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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

One of the terminals on my brake light switch broke. If I remove the switch will I have to bleed the brakes? The brake lights were working so I think the inards are ok but one terminal broke right at the rivet so I was hoping I could solder it. Any suggestions.
Greg & Grimm
1952 MGTD (should be 1951)
G.J. Cenzer

I have just replaced the brake light switch on my 51 TD and yes you will need to bleed the brakes as air will have entered the system. If you can re-solder the terminal tag then you will save yourself a job.

David Tinker. Wales. UK
David Tinker

I have replaced brake light switches on both the TD and MGB and have never had to bleed the brakes afterward. In both cases, the master cylinder is higher than the brake light switch so brake fluid leaks out of the fitting for the switch, but since there is a slight pressure on the fluid (equal to the head of fluid in the master clinde plus the distance the master cylinder is above the fitting), no air will enter the system until all the fluid is gone from the master cylinder. If you have a new switch ready to put into the fitting imediately, you won't even loose more than a drop or two of fluid. The only air introduced into the system is that trapped in the switch, which amounts to a negliagable amount of air that will remain forever in the switch (you can fill the switch with a syrenge if that small space is of a concern to you.

Soldering the terminal back in place may or may not work. I have soldered the rivets to the contacts and terminals of various switches in an effort to reduce the resistance of the switches and have found that the results varied from excellent, to not at all.

You may find that the replacement switch will not last very long. The replacements on the market today seem to be rather whimpy, one lasting only about two weeks on our MGB. If you find that the switch fails in a short time, you can install a relay and arc suppression circuit in series with the next switch you install. Directions for installing and a parts list are available at: http://www.omgtr.ca/technical/brakelightrelay/brakelightrelay.htm
Be sure to install the relay and arc suppression circuit a the same time the new switch is installed, otherwise the contacts of the new switch will start burning with the first use and develope a hight resistance. Good luck - Dave
David DuBois

G. My experience is the same as David DuBois' in regard to having to bleed the system. While you're at it, save yourself a few bucks and go to your local NAPA store for a NAPA/Echlin SL144 switch.
FYI, the NAPA/Echlin SL144 is the grub screw version. It's strictly an lbc switch, i.e., 55-63 Austin, 48-64 English Ford, 51-56 MG, 49-64 Morris, 48-64 Rover, 49-64 Singer and 50-64 Triumph. Their SL147 is a blade terminal switch with a similar lbc list including 57-70 MG.
Bud Krueger

Bud thanks for the info. Will hit local NAPA store today. Greg & Grimm
G.J. Cenzer

Nother interesting point on the switch. Both MGTD shop manuals that I have (and the parts book) indicate that the stoplight switch should be mounted on top of the 4way fitting where as Moss catalogue shows switch mounted on bottom of 4way fitting which is where mine is located. Semms that on top would be a better location more away from any hazards. Greg & Grimm
G.J. Cenzer

NAPA part numbers are still good. Bought one this morning. Thanks for info. Greg & Grimm
G.J. Cenzer

I also purchased a switch from LBCC and the diff. in quality sure shows up. The NAPA part appears to be much higher quality and a better design. The mounting face on the LBCC one is dead flat where it intersects the mounting thread, whereas, the NAPA part has a slight rising to the mating surcae which to me would give a better seal. The screw terminals also look to be better on the NAPA switch.
Greg & Grimm
G.J. Cenzer

I think that with the switch mounted in the top position one may have trouble getting a screwdriver to clear between the floorboards and the switch.It might pay to check it out before changing positions.
Sandy
conrad sanders

AH! HA! That would indicate that the swirch (during production) would have been installed prior to installing the wood floor boards, which would make sense from a production standpoint, but then from a servicing stand point the terminals whould have been rotated 90Deg.
Greg & Grimm
G.J. Cenzer

Kind of a situation where they installed the switch and then built the car around it ; ) Cheers - Dave
David DuBois

OK NOW, today I installed the new NAPA brake switch, put in two new bulbs, checked all wire fittings at the tail light assy., all sockets are super clean. Still no stop lights working. Don't know where to look next
G.J. Cenzer

check for power at the green lead going to the stop light switch, with the key on there should be power there. You can trace it back to the fuse panel. If you have power then depress the pedal and check for 12Volts on the other terminal.If there is 12Volts then that lead goes back to the stop lights, but only if you do not have direction lights. If you do have the DL relay then the problem is in dirty contacts therein.Polish the contacts and watch the stop-lights light up.
Sandy
conrad sanders

Turn ignition on, see if the wire (17) from A4 (the fuse block) to Stop switch is hot (fuse may be blown and then the wipers won't work either). See wiring Diagram in Workshop Manual (1st see if A4 is hot, the the post on the switch) Often you have blown this fuse working on the wiring.

If hot, have somone step on brakes, the 22 wire on brake light switch so become hot (switch closed).

If so, go to junction in wire at stop lights and see if power is getting there . then to contact in socket.

Don Harmer

Bud,
Thanks for the part# and info (Echlin SL144 switch)!
My brake switch failed last weekend leaving me w/ alway "on" brake lamps. As always the info this BBS was "spot-on". Whilst at it I put in a piezo "beeper" and switch for my "haunted right turn signal".
Cheers & Best Regards,
David 55 TF1500 #7427
David Sheward

This thread was discussed between 06/05/2004 and 13/05/2004

MG TD TF 1500 index

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