Brake Switch Fitting

[PatGalvin]

What is the long rusty fitting on this 5-way brake fitting? Should I keep it or remove it? I recollect it might be some kind of restrictor?

Pat

 

[PatGalvin]

Sorry - it's from a 59 TR3. Forgot to mention that.

 

[TR3driver]

It's a residual pressure valve. What it does is hold a small amount of pressure in the hydraulic system, so the caliper pistons don't get pushed away from the rotor when the spindles flex.

If you take it out entirely, the hard line to it (from the MC) won't fit right. But I disabled my RPV many years ago, as it also makes the brakes drag a bit. The only ill effect is a low brake pedal after 'spirited' driving; which can be disconcerting if you aren't expecting it and might be a problem on a race course. But it only takes a quick pump of the pedal to get the brakes back.

TRF sells a spacer kit, designed by the late "uncle jack", which IMO is a better solution to the spindle flex problem.

PS, here's what the RPV valve looks like disassembled:

 

[PatGalvin]

Hi Randall

I'm replumbing all my brake lines using the Moss CuNi kit and thus far, few have fit correctly. Either too long or too short. I can probably route the new brake line so that it plumbs up flush to this valve.

But is there any reason to keep the valve or is it just owner judgment? I have no idea if my valve works correctly. This is a rescue car and I've never had the pleasure of driving it (but that day will come).

Do you just remove the spring and plunger and leave the fitting in-line? Or do you remove entirely and replumb with new brake line, which I could do.

Thanks for great photo. Looks like studio photography. My photo backgrounds usually have piles of tools, residual dirt, or car parts...

Pat

 

[Don Elliott]

Pat - The tubing should look like the photo of my 1958 TR3A. I re-did this in 1988 exactly as the original tubes. If you don't follow the bends etc, you risk gettting them cut by the suspension etc.

 

[Don Elliott]

Here is my restrictor.

 

[Don Elliott]

And here are the rear brake pipes for the RHS.

 

[Geo Hahn]

...Do you just remove the spring and plunger and leave the fitting in-line?...

That is how I did it.

 

[TR3driver]

If you don't follow the bends etc, you risk gettting them cut by the suspension etc.

Yes indeed. And apparently the copper-nickel alloy cuts easier than the original steel.

 

[TR3driver]

But is there any reason to keep the valve or is it just owner judgment?

Any modification to the braking system is literally taking your life in your hands. I am NOT recommending that anyone make this modification, only stating what I have done to my own cars, and why.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Do you just remove the spring and plunger and leave the fitting in-line?[/QUOTE]That's what I did.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] Or do you remove entirely and replumb with new brake line, which I could do.[/QUOTE]That's what the factory did, on later TR4A I believe.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Thanks for great photo. Looks like studio photography. [/QUOTE]Not so great, the color values are AFU. I was worried the valve wouldn't show up against the dark background of my workbench, so I grabbed a piece of brown wrapping paper. Somehow, the brown seriously confused my camera, and I didn't bother to fix it up.

 

[mrv8q]

I'm going to follow up this post w/ pix of my brake switch:

Pretty nasty after 50 years; I envy Don's pretty switch in his pic....

I guess cleaning it by soaking in a carb cleaner bucket? Thanks, all, for this discussion. Onto clutch hydraulics, while this soaks.....