VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Filling '30 Chev. 11/2-ton trans, differential

Hello -- I am getting ready to put fresh 600W oil in the transmission and differential of a 1930 Chev. 1 1/2 ton truck and would appreciate some information.
I see one small fill plug on transmission, on the driver's side. Is that the only fill hole?
With the differential, do you pump out the old oil? I don't see a drain plug.
Thanks in advance.

There is a drain plug on the bottom of the transmission and a filler plug on the side of the transmission. After the oil is drained from the transmission, refill until the oil is just a little down from the bottom of the transmission filler plug hole. You can put your finger in the hole to feel the oil level.

On the rear axle you can either pump out the oil or remove the rear cover to drain the oil. If you do remove the rear cover then you will have to replace the cork cover gasket. Again, use the same procedure as above when refilling with oil. The oil should be slightly down from the bottom of the filler plug hole.

Junkyard Dog == Thanks for responding; you are a big help. Thanks to you, I have the rear axle situation figured out now, but I'm still uncertain about lubricating the four-speed transmission.
When I lift the floorboard on the driver's side, all I see is a small filler plug on the driver's side. It is much too small to put a finger in. Is there another filler plug? If so, where is it? And what is the small filler plug I'm looking at?

Look on the passenger side near the emergency lever.

Yep...there you will find the large filler plug.

Ah, ha! I now see the square head of the large filler plug you're talking about. Thanks, JD and Chipper -- that solves the mystery. One last thing... do I also need to fill the little one (on the driver's side) with the 600W oil?

I don't think the little one on the side of the differential is a drain plug....

You can also take a couple of the lower bolts out of the differential inspection plate and most of the old lube will drain out, it works best if you do it after a 30 minute drive and the lub oil is warm, But on a really bad differential, that has been setting out for several years, I have pulled three bolts out of the bottom of the inspection plate and after letting it drain overnight pour in a Qt. of motor oil or solvent and let if all drain out before putting the bolts back in and refilling with fresh lube oil, just be sure you don't fill it so full with motor oil or solvent that it will run down the axle housings and get the brakes oily.

Mack for most old Chevys all you need to do is wait a while for the oil to drain from the transmission past the worn out torque tube seal into the rear end and out the axles. Since most people do not know that there is a seal just behind the upper torque tube bushing and the original is cork which does not last forever, the vast majority overfill the rear end and ruin some real nice brake linings.

The smaller filler plug I was refering to is near where the speedometer cable comes in, on the driver's side of the transmission. I was wondering if it needed the 600W oil, also.

The small plug above the speedo-gear worm drive was for the factory to quickly get lube to the universal joint. If it were me I would put a wee bit of oil in especially if everything was new & dry when assembled.

35 pickup man is correct. By a "wee bit" that would be about 1/2 pint only.

Right, I thought you were talking about one of the "plugs" on the side of the differential.

I have been told that when you put sealed bearings in the transmission it is necessary keep filling the U joint bell, since it won't get lubed from the transmission, but the lube oil may drain down into the differential, is that true?

Thanks, one and all ... I'm all set now.

Hi MrMack- replacing the seal at the rear of the driveshaft torque tube bushing and then adding a vent fitting should eliminate the problem of oil draining into the differential-There is not a way to check the level however -If the rear is not overfilled and no leaks at the U joint bell then I have to "assume" the oil level in the joint is ok.I am considering putting a check/fill plug in the trans rear housing on my '32 as I would like to be able to check the level.I do have sealed bearings in both my trans and diff.