OK, here are some pics of the installation: No 1 shows the remote booster mounted to the RH inner wing just below the jack and fwd of the radiator. This is the smaller of the two sizes commonly used, typically used one for each of the twin circuits on cars like RHD 105 series alfas with the master cylinder under the floor and organ style pedals. You can get a larger size which is used for cars with a single circuit like earlier alfa gulias etc but the physical size makes it hard to fit under the bonnet. There was a bit of thought involved in finding a spot that wasn't going to get too hot, block airflow into the radiator, or foul the bonnet stays when the bonnet is closed. An alternative position is inside the RH wheel arch but we discounted that because it would get too filthy and these things should be kept clean.
No 2 shows the new twin circuit master cylinder (std for later R4s, fitted specially by me on Betty Bleu 'cos I didn't like the idea of suddenly losing all my brakes) with the front wheel pair line going forward to the remote booster. Just to the right of the expansion bottle and master cylinder is the mount for a little drag brace which helps hold the booster to the inner wing. The drag brace came out of the junk pile, not a Renault 4 part.
No 3 shows the booster and the stud on it which attaches to the drag brace, just below the union in the brake pipe. The heavy hose is a vacuum hose from the inlet manifold. The brake pipe to the left is the input from the master cylinder. On the end at the RHS of the photo (towards centre of car) are the two output brake pipes to the two front wheel cylinders.
No 4 shows inside the RH front wheel arch, forward is to the right of the photo. The two nuts with bolts poking through the inner wing are upper, existing mount for handbrake return spring and lower is another mounting stud on the booster cylinder.
No 5 shows the drag brace and the pipe run.
No 6 shows the vacuum tapping in the inlet manifold.
The installation was put in by my local brake place. Given there is the early type of pressure limiting valve on the rear circuit, which is not triggered by rear ride height/load, we felt having power assist to the rear circuit was of limited use and would only put it in if the braking felt really strange. It feels OK though. But I imagine the additional booster would help up to a point and I occasionally toy with the idea of throwing in another booster for the rear, perhaps somewhere low down on the LHS of the engine bay fwd of the muffler.
The biggest issue doing this aprt from finding somewhere it would fit was that with dual circuit and worn brake drums it was hard to get enough adjustment or you could bottom the pedal under heavy braking and have to pump them. This was fixed partially, or at least improved, by fitting bushes on the brake adjusters inside the drums, and building up the strut that goes between the bottom of the brake shoes to space it out further, but it was pretty horrible and ultimately just a bodge until we could fix it properly. We fixed it definitvely by putting on brand new drums. Like many small car drum set-ups Renault brakes work pretty well when all the bits are brand new and up to spec and lousy if not.
Hopefully this answers all your questions, if not let me know.
Cheers,
Piet
