Sunday morning I spent some time testing a brake proportioning valve that @Racer65 sent me.
I’d tested the stopping ability in my Land Cruiser many times in my short ownership but not in a controlled and measurable environment like I was today. As you probably notice in your 40, brake distances are not all that impressive and the rears lock up easily. I was excited when Roger asked me to try out this new proportioning valve.
The test was pretty simple. Panic stop from 30mph in a straight line with my old proportioning valve and then retest with the new one from City Racer. I found a large, empty parking lot by my house where I could easily get up to speed and use a light pole as my braking point indicator. I marked each stop with chalk and measured the distances from the light pole. My vehicle’s brake system is stock with drums in back and front disks.
My first 4 stops were with the old proportioning valve.
- 1st attempt 71’ – rear brakes locked
- 2nd attempt 70’ – rear brakes locked
- 3rd attempt 57’ – rear brakes locked (I found this odd that I would be 13’ shorter so I did it again)
- 4th attempt 58’ – rear brakes locked (my only guess is that the brakes warmed up by now and were more effective)
Then I replaced the valve. Super simple, unscrew the two hoses and unbolt the valve, then reverse those steps and bleed the brakes. I used the handy brake bleeding tool that I used when changing my clutch master/slave and my brake master.
Old Valve
New Valve
Comparison
After replacing the valve, I went for a short test drive and noticed that the pedal was noticeably harder, very different feeling like I had to work a bit harder to get the vehicle to stop… but not so bad that I thought something was wrong, just different.
I drove down a steep hill to check the brakes before I ran through the panic stop test. Prior attempts on this hill showed my rear brakes would lock up VERY easily. Now with the new valve, my rear brakes didn’t lock up at all, but the stopping distances felt similar to before. The pedal still felt odd.
I then drove over to the parking lot to do my official test with the new proportioning valve.
- 1st attempt 62’ – no brakes locked
- 2nd attempt 51.5’ – front brakes locked barely, rear brakes didn’t
- 3rd attempt 67.5’ – no brakes locked (something happened during this stop that I could feel in my brake pedal, it pushed down further and felt "normal" like before I changed the valve. So I decided to do an extra few stops.)
- 4th attempt 45’ – front brakes locked, rear brakes didn’t
- 5th attempt 49’ – front brakes locked, rear brakes didn’t
I took it on a spin after the fifth attempt with the new valve, my brakes suddenly worked really well now!
I think on my 3rd attempt after replacing the valve, what ended up happening was my front calipers finally engaged for the first time since owning this thing. The old proportioning valve was so heavily biased to the rear brakes that the fronts were either barely used or not used at all. In my panic stop attempts before the valve change, my steering acted like the fronts were not being locked up at all. After changing the valve, I believe more pressure was being pushed in to the front calipers causing them to break loose and actually work.
I also noticed the front end would now dive down a little like most vehicles do when coming to an abrupt stop which tells me the fronts were never really being utilized. The stopping distances with the new valve are noticeably shorter. I also like how the weight transfer pushes the front tires in to the ground while the front brakes are now being utilized much more.
Roger also shared… “The advantage of having a valve made to OEM spec is that it's specifically tuned to the weight transfer on a FJ40, as Toyota had designed it. It's also easier to fit than the adjustable valve, because the geometry is identical to the original.”
All in all, I’m a huge fan of these brakes now! Stopping distances are measurably improved, attitude of the vehicle when stopping is improved and it’s simply more predictable. Two thumbs up from me.
Cheers,
Adam