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1947 hydromatic help

Started by Craig Lewis #21155, September 26, 2004, 03:24:23 AM

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Craig Lewis #21155

I have just finished complete rebuild on my flathead,which of course set me back a bit but worth it, engine is like brand new.
I have my hydro out and want to have it checked out before reassemblying back to engine. I have never driven this car. Bought it and began full resto. Engine was in bad shape. Anyway I have no idea what shape the hydro was in before I removed it. I thought about putting it back and trying it out but it seems kind of half assed to do that. My first concern is that when I pulled the drive shaft I lost some fluid out of the spline (do you thing it is a bad seal) I had no leakage while it sat before I took out the shaft and when I rolled it a few times when moving it around before I began teardown, I noted no leakes, is it normal for fluid to pour out when you pull the shaft from the spline? Also I noted that when I got it on my bench the tourus has slight play about an 1/8 to 1/4 inch up and down did something come loose?

Does anyone know anyone who can work on these old hydros, I fear taking to a tranny shop. They may accept it in and not know what they are doing and bugger it up. Im in Arizona if anyone can suggest a place.  

Gary Phillips

Im interested in a 41 Cadillac that has a Hydro-matic.  Do you have any general advise on the transmission.  How reliable were they in 41; how difficult might it be to find someone (in No. California) to work on it?   Anything else you can pass on would be appreciated.

Rusty Shepherd CLC 6397

Doug Houston is the expert on this topic (and several others)and will probably add to my reply if he sees it, but pre-war Hydramatics were not nearly as reliable as post-war units, which is why his Oldsmobile and Cadillacs have those transmissions in them. They were used throughout WWII in tanks (two Cadillac 346 V-8s and two HMs per tank)and many of the internal parts in the post-war units were beefed up due to wartime service. Id say theres a good chance that pre-war Hydramatic Oldsmobiles and Cadillacs still extant would have post-war transmissions in them. Doug can probably tell you how to determine if the only youre looking at does, but one way should be pump sing or slight whine that was present in the pre-war Hydramatics and not in those made post-war. One thing to keep in mind on all early Hydramatics, both pre- and post-war, is that when shifting into reverse, it is very important to pause in "Dr" or "Lo" and allow the transmission to engage in either of those positions before shifting into "R". Failure to do so causes gear clashing and drastically shortens the life of the transmissions. Also, youll notice there is no "P" position, but the transmission can be locked for parking by shifting into "R" and waiting for it to engage before turning the engine off.

Jeff Maltby 4194

Keiths Transmissions in Castro Valley (S.F bay area) Calif can rebuild any classic/vintage car tranny. Area code 510 information will get you to him.

Doug Houston

Well, as long as my names been mentioned in vain, this is what I know.

If the original transmission is in the car, and shifting properly, perhaps best to leave well enough alone. But for how long, who knows?  Now, possibly, the trans has been replaced with a postwar unit. There have been 60+ years for this to have happened!

The quickest giveaway is to peek down at the transmission from the drivers side of the engine. On the postwar models, there is a large Hexagonal plug-like thing at about 1:00 on the transmission as youre viewing it. Thats not there on the prewar transmissions. Its the pressure regulator valve.
 
On the controls, the selector detent is entirely in the steering column hub, where the indicator is on the prewar models. If the detents are light and not sharp, its a prewar box. The detent was moved to the control valve body inside the transmission after the war, and is very pronounced. Another of the many improvements made in 46 was the addition of a "reverse blocker piston" in the control valve body. This keeps you from yanking the lever into the reverse position until after the transmission engages. Even then, the rear wheels must be OUT OF MOTION before you can drop it into reverse. Whats happening here is that the drum of the reverse planetary must be stopped for a pawl to engage it and lock it. That wasnt there on the prewar jobs, and many a reverse planetary and reverse pawl were chewed up.

In order to make the transmission easier for rocking the car in snow or mud (Heaven forbid!) a new cone clutch reverse engager was incorporated in the transmissions from 1951 on. I have a 51 transmission in one of my 41s, and you can yank the selector into reverse as soon as the engine fires, with no problem. On that one, the 2-3 upshift is a little brutal, but I can live with it easily. The other two 41s have 49 Cadillac boxes in them, and Ive never driven a more enjoyable transmission, even in my modern cars.  

Bob Chesnutt 21760

There is an elderly gentleman here in Tucson that has a transmission shop.  I would expect he has experience.  I know his son so if you want me to check, let me know at bobandhelen@aol. com.

Bob C

Rusty Shepherd CLC 6397

Doug, I wasnt using your name in vain and I wasnt being sarcastic..sorry if it came across that way.  I wish I had just a small portion of the knowledge of old Cadillacs and Oldsmobiles that you have..as well as your Sixteens, 41 Cadillacs, and 41 98 Phaeton, probably the three cars Id most like to own.

Robt.Vonheck -via SunDiego Calif.

-While youve received some really great advise here by the knowing DougHouston and all;  --heres a great source for free-assistance and repair, that is the best i know of (you can scroll-down to the page-bottom for link to their home-page)...  
~Bob vH
[left-click:]  http://www.autotran.us/HMBAdj1.html TARGET=_blank>http://www.autotran.us/HMBAdj1.html

Jeff Maltby 4194

Great post Roberto.

The CLC boards where meant for this type posting.

Thanks

Jeffo