TR2/3/3A Spring loaded valve in the top of the 4 way brake line fitting?

What is the purpose of the spring loaded poppet valve in the top of the 4 way brake line fitting? I got mine all cleaned and the springs seem to work but is this thing needed? Never seen one in any other of my cars. Thanks and have a good day!

John

It works like a check valve -- the idea is to keep the brake pads close to the rotor - otherwise they tend to get knocked back due to flex in the spindles on cornering, etc.

Some omit the guts to disable it (you still need the body of it to connect the line) as it can cause some brake drag up front. I've experimented both with and w/o and can't say there is much difference.

To notice the pads getting knocked back, you have to drive pretty hard. I never notice it unless I've been driving close to the limit on cornering. And even then, all it does is cause the brake pedal to be somewhat lower than normal. I might notice it more because I use relatively wide, sticky tires.

But, I pay attention to the brakes and whether they release fully. To me, the drag caused by the valve (more correctly called a residual pressure valve) is quite noticeable. My feeling is that it also accelerates brake wear and wastes a tiny amount of fuel. So I'm one of those that remove the plunger to disable the valve. (As I recall, you could connect the line directly to the 5-way, but the stock line is too short to reach without the valve body.)

A better solution IMO is stiffer front spindles. TRF sells both uprated spindles, and a spacer that fits over the spindle to provide a lot of extra stiffness. The downside of the spacer is that you have to change shims to adjust the wheel bearing clearance. These mods were developed and tested by a well known Triumph racer, and are recommended by Kas Kastner in his newer books on TR competition preparation.

PS, the contact information in the flyer below is obsolete, as Jack Drews passed away some years ago (while racing his TR4!). However, I believe you can still buy the components through his son Tony if you prefer (he also supplies TRF):
[FONT=Trebuchet MS, Arial, Helvetica]For further information, contact Tony in lieu of "uncle jack" at tony@tonydrews.com or 309-764-4506.[/FONT]

I bought one of the kits with the spacer and shims from TRF a couple of years ago. I recall seeing them in a recent sale catalog , but don't recall when. So I believe they are available.
Charley