Headlamp surrounds screw thread size?

[Stevemorris]

Hi all

Another thread size query if I can?

Someone has fitted self tapping screws in the headlamp surround/covers on my car. Looking at the captive nuts I think I can save them by running the correct tap through. Does anyone know what the correct thread is please? I have a new set of correct screws and they are measuring 3/16 with a tpi of 32. I’m thinking this is UNF???

Thanks, Steve.

[Heuer]

Read this first: viewtopic.php?p=35881#p35881

You can then input the part number into this decoder: https://www.decode.fyi/ and you will get the technical spec of the part.

This document is also a good resource: Jaguar Nuts, Bolts and Fasteners specs: https://www.dropbox.com/s/vbkgbwl4b3tyc ... s.pdf?dl=0

[chrisfell]

Unfortunately for those of us who do not use a VPN to hide behind or get round controls, David’s link goes nowhere interesting - just a thread of purple screens.

The headlamp cover surround screws are 5/32 32. Replacements in stainless steel are available and not expensive. I use a tap to restore the threads in the captive nuts and a die to do the same for my screws.

[44DHR]

Steve,
I think this is covered at post #4 in the attached link regarding the thread size, even though that states 8/32 inch with an UNC thread, which seems too big and too coarse to me, unless this is the replacement size to tap out stripped original threads. There still remains some confusion as to the original exact dimensions and thread type, with you saying 3/16 inch and Chris saying 5/32 inch, you both agree on 32 TPI.

Regardless of the original screws, my post #6 gives an alternative solution to the screws and nuts.

viewtopic.php?f=4&t=21858&p=176455&hilit=Screw#p176455

Regards,
Dave

[mgcjag]

Think you will find they are 8-32....Steve

[Heuer]

Unfortunately for those of us who do not use a VPN to hide behind or get round controls, David’s link goes nowhere interesting - just a thread of purple screens.

"Nowhere interesting" - really? All the information is in the text not in the purple picture eater:

The chrome finisher assemblies around the headlamp apertures (#BD16789 and #BD16790) are retained by a total of 12 chrome head slotted screws. On the early cars they were #BD19013/2 "Screw, Self-Tapping"' which went into #BD8633/2 "Spire-Nut". Jaguar Spare Parts Bulletin P.115 states the change took place at cars 881261/850843/890251/861557 and the newer screws are Phillips head.

[44DHR]

Steve is correct at post #5 with the machine screw defined as 8-32.
There is confusion over using the thread diameter as a measurement rather than using the screw gauge, which itself defines the thread diameter.
The “8” is the screw gauge size and the “32” is the number of threads per inch. Defined as 8-32 as a fastener with an imperial thread. Screw gauge “8” is approximately 4.16 mm diameter.

The measurement of 8/32 inch is 1/4 of an inch which is much larger at 6.35 mm.

I won’t post a photo as you may not see it.
Cheers,
Dave

[Allrand]

881261/850843/890251/861557 Something amiss there. Maybe the change was from slotted to phillps. My car is 861460 and has slotted machine screws, definitely not self tapping.