So about a year ago I purchased a 1947 Oldsmobile 76 fastback coupe. This car was off the road since 1982, but kept indoors most of the time since then and was last run 3 years before I bought it. I got it running again the week I bought it.
As long as I have had it the original Hydramatic automatic transmission has not been right. When I first drove it last year it only had first and reverse. A couple more times around the block other gears started to wake up and I gave it a trans fluid change (still had the whale oil in it) and dropped the pan to clean out the significant sludge and change the gasket. While I was in there I found some teeth in the pan which I think are from the reverse gear as it sometimes grinds or fights going into reverse.

That is about the extent of what I can do my self.

The trans tends to overheat (like 240 degrees) and smoke if ran continuously for over 20 miles or over 30min. After ~3 miles and or 5 minutes I loose reverse...The selector will go in but the car won't move or occasionally will creep forward. After 35min-1.5hours with the ignition off it will cool enough to go into reverse again. Also when it starts to overheat 1-2 or 2-3 shifts (not sure which) devolve into some weird banging slippage where its hard to get over 30 in HI and the trans repeatedly bangs like a bad flat tire. I've been able to bypass that by shifting to LO flooring it to get above 30MPH then letting off and shifting to HI. and accelerating up to the 45-50MPH speedlimit.

I'm not equipped to pull the ~500LB cast iron trans out and even if I could I'm not knowledgeable enough to service it correctly without help form someone that knows these.

I'm hoping someone knows a reputable shop around Waukesha Wisconsin that has experience rebuilding these early Hydramatics.

 

Good luck on that hydra-matic. It is hard to find anybody that knows anything about these old transmissions. The guy that rebuilt mine about 4 years ago passed away earlier this year. Mine was not as bad as yours but I knew I should have it rebuilt while there was somebody around to rebuild it. You are correct to not try to pull it yourself. These thing are a beast. Good luck on your search.

 

Before you throw in the towel you might try adjusting the long rod that goes from the carb linkage to the transmission. Mark where you start so you can go back if this doesn't work. Try small 1/8 turn on the rod and try your shifts after each adjustment. This rod adjusts the length of time for shifts some what and the gear that it needs to be in. It could be that you are between gears and the transmission is searching for the right gear for the RPM it is in. Sometimes a little adjustment helps a lot. It won't help finding the teeth at the bottom of your pan though, you will have to address that at another time...Good luck....Tedd