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MG TD TF 1500 - Brake light switch wire attachment

I have a new wiring harness from British Wiring and I'm at loss as to how the two wires attach to the brake light switch. It would appear that I need to add 'bullets' to the wire ends and 'plug' them into the terminals on the brake switch. It appears that there are suppose to be clips to then retain the 'bullets' in the terminals. Is this about right? If so what 'bullets' do I use and where do you get the clips or do I improvise?

As always your help is greatly appreciated!

Happy New Year!
Jim Budrow

Believe it or not, my car still has the original harness in it, which needs replacing. On mine, the ends of the wires are tinned and just inserted under the screws on the switch.

Now it is possible, that over the years someone removed something, but I am inclined to think this is how it was.

Larry Ayres

Larry is spot on. There are quite a few bullet-less connectors on our cars which were simply tinned wires under a grub screw, or a push to open clamp. The ignition switch, voltage regulator, brake lamp switch, sidelamps, and headlamps come to mind. Strangely enough, the horns are bulleted, with special larger bullets. On my particular car, the brake lamp switch has terminal screws where soldered on ring connectors may work best.

Others may add to this list, or offer corrections. Afterall, the cars are over 50 years old, and it is sometimes hard to tell period modifications from original.

Dave Braun

What type of terminals are on the brake switch? It should be brass posts with a screw in the end if it the original type.There is a transverse hole into which the twisted end of the wire is inserted and then held in place by tightening the screws.
There are aftermarket types that have a blade type post and another that has a round projection that is smaller than a lucas type bullet. This requires a female end for the wire, and is usually available from auto parts stores.
Consider putting a relay into that circuit as the replacement units seem unable to take the current draw.
Sandy Sanders
Sandy Sanders

I installed a new NAPA switch with grub screws in my TD. Unfortunately my switch does not have the transverse hole but rather a deep slot. The screw hole extends past the bottom of the slot so when tightened the screw severed/weakened the harness wires, which completely broke off weeks later leaving me with no brake lights. My solution was to fill the hole to the bottom of the slot with strands of wire...and then insert the harness wires and tighten the screw. So far so good. Good luck. Tim
Tim Mayor

Jim, NAPA sells two brake light switches, one has the grub screw system and the other uses push-on spade connectors. I don't recall the NAPA numbers off hand, but a search of the BB archives should locate them. You might look at for info about the relay.
Bud Krueger

Well, genuis that I am, I installed the switch a couple of years ago without looking at it carefully. Now I have to lay on my back and try and see if there are screw threads in the end of the posts/terminals. Not easy with these old eyes but as I'm typing this it has occured to me that my wifes new digital camera won't mind at all. I would bet that I have the switch requiring the screws as it is not made for the spads. Someone (not me this time) put a 'c' type clip around the post where apparently the wire is suppose to be inserted. Fooled me or I have a unique switch.

Thanks for all the quick replys!

Best regards,
Jim Budrow

The original brake light switch on the T series cars had grub screw type terminals, while the switches on the early MGBs (and perhaps the MGAs - I don't know just when the change over occured) has spade lugs. When the original switch on our TD finally died of old age, I cycled several switched through that all died prematurely because the replacement switches sold today are very poorly made. In the process of replacing the switches, I got a switch with spade lug type terminals just to make it easier to change the switch and they were cheaper (same switch, just different terminals). There is a third type of switch with a different terminal arrangement yet. These are a very heavy duty switch (for those tired of the wimpy switches sold by the major suppliers and NAPA) and that is very expensive. The lugs on this switch have a grove near the top and take a connector that slides on across the top of the lugs. this is available from Ron Francis Wiring at:
Jim, if you can send me a picture of the brake light switch in your car, I can tell if you have any of the three types of lugs discussed above, but I would suspect that what you have is the grub screw type of lugs, either with the transvers hole as described by Sandy or the slot described by Tim. Sandy is correct, if your switch is a replacement switch and is not the type sold by Ron Francis wiring, you need to add a relay to the circuit to keep the switch from burning out. For instructions on how to wire in a relay, see my article on Brake Light Relay at:
Cheers - Dave
David DuBois

Went through 3 switches within a few months (the third brake light added to problem)... added Dave's relay and haven't had a problem since!!!
gblawson - TD#27667

If you tin the wires, it will give them enough strength to not be sheared by the screws.

