The Stovebolt Site Forums The Shop Area Driveline 1941 GMC rear inner seal

I have a 1941 GMC series 400 2-ton truck. The rear inner seal is leaking oil. I'm suspicious the felt is the culprit. The shaft and old seal are not badly scratched. Any help is greatly appreciated! I'm very happy to find this forum!!

Thank you!

Matthew

Hy Matthewnotmatt, welcome, could you please post your trucks complete serial number. According to my old Victor seal catalogue there are a couple of different seal possibilities. You should also inspect the old seal looking for part numbers and if you could measure and post the dimensions of the seal that would also be helpful.

Thank you for the reply <3
My VIN is 1574114307
If that's not the number you need I'll crawl around the thing and find the serial number. The engine number is impossible to read, but I'll keep trying!
Also, there are no numbers stamped on the seal. Mystery seal.
Here are the measurements for the inner seal, my calipers are in metric... if that's a problem i can go get another one that's standard.

Inner seal:
79mm inner diameter
120mm outter diameter flange side
111mm outter diameter non flange side
13mm felt thickness (approximate, it was swollen)
29mm deep front to back
1mm thick metal

Okay, I think I found the serial number. There's an ID plate on the drivers side firewall. The number is "i574-ii4307". I used lower case i's to avoid confusion with the number 1.
I also found a number on the floating axle "3412*F"
And on the transmission pumpkin "19750"

I also got some calipers in US Standard measurements this time, much better.

4.49" - Wheel Drum inner diameter
3.12" - Shaft inner diameter
4.37" - seal outer diameter non flange side without felt
4.48" - seal outer felt washer diameter
4.75" - seal outer diameter felt side
3.12" - seal inner diameter (same as shaft diameter)
1.15" - seal thickness

If possible I'd like to buy a new inner seal, ideally with improved design. I found felt washers on McMaster Carr (https://www.mcmaster.com/felt-sealing-washers), that's an option to keep the metal seal and replace just the felt. Not completely sure how I'd get the felt in there without destroying it...

Hy again Matthewnotmatt, Okay, by size only Chicago Rawhide part number 31269, or National part number 455145. Once you find a supplier of either of those part numbers, take your old seal with you for comparison purposes. The other identification I was looking for was the letter designation of the model of your truck, AC, AF, ACS, ACW, CCW, CFW etcetera. My old Victor seal catalogue is the most complete book I have, but unfortunately I need the letter designation to zero in on the correct part number. I did try to confirm which Victor part number was the correct one by using my seal interchange catalogue, unfortunately none of the possible Victor part numbers appeared in my interchange catalogue. I hope the numbers I did find are helpful.

Thank you!! I'm still learning so much about this truck! I'll get the correct model number for the truck and get back to you. I'm away from the truck for a few days, I'll update here on the forum when I do.

I'm researching the seals you sent me from Rawhide and National. I very much appreciate a tip in the right direction. Finding this mystery seal doesn't seem so hopeless now

M

Okay!!! I think i got somewhere. I'm back in LA and i got some help with the seal measurements. Just got a replacement in today. It's not the felt style, it's newer. Wish me luck! I'll post the results here.