4 years 7 months ago - 4 years 7 months ago#75834by cjj
As you may have seen from a previous post, my brake servo, along with everybody elses, was flexing where it bolted to the bulkhead.
Not only is this just plain wrong, it will weaken the metal over time resulting in stress fractures and the flex reduces the efficiency of the brakes. Some of the force that you are applying with your foot is being used to flex the servo rather than stop the car.
You can see how bad it is from this video.
Well, I seem to have fixed the flex in the servo and it was fairly simple.
Basically, it is working on the principle that a sheet of metal is strongest when a force is acting on it in the same plane.
If you can imagine a sheet of cardboard.
Now imagine pushing it in the middle and it bends easily, this is what is happening on the bulkhead.
Now imagine standing the cardboard on its edge and pushing the opposite edge. It should be a lot stronger.
So, what I was looking for was a flat surface in the same plane as the direction the servo was moving in.
If you look at the latter half of the above video you will notice that there is a "shelf" which is in the same plane as the movement.
This is where the blower intake bolts to.
There is a very handy looking row of three bolts there. Hmmm
There is also a nice bolt at the top offside of the brake servo bracket.
So the basis of my design is a spreader plate with three holes to match the 3 bolts holding the blower intake in place, and a bracket that would reach the bolt on the top of the servo bracket.
As it happens, I had a TV wall bracket that I was just about to chuck out which was nicely bent into a channel shape for strength.
So, an angle grinder, a welder and a drill later, we have.......
I know I won't win any awards for my welding, but it does the trick.
I have cleaned it up and sprayed it and now have finally fitted it.
It is a bit industrial, but it was to test an idea. It could be reduced in size, or made from stainless. It could even be made from the spreader bar and an adjustable tie bar to the servo.
Anyway, here is the prototype fitted.
I also tested it and you can see the difference from the vid below.
Appologies for the standard of the vid but my helper wasn't available and I had to press the pedal and hold the camera at the same time.
Ironically, Brown and Gammons just rang me this evening to tell me the bracket I had ordered off them wasn't in stock but they were expecting some in 2 - 3 weeks.