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MG TD TF 1500 - Glove box knob bolt

I looked in the archives and I did not find an answer to my question. My question may border on the absurd.

The glove box knob on my dash is held on by a screw, not a bolt. So, naturally I thought I would replace the screw with a bolt, not only to be more original but the screw never firmly held the knob anyway. Naturally, the screw also messed up the threads in the knob. So, I do not know what the proper bolt is to use to hold the knob onto the glove box cover. Further, I have a hole in my knob that I need to fill, drill a hole and rethread.

Like I said it is kind of a whacky question. Does anyone know the proper bolt size for the glove box knob? Any suggestions on what to use to fill the hole? That 2 part weld stuff?

Also, if someone has an original knob, it would be nice to see a photo of it so I could compare it to the one I have which I have been told is original. Mine is black, looks like bakelit and octagonal.

Complusively yours,
Milton
Milton Babirak

I forgot to mention that my car is a 1951 TD.
Milton
Milton Babirak

I'm not sure if it is a screw or a bolt. I would imagine if it is threaded it would be a #2BA, but not sure. A US 10/32 may work. Anyway, to fix the knob I would use JB Weld. I will check the TD to see what the knob is held on with, but it may be a few days before I can get out to the garage.
D. Sander

Mine is indeed held on with a chrome screw, not a bolt. I believe a screw is the original fitment.

I tightened mine up a bit with a dab of silicone seal, and then let it harden. Worked so far (27 years).

Tom
t lange

I am with Tom, pretty sure that when Craig Seabrook put my dash together he used a chrome screw and he is pretty picky about using what would have been original. I can post a picture later if you want.

Regards,
Rich
Richard Taylor TD3983

D. Sander and Rich: Yes, I would appreciate it if you would check yours. Thanks!
Milton Babirak

Milton, here is a picture of the screw, hope this helps.

Regards,
Rich

Richard Taylor TD3983

Rich
Thank you very much. That looks like the very same screw I have in my knob.
By the way Craig Seabrook did my dash as well. Craig is very attentive to detail and if he uses a screw to secure the knob, then it is highly probable that a screw is the proper hardware and a bolt is not.
One thing that still makes me wonder though is that these screws are Phillips head screws. Did they have Phillips head screws back in 1951?
Milton
Milton Babirak

Milton - Yes - I once worked on a 38 Caddy that had them from the factory.

Tom
t lange

In the early 1930s, the Phillips head screw was invented by Henry Phillips. Automobile manufacturers now used car assembly lines. They needed screws that could take greater torque and could provide tighter fastenings. The Phillips head screw was compatible with the automated screwdrivers used in assembly line.


In 1908, square-drive screws were invented by Canadian P. L. Robertson. Twenty-eight years before Henry Phillips patented his Phillips head screws, which are also square-drive screws.The Robertson screw is considered the "first recess-drive type fastener practical for production usage." The design became a North American standard, as published in the sixth edition of Industrial Fasteners Institute Metric and Inch Standards. A square-drive head on a screw can be better than a slot head because the screwdriver will not slip out of the screw's head during installation. The Model T car made by the Ford Motor Company (one of Robertson's first customers) used over seven hundred Robertson screws.


It seems Henry Ford tried to buy the Robertson patents and P.L wouldn't sell them so Ford changed to Phillips.... (how many scratched fenders/paint has that resulted in over the years)....???
gblawson(gordon- TD27667)

On British cars, the heads would be PoziDrive rather than Phillips.
A similar looking cross slot, but with a different profile that helps prevent the "walking out" or slipping of the screwdriver..
These can be identified by the faint lines marked between the slots on the head.
Phillips screwdrivers do not work well with PoziDrive screws.. tend to slip out more easily.

Onthe MGB, for instance, there are no slotted or Phillips screws, all are PoziDrive.
Don Harmer

Don - I always thought it was Pozidriv. My glove box knob screw has no such markings.

Tom
t lange

An update tomy comment, and correction:

They are Posidrive not Phillips ( and not PoziDrive)
See attached picture and this short article


Posidriv, Not Phillips
by Bill Nero, 4 Avon Dr.,
Freehold, NJ 07728
email. billN@aol. corn
reprinted from Six Pack’s“Triumph TR6” magazine.
Summer 1998 issue.

