THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

Has anyone ever installed a proportioning valve in their Pinzgauer? With weight in the back I don't think it is an issue, but when the truck is empty the rears can lock up occasionally. A load sensing proportioning valve might be a better option if it were available.

There is one on my Puch G-Wagon that was built for the Austrian/Swiss market. I seem to remember that Willy (SAV) told me that the Pinzees built for Austria also had them. You might check with him for more info. I think he said that parts for it were hard to find.

edit: it's shown in group 07-03 as item #56, brake regulator

The TD's have a rear proportioning valve fitted, although I've never had a problem with the 712.

There are driver controllable variable proportioning valves (added a knob to the dash) available from your local racing supply store. I looked into them for a Lotus 7 replica. Readily available and not too costly. May be worth considering.

There are driver controllable variable proportioning valves (added a knob to the dash) available from your local racing supply store.

I've worked with these on race cars; they work by adjusting a mechanical linkage between two single master cylinders, one for the front, one for the rear. Some vehicles (and I never thought to check on a Pinz) use a dual DIAGONAL system, where one circuit supplies pressure to the right front and left rear wheels, and the other circuit supplies pressure to the other diagonal wheels. The racing system only spits the front from the back.

The problem is that under low to moderate braking, the weight shift is not so great so the rear axle has more weight, more traction, and therefore can handle more braking force. Under a panic stop the weight shift is considerable so the rear axle can hardly tolerate any braking force without locking wheels. You can't adjust the manually adjustable proportioning valve fast enough to do any good.

I've tried to get in the habit of pulling the yellow 4x4 lever during hard stops - while this takes valuable time in a panic situation, this forces the front axle to turn at the same speed as the rear axle, so the rear can't lock. And in fact, the rear brakes can help though the drive shaft to help brake the front axle, too. Properly operating Volvos do this automatically by sensing high braking pressure and triggering the 4x4 switch. I have had a few situations where I know I could not have stopped as fast as I had if I had not pulled the yellow lever.

Interesting re: the yellow lever!

Interesting re: the yellow lever!

Did I screw up by saying "yellow" lever? I'm going by memory (on a business trip) but I meant the left most lever for engaging the front axle into 4x4 mode. NOT the diff lock. Sorry if I confused anyone.