Thread: Patrol Diffs

I once ripped a rear hose on the RRC and had to finish a weekend and drive back from the wrong side of the mountains on just the fronts, of course the weekend wasn't complete without tearing one of the secondary fronts as well so drove back 200K's + on one brake.

Interesting times coming down hills in low range with an 82 auto 2door.

I'd run the primary circuit to the fronts, get some braided lines. Blocking the front port of the proportioning valve may effectively stop everything working. The piston in the valve requires pressure to move a tapered end piston which at a certain level will start to allow flow to the rear. The spring pressure will set the pressure and the taper will vary the flow. If the bypass to the front circuit is blocked the circuit is deadheaded and fluid being incompressible may have no effect on moving the piston and you'll get no flow to the rears. Having said that there should be a reverse flow bypass to allow pressure to return from the rears past the now closed piston when pressure is released. You couldn't run the front "sensing" line back to the reservoir as the flow would be unrestricted, pressure in this line to the fronts will vary with pedal pressure as the calliper pistons move.

Originally Posted by clubagreenie

I'd run the primary circuit to the fronts, get some braided lines. Blocking the front port of the proportioning valve may effectively stop everything working. The piston in the valve requires pressure to move a tapered end piston which at a certain level will start to allow flow to the rear. The spring pressure will set the pressure and the taper will vary the flow. If the bypass to the front circuit is blocked the circuit is deadheaded and fluid being incompressible may have no effect on moving the piston and you'll get no flow to the rears. Having said that there should be a reverse flow bypass to allow pressure to return from the rears past the now closed piston when pressure is released. You couldn't run the front "sensing" line back to the reservoir as the flow would be unrestricted, pressure in this line to the fronts will vary with pedal pressure as the calliper pistons move.

All flexible brake lines are braided. Usually the braid is hidden behind a protective cover. The externally braided lines aren't road legal in NZ, are they in Australia?

The proportioning valve works fine with one input. The other line is just working as a T.
But I found with bigger front calipers, the proportioning valve was best out of the system altogether. It started leaking, I removed it temporarily and found the braking was better.

Some braided lines are legal. Depends on the supplier. Enzed are ADR approved and have listings for most common vehicles (incl RRC & D2 since I supplied them with some samples). You are correct in saying that all lines are braided in the sense that even the rubber includes a nylon embeded in the rubber but they still swell and especially break down the rubber on the inside which (again, especially in RRC's with the small hole into the area behind the piston) ends up insdie the piston back and blocks the return flow and stops the piston releasing. Stainless braided hoses can be rubber or teflon lined (prefereble). There are some hoses which are approved where you buy the hose end components and assemble yourself (scary stuff when you consider some of the types that could be doing it). They are approved as an assembly but only when assembled by an "authorised person", a loose definition again.

Originally Posted by clubagreenie

Some braided lines are legal. Depends on the supplier. Enzed are ADR approved and have listings for most common vehicles (incl RRC & D2 since I supplied them with some samples). You are correct in saying that all lines are braided in the sense that even the rubber includes a nylon embeded in the rubber but they still swell and especially break down the rubber on the inside which (again, especially in RRC's with the small hole into the area behind the piston) ends up insdie the piston back and blocks the return flow and stops the piston releasing. Stainless braided hoses can be rubber or teflon lined (prefereble). There are some hoses which are approved where you buy the hose end components and assemble yourself (scary stuff when you consider some of the types that could be doing it). They are approved as an assembly but only when assembled by an "authorised person", a loose definition again.

When you say nylon, you probably mean aramid (aka kevlar) which is a lot stiffer than stainless steel. They don't swell more under pressure than stainless braided hoses do.
The braiding type and location doesn't dictate the liner material.

I had no problems with my stock RRC lines at 25 years old. I fitted longer ones then.
I've never had brake line problems with any of my vehicles, but the RRC is the oldest