Over the past twenty years I have enjoyed restoring British sports cars ( I know, I’m a glutton for punishment!). Occasionally, I bump into a newcomer to the hobby (or a “lifer” like me) that vents his frustration about “those nasty little Phillips screw heads that always round out when you try to remove them!”. The reason they round out is because they are not Phillips head screws they are posidriv screws. For those of you who know about this bit of restoration trivia now is the time to find another article, if not, read on.
All original “plus-head” screws on British cars were, in fact, posidriv screws. A posidriv screw can be identified by four thin slashes that are stamped on the head of the fastener (see the illustration below). In addition to the surface slashes there are four additional wedge-shaped cutouts located inside the opening in the head of the fastener. The posidriv screwdriver tip is not as tapered as a Phillips tip and it has four additional wedges that fit tightly ‘into the fastener. Therefore, if you use a Phillips screwdriver to undo a posidriv screw, it will tend to ride out of the recess in the screw and will round the comers of both the tool tip and the screw recess. As far as I can research, British car makers chose to use posidriv fasteners because the fight fit that could be achieved was ideally suited to their mass-production methods of the period.

See Attached Picture

Well, knowing about posidriv is only half the battle, the other half is getting yourself a set of posidriv screwdrivers. After doing some searching a number of years ago I found that Snap-On Tools had an excellent set of five posidrivers whose tip sizes range from your smallest chrome trim screws to those big ones that are holding your door latch mechanisms on. Since Snap-On does not sell at stores you will need to catch one of their sales tracks stopped at a repair shop, or pull up to a Snap-On truck stopped at a traffic light and ask him to pull over (like I did!). If you can’t find a Snap-On dealer try MAC Tools or one of the other “traveling tool dealers”
If you have read this far you are probably suffering from “British Car Restoration Overdose Syndrome” and you should not be left alone for long periods of time. However, if your still feeling “frisky” go out to the garage and enjoy your new posidriv screwdrivers!


Don Harmer

Not true that all crosshead screws on Britcars are Pozi. They were Phillips up to about the end of MGA and beginning of MGB, c1962. I've been looking for years for the actual date of introduction for Pozi. Pozi was developed and patented by Phillips, as an improvement for use with power drivers in production. I well remember the day c1971 when the SnapOn guy came in with the first Pozi driver we (and he) ever saw, but most if not all screws on all MGB from 1962 are Pozi. I still have and use constantly the #2 Pozi I bought that day! I have no idea why all manufacturers did not adopt Pozi, as it is clearly superior to almost everything else, with Robertson next. There are now deck screws with a combined Robertson/Pozi head, also a Phillips patent.

Excellent Wiki article on screw drives - but not the date for Pozi.
http://en.wikipedia.org/wiki/List_of_screw_drives

FRM
FR Millmore

I still maintain it is Pozidriv, not Posidriv or PoziDrive. I don't believe I have ever seen one on an original T-type, anywhere. My glovebox screw certainly isn't one.

Tom
t lange

I've only seen Phillips head with a plain 'cross'...not that the angles or whatever might be different....don' know? But have not seen the little extra cross?


Pozidriv was jointly patented by the Phillips Screw Company and American Screw Company in the USA. Developed by GKN in the 1960s, the recess is licensed from Trifast PLC in the rest of the world. It is the de facto standard in Europe and most of the Far East, where Phillips is almost nonexistent. The proper Pozidriv screws have a flatter bottom to the socket, and steeper sides, so the driver doesn't cam out as easily. The name is thought to be an abbreviation of positive drive.
gblawson(gordon- TD27667)

"It is the de facto standard in Europe and most of the Far East"
I guess that's why we used to grind off the tips of the Phillips screwdrivers for use on Japanese motorcycles, back in the '70's.
Al
A W Parker

Phillips screws can be a pain and buggered up screws are one of those things that screams wrong tool used. I have stripped, reamed out, broke and defaced screws about every way imaginable. I have found that an impact screwdriver is a tool that all mechanics should have and it saves mucho curse words:)
Richard Taylor TD3983

This thread was discussed between 27/07/2011 and 29/07/2011

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