Bolts Spitfire?? Forgot where they came from ?

[Michael Watts]

X5 bolts cut diagonally on thread any ideas where they came from ? Thanjs

[JohnD]

That's a "dog bolt" supposedly for easy insertion into a difficult to reach hole.  

They were recently the subject of a thread on the TRR MSB: Dog bolt size - TR4/4A Forum - TR Register Forum (tr-register.co.uk)

John

[Pete Lewis]

often self threading bolts were used in places like battery earth cables  

as they clear paint and make a good connection to body earths etc

Pete

[Graham C]

Would you expect to have such a large washer in conjunction with a spring washer?

Suspect these have been included by a previous owner with them being black.

What work have you been doing?

Graham

[Colin Lindsay]

Possibly seatbelts? They may use more modern fittings and threads than the original parts. The size of that washer gave me the idea.

[rlubikey]

Or the seats? You say 5/16 " unf x 1. 5/16" in your other thread Michael - I don't know off hand if that's the seat runner to floor bolt size. Those bolts have the plain section nose to "feel" their way through the carpet to the weld-in nut. Don't know about the helical cut. Perhaps to clear carpet fabric as it threads in?

Cheers, Richard

[dougbgt6]

Richard,

They ain't seat runner bolts. I ordered some to replace my passenger seat bolts and promptly lost one up the runner, got to take the seat out to recover it! 

Doug

[GrahamB]

On 28/04/2023 at 19:53, Graham C said:

Suspect these have been included by a previous owner with them being black.

After having worked on most areas of my Spitfire, I have never come across this type of bolt.  Nor have I found them specified in the parts manual.  They could have been used as a non standard part to secure the seat runners through the carpet but then you would only require 4 for each seat, not the 5 that you have.  Drive the car and see which part falls off ??

[Pete Lewis]

as i said these type of bolt with a lead in and some thread cutting self thread cleaning ability are used to clean threaded holes that by process get painted so use of a std bolt would 

seize if tightened with  a power  wrench they use these as a much simpler operation than having to run a tap in first 

Im with Graham  never used on Triumphs  as i doubt they were ever available  maybe if heading to the 80s when more torque controls were industry introduced  but not 60s/70s

pete

 

[rlubikey]

I've just found five of those bolts same as Michael in my "Random Nuts & Bolts Off 1977 & '79 Spitfires" box. You're right Doug (never doubted you!) they're bigger than the seat runner bolts. All five bolts have the captive spring washer and are un-painted with a dull silver plate or passivated finish. I feel sure they're off a Spit but no idea where. The mystery deepens!

Cheers, Richard

[dougbgt6]

Ha!

 

Just got this email from Richard Waddington.

"Just received my Courier and read your question about the strange bolt. I think they are petrol tank mounting bolts. Five shown in the original manual and they look familiar after recently refitting my tank. Why the strange thread? No idea!  Cheers. Richard"

And a quick look on Rimmer's reveals SH605061 (5)

Doug

[Pete Lewis]

commonly used bolts with a thread clearing ability to clear painted threads to speed up assy rather than tap the painted holes out first

Pete