Replacing TR 3 Stop Light Switch

[Camping57]

I have tracked down that my non-working brake lights on my TR 3 are due to a non-functioning stop light switch. Now I get the "fun" of replacing the switch.
Just reaching the wire terminals to troubleshoot the switch was difficult and I am wondering if anyone has experience in the easiest way to access the switch for removal and replacement. Looking at it I'm not sure if I'll have wrench access without pulling the carbs and I really don't want to do that unless I have to.
Has anyone else changed out the switch? How did you do it?

Dick

 

[donbmw]

I have changed my switch twice in the last year. I found it was not easy to change switch going down through engine bay. If your remove the front wheel the switch has easy access.

Don

 

[Camping57]

I didn't think of that. Duooh!

 

[jsneddon]

get some of those brake line wrenches (an almost completely closed box end wrench with a notch cut out to go past the brake line) from Sears or even "Cheap Chinese Tools-R-Us" (Harbor Fright) /ubbthreads/images/graemlins/smile.gif

In a pinch you can cut one yourself out of an extra box-end wrench. It will probably take a lot of wrenching to break those suckers free and you don't want to round off the flats.

 

[Camping57]

Looking at the parts diagram it looks like the switch screws into the side of the Tee fitting and I won't have to take off any of the lines. Is that right?

 

[Andrew Mace]

Correct, although you'll lose a bit of fluid. If you're quick, it will be very little!

 

[Geo Hahn]

I have heard that the replacements available are not as durable as the originals (can't say from experience as mine is original).

Somewhere I recall someone found a replacement (possibly a Ford part) from NAPA that is perhaps more durable.

Another alternative some use is a TR4-style set-up... a push button switch mounted to the master cylinders bracket and operated by the forward stroke of the pedal/fork. May also have the slight advantage of coming on sooner than the pressure-activated switch.

 

[donbmw]

The first switch I replaced worked fine for awhile. At some point one night I noticed that my brake lights did not come on as I got on the brakes. It would take alot of pressure to get them on and sometimes they would work right. The next switch has been working fine for the last few months. The first switch came from VB the last one from Moss

Don

 

[Harry_Ward]

I replaced my switch three times in less than two years and bought all from Moss. I found out that NAPA sells the exact same switch complete with screw connectors for a lot less than Moss. As insurance of not having to take the tire off and rebleed the brake lines again I installed a reverse push button switch off the brake master cylinder housing (also from NAPA). It's been trouble free for three years now and the brake lights do indeed light up alot quicker. I'm not sure why the switches go bad but I can tell you that the pressure/plunger and spring inside gets jammed to far into the housing causing the switch to fail. Once removed from the car I have been able to clean it and get the switch to work again but it requires more pressure to activate it. I also removed my restrictor valve several years ago and think this might have something to do with it or I have junk (scientific term) in the brake line system causing it to jam.

Harry
CT

 

[Andrew Mace]

Just curious...those of you (above) who have replaced one or more switches recently...are you using silicone brake fluid or glycol-based brake fluid?

 

[Harry_Ward]

Andy,

Dot 5 silicone

Could be...

Harry
CT

 

[Deleted member 451]

I probally changed my switch 6-7 times in the last 4 years. I finally got tired of it and put a plunger switch on the pedal housing. You can get them anywhere and it takes less than one minute to change when they go bad. They tend to go bad a little faster because most are made to be mounted on the inside of the car. I think the engine heat gets to them after a while. Until someone comes up with a really good pressure switch I'll stick with this.