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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Brake Light Switch

Time for my annual brake light switch change. In the past the Ron Francis switch was mentioned. Has anyone used that with success? Or have any other suggestions? I use silicone fluid if that matters. George
George Butz III

Hi George,
I seem to get two to three years out of mine. I also use dot 5 ( and have had zero brake issues in13 years ecept with the switches )I have actually cut open failed switches to see what the heck is going on. The one I cut open showed dot 5 behind the contacts in the switch,stopping the contact movement. It is a thinner fluid than dot3. I installed a brake relay which seems to help. I usually buy the switches from NAPA in a three pack. Sorry no flat out solution here.
Stay well
Keith
K. McKenzie

George; I have had a Ron Frances switch on my MGA for more than 5 years without a problem.
Bob Wrenn

I put Dave Dubois relay on mine by the switch and it's working fine. I eliminates the strain on the new crap switches. PJ



PJ Jennings

Since I installed LEDs in the taillights I haven’t had any issues. No need for relays as the current load is nearly nil. Knock on timbers!
W A Chasser

By the "Ron Francis" switch are we referring to the SW-32 Low Pressure switch?

https://www.ronfrancis.com/prodinfo.asp?number=SW%2D32

Thanks.

Peter
P G Gilvarry

Rubber seal , copper contact disk , spring underneath, two contact points. It all fits in the metal housing.


K. McKenzie

George
The brake relay is the best "fix". Search the archives and/or TTalk. Plenty on the issue. Not related to type of fluid. It's electrical "arcing" and burns out the switch. Did it years ago, no problems

http://www.ttalk.info/Tech/BrakeLightRelay.htm

http://www.omgtr.ca/technical/brakelightrelay/brakelightrelay.htm

Randy
R Biallas

I have still had two burn outs with the relay as outlined above. I have switched to LED's now and I will see if the reduced current draw helps . They sure are nice and bright!
Stay well All !
Keith





K. McKenzie

Keith - which LED's are those - where did you get them?

Thanks. Tom
t lange

After some failures with the Ron Francis switch on my other British cars I contacted them and was advised some of these fail as owners are running higher wattage halogen or other type bulbs that over stress the contacts in the switch. The tech suggested using a relay which I have done on some of my cars but not all. Some MGs and Morris Minors with turn signals have a relay box to shut off a stop light when the signals are used and these relay boxes may cause additional load on the switch.
John Quilter (TD8986)

Not sure how a halogen headlamp would affect the brake lights since it is a different circuit. Never seen halogen taillight bulbs. Can you expand on your explanation? I’m curious to find out if I’m missing something

Bill Chasser
TD-4834
W A Chasser

Hi Tom,
Abingdon spares. Full kit 4 LEDs and flasher. Currently sold out
K. McKenzie

George,

The MGA uses the same part, The MGAGuru made a detailed investigation into these switches, giving feedback information on bad units.

https://mgaguru.com/mgtech/electric/et119a.htm

My switch was Lockheed P/N 23388 it failed after 10 years, I found an original Lucas one, P/N 31082, it has now lasted 16 years.

John

J Scragg

Thanks for the comments. I haven't looked at the current path through the relay box yet, but John Q's comment may be part of the problem. Some years ago I switched to 1157 halogen bulbs which likely do draw more current. This was way before any LED taillamps were out, and they are about twice as bright as the regular bulbs. Since I already have another cheap switch I'll just put it in for now, and consider building the relay deal. Also neat info from the MGA guy. Thanks and keep those hands washed! George
George Butz III

W A Chasser & George Butz III. Yes, that is what I am using in my car. The bulbs look more like a cylinder with a pointed tip than a traditional round shaped 1157 bulb.
John Quilter (TD8986)

Brittrix supplies the LED light boards to Abingdon Spares. You can also order them directly from Brittrix at www.brittrix.com. They supply 25 different LED light boards for over 350 different classic British vehicles.
Lew Palmer

The best quality in brake switches I have found are from Harley Davidson - they run Silicone Fluid too !.
A L SLATTERY

Old switch. Note the contacts are likely rivets, with only the tiny rim as contact area. Note burned area on the right one, which matches the burned spot on the contact disk. Otherwise, the diaphragm and internals were perfect. George


George Butz III

So this is an electrical issue and nothing to do with the type of fluid used, even silicone.
John Quilter (TD8986)

In this case, yes. But can't tell about K. McKenzie's switch above. That is a different design and manufacturer.
George Butz III

This thread was discussed between 14/04/2020 and 21/04/2020

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.