I had an hour or so to kill at the factory this morning, I was waiting for a guy to collect something I had sold on ebay.
Down the side of the bench was the front prop from Philip's D2 with a failed u/j, so I thought I'd have a look at that.
Stripping it down is a bit of a fiddle but got all the double-cardan joints out, and that's when the fun began.
We keep greasable joints and a centering bearing on the shelf, plus we have a couple of spare propshafts, so we are not stuck for transport should a propshaft fail.
Reassembling a new u/j isn't rocket science, but after a while I realised that I had an issue with the joint and the design of the cap seals.
The seal is a pressed steel circular housing with a rubber insert that is assembled to it, but not part of it, so that the rubber part can and does come out.
That in itself isn't a big issue, it is only a few seconds to wrap the rubber back inside the housing, but what was a big problem was that the seal wouldn't go back over the sharp edge of the step that it sits on, so once it has come away, you have to spend a few minutes wiggling it back on again, and its natural tendency is to come off as soon as you turn away. Once it has the u/j journal inside the cap, you cannot move anything enough to get the seal re-seated.
So instead of leaving the seals on the caps to hold the rollers in place, I fitted them to the spider. Now the spider won't fit back inside the yoke as the seal housings are jamming against the cap holes.
I spent over 2 hours trying different ways of doing it, accompanied by various choice expletives, but I just could not get the sodding thing together.
We had some other brand greasable joints in the box, one in a certain blue packet, but that was OK as the seal land didn't have a sharp edge and the seal rode onto and off with no issues at all, it is purely the design of the other seal that has caused the issue.
I gave up in the end and came home for a late lunch.
I couldn't believe that a stupid bit of design had made a mess of what should have been a 30-minute job.
Got to get some more joints, but this time I'll be looking closely at what I am buying!
I'll get some shots of the parts tomorrow.
Peter
Down the side of the bench was the front prop from Philip's D2 with a failed u/j, so I thought I'd have a look at that.
Stripping it down is a bit of a fiddle but got all the double-cardan joints out, and that's when the fun began.
We keep greasable joints and a centering bearing on the shelf, plus we have a couple of spare propshafts, so we are not stuck for transport should a propshaft fail.
Reassembling a new u/j isn't rocket science, but after a while I realised that I had an issue with the joint and the design of the cap seals.
The seal is a pressed steel circular housing with a rubber insert that is assembled to it, but not part of it, so that the rubber part can and does come out.
That in itself isn't a big issue, it is only a few seconds to wrap the rubber back inside the housing, but what was a big problem was that the seal wouldn't go back over the sharp edge of the step that it sits on, so once it has come away, you have to spend a few minutes wiggling it back on again, and its natural tendency is to come off as soon as you turn away. Once it has the u/j journal inside the cap, you cannot move anything enough to get the seal re-seated.
So instead of leaving the seals on the caps to hold the rollers in place, I fitted them to the spider. Now the spider won't fit back inside the yoke as the seal housings are jamming against the cap holes.
I spent over 2 hours trying different ways of doing it, accompanied by various choice expletives, but I just could not get the sodding thing together.
We had some other brand greasable joints in the box, one in a certain blue packet, but that was OK as the seal land didn't have a sharp edge and the seal rode onto and off with no issues at all, it is purely the design of the other seal that has caused the issue.
I gave up in the end and came home for a late lunch.
I couldn't believe that a stupid bit of design had made a mess of what should have been a 30-minute job.
Got to get some more joints, but this time I'll be looking closely at what I am buying!
I'll get some shots of the parts tomorrow.
Peter
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