Lotus Elan

Bonnet catch bolts

PostPost by: Bigbaldybloke » Sun Feb 10, 2019 1:51 pm

I’m just about to complete and install my Plus 2 bonnet. On trying to secure the plunger part of the catches to the square tubular rail, I can’t get the bolts in more than about a turn before they bind and become tight. I’ve tried both UNF and UNC, but both are about the same, what thread should they be as I don’t want to tap them out to the wrong one. (Still need to refurbish the catches but not going to fit them until the dash and bonnet release cable is all sorted just in case the bonnet accidentally latches closed!)

Thanks
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PostPost by: The Veg » Sun Feb 10, 2019 1:57 pm

Are you using the old bolts or new ones? If the latter, is it possible that you've got coarse-thread bolts but fine-thread holes? Seems like most things in my Plus 2 are fine-thread.
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PostPost by: Bud English » Sun Feb 10, 2019 4:38 pm

The parts manual says XUFS0420 or 1/4-28 x 1-1/4" screws. Ref: http://rdent.com/manuals/index.html
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PostPost by: Bigbaldybloke » Sun Feb 10, 2019 5:35 pm

So decoding the part number, does the F mean it’s a UNF thread and a C mean it’s a UNC thread? What does the rest of the code mean, is there a legend or table somewhere?
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PostPost by: oldelanman » Sun Feb 10, 2019 6:13 pm

Bigbaldybloke wrote:So decoding the part number, does the F mean it’s a UNF thread and a C mean it’s a UNC thread? What does the rest of the code mean, is there a legend or table somewhere?


http://www.lotuselan.net/wiki/Intro_-_S ... ber_Coding
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PostPost by: types26/36 » Sun Feb 10, 2019 6:32 pm

Generally speaking if the thread is in alloy or cast iron the thread will be a course thread (unc)
If the thread is in steel it will be a fine thread (unf & some others)
1/4-28 is a UNF thread.
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PostPost by: Bigbaldybloke » Sun Feb 10, 2019 9:22 pm

Thanks all, I ran a UNF tap through them and the new bolts now fit fine. Basically I think they were clogged up with paint and crud.

The link to the explanation of the part number codes is excellent, thanks for that, I tried to search for it myself but didn’t find it.
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PostPost by: Bud English » Sun Feb 10, 2019 9:37 pm

It's also in the introduction to the parts manual referenced above. I probably should have mentioned that.
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