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MG TD TF 1500 - Grub Screw Questions

We are renewing the dash/fascia now including wiring and have two questions on switch/instrument grub screws. As always, any thoughts and recommendations are very appreciated.

First, some of the grub screws are showing their age with wear and deformed slots (King Kong must have worked on the wiring at one point). Is there a good source for replacement brass grub screws? If not, anyone know the correct bsf and metric sizes (early flat faced gauges and switches)?

Second, experts tell you not to tin the ends of the wires when using grub screws (less conductivity, cold flow, mechanical interface/wire breakage etc). However, our car has some wires tinned and some wires bare. And, most of the bare wires show considerably more deformation and strand brakage than the tinned wires. What is the consensus of the forum about tinning wires in real world conditions?

Thanks for any help.

Regards,

Bill

WHTroyer

I think the rule was if it is under tension you don't tin. Solder tinned wire [multi strand] can give way under pressure and they will cause a looser connection over time. That could possibly cause a hot connection. Ideal for the Prince of Darkness.

In the Royal Air Force we were taught to use ferrules and crimp to get the strongest and safest connection when clamping. No solder was permitted. Plessey Plugs were a different animal as the cables are supported by the plug case anyway and individual wired were soldered directly into pins - Not under pressure.

There is a school of though that you can touch an iron to the very end of the copper strands to help hold them together once twisted together. But no solder should be under the grub screw that holds it in place.

Just my 2c worth

Rod
R D Jones - Ex Pat

Bill, the last time I looked, Moss sold new grub screws if you need them. Sorry I don't remember the part number or the size they sell. PJ
Paul161

Thanks Rod.

Do you recommend twisting the strands before inserting the wire into the grub screw?

When dealing with multiple wires in a single grub screw, as with the regulator, do you insert each wire separately or twist them together before inserting them?

Don't want to mess this up at the end after all the work in rewiring. Certainly, don't want any smoke or fires.

Regards,

Bill
WHTroyer

"When dealing with multiple wires in a single grub screw, as with the regulator, do you insert each wire separately or twist them together before inserting them?"

Insert them singly. I try to leave as much slack on the wires as possible so they can be cut back in the future if needed.

If you can't find any grub screws anywhere else, contact me at SUfuelpumps@donobi.net I amy have some. Cheers - Dave
DW DuBois

Paul,

I looked through the Moss directory and could only find grub (set) screws for the regulator. I will call them and find out if gauge and switch grub screws are available.

Regards,

Bill
WHTroyer

Bill
When I did mine, I did twist the wires and put them in individually.
I did not solder tin the wire at the regulator or fuse block connections at all.
The only ones I soldered on were the bullet connectors that push into the barrel connectors. For the lights and where the rear harness connects to the main harness. Anything that needs to connect to a screw terminal - Crimp a spade or ring terminal to the wire.

Rod
R D Jones - Ex Pat

Dave,

Thanks for the guidance and information; and, appreciate your offer for help. I'll try to measure the screws (threads/diameter) and look online for them. Will email you for help if I can't find them.

Regards,

Bill
WHTroyer

Rod,

Thanks for the information. I bought a crimper from British Wiring for the bullets and other terminals.

The grub screws are a new experience. Read that if might not be a bad idea to carefully polish the ends to help prevent wire damage. But, generally, could not find specifics on inserting/connecting bare wires.


Regards,

Bill
WHTroyer

Most of you probably found/know this, but I just saw this in an online copy of the "Instruction Manual for the MG Midget Sports Car".




WHTroyer

If you Google "Lucas PLC 6 Ignition Switch" there's an ad on E Bay for the grub screws you seek. This has been running for a couple of years now. Cheers
Peter TD 5801
P Hehir

Great quote. Further to the soldering issue, The RNZAF taught us that solder wicks up the wire and gives a stiff point at which the wire can fail in fatigue. We didn't have crimp connectors at that time (1960), so used a technique similar to the quote.

We also used waxed thread to whip wires into a mini-loom when we re-wired bomb carriers and the like ( I was an Armourer), but I've never seen that done on a car. Except mine, behind the dash panel.

David
DavePro

The size for the PLC switch grub screws is 2BA, but an ordinary 10-32 set screw from your local hardware store will work fine. If you insist on brass, go get some 10-32 brass screws, cut the head off, and cut a screwdriver slot with a hacksaw.
Lew3

I don't know what Moss charges. Many of these are BA2 screw threads.
These are very close to out 10-32.
Some of my switches were missing them.
I a very short time I made some.
I parted off q brass screw, chamfered the end, slotted them and done.

Actually faster than setting at the computer and ordering them.
Jim B.

JA Benjamin

Peter, Googled the information on the PLC ignition switch 2BA grub screws. My luck, the listing now reads "over 250 sold and 0 available". :-( Maybe he will have more in the future?


David, hope the results of my wiring has little similarity to rewiring bomb carriers. Worried enough about it as it is. :-)


Lew, found some brass 10-32 set screws that could be shortened and polished as below. I only wanted brass to be easier on the copper wires than steel, but that might be more surface finish than material.


Jim B, had not thought about making the grub screws until you and Lew mentioned it. I have a small lathe and could buy a few 2ba brass screws. Have to think about the slotting process. Called Moss earlier today and they said they don't sell the switch grub screws.


Thanks everyone.

Regards,

Bill
WHTroyer

Just looked at "Frame Up" on line catalog and they list them under DASH.

https://fromtheframeup.com/
Richard Cameron

Thanks Richard.

Found the screws at "From The Frame Up" after reading your post and will order from them.

Regards,

Bill
WHTroyer

This thread was discussed between 04/07/2016 and 06/07/2016

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