What Are '41 Buick Transmission Seals Made Of?

[Matt Harwood]

I've got my Century's transmission partially disassembled for cleaning and painting. I was considering powdercoating the case, which involves temperatures of 350 or so. The transmission is in great shape and doesn't need any repairs save for new gaskets. Do the front, rear and shifter shafts have fragile seals or can they withstand the heat?

Any advice is appreciated. Thanks in advance!

[37sedan_mod47]

Matt, most elastomers I know of would be damaged beyond service at those temperatures, even some of the more modern synthetic compounds (some of which can withstand brief temps of 350-400 deg. F.). Your seals are most likely made of Nitrile or Butyl rubber, both of which are good for 250 deg. F. max. I would recommend replacing your transmission seals regardless, since they may be 50+ years old. Nothing sucks more than an oil leak on a newly restored and rebuilt car.

[palbuick]

Hi Matt

A couple of good coats of good enamel will do the same as the powder coating, will look just as good.

Plus saving time and money over powdercoating. I have the side shifter seal if you need one. Recently went through my 40 Trans, and painted it the same color as motor, What color are you planning to paint trans?

Jim Schilf

palbuick@aol.com

[Matt Harwood]

Hi Jim,

Thanks for the advice. I'll take that seal--let me know how much and I'll send off a check ASAP. I've decided to paint the transmission instead of powdercoating it. There just isn't a practical way to insure that powder won't get inside and to keep it from getting damaged by the heat.

What about modern O-rings instead of the cork seals? I noticed that there is another cork seal on the input shaft--how about 2 O-rings there instead? Are there modern replacements to replace the cork? Any thoughts?

Thanks. Jim, drop me an E-mail at toolman8@ix.netcom.com and let me know how much and where to send it. Thanks!

[Charles2]

I just finished disassembling, cleaning, inspecting and reassembling the transmission from my 1940 Special. I think it is the same gearbox as in your Century. As best I can tell, this is the first time the transmission on this low-mileage car had been apart. The seal on the shifter shaft (the one that runs across the transmission) was made of leather; I replaced it with a neoprene-type seal. The selector shaft (the one running vertically) has a small fiber seal of some sort on the inside of the transmission. This one was in good condition so I didn't replace it. You could use an O-ring of the appropriate size as a replacement for this small seal if necessary. Bob's Automobilia has replacement seals for the shifter shaft.

[Charles2]

I forgot to mention that there are no seals on the input and output gear shafts, the front bearing is shielded and has a slinger and the universal joint is lubricated from the rear of the transmission. But, there is a small cork and rubber seal in front of the casing on the input shaft. This fits in the throw-out bearing support and (hopefully) serves to keep transmission lube from working forward to the clutch disk. Bob's also can provide this little seal.

[Matt Harwood]

Thanks, guys. I decided to paint the transmission instead of powdercoating. Still, as someone mentioned, it's probably a good idea to replace all the seals before reassembly. I also received an E-mail from an old Cadillac mechanic who says that there are O-ring replacements for all the cork seals on the selector shaft and the input shaft, which I'm going to try to find. Thanks for all the advice and we'll see how this works out. I'm pleased that the transmission is so easy to work on, but deathly afraid that once it's back together in the car, it will leak. What a nightmare that would be!

Anyway, thanks for the advice!

[Charles2]

Matt,

The only place on that particular transmission that is prone to leaks is the torque ball assembly. You need to put in a new seal and fit the torque tube ball to the torque thrust and retainer assembly. This is done using gaskets of different thicknesses. If you don't do this, the back-and-forth movement of the torque ball in the thrust/retainer assembly will pump gear lube out at an amazing rate. You can get torque ball assembly seal kits, again, from Bob's Automobilia for about $25. You might get a bit of seepage from loose seals on the shifter shafts. I replaced the seal as much to keep dirt out as to keep lube in. Leakage around the input shaft and output shafts is controled through mechanical design, not seals.