The GMC CCKW

question for expirienced mechanics, the back seals come with at least two materials (rubber and leather) and some variety of thickness, their position also differs as the tightening of ball bearing nut changes the position od sealnut, hence question, with some distance washers it is possible to establish right distance of lip seal extruding over hub.

But what this right distance would be ??? Obviously if its too small oil will get into hub, if its too big the seal will wear out pretty quickly.

Assuming banjo axles:

Push the axle in with the gasket on it and see if you hit resistance about 1/32 of an inch from hitting the hub. If not, tahe a screw driver and pry the seal out of the nut a little. Make sure you do this evenly or it will leak. Repeat the above process of testing for the 1/32 inch

Many thanks for your reply, however are you sure that 1/32 isn't too small ??
at present I did have seal extruding for around 0,9-1 mm on one and 0,6 mm on the other, this measurment roughly equals to 1/32 inch and there was oil in the hubs, instead of prying the seal out I used additional washers, as a result I have 1,5-2 mm (1/16 inch) now, I am planning to drive some 300 miles this weekend I will post running report later

then again with so big elements as axle shafts and flimsy rubber it is really difficult to establish right measurment, actually I did measure with calipers without axle shaft, when pressing axle shaft againts rubber the measurment could be little differnt, after all it is not NASA space shuttle but 70 years old truck

1/16 will work too. The idea is that if you press too hard, you will burn off the seal. Don't forget to put some grease on the face of the seal.

While reinstalling the rear axles in my truck, I somehow ended up with one rear seal that sat significantly lower than the other three. It was actually flush with the outer surface of the hub face.

I found some 0.010" thick round shims in the McMaster Carr catalog that worked perfectly for moving the installed height of the outer nut out to where it would just contact the axle shaft.

http://www.mcmaster.com/#3088a333/=qdtg3z

The ID of these shims is 2.000", so I had to open them up a little with a file, but after installing three of them between the outer nut and the spider washer, the seal is right where it needs to be.

Best Regards...

That is a GREAT way to solve the problem. Better than my way! I will have to order some.

The civy trucks of that day with GM banjo axles did not have that seal. It was added after the best way they could without a redesign. The splits have a MUCH better system.