I was under the car yesterday looking around, in prep for journey to Phoenix, and noticed really dusty grease zerks on halfshaft u-joints.   Figured grease would be a good thing.....unknown as to last time......      Connected up easily to one of the zerks and after about two pumps, I noticed grease coming out of the backside of the u-joint???????????

Thought this was rather odd, and after scraping around in there with a long screwdriver to get the grease out, I discovered some sort of a hex fitting installed in place, with a 3/16" or so piece sticking out of the hex fitting....that moved in and out a bit......

Has anyone seen this in their halfshafts before?????

Are these some sort of a anti-too much grease device for u-joints?????

Similar results on the rest of the u-joints, about 1-2 pumps with grease exiting  this piece, excepting last one....but figure two pumps is grease in......better than none.

Never seen anything like this, figured I'd check and see if this was normal for some app's or something that a vendor came up with to keep grease out of the engine compartment?


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Also never heard of such a thing. I'd remove the fitting, cap or plug the hole & take a spare with me! No telling what brand it is without removing it, I suppose.

These are in such a position that removal is not possible without removing the u-joint. They are up against the hub of the half shaft..... No means to get in there....it was a battle with just a skinny screwdriver trying to get the excess grease out!

I can only surmise that with problems related to "over greasing" and the mess in the engine compartment, that this was some sort of device to let a user know that the u-joint was potentially full...... again, perhaps from a vendor that was trying to provide a "fix"......


OK. What concerns me is the possible extra drilling plus maybe threading to add the thing, in a highly stressed steel forging like u-joint. Was this in the '74?

Yes, in the 74.  Dead smack in the middle of the cross area, on the flat side.    All the cap ends look evenly rusted.....so work was done a while back! When I wiped the dust off the cap rubber seals,, they looked fantastic still!\

I was wondering if it wasn't some feature to prevent overgreasing by monkeys with power grease guns!!??

I plan on looking back in the records that I do have, and see if I can't figure it out......

Dennis Quella has sold that design U-joint for years! There is a small plunger as part of the fitting that pops up to release the pressure caused by pumping in too much grease during service.  I have installed many of them into stock half shafts and IMHO they are among the best joints available for the stock shafts. Why in the world would you remove the fitting and plug the hole?? It is there for a reason . If you overgrease the joint, it gives the pressure surplus grease somewhere to go instead of blowing past the rubber seals. You can also "flush " the old grease out of the joint without damaging the seals. 





Well, thank-you for the clarity!   I was thinking that this was the purpose..... I just pity the fool that pumps and pumps and pumps, while he's waiting for grease to come peeks out the seals.......(way I was taught!!!)...cuz the resistance will never change........blop!

I think that the idea of drilling and tapping a hole in the middle of the joint would take away from it's structural integrity...!  ...which may or may not have merit....all would depend on how much HP is being applied to any given u-joint and for how long......!

Thanks again!

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