"tin the wires" ...couple of different schools of thought on this practice, (as debated by "electronic types" all the time.)
Many in the electronics world argue that you do not get as "good a contact" when tinning a round wire as the contact area is greatly diminished over that of a "flat" wire. Others argue that if you don't tin, then the set/grub screw can actually cut the wire, if too tight.
In "our world" there are a few places in "T" wiring where you have more than one wire under a set/grub screw that even complicate the debate more!
My practice with the M.G. has been to tin the wires ...but then before inserting them to "flatten" them slightly using a pair of vise-grips, them a small drop of lock-tite on the screw, followed by a squirt of dielectric grease to keep the contact from corroding from the weather.
On the brake switch that is subject of this thread....I tried several of the "replacement switches" form the usual source and also found them to be of poor quality before switching (pun intended) to the better built (and cheaper) NAPA unit!
I guess you would call this my "nickles worth". LOL
David 55 TF1500 #7427
OBTW : Haven't touched my brake switch for about 5 years now and it was installed (the last time) following Bud's relay method!
David Sheward

Dave S. - Perhaps the reason you had good luck with the switches from NAPA is because of the relay? The switches I got from NAPA in our area were the same as the ones from the Moss and V/B and a local MG parts supplier and didn't last any longer (I have often wondered if NAPA stores in different areas get their parts from different sources). I did find that if aswitch had been installed and used for even a short period of time before installing a relay, the chances were greater that it would still fail than if the relay was installed at the same time as the switch. Cheers - Dave
David DuBois

Hmmmmm. I wonder if we ran Nappa out of the "other" switches or if Moss came onboard with a better one now.
I am sure that back when I was fussing with mine there was an obvious noticable differance in quality of the switch.
(and price!)
Warms up I'll have to look in my spares and see if I kept any of these.
No doubt more info on this in the archives of this BBS!
David Sheward

Jim ,
OBTW ...In the course of your re-wire if you do need some "bullets" I have been getting mine here:
Decent prices from what I have found! I keep some in my spares.
They ARE the right size for our cars!
Do a search on their site for "Lucas".
David 55 TF1500 #7427
David Sheward

David S. Would you, or others, share your technique for soldering on the Lucas bullet connectors? I'm familiar with the crimp on ones, but would like use some of the solder connectors. Thanks.

L Karpman

Larry - Start by heating the bullet and tinning the inner surface with solder (I hold the bullet with a pair of hemostats in a vice for this whole operation). Next, strip about 3/8" of insulation from the the wire and tin the exposed wire. Push the wire into the bullet until the end protrudes from the end of he bullet and apply the soldering iron and the end of the solder to the end of the bullet and the wire until the solder melts and flows. After everything cools, clip the end of the wire flush with the end of the bullet and remove any solder on the outside of the bullet with a needle file. If you have bullets that are ment to be crimpped, you may find that solder will not adhere to them due to the plating used on them. Even some of the bullets that are meant for soldering, sometimes have a plating that solder won't stick to and require filing the inside of the bullet to remove the plating. Cheers - Dave
David DuBois

David DuBois is "spot-on" in his directions. Only things I would add ...most of the "standard" crimp-ons at Napa are wrong size as well as problem Dave points out with getting them to "tin" and/or take flux correctly! (and IMHO, just plain ugly on a "T" if multi-colored!)
Follow the link in this post for Tripple C (I don't work for them!) They are period correct, easy to soldier, right size, and reasonably priced!
Tip # 2: Do get thee to Nappa and pick-up a small tube of "dielectric grease" ...apply a thin coat to the connections.....also use it when you install lamp bulbs! If you do this you should never have to deal with corroded wires or "rusted-stuck" light bulbs again!
David 55 TF1500 #7427
David Sheward

Thanks Daves X2. I use Triple C for the connectors and some other items, and your instructions/input are much appreciated. As for the dielectric grease, good advice, as I have always used it on my Jags.

L Karpman

This thread was discussed between 15/01/2007 and 18/01/2007

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