Repairing the V8 Ambo propshaft.

Transmission is easy -- keep the one in it. Just have to change the yoke, the seal is the same as an open drive AMC. The trans would have that flange on the back, but not hurting a thing to leave it there. The big hurdle is that the 56-66 AMC torque tube cars have coil springs, and the tube is the main locating arm for the rear axle. So you have to add something (ladder bars, three/four link, etc.) to locate the rear axle. Or even leaf springs. The Chevys used leaf spring, and I think there was a pivot between the axle and leaf spring. Easy enough to remove the pivot and u-bolt an axle made for open drive down. In both cases the rear axle would need to be changed, as the pinion shaft isn't made to bolt a yoke to. AMC made a special adapter for 66 American V-8s for the AMC 20. Even on those the pinion shaft was drilled and tapped for a retaining bolt. Hard to drill and tap a hardened shaft!

Here's the propshaft place. They have some serious machinery, some of it goes back to WWII. Yes, that's a Milwaukee. Back then, they were a general engineering outfit.



The chap managed to separate the two halves of the shaft, said it took 30 tons.
Then he put in a new centre bearing. I'll ask him if he took a pic.
I could feel and hear that the old bearing was rough and clicking. Only 65,000 miles but any grease must be long dead.
The rubber housing of the centre bearing came off easily, it's on a crimped sleeve. Then he pushed the two halves back together.

Here's the original double cardan. See those thin yokes with the sharp inner right-angle. That's how to design something so it will crack, and they had. The bearings were rotating in the yokes. Not AMC's finest hour.



So that was cut off, and a new flange fitted, and the original sliding spline, with a new single uj. The pivot of the uj is where the centreline of the double cardan was.



There is minimal articulation in the double cardan. Perhaps 3-4 degrees. Now, I have read that ujs don't like running in the same place all the time, it wears them rapidly. I wonder if the double joint was intended to improve longevity rather than smoothness, by sharing the load.

At the gearbox end, the slider was corroded in way of the seal. I guess the car had stood, perhaps for some years and condensation fell down to that point. You can't see it in the pic, but that corrosion was only around half the circumference.



I put a Speedi-sleeve on it. Perhaps that will reduce the fluid loss, I hope so as the box pretty much empties itself in a couple of hundred miles.



Then I put it back on. Not easy. Without the prop in there, the gearbox output shaft sags and there's no tapered lead on the slider, so getting it to align with the splines and then go into the bush in the gearbox rear extension, is a real mare.

Anyway... then I took it for a run. Went past the 60mph where the noise and vibes used to start, up to 75mph which is as fast as I want to go on the old timing chain & gears. No noise, no vibes.
Hooray. Next week we have a 300 mile outing. If it's still good after that, double hooray.

Ivor

That center piece looks a lot like a Jag axle flange. Neat that they kept the original drive shaft end and trans yoke, just fabbed a new center section. I don't think the CV joint was for longecity -- I've pulled 100K+ u-joints out of torque tube cars that were as tight as the day they were put in at the factory. Six cylinder models, mind you, but the V-8 used a larger joint. Pre 56-62 V-8s used a single joint, even the vaunted 57 Rebel, so strength isn't an issue. Lincoln also used a similar joint (if not the same) in the early 60s, just for a few years. I wonder if it was something one of the U-joint vendors sold both companies?

In my car - BW Flashomatic box - I think one would struggle to change the seal in the car as it's recessed so far into the rear extension. Unless one has an expanding seal puller.

The rear extension housing can be removed with the box in the car, so I have read, but observing scrupulous cleanliness of course.
Do you have a TSM? It's all in there.

There will inevitably be some leakage when the TT is pulled out. This is because the front slider of the propshaft forms the seal, so that does not of itself indicate a seal problem.
If the seal is leaking in service, there will be a drip from the drain immediately in front of the TT flange.

I had hoped that the Speedisleeve would cure my box leakage, but yesterday I saw a small puddle when I parked, and I can see that's it's dripping from the front of the bellhousing, so I guess the front pump seal. Oh well, I carry a gallon of ATF and a filler funnel.

Ivor

There are a lot of stop leak products out there that revive hardened seals.