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MG TD TF 1500 - TF 3 bow top frame

Greetings and salutations.

It would be most beneficial if someone could help me sort out two issues I have with the top frame for the TF.

The first issue is with the pivot node that connects the rear bow/strut to the strut that rises to support the middle bow of the top frame. This node is directly adjacent to the plate that affixes the entire frame to the body proper (on the rear quarter panels)

All the pivotal points on the frame are riveted, yet the aforementioned node, on both the TF frames I possess, have these nodes fastened with a nut and bolt (without an interspace brass washer).

This appears to be a user installed "fix" applied at some point in its life, given that this node has substantial mechanical force applied during its operation when in use.

My thoughts are that this should also be riveted in keeping with the design construction of the the rest of the frame.

The second issue, also related to the top frame, regards the mounting of the side curtain buffer rubbers on the strut supporting the middle bow.
The buffer locations on the strut show two mounting holes. Closer examinations of these holes seem to indicate that they are threaded.
The diameter of each hole is marginally less than 0.098" indicating that it may be a 6BA machine threaded screw - either countersunk or perhaps a round headed affair.

None of the current T series suppliers list fasteners for these buffer rubbers but do furnish the buffers if required.

Any feedback would be greatly appreciated.

Peter
TF8502

P Pichler

Hi Peter, I think that all TF's were 3 bow. The TD went from 2 bow to 3 during it's production and I'm sure that they didn't revert. Can't assist with the riveted fixing you're enquiring about but on the TD the buffer rubbers were secured my a small metal threaded screw, not a machine screw. More like a tiny wood screw. I do have the originals still affixed to the frame and could take a pic if nobody else is able to provide more detailed info. Cheers
Peter TD 5801
P Hehir

Peter: Can you use a graphic editor and circle the place you are describing?

Peter is correct about the rubber buffer screws. They were very tiny flat headed wood screws. Does not seem to make much sense but that is what they were.



Christopher Couper

My unrestored frame.

Matthew.

M Magilton

Thank you Peter, Chris and Matthew for your prompt responses.
Peter, I have had a closer look, using a magnifying glass, at the holes in question. One top definitely has machine screw threads, while the other top has smooth bored holes.
A #4 sheet metal screw has a shank diameter of 0.112" which would fit this hole correctly. (in my previous post I had incorrectly specified a hole of 0.098" which in fact is for a 7BA screw. A 6BA has a diameter of 0.11").
I believe I will stick with the sheet metal screw recommendation based on the current feedback. Undoubtedly, this will likely be about 3/8" long, slot headed screw with a blunt (type J) point, in keeping with the design criteria used on other TF sheet metal screws (radiator and bonnet side louvered inspection panels)
Thank you.

Chris, the image you included with your response addressed my query to the point.
Your picture shows the three riveted pivots in this location.
My question was regarding the rivet on the far right side of the photo, which had been replaced on my two tops, on both sides, with bolts and nuts.
Clearly this was due to the rivet having failed (most likely too loose) and replaced by a previous owner).
Thank you.

Peter


P Pichler

I have seen other cars that had some of these rivets replaced by nuts/bolts and other creative means.

Replacing it with a correct rivet would be best but I suspect you would have to have it down at a shop that had a pretty good sized press.
Christopher Couper

Chris, all that was required was to cut away the hammered flare on the opposite end of the rivet head.
It then was pushed out.

Having acquired a correct rivet and a suitable brass 1/4" x 1/2" x 0.062" washer, the disparate parts were assembled, the stud portion of the rivet heated to a cherry red (taking care not to affect the brass washer), and then imparting multiple hammer strikes to that area to produce the required flare.

To effectively achieve this the two frame struts in question had to be tack welded together, temporarily to provide a tighter composition and alignment at the pivot.

All went well, thank you.

Peter
P Pichler

Peter: Very clever with the heating and tack welding.

I would have hauled my frame all over town until I found someone willing and with the proper equipment to do it cold which probably would have taken months. :-)
Christopher Couper

If you have a small lathe it’s not hard to fabricate a rivet by turning off the thread and square shoulders from a cup head bolt. The dome is quite similar to the original and can be ‘adjusted’ with a file if necessary. They tend not to be high carbon steel so can be riveted cold - just need to guesstimate how much shank is needed to spread into the countersink with a ball pein hammer. As well as the brass washer I add a sacrificial paper washer which soon deteriorates and allows the joint to move freely.
Ideally a ‘set’ which fits the dome perfectly would be used but a piece of very hard wood worked for me.
As I was single handed, instead of a tack weld I clamped the frame to the edge of the bench and riveted on the floor.
C I Twidle

If you have a small lathe it’s not hard to fabricate a rivet by turning off the thread and square shoulders from a cup head bolt. The dome is quite similar to the original and can be ‘adjusted’ with a file if necessary. They tend not to be high carbon steel so can be riveted cold - just need to guesstimate how much shank is needed to spread into the countersink with a ball pein hammer. As well as the brass washer I add a sacrificial paper washer which soon deteriorates and allows the joint to move freely.
Ideally a ‘set’ which fits the dome perfectly would be used but a piece of very hard wood worked for me.
C I Twidle

This thread was discussed between 04/06/2019 and 05/06/2019

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