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When to replace UJ tendon?

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Created by excav8ter > 9 months ago, 5 Mar 2023
excav8ter
573 posts
16 Apr 2023 9:37PM
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I picked up another tendon and a new UJ yesterday.


segler
WA, 1656 posts
17 Apr 2023 11:22PM
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It was said above: "Chinook and streamlined have the holes in the same locations."

Actually, no, they don't. Not quite. They have the same diameters, but the hole position on the Streamlined is slightly further from the end, than do the Chinooks. I use Chinook tendon hardware with Streamlined tendons. In order to get the Streamlined tendon to bottom out such that the holes line up, you have to shave a little off the the ends. Use a dremel. I have been doing this for years.

jdfoils
431 posts
18 Apr 2023 6:36AM
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segler
WA, 1656 posts
18 Apr 2023 11:38PM
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Thanks for the picture, which replaces a thousand words. Yes, it does show the Streamlined hole about 1mm further from the end.

What I do know is that I MUST shave the Streamlined ends to get them to fit into my Chinook hardware. No shave, no go, the bolt won't go through.

jdfoils
431 posts
19 Apr 2023 12:42AM
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Select to expand quote
segler said..
Thanks for the picture, which replaces a thousand words. Yes, it does show the Streamlined hole about 1mm further from the end.

What I do know is that I MUST shave the Streamlined ends to get them to fit into my Chinook hardware. No shave, no go, the bolt won't go through.


Not sure what you think you see in the previous photo so here is another one with a rod thru the lower holes to show location. A bitten is placed on top which shows the Chinook tendon is slightly longer (3.101"), the streamlined is 2.090"

Not sure why you would use a streamlined in a Chinook universal, my experience is that the Chinook ones hold up better and as a bonus are cheaper and easier to source. Both of there were used unmodified in a streamlined universal. They have seen roughly equal use. The streamlined has small cracks eminating from both sides of one of the holes, the Chinook one has no damage. The Chinook one is also drilled more accurately with the two hols very close to 90degrees apart.



jdfoils
431 posts
19 Apr 2023 3:40AM
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Some more scrounging in the shop. Added a broken Streamlined and a new Chinook




segler
WA, 1656 posts
20 Apr 2023 11:16PM
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All those pictures show the Streamlined hole about 1mm further from the end than the Chinook.

That 1mm is the difference between fitting or not fitting into Chinook hardware. The Streamlined bottoms out with the hole too high to line up with Chinook hardware holes, and then the bolt does not go through. I shave it to move the hole down and get the bolt all the way through. That simple. I have verified this over many years.

Maybe newer Chinook hardware has a deeper bottom. Mine don't.

jdfoils
431 posts
20 Apr 2023 11:49PM
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Let me clarify the photo for you. There are 3 tendons and two half tendons with a rod which is the same size as the major diameter as the bolt which gets inserted thru the holes. All 5 of these are sitting flat on the table, meaning that the hole at the bottom end of each of them is the same distance from the end of the tendon for all of these.

The streamlined tendon on the far left looks a bit funky, this is because it was not cut square and flat, but is cut at a slight angle and has a slight dome shape.

segler
WA, 1656 posts
22 Apr 2023 3:10AM
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Understood, thanks.

Try it by experiment. Put a Streamlined tendon into a Chinook base. Line up the holes and look through. In my experience over several years with admittedly old Chinook hardware, the hole through the tendon is about a half diameter too high, and there is no way I could get the bolt through. For my Chinook hardware I have had to shave the end of the Steamlined tendon. Both ends, actually.





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"When to replace UJ tendon?" started by excav8ter