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MG TD TF 1500 - A challenge for Peter

Peter: I know you a a stickler for originality so I have a challenge for you that can help save the world (at least for the MGTD/TF).

As you have noticed in your floorboard machine screw quest there appears to be some variability in the aspects of screws and captive nuts and attachments.

One area that has always puzzled me and I think there may be a logical answer, or its just random, is the use of the cone or tapered end machine screws. What was the reasoning and how would we actually go about determining if these were applied logically or not.

Note almost every car has had its floorboards out for one reason or another so expecting to find cars with the exact screws in their proper holes is unrealistic.

Good luck and I anxiously await your answer or the feelings and insights of our peers.
Christopher Couper

I really don't know how to thank you Chris! :-( ..

This is a tough one. I've borrowed a set of boards that I thought may have been original, based simply on their poor & distressed condition & saw the machine screw for the gearbox filler cover plate pivot, which up until then, I had no idea existed. So a good place to start would be to first determine the location & size of all of the captive nuts & machine screws associated with the floorboards. I've recently learned that there were 2 holding each seat & only a week or two ago discovered that the cover plate also had one, possibly two, securing the filler cover plate pivot (& maybe another for the stop). There are the 2 @ 1/4" BSF "D" nuts per side at the front of the boards. As to the shape of the end of the screws it almost certainly falls into the category of who supplied the current boxes of screws then in use, much like the individual tools or the threshold screws. As the tapered jobs have one more step in their production they may even have fallen foul of the bean counters. That's all I've got buddy, which really isn't much at all. And we haven't even touched on the rear floor! Once the info is agreed to by those far more knowledgeable than I, I'd suggest it be added to the terrific drawings made by Mr Chalberg & then added to your site. Cheers
Peter TD 5801
P Hehir

I've got no real evidence, but I wonder if the tapered bolts/screws were used wherever there were captured nuts? I've noticed on my MGA that all the bolts holding the fender on are pointed and they all go into a captured nut. I've also got a TD firewall with the toeboard attached and the bolts going through the captured nuts along the bottom edge of the firewall (top of the toeboard) are all pointed.

Perhaps this made it easier to thread those bolts on the assembly line?
David Littlefield

I think Dave is close.
I had purchased 1/4 BSF SS FH slotted wood screws with the intent of using them to secure the floor boards to the captive nuts on the drive shaft side rails.
I wound up putting bevels on them. Without the bevels it is very difficult to engage the screws.
Another spot with similar issues is the inner corner of the foot kick board where Peter is working.
I also had to bevel some of the hex head screws that hold the rear wings on.
The ones that engage the semi vertical stantion.

Some times on Detroit cars you get bolts with the threads removed at the start and with a nib protroding to help engage a captive nut or threaded hole.

Jim B
Jim Benjamin

Even though I'm certain my floor boards had been out at least once before my restoration, every hex headed and slotted screw in the floor boards, transmission cover and toe board that went into a captive or t-nut was tapered to a point. I made sure I put them back in their same places.

In fact, when I bought new floor boards from the Whitworth Shop, I was disappointed that they came with American T-nuts. I found all the old boards back in my yard, and pried off all the BSF t-nuts, tumbled them, and installed them in the appropriate places.


Dave Braun

My thoughts is that most of the original ones were beveled. For some years none were readily available, and when repros came out they had blunt ends. Abingdon Spares supplied some with the bevels, but some of those were Phillips. George
George Butz

The pic from Matthew seems to confirm this. Cheers
Peter TD 5801

P Hehir

Except for the one on the left that is in a captive nut (T-Nut) and it's flat.

Dave Braun you might be the best source so far. So when you mean every, do you also mean the ones that went into the T-Nuts?
Christopher Couper

I have had pre-war Morris cars and they use the same 1/4" c/sunk slotted screws with the point on the end.
Part of the pointing process is to remove the first couple of threads to form a small parallel section which also helped the screws engage.
Max Irvine

Most of my floor board screws are pointed except for a few that were swapped out due to stripping or seizing. I also seem to have two different lengths in the pointed screws. These screws are all Phillips on this late TF (not certain when the change from flat drive happened). The two screws for the master cylinder cover plate are dome headed wood screws on my car.


M Magilton

I think you have your answer Chris. The originals were almost certainly pointed. I can account for 2 captives per seat, 2 for the gearbox filler cover plate (pivot & stop), 4 captive D nuts (although they're in the toe board), so far. As I'm still playing with the doors I'm some way off from fitting the floor, so there may be more? Cheers
Peter TD 5801
P Hehir

Interesting that TF had Phillips. The ones that came from Abingdon some time back appeared to be very old, so perhaps factory? George
George Butz

Chris -

Regarding pointed tip bolts through the T-nuts and D-nuts ...

Photo #155 of TF9052 shows bolts with pointed tips though a round T-nut on the floorboard and a D-nut on the toe panel.

I made a diagram and list of floorboard bolts in my TF. I think that most of it is correct. I will be updating it soon, including using some of the info in this thread. Here is the link to the current diagram that needs some minor revisions:


Photo #155, TF9052

LM Cook

Great effort Lonnie! On your next update I'd suggest mentioning that the drawing is for a LHD vehicle & that perhaps a RHD version be produced. A couple of other inclusions that I'm aware of would be to add the two captive nuts for the gearbox filler cover plate (see pic of original RHD floor below) & also to note that TD's (& possibly some TF's?) had slot head screws.

Perhaps an alternate presentation would be to number like with like. For example as 2L & 3L are identical they could be shown as 2L with a quantity of 2. You could even remove the L & R notation to further reduce the number of entries in your list. This would mean item 2 now has a quantity of 4. This would require the addition of a QTY column perhaps making the table easier to read. Your work, used in conjunction with Roy's dimensioned drawing, would make the construction of accurate flooring with the correctly sized & located fixings, achievable by anyone. Many thanks. Cheers
Peter TD 5801


P Hehir

Peter, did you mean the master cylinder filler cover plate? I don't think I would be putting gearbox oil down there.
I also wonder if other TD owners have T nuts here? I have only seen wood screws but not really studied these. They are shown as wood screws in the TD Drivers Handbook too.

M Magilton

I did mate. I'd be lost without you Matthew. I wouldn't be putting gearbox oil down there either! I assume they are original not only because of the condition of both the nuts & the floor, but I can't imagine anybody going to the trouble of sourcing & fitting captive nuts in a replacement floor if they weren't there originally. I've also seen one of these master cylinder captive nuts on at least one other TD. This was pictured on this site a little while ago, but I can't recall the thread title.

My Driver's Handbook on page 33 bottom illustration shows two fixings, one for the pivot & one for the stop & both are round head slots. These could be either wood screws or machine screws, though in the pic above they were obviously for machine screws. As they need to be accessed every 1,000 miles it makes sense that machine screws would be used, as wood screws are designed to join two items together & be driven all the way home. Cheers
Peter TD 5801
P Hehir

I seem to recall the car I mentioned above was for sale & may have been painted blue. There were a few pics & in one of which the car was on a hoist & the captive nut was clearly visible. I'd assumed the other had probably fallen out. Cheers
Peter TD 5801
P Hehir

Yes Chris, except for the seat rail bolts, if they went in a t-nut, they were pointed. The longer ones were typical for the difficult to line up gearbox cover.


Dave Braun

This thread was discussed between 26/07/2015 and 28/07/2015

MG TD TF 1500 index

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