The shift quadrant position change is no big deal.. Us guys with Chevys of the 50's and 60's replaced the early powerglides with T-350 and T-400 long before anyone made the replacement instrument panel indicator.

And last of all.. Yes, adjustments must be made.
Did You Drive Your Cadillac Today?