You ever hit one of those moments where you discover you're an idiot?
Back when I swapped out the rear calipers from single piston sliders to dual piston (same as the front) I started to battle a brake-bias issue. Keep in mind that I also swapped out for the dual-master pedal box, moved the brake switches inside above the tunnel, and a few other brake-related modifications. I knew the brake bias was going to be an issue, but
should be completely solvable with master cylinder sizing and the balance bar. I was not prepared for the gong-show that transpired.
Removing the pedal cluster from the car is a bit of a nightmare. Back when I put it in, I was a much tighter budget. I used a cluster I acquired by doing some fab work on a friend's rally car, and had to modify both it and the car to fit. But in order to swap master cylinders, I have to remove the pedals which is basically a two-person job. Over the course of a few weeks I swapped master cylinders two or three times, I added a
second bias valve to further lock out the rear, I tried everything. Eventually I just accepted that the brakes were like pushing on a brick wall (masters too big) and that I had 'workable' bias unless it was wet...in which case, heads-up! The back end is coming around unless you're paying attention!
With the German Look well sorted, and the '58 Beetle equally well-sorted, I pretty much stopped driving the Rally Bug due (in part) to the brakes being awful. The fact that it's 220F inside the car, probably factored in too. Well, the German Look is currently in Denver. The '58 Beetle is in Toronto, and I'm all the way on the west-coast of Canada without a running Beetle. It's also been enough years that I really want to start driving the Rally Bug again.
I pulled the pedals, as posted here, ordered another set of master cylinders, and popped it all back in. I
absolutely have the right master cylinders this time. Pedal
travel is ideal. Bedding in the brakes, though, the rear wheels came back covered in brake dust and the fronts had nothing. Hmmm. Okay, so my
previous bias setup which seemed to be 'okay' in the dry is way off with these new masters. Dial in more front bias, max out the extra proportioning valve, and...well...it's barely passable. Definitely still rear biased, but only slightly. Braking the car feels like it's under-braked, which shouldn't be the case at all. I've spent a week away from the car, continuously using that 15% of my brain that does nothing, trying to solve the problem. I played around with the suspension last evening in the shop, and noodled some more on it. Nothing is making sense, why can't I get enough front brakes?! Resigned to swapping back in the single piston sliders on the rear (and playing "whats the right master cylinder" game again) I went to bed. About an hour later, it hit me.
I've never actually labeled my master cylinders (until last week). I've always set cars up with Clutch, Front, Rear, Throttle. If you always do it the same way, it's pretty hard to mess it up.
HOWEVER, suppose you then immediately go into two brake switches, and then a couple of curly-brake lines into the tunnel or other areas. Is it possible, somewhere down the line, I connected the wrong line to front, and the wrong line to rear? For the past five years, anytime I've pulled the car into the shop to try and solve the problem, I've simply put the front line back to the same brake switch, and the rear line back to the same brake switch.
I'm an idiot.
Last week's bias adjuster:
The bias adjuster now:
I have
literally been dialling in maximum rear bias for the better part of five years, because I never checked to confirm the knob was still labeled correctly. Sure enough, spun the knob fully the other way, and the bias-bar bearing is full front. Sigh. On the plus side, the car will probably stand on its nose tonight
