TR2/3/3A TR3 brake restrictor valve

[bnw]

Mine is completely restricted. What does it do? Why is it optional on the TR4? Can I eliminate it?

 

[TR3driver]

The idea is that it forms a kind of weak check valve, that won't let fluid flow back into the master cylinder until the pressure reaches some low amount (like 5-10 psi). The problem is that the front spindles flex under hard cornering, and without the valve, the pistons can get pushed back and cause low pedal the next time the brakes are used.

I disabled mine many years ago (by removing the internals from the housing) and never regretted it. If you don't drive hard, chances are that you'll never miss it. And at least in my experience (and my driving), the pedal is never low enough that I can't get brakes the first time, it's just sometimes lower than usual.

But there is also a good chance you can 'repair' yours, by disassembling and cleaning it.

PS, TRF sells a kit with uprated spindles and a spacer, that should completely eliminate spindle flex.

 

[bnw]

My days of driving a TR3 like a lunatic are long gone. I learned many years ago that the harder I drove my TR3s, the more money it cost me. I became a professional auto repair technician 40 years ago because I needed to fix in order to drive. I'm going to gut it and forget about it. Just for the record, I haven't given up on spirited driving at all. I drive a 1998 BMW M Roadster, the roadster all our British cars wanted to be but never quite made it (closest being a couple of series one XKEs I've had) When my TR3 finally hits the road, I will baby the heck out of it and enjoy every minute.

 

[Geo Hahn]

Drive the way you like but I've never taken much joy from babying the TR... quite the opposite.

I too disemboweled that valve and made a note of its passing (just in case I needed to undo):

 

[bnw]

I'm just not interested in doing another cluster shaft, exhaust valve, a couple of wire wheels, adding an auxiliary heater to do Portland to Chicago and back in the middle of winter, rebuilding side curtains, rod bearings, main bearings. pistons and liners, multiple starters, voltage regulators, and generators all over again. I'll stick to local fair weather driving and take the Beemer (50000 miles so far) on long trips.

 

[TR3driver]

+1 on the fair weather (what's a heater? side curtains??), but I put well over 200K on the wrecked 3A, and I hope to match that with the '3. With the 3A, the more I drove it, the more reliable it got. The 3 isn't quite to that point yet (at the moment the OD is spread across the workbench) but I still have hopes.

Won't be driving to Breckenridge this year, but I do plan to take at least one longer trip (2500 miles or so) later in the year.

 

[vivdownunder]

Moisture build-up in DOT 4 brake fluid seems to cause the internals to rust and seize up. In most cases easily cleaned up and re-used.

Part of the idea was to keep the pads close to the rotors as they wore down, thus keeping the pedal high. That was the thinking of 55 years ago when disc brakes were first released on the TR3, just beating Jaguar.

Removing the internals doesn't make much difference, and during TR4 production the factory removed the restrictor altogether.

As the pads wear down, they stay close to the rotors of their own accord.

Viv.