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MG TD TF 1500 - Horn Push Nuts
|While removing my horn push to begin restoration of it, my TD "ate" one of the nuts off the back of the screws that hold the retaining plate. I have spent hours hunting it. Does anyone know where I can obtain one? Does anyone have a spare? I don't see them in the Moss catalog.|
|I not too sure if it's the same on the TD ...but if memory serves me my TF has "440's" on it.|
I have bunches of stainless steel 440's send me an address off line and I'll stick some in the mail to you if those are what you need! firstname.lastname@example.org
David 55 TF1500 #7427
|The small nuts on T-cars are usually 2BA (nearly the same as 10/32 or 4BA which is 0.1417 in diameter and 38.5 threads per inch |
If the screw is 4BA then a 4-40 nut won't fit
(a @ 6-40 is 0.1380 in dia and 40 TPI so you might get a 4BA nut on a 6-40screw, but not the other way around)
You might get 6-40 brass nut to fit in however.
I don't see how a 4-40 nut would fit at 0.112 in dia.over a 0.1417 screw.
However, a 4-48 would fit a 6BA screw however (0.1102 vrs 0.112 dia and 47.8 TPI)
You can order 2BA, 4BA and 6BA nuts (&screws) from British Fasteners ( see the thread on taps and dies)
I got mine from John Marks when he rebuilt my instruments.
|The nuts are almost certainly NOT 4-40 unless someone replaces the screws after manufacture. Without looking at mine, I would guess they are 4BA. However, I also remember that the nut is considerably larger than a standard 4BA nut - something like 1/4" BSF with a 4BA thread.|
I would replace with a long 4-40 screw with a washer under the nut.
|Thanks for the input guys, but you can't replace the horn push screws without knowing the thread size for sure, as they do not simply push through the horn push, they are threaded into it and the nuts on the back simply secure the back retainer plate. At least on mine that's the way it is.|
|I just went to the basement and made a few measurements. The replacement horn push that I have has 5-40 screws in it. I purchased that push from someone on the internet, so have no idea where it came from, but I am fairly sure that it is not original. However, based on the measurement and comparing it to Don Harmer's original chart of standard threads, taken from the Machiner's Handbook, my guess is that the original screws are 5BA. The 5BA screw is 0.1260" (according to the chart) and the 5BAs that I have from SU fuel pumps measures 0.1222" with a michrometer. Also the 5BA has a thread count of 43 TPI. Yes, I know that MG used 2BA and 4BA hardware almost exclusively, but some of their vendors used different sizes (the only true Whitworth bolt in the whole car is for the adjusting link on the Lucas generator). Larry, if you want to send me either the one remaining nut or the screw itself, I can determine what it is and probably rethread a standard nut to fit. Cheers - Dave|
|David: If you could throw the nut in the box with the relay when you ship it, that would be great! Thanks!|
|I needed a couple of those and Abington Spares had them.|
|If the one David is sending does not fit, that's where I'll go. Thanks.|
A quick look @ the Moss catalog tells me the horn push for TD/TF totaly different animals!
A "review" of that jogged the old brain cells...(screw & nut securing my horn push to scuttle was missing!)
That is where I used a 4-40!
Still have quite a few left, but not much good for your applacation.
"Nevermind" said the man with more screws than brain cells!
David 55 TF1500 #7427
|Abingdon Part# 39-003a Horn Screw and Nut|
(make sure you check on that part# when you order)
|Yep, thanks, I had just looked it up on line.|
|I have also lost (misplaced?) one of the nuts from my horn push/dip switch assembly. This thread is from 10 years ago and the AS part number given is no longer valid. Did anyone ever come up with the correct size nut?
This thread was discussed between 09/09/2006 and 27/05/2016
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