The GMC CCKW

After servicing the hubs on my banjo front axle (clean, repack bearings, new seals - NAPA 36220 CR) I was having difficulty adjusting the front wheel bearings. When tightening the inner nut, the hub would become difficult to rotate, but there was still a lot of radial movement in the end of hub when I tried to move it up and down. After checking things over several times, I finally noticed that the inner metal surface of the grease seal was rubbing on an outboard surface of the spindle base. If you look closely at the attached image, you can see shiny spots on the seal surface where it contacted the spindle.

I checked the clearances with a caliper, and found that the stepped area of the spindle that the seal rides on is only 0.485" thick. With the seal installed flush to the inner surface of the hub, the distance between the seal surface and inner surface of the bearing race is close to 0.800" - resulting in 0.300" of interference.

I had to drive the seal farther into the hub in order to obtain sufficient clearance for the seal. I drove it until I measured approximately 0.435" between the seal surface and the bearing race - which should provide about 0.050" of clearance.



TM9-801, Sect. 35, paragraph 201 c (3), talks about installing the seal with either a "Replacer Tool" or a "block of wood".

Has anyone ever used the "replacer tool" ? Does it have a step or recess cut into it in order to install the seal to the correct depth? If the "block of wood" method is used, there are no instructions indicating how deep the seal needs to be installed.

Has anyone run into this before? Or is there something on my truck that is way out of spec? Note, both L and R hubs have the same issue.

Best Regards...

If they gave you a seal = for a DUKW, you will have a problem. They are NOT the same as a CCKW, The spindle is different

Thanks, Dr. D.

I am pretty sure the seals are for a CCKW. It is the PN listed on the cross reference page of this site. It is also correct dimensionally - at least with respect the to ID of the hub and the OD of the spindle.

I started looking through the manuals and found this cut-away in TM 9-1801. The seal offset required to clear the spindle base is actually shown in the drawing.



The thing that is different between the seals that I have vs. the one shown in the diagram, is the small metal ridge on the inner surface of the seal that appears to contact the outer bearing race when the seal is fully seated. This would definitely help set the seal depth when the seal is driven home. The NAPA ones that I have do not have this ridge, so I had to use the caliper method.

I'm just used to always driving the grease seal flush with the inner surface of the hub on any vehicle that I have worked on in the past- so this just seemed a little strange to me. This will obviously not work for the CCKW...


Best Regards...