Chevrolet C8 1940 Cab 11 restoration, The Netherlands

Alex van de Wetering · #1 31-01-17, 22:02

I am hoping one of the fellow C8 owners can help me out on the following.....I can't figure out the universal joint!

After cleaning the grease from the parts I found out my C8 has a mismatch of yoke and spider, and some things are welded to make it work.....I have a feeling the rearmost yoke that attaches to the drive shaft is the original C8 part....and the front yoke with gear for the speedo is from something else.(?)....but I am not sure.
I have checked the parts manual, but I haven't been able to find the parts numbers in the master parts list. So, basically....before I can start searching for the correct parts, I have to find out what they actually look like! Anyone have a picture of the proper joint???.......the C8 setup is not shared with C15 or any other of it's sisters.

Another thing I wonder is if I have the proper “trompet” shaped "ball collar" that protects the U-joint from the outside world.......it has the remains of a seal at the rear end, but it doesn't seem to have a screw-on cap as I have seen on other (civvy) examples.

Alex

Mike K · #2 01-02-17, 05:31

Alex

I can help you

The C8 uni joint and drive shaft design , is from the USA 1940 1/2 Ton pickup with 4 speed gearbox . The 4 speed gearbox was an option on the 1940 1/2 Ton pickup, you could order either a 3 or 4 speed gearbox.

My uni was broken, it seems to be a weak point in the driveline. Maybe Jim carter can help you.

Maurice Donckers · #3 01-02-17, 08:06

There was a guy sometimes traveling with me to shows with a C8 , even after renewing the u joints and other hardware , it still smashed to pieces . I solved the problem by putting a C15 rear end on the gear box and a modified C15 ordinary prop shaft behind it , and deleted the prop in the tube system .
After that he drove years around trouble free.
So maybe also an option for other C8 owners.

Alex van de Wetering · #4 02-02-17, 22:37

Mike, Maurice,

Thanks for your replies. So, that means we have at least 3 C8's with a U-joint that failed. Do you guys remember which part actually failed? the spider maybe...or the front yoke?

Thanks for reminding me Maurice....I couldn't remember who told me about the C15 upgrade!
Based on both your experiences I am now also looking at upgrading the U-joint. I am hoping to find something that will work with the tube and ball collar.

Attached is a picture that Andrew posted some years ago.....based on that picture I think my C8 has the original rear yoke, but had the front yoke and spider replaced.
My front yoke seems to be of a heavier design than original, so maybe I can save the it after cleaning up the welds and finding a spider that does work with both the front and rear yoke.
Another option would be to replace the complete joint for a heavier example, but than I would have to find one that has 17 splines to fit the C8 prop shaft.....so far it seems only Passenger Chevs and 1/2ton trucks at the time had 17spline shafts. I am also looking at GMC CCKW parts as they seem plentiful and cheap and they are probably a lot heavier than the C8 parts.

Thanks guys,

Alex

David DeWeese · #5 03-02-17, 01:23

Hi Alex,

Took some photos today of the joint assembly that was originally on my C8. If you want I can remove the yoke on the transmission and see if there are any part numbers..

Thanks, David

Bob Carriere · #6 03-02-17, 03:27

HI Alex.

Those enclosed driveshaft tubes a much more avaialble here in North America and they regularly come up on Rbay as NOS stock.

Around here any young hot rodder who installs a large V8 in an old GM truck usually scraps the enclosed tube/driveshaft system as being too weak ofr larger engines.

I have a complete 1940 Chev one ton truck that has the complete power train. It is in bad rusted condition. Crawling underneath it has the same 4 speed tranny as a CMP...... left hand bellhousing clutch..... and fully enclosed driveshaft. It would not be difficult to replace the rear cover of the civvy 40 model with the open system of the CMP. A new driveshaft and suitable yokes and u-joints could be found to fit the new set up.

The ease of doing the conversion is demostrated by other C8 owners who have done exactly that.

Too bad the NOS parts here in North America are so heavy to ship overseas.

I would not trust the welded joint in your truck. To get your truck on the road you could do the conversion and at a later date if you ever find all the parts needed for the original set up..... replace the parts......to return to original set up. All of which can probably done from underneath the truck.

Good luck.

Bob C

cletrac (RIP) · #7 03-02-17, 05:55

The 40 to 46 pickups all used that setup. They also usually had a 4:11 gear ratio.