Land Rover Series II/IIA brakes are backwards. Only sort of this kind of backwards. Usually. By this I mean that the brake (and clutch) pedals are pushed forward, and the rods in their master cylinders are pushed toward the firewall. Like so:
(Defender TDI clutch - setup is the same as Series apart from return spring)
Originally, they used the same little box and pedal for the clutch and brake, but then decided that the brakes needed softer pedal feel (or something) and moved the pivot point for the brakes only. Which means that the two pedals sweep differently. I’ll get back to this.
As you can imagine, a single brake line system has the room to be installed this way, but a double kind of doesn’t. Forget having a booster. When those two things started to sound vaguely important and penetrate the mental haze of brew in Solihull, Rover decided to solve this problem by completely changing everything. Like y’do.
The tower is now taller than ever, hinges at the top (pushing the cylinder forward) and now fits a very bulky master and a very bulky booster. This is made to fit by “ha ha, fuck you”. By which I mean the fender tops got carved out on Series III models to even make this possible.
There is one additional complication, and that is that the pedal sweep (hinging at the top) is even more differenter than it was when the SIIA upgrade happened, and now requires a much larger cutout hole in the firewall, and will also no longer work with the original return spring.
All this is useful info for someone swapping a Mercedes diesel into a Series II. Specifically, “this car, while now not much heavier, is faster. Also, single line brakes suck ass. Also also, there’s a vacuum pump right there. Come on, man.”
After reading all this, if you were spergy enough to do so, you might assume that the natural way to go would be to get a Series III fender top, cut out the hole in the firewall, and install normal SIII parts for this application...
First of all, where am I going to get a SIII fender top at this time of night? All joking aside, that’s something to buy (from a source I have) and/or make by cutting JIANT HOELZ in the existing fender and weakening it. The SIII style fender cutout also looks ugly, and is visible with the hood closed. Uh, no.
Second, there isn’t really any financial advantage to going with the standard parts, and the standard parts aren’t even that good. By the time the new pedal and tower and the rest are counted, with the fab time on the firewall and the rest, I think there are more productive things to do.
Which brings me to: BACKWARDSNESS. BACKWARDSNESS NOW, BACKWARDSNESS FOREVER.
You see, there *is* room for a booster without cutting the fender, if I just change the geometry of the setup. Oddly, not changing the geometry of the setup in *way* as much as the new and improved Proper Landy way of doing it.
In this highly technical and extremely precise drawing, you can see that if I hack up an existing tower, it will be possible to set up a “dogleg” pedal lever that will permit the master cylinder *and* booster to fit without cutting up the fender. I’ve made the measurements, verified sweep with some carefully bent wire mockups, and it works. Of course, this is a small booster (7" single) and the pedal lever ratio will change, but only to about what you get with a traditional Landy vacuum servo setup. Setup will probably be a Speedway/Summit unit like below:
Strong unit, no tookey plastic reservoirs, no fender or firewall butchery, line hookups in the same place as original, and while pedal height adjustment will require removing the fender, as a matter of practicality it already does with the stock brakes. Plus which, Rover power brakes require even more.
I’ll post pics when I’m done.