Propeller Shaft (mis)Alignemnt

[Adam Gravois]

I'm reinstalling the propeller shaft, and per the Haynes guide, checking its alignment. It's not perfectly straight--I'd say off by a millimeter or two over an eight inch-distance. More vexing, the joint is low, so I have no idea how to correct this offset.

How much misalignment is acceptable?

I can't raise the center bearing (without bending its mount, which sounds like a dodgy fix). Is there another point I can adjust? Does sliding the transmission mount around lower the transmission?

[alotawatts]

Not sure if this will help but - The center bearing mounts use washers as shims. If you have a HAYNES Bible you probably know that.

[Adam Gravois]

I can shim it lower, but not higher, which is what it needs.

But, I had an epiphany over breakfast this morning: shim the tranny mount. One, maybe two washers between the mounting bracket and the car frame would lower the front end of the propeller shaft and get it in alignment. Any reason why this might be a bad idea?

[Mike W.]

I can shim it lower, but not higher, which is what it needs.

But, I had an epiphany over breakfast this morning: shim the tranny mount. One, maybe two washers between the mounting bracket and the car frame would lower the front end of the propeller shaft and get it in alignment. Any reason why this might be a bad idea?

Yes, the U joint is expected to have some angle to it, that's the whole point of it, but while it will absorb some angle, the flex disc is not really a u-joint, it's more of a shock absorber for torque, that one, the transmission to driveshaft is more important to keep straight. Don't worry about there being a bend or slight angle at the center bearing u-joint, that's what its for. Less is better, you don't want any more than you have to, but not to worry about it.

[Adam Gravois]

the flex disc is not really a u-joint, it's more of a shock absorber for torque, that one, the transmission to driveshaft is more important to keep straight.

That's an excellent point. Definitely don't want that compressing and uncompressing with every rotation. Hm, the best way to measure that would be, perhaps, calipers measuring the thickness of the giubo or the giubo and flange?

[Mike W.]

No, just try to keep it straight with not completely trashed motor and tranny mounts, the rest of it will take care of itself. A calipers would measure thickness, but not angle.

[Adam Gravois]

Thanks for the tip, Mike. That sounds way better than making imprecise measurements of the giubo's thickness and stressing out over the ambiguous results. The mounts are all fairly new, so I think I'm good there.