66 Driveshaft U-joint Question

[Mike S.]

I started reassembling the rear suspension today, beginning with the differential and crossmember. I then attempted to install the driveshaft, which had new Spicer u-joints installed by a local driveshaft shop several weeks ago. I kept having problems getting the u-joint properly seated in the pinion flange. One side would seat properly and I could install the u-bolt finger tight. However, the other side of the u-joint extended beyond the small tab on the flange, keeping it from fulling seating.

I then tried to connect the other end of the driveshaft to the transmission yoke. Same story - u-joint was a little wider than the distance between the tabs in the yoke.

I pulled the drive shaft out and measured the width of the u-joints. Both were approximately 3 21/64 inches wide. I then measured the pinion flange and transmission yoke. Both were approximately 3 5/32 inches wide as measured between the tabs.

The other ends of the u-joints - the ends secured by clips in the driveshaft yokes - appear to fit properly.

Did the shop install the wrong u-joints, or am I doing something wrong and incredibly stupid? The car is a 66 BB, M21 of unknown origin, rear end from a 69 SB. As always, thanks for your valued advice!

Mike

[Philip Whitaker Member# 2024]

Re: 66 Driveshaft U-joint Question

I just did a set of Spicer U-joints, and I had to seat the caps on the joints. It takes moderate pressure to seat the caps, as the ones that I used snapped into place. Once the caps snap on they are dificult to remove. I don't know if this is your problem, but you might check it out.

Phil

[Rainer S.]

Re: 66 Driveshaft U-joint Question

I just rebuild my 63 halfshafts and drive shaft, with new joints. As a safety measure, I added a bit of grease in the caps, and when I pushed the caps back on, I could not seat them, due to the excessive amount of grease. I had to remove the grease I added. Seams, that the grease installed by the joint manufacturer,is just enough. Maybe you mechanic added grease, like I did.

Rainer

[Mike M.]

Re: 66 Driveshaft U-joint Question

agree with previous post but to make sure you didn't get incorrect u joints( they are available with differing widths), compress with vise grips) the trunions that are causing a problem , mic them then compare to the measurement of the flange they are to insert into. Even if the u-joint is the correct size, one usually has to insert one of the trunions and snug the u-bolt on that side, then snug the opposite sided trunion and tap that trunion towards the center of the u-joit and keep tightening till it seats in the flange. good luck, mike

[Joe L.]

Re: 66 Driveshaft U-joint Question

Mike-----

First off, I'm going to assume that you are using u-joints with grease fittings. "Lubed-For Life" type (without grease fittings) are pre-packed at the factory with the correct amount/type of grease and your shop or you should not have added any.

I think that you have the correct u-joints. The problem is excessive grease in the unit. You must remove the caps and CAREFULLY remove as much of the grease as you can. If the unit is over-filled with grease, there is absolutely no way that you'll be able to press the caps on since the grease is a fluid which is incompressible. You could even break the caps or blow the seals if you try to compress the caps with too much grease in there. I've been "down that road".

After removing as much grease as possible, re-install the caps. You'll likely now be able to install them and fully seat them so that they will fit between the end retainers in the pinion flange. If not, you can use a c-clamp to compress them further.

AFTER INSTALLATION, grease the u-joints with a grease gun. Use GM #12377985 or equivalent lithium-based grease.