Drive Shaft
BEFORE
AFTER
Rear "Fat" Drive Shaft
On the Military Vehicle forums there is a bit of discussion regarding the early use of a "Fat" rear drive shaft for the Very Early Production GPW. A few members reported that their GPWs came with a fat shaft, but no known examples of Ford marked shafts have been found. It has been concluded that the most correct application would be GPW marked regular drive shaft. Anny installation of a fat shaft would have been done in error by the motor pool or a post war replacement due to lack of GPW parts.
Just to be different, I am installing my fat shaft on the rear to keep the controversy going holding to the notion that the shaft was swapped in the motor pool.
Front Drive Shaft
The front drive shaft is fairly straight forward. Sand blasted, cleaned and primed, I am ready for painting and installation of the universal joints.
I am always pleased to find distinct GP or GPW part numbers. It confirms this is the correct drive shaft for the front Transfer Case to Differential connection. I'll clean up the yoke and install new grease fittings and universal joint along with the grease retainer cap and rubber (formerly cork) washer.
There are several good videos and tutorials on correctly installing the universal joints, so I will not repeat what others are saying.
Front and Rear Drive Shaft Lengths
Over the last 80 years WW2 Jeeps have had many components replaced. Drive shafts were taken from CJ2/3s and probably from other vehicles to replace the over used and damaged GPW/MB drive shafts. As a result many lengths and different markings can be found.
Chuck Lutz provided this handy chart for gauging the proper length of the WW2 drive shaft. Keep in mind that the measurements can vary depending on how far down the splined yoke is sitting on the actual drive shaft. A better measurement would be the actual length of the shaft itself from the center of the flange holes to the end of the splined shaft.
The length of the rear drive shaft without the yoke is 18 7/8" long. A correct length "fat" drive shaft should be the same, and the length of the fat tube, measured from the front of the tube to the back of the tube. is 12 3/8". Keep in mind that Ford did not produce a "fat" drive shaft for the rear. Any installation of a fat shaft on a GPW would have been done either in error, or because no other part was available other thand one of the fat MB drive shafts.
Perhaps someone who thinks Ford made a fat rear shaft probably had one of the Spicer or MB fat 18 7/8" long shafts slipped onto a GP marked yoke.
Below is the Ford drawing for the tube of the drive shaft, front and rear. The lengths are:
FRONT: Tube length 13.25"
REAR: Tube length 11.59
Final Assembly and Installation
Final assembly is fairly easy. Just remember to point the grease fittings toward the center of the shaft, not towards where the transfer case or differential yokes are. Also try and put them on the same plane so you can grease them all without moving the vehicle. If one is on the top side and one on the bottom it takes more time to do your maintenance.
I installed the drive shafts onto the differentials then supported them with a block of wood while I installed the Bell Housing, Transmission and Transfer Case pack. That is covered in the Transfer Case Section.
