66 Driveshaft Help Please

The universal is a double cardan CV joint. The part that eventually fails is a little spring and ball mechanism between the shaft and center section that keeps the joint from "flopping" between the two cross joints. It looks like two standard universal joints back to back, and that's exactly what it is. Without the ball and spring mechanism in the center the joints don't stay aligned and cause a bad vibration. Lincoln is the only other manufacturer who used a similar joint, and that was in the early sixties and only for 3-4 years -- like Rambler (only used 63-66 in V-8 torque tubes). Prior to 63 Ramblers used a single universal joint behind the V-8 (all sixes have just one joint).

There isn't enough info in the TSM to recreate that centering mechanism. If yours is worn (they last 40-50 years thanks to being fully enclosed) you have few choices. Since they have lasted so long you can't find a repair kit. Blaser may have one, but I doubt it. I think Blaser is the one working to recreate it, but partner with Galvin's and one or two other AMC vendors so they can make enough to spread costs so it can be reasonably priced. I could be wrong on that -- they could be working independently or the other way around.

Your other option is to eliminate the CV joint. That would mean finding a U-joint base and lengthening the tubular potion of the driveshaft. The end on the shaft can be modified to work, but the shaft still needs lengthening. There are no issues by doing this, the older Rambler V-8 models only used a single joint. The CV joint was used to make power application a bit smoother, but it's not absolutely necessary.

 

Once you get it taken apart, what needs to be replaced should be plain to see.

 

I betcha anything, all it is, is the u-joints simply need to be replaced.

 

 

You will need to find a good AMC mechanic to work on your car, because the double u-joint set up is more difficult than a single u-joint job. This is important because if the person does not like the car, very likely they won't do good work.

 

Maybe contact your nearest AMC Club to find a good mechanic.

 

IF there are any parts that need to be replaced, there are at least two junkyards in my area that have the parts:

 

1) John's Auto Salvage in Seguin Tx (see website on Internet)

 

2) CTC Auto Ranch in Denton Tx (see website on Internet)

 

...I think my local Pick and Pull has two intermediate sized mid sixties Ramblers in the 'Classic yard' right now...

 

 

It's possible that  the center section from another vehicle will work, but I doubt without changing the length. You can change it a little without affecting shaft length enough, shorter by 1/4", I wouldn't go that much longer... maybe 1/8"...

The joints themselves usually DO NOT wear out due to being inside the tube. I've seldom seen a worn joint in a torque tube car, have pulled several six cylinder versions out with 100K or more on them and the joints are still tight. That centering device is under a lot more stress, and the bushings and spring "wear" as much with age as anything else. Once the spring weakens enough for the center to flop just a little the bushings go fast. I don't know how the Blazer double Cardan CV joint works to keep it from flopping, only that it's different from the early 60s AMC/Lincoln joint.

I looked up  the specs on the two u-joints. K5 uses a Moog 369, Classic/Ambo a Moogh 515. Almost an inch difference in width of joints! If you could find a double-Cardan tyep joint that use the same size U-joint it wouldn't be hard for a driveshaft shop to change the end. Needs to be the same size so it will fit the transmission yoke. If it's the same size caps AND same length it would be really easy to change out. You can get conversion u-joints that have difference diameter caps, but they still have the same width cross. That might not help...  Might be good to take it to a driveshaft shop and see what they can find.