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Wednesday
May212014

Spring Brake?

I've managed to sort out the binding brake issue. I was going to fit a rose joint to take out any possible misalignment in the servo input rod, but after inspecting the clevis, it's bang on central. Adding a rose joint would put the rod out of alignment in my case, so I didn't bother.

My first attempt at a fix was to re-adjust the clevis on the servo input rod, to see if it was depressing the rod even at rest - but this didn't make a blind bit of difference. So, after doing some research, and asking my fellow MOC members, I've found out that binding brakes has been an issue on these servos for quite a few people. It's only come to light on Vikki now due to the lack of milage I've done.

What happens is that the pedal does not return to the fully up position due to a slight residual vacuum in the servo. This has the added effect of keeping the output rod pushing on the master cylinder, hence keeping the brakes slightly on. I've proved this is what is happening to Vikki, as when I feel the brakes bind, I can get it to stop by lifting the brake pedal with my toes. :/

People using the same type of servo in the US (in hot rods and the like) routinely fit pedal return springs to ensure the pedal always comes back to it's proper positon when not in use.

What I've done is fit a spring between the clevis pin on the pedal, and a bracket hanging from an existing bolt in the pedal box:

The spring is a new Land Rover pedal spring sourced from eBay (2 for approx £3), and the bracket is some spare flat metal bar I had left over. The spring is attached to the clevis by way of a small coupling made of the same metal bar. You can just about see it in the next pic.

It sits with the pedal lever in between the clevis forks. It's not very clear, and I couldn't get any better photos due to it being so tight in there - so I did a little sketch of what's going on through the side of the pedal box:

The clevis and servo input rof is in yellow, the pin in blue, the coupling and the new bracket in green and the brake light switch in purple.

I fabricated the coupling and bracket and fitted them today after work. After 45 minutes of blatting around town on the dual carriage way, round the suburbs and through the centre during rush hour with all the stop start that entails, there's been no issues at all with the brakes.

No squeeks, no burning brake smells, no smoke. And she takes of like a bullet now - no hesitation or fighting the friction of the pads. And I guess it'll do wonders for the fuel economy as well. Nice :)

 

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