My 1974 144 rally car is Australian built, of course. Volvo in its wisdom put the brake booster etc on the left side with a heavy crossbar to actuate it. The whole assembly adds complication and weight.
I’ve long thought about getting rid of it all to save the weight and complication. I did the sums and thought if I moved the master cylinder to the right hand side and changed the pedal ratio, it just might be ok.
Well, I did it. What follows is for information only and in no way should be construed as advice!!
Volvo put two holes in the pedal box. One was for the normal pedal pivot and the other, about 22mm lower, was unused. The first photo shows a pedal box with the holes marked. No idea what the lower one was for, but if I used it to pivot the pedal and put a hole in the pedal 22mm higher than the normal one that was used to move that big crossbar, I might be in business. My sums say the pedal ratio would now be 8:1 rather than the original 4.5:1. The second photo shows the pedal, redrilled, with a new master cylinder actuating rod.
Next was to make a bracket to hold the master cylinder using the bolts from the pedal box that previously held a bracket at the left side of the old crossbar. Time consuming, but not overly difficult. That’s the next photo. The last shows the master cylinder mounted.
Does it work? Yes, I can lock the brakes on tarmac without feeling like I need to take my right leg to the gymnasium. The feeling is quite different to the boosted brakes: not as hard and more progressive. Normal braking isn’t much different. Hard braking definitely needs more effort but not crazy stuff.
The final photo shows my temporary brake plumbing plus some rally-specific gear in the background. I wasn’t going to do the plumbing properly until I was happy that it worked. I’m also running a 240 master cylinder which I think is pretty much the same as the later 144 one, but allows me to get both outlets on the right side. So a bit of tidying up to go and I need to work out how to put a return spring on the pedal.
I’ve read dmcs excellent post on fitting a 240 caliper over 164 vented disks on an 144. I’m going to use the front calipers from a 240 with ABS because they only have 1 fluid line and one bleed nipple. Very good for the rally car. These calipers were never sold in Australia but I sourced a pair from the US. They need the mounting holes machined from 12mm to 1/2” (I’ve done that) plus about 4.5mm machined off the mounting ears - then they fit perfectly over my vented 164 disks. They also use the same pads as the 144. So simpler and a bit lighter overall.
EDIT: I’ve just weighed all the old booster apparatus, crossbar etc including the vacuum pump I fitted, less the weight of the new bracket to hold the master cylinder. We’re over 9.5kg lighter. A good outcome, methinks.
