Welcome to our resource for MG Car Information.



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 MGA - Brake light switch (again)!

A friend of mine with Mk11 Deluxe has had his brake light switch replaced 3 times in the last 7 years since restoration - has used silicone brake fluid through out (I understand the current switch is a Hella - Made in Germany). He is frustrated with the failures and asked me to assist in installing a mechanically operated switch.
I am interested in obtaining photos of mechanical brake switch installations and a switch recommendation. Can anyone help?
I will also try to convince him that a good hydraulic switch is the way to go - like Barney I don't believe silicone fluid should effect the switch. Any recommendations for Australian hydraulic switch supplier?
Mike Ellsmore

Try this switch.
CM Harter

Yup, had the Ron Francis switches in my 3 cars now for years, and no problems. I buy mine direct from Ron Francis, but I think they are available in Australia from the likes of Rocket Industries.
Gary Lock

When my brake light switch went bad, I replaced it with a new one which I bought direct from Ron Francis in the USA. It worked fine for the first seven months, after which it only worked if I pushed the brake pedal mightily hard. I am using silicone fluid in the system. I fitted a relay for the switch and the brake lights come on with the slightest touch of the pedal.

F Camilleri

In Tech Sessions from MGA Mike Ash in Volume 2/Number 1 describes the installation of an alternative switch that is mechanical and not pressure based. Pressure switch issues seemed to crop up on my MGA and we were living in the DC metro area at that time where traffic was heavy, so I switched to a mechanical switch as described in the tech note. I has been almost a decade since I made the change and the mechanical switch has worked flawless. This is practical alternative and an out of sight modification. Installation is very simple and doesn't require anything specialized. Another option to consider.
Bill Haglan

A mechanical switch, if it is not a cheap automotive type switch will work. You need to look through electronic catalogs and get a good brand like Microswitch or the Cheery brand. The automotive mechanical switches that are used in the MGBs are every bit as bad as the hydraulic switches. I firmly believe that the brake light switches of today are produced for much lower current draws than the one back in the days of our cars. The Ron Francis SW-32 switch mentioned above used to be quite good, but I am seeing more reports of them failing after a short period of time.

The best (and easiest) way to solve this problem is to make up (or purchase an already made) relay circuit and place it in series with a new brake light switch. I did that on my TD and MGB (both everyday drivers) about 15 years ago and have not had a brake light switch failure since then. You can find instructions for making up a relay/arc suppression circuit in the article, Brake Light Relay in the Other Tech Articles section of my Homepage at: Cheers - Dave
David DuBois

I added a mechanical switch years ago and it works just fine. I made a sheet metal bracket and clamped it to the steering column. I used an early chevrolet switch as they are designed to take the electrical lode without using a relay.
Ed Bell

Here is a photo of my switch.

Ed Bell

Thanks Ed (and all) - yours is what I was thinking of. I have found a local source of industrial limit switches that can be easily adapted - around $20-25 and come with NO and NC contacts
Mike Ellsmore

Interestingly Hella are now advising that their hydraulic brake light switches are not compatible with silicone brake fluids.

Mike Ellsmore

Switches for later model Harley's are silicone compatible, readily available and similar thread.

I B Morris

Hi Mike,

As Ian says above, a Harley switch has worked well for the last 7 years in my car after a string of other switches failing.

M Wellard

Hi all,

On as summer evening my wife drove the MGA and I was following, noticing to her she didn't use the brakes during the whole trip. She actually did use them, but the brake lights only worked when the brakes where pushed real hard. I didn't want to be hit in the rear, but it was a nice warm summer, and I didn't want to wait for a new switch, so I looked whatever I had laying around to solve this overnight. the bracket is made out of some scrap aluminum and mounts to the existing screws, and the standard switch is wired parallel over the existing pressure switch. I wanted to replace the pressure switch later, but although you can

Rik de Krom

We eventually went ahead and fitted a mechanically operated switch by attaching an aluminium mounting bracket to the support bracket of the pedal box using the pedal stop bolt (if that isn't as clear as mud, the photo might help!). N.B. The pedal box support brackets on the this Mk 11 Deluxe (imported from the US and converted to RHD) are spaced wider than for a conventional MGA to facilitate the Twin Cam setup if you thought your layout looks a bit different.

Set up works fine and the original system can be restored easily for concours fanatics as connected using spade connectors to original wiring.

Mike Ellsmore

This thread was discussed between 14/04/2014 and 05/05/2014

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.