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MG MGA - What thread are T-Bolts for conv. Top??

Does any one know what thread the T-bolts or "wing Bolts" for the MGA convertible top are?

I bought a 57 MGA roadster 2 weeks ago. It didn't come with the T-bolts (the bolts that hold the convertible top to the windscreen when top is up). I got a set from Moss only to discover that the PO had drilled/tapped the holes on the convertible top frame to a larger size.

I went to my local "has everything" hardware store (McGucken's) but they didn't have anything that was the same size/thread as these Moss T-bolts. I'm hoping to weld the holes on the top frame shut and drill/tap to the correct thread for the T-bolts. Any thoughts?

Thanks very Much,
Steven in Denver
SJL Loe

Steve - They are probably British Standard Fine. I am sending you a chart of standard threads that lists American, British and Metric thread. Good luck - Dave
David DuBois

Wow. That's an eye opener. BSF, BA, UNC, UNF, BSW, etc. I had no idea there were so many varities of fastener in England. Must have driven the English completely bonkers!

Thanks!

-Steven in Denver

<a href="http://stevenloe.com/mga_photos/">Pics of the new car</a>
SJL Loe

Steven - UNC and UNF (Unified Nationl Course and Fine) are both American threads and are also known as NC and NF or SAE (National Course and Fine and the fine threads are also known as Society of Automotive engineers threads), so the Brits are not the only ones driven bonkers by different threads. Cheers - dave
David DuBois

And over the years some of us Brits have, out of necessity, built up comprehensive spanner sets and taps and dies for each thread type. It all depended on which make of Brit car you bought!

You missed BSP.

Steve
Steve Gyles

I wrote an answer to this question on April 2, 2001 entitled "Top Frame Header Wingnut Boss Threads", which is in the archives.

Short answer is BSF 5/16 - 22. Any good nut and bolt specialty shop has a kit which provides the proper drill to drill out the old holes and coils (and the tool) to insert. I think its name is "Recoil".

I still have the kit with a few extra coils somewhere if you can't find it.

Joe
Joe Wiley

Helicoil is the brand name Napa and Carquest both carry a kit. The kit has a oversized tap an instarrer and some helicoils, you will need the proper size drill bit as listed on the side of the tap in the kit. If you need help contact me I'm in the south Denver area.
R J Brown

It looks like the PO has already drilled/tapped the holes out to a larger size. Actually the 2 holes are completely different sizes! So helicoils are probably not an option. I'll have to weld the holes closed and drill & tap.

Thanks very much for all the info and help!

-Steven

Denver , CO
SJL Loe

Steven - Before you do any welding, check the drill size required for the Recoil repairs. If the hole has just gone one size larger, you are probably still in spec for using the recoils and it is a lot less fussing around than brazing the hole closed and redrilling and tapping.

You can get the Recoil kits and/or the proper BSF tap from British Tools & Fasteners at: http://www.britishfasteners.com/Merchant2/merchant.mvc

Steve G. I didn't mention BSP, but they are also covered in the chart that I sent to Steve. Cheers - Dave
David DuBois

You can also locktite a bolt in the existing hole then cut it off flush and drill and tap in it. better result than welding up.
R J Brown

Or just grind the existing arrangement flat and weld a standard hex nut into place instead. No one has ever noticed on my car - the old threads were stripped.
dominic clancy

This thread was discussed between 12/04/2006 and 13/04/2006

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This thread is from the archive. The Live MG MGA BBS is active now.