Colin Heseltine Posted March 29, 2021 Share Posted March 29, 2021 Can anybody confirm what thread is used for the seat belt boss behind the drivers right shoulder on a 21 plate 420R. As it is a metric chassis will this have been changed from the originally used 7/16"UNF. I do not have any metric fine thread taps and do not want to attempt a 7/16"UNF unless I am certain that is what it is.Colin Link to comment Share on other sites More sharing options...
ScottR400D Posted March 29, 2021 Share Posted March 29, 2021 Still 7/16" UNF. Certainly according to the recent assembly guides. Have you damaged one? Why do you need to tap? Link to comment Share on other sites More sharing options...
Colin Heseltine Posted March 30, 2021 Author Share Posted March 30, 2021 Scott,Thread not damaged but full of paint. I did not want to try the tap until was sure what thread it would be. Going to mount a small bracket on the pillar with a popper base for the half hood side strap to fix to.Colin Link to comment Share on other sites More sharing options...
Area Representative paul richards Posted March 30, 2021 Area Representative Share Posted March 30, 2021 Confirm. 7/16 unf Link to comment Share on other sites More sharing options...
Colin Heseltine Posted March 30, 2021 Author Share Posted March 30, 2021 Paul,Many ThanksColin Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted March 30, 2021 Share Posted March 30, 2021 The standard for all cars is 7/16" UNF for seat belt anchor bolts, one of the international imperial oddities like wheel diameter in inches and flying altitude in feet (except for Russia and China). Link to comment Share on other sites More sharing options...
Nigel Riches Posted April 3, 2021 Share Posted April 3, 2021 Hi Colin, if you only need to remove some paint from the threaded hole you could use a suitable sized bolt and run a half round or triangular file down the treads to form a thread chaser / cleaner, much cheaper than buying a tap for a one off use. Link to comment Share on other sites More sharing options...
Colin Heseltine Posted April 19, 2021 Author Share Posted April 19, 2021 Got hundreds of taps including the one needed to clean out the thread. I just wanted to be 100% certain before running tap down hole.Colin Link to comment Share on other sites More sharing options...
rj Posted April 19, 2021 Share Posted April 19, 2021 7/16 UNF and it's part of a EU directive, so it won't change. It also is in German cars like the VAG group. Link to comment Share on other sites More sharing options...
Colin Heseltine Posted April 20, 2021 Author Share Posted April 20, 2021 Got hundreds of taps including the one needed to clean out the thread. I just wanted to be 100% certain before running tap down hole.Colin Link to comment Share on other sites More sharing options...
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