95 4.3 and 4L60 double cardan two section driveshaft drivetrain..

Very weak vibration from the rear over a couple months. As it got worse, it was felt more than heard in the chassis. Steady vibration at 52- 56 mph on level road. It felt more like defects in the pavement than the truck.

Greased the center ball sections in the double cardan joints in the rear driveshaft and the vibration is gone.

There is a special grease needle that screws onto the grease gun that is required to grease the center ***** between the two U joints in that cardan assembly. Its NOT good enough to just grease the U joints!

The center ball and spring mechanism is greased thru a small dish shaped orifice thats nearly impossible to see on a dirty driveshaft under the vehicle. I remove the rear shaft to get easier access to these grease ports. Removing the shaft aplows exercising the joints to check their condition. That joint will feel of spring pressure when the cardan joint is pushed in line with the driveshaft. If not, its worn out.

The grease needle was plugged and wouldn't push enough grease into the ball joint. I had to squeeze on it so hard that it felt like the lever was going to break off!

It seemed to help to center the cardan while greasing it.

Many years of driveshaft use this design. It's also on the front driveshaft in the 78 K5.

Those cardan joints are rather difficult to rebuild so make sure to grease all the joints!

 

That's regular maintenance on my 94 Blazer. Grease gun and play grease monkey under the lift trying to get to all the points.
When pulling the driveshaft just make sure you work on a solid floor and not on a gravel place. It's so easy to have the caps come off the needle bearings and the needles fall out A large piece of cardboard may do the trick.
How do I know? I've been looking for a single needle on a concrete garage floor for 20 minutes once.

Putting those needle bearings back with new grease is a good idea as well.

 

There are no caps to fall off on those shafts, they arekept in yokes but yes, on the 78 that can happen on both shafts.

if the grease needle hadnt been plugged it could have saved removing the shaft!

This is not my month for doing good repair work! Ive looked excessively stupid lately...

 

Good if the driveshafts are of that type.
Happens sometimes that you have no luck or stumble from one problem into another. I have been working on an accessory bracket from a Studebaker Avanti... have since taken it off about 8 times to get all things squared, bolts shortened to proper length and the alternator fitted.

But at the end if it is properly fixed it gives you peace of mind and won't bother you for a long time.

 

Exactly!!

And this problem was solely caused by my not doing proper maintenance.

Havent touched a Studebaker for years. Dad Had a 58 Lark. First car I ever worked on. I drpooed the glass gas filyer bowl right beside the trouble light and at about 10 years old, got an instant appreciation of what would have happened if that bowl broke that hot bulb with my face in there!

If itll help my neighbor was into Stude restos for years.

 

Dang, a new thing to look for to grease and I pride myself on being thorough in my preventative maintenance.

Any pictures that show where and how to grease these?

 

Haha Haha love it..."something else to grease!"

Yes, I'll post pictures this week, its out driving without me.

 

78 K5 . Looking back from inside of front right wheel to double cardan joint fastened to transfer case. Two U joints connected with a ball joint in between.

Close up of grease zerk on front U joint and to the left , the grease port for the cardan ball, a dimpled place with a hole. The ball aligns the two U joints and must be replaced when replacing the U joints. A special tool is required to grease these ports.


The blue paint was Sherwin Williams industrial paint from Tacoma Screw Co. Very good quality paint. Grease resistant. The parts were stripped with hydrochloric acid, washed and painted.