RiverPatrol wrote:One path that might work is to upgrade to a dual master. Not necessarily going whole hog with a booster, just a replacement for the original master cylinder. These folks have a dual master already modified to bolt on to the firewall:
http://datsunpartsllc.com/cart/index.php?p=product&id=164&parent=11 . I know a couple of people that have used them. This path would obviously require a little bit of brake line creation off the master, and perhaps a proportioning valve? I've read where the master cylinder does the proportioning, but I've also heard that a proportioning valve is needed. That's the kind of stuff that we need a quick, down and dirty, streamlined 'How to' for. We have new members that come here looking for a simple solution to their brakes on the Patrol they just purchased, let's help them out. And us as well...
The Wilwood unit does balanced 50/50 internal proportioning between the front and rear reservoirs, and each reservoir sources its own outlet; so the decision of whether or not to add a proportioning valve is a judgement-call. You can make the Willwood piece work with a P-valve, or without one.
The stock brake layout on the 60 Patrol did not include a P-valve. All the brake line pressure comes from a single master cylinder reservoir, through a single outlet, and is then split between front and rear by a passive (non proportioning) T-fitting. Proportioning duty is handled by the fact that there are twice as many wheel cylinders up front as in the rear; so the net pressure applied to each cylinder is less up front, allowing the rear wheels to lock up first if you stand hard on the brake pedal.
Now, back to that Wilwood master cylinder - It has two reservoirs, so there are a number of ways you could successfully plumb it in. I have broken some of these methods down according to some specific scenarios:
Scenario One would allow you to install the Wilwood master directly to the patrol's single stock master cylinder outlet brake line - you would need to Tee the two outlets from the Wilwood part together, and then hook the single Patrol outlet line in into the T fitting:
outlet 1 outlet 2
|_____Tee_____|
|
|
original patrol brake line
This is the "quickest, easiest" way to restore your Patrol's operational brakes with the Wilwood piece, but it is in no way ideal, because you would be Tee-ing 2 outlets into one line, and then the stock Tee would just split the 1 line back into 2 to route the fluid to the axles... Also, this method preserves one very basic, inherent shortcoming in the 60 Patrol's original brake circuit design - if you lose pressure ANYWHERE in the system, then it affects the braking performance at ALL FOUR corners.
So, One better way to hook up the Willwood master would be to take advantage of the dual reservoirs, and eliminate the factory Tee (the one on the frame directly below the master cylinder), and run the outlet from the rear reservoir to the stock Tee on the rear axle, and to run the front outlet to the stock Tee on the front axle. The advantage of this method is that now each axle has its own dedicated pressure circuit, so if one reservoir (or wheel cylinder) starts leaking, it will not disable the brakes on BOTH axles - obviously, this is MUCH better from a safety perspective. This method also still preserves the same stock front to rear brake proportioning bias inherent to the original Nissan design.
Regarding the topic of using a Proportioning valve, versus not using one- The decision whether to use a P-valve or not is really only relevant if you want the modify your Patrol's default front to rear brake bias; maybe due to a power brake or disk brake conversion, or due to the installation of larger off-road tires, etc...
But, the reader's digest summary is that if you want to use the Willwood Master cylinder, you do not NEED to add a P-valve. You only need to decide whether you want to install a 2nd Tee (not recommended) or eliminate the existing tee and plumb it front to front, and rear to rear (highly recommended)
If I have time before dark when I get home today, I'll test the master cylinder in the Deathtrap Patrol. If it turns out to be shot, then I will probably order the Wilwood cylinder and plumb it in using the "front to front, rear to rear" method I outlined above, and I will be sure to post a step by step how-to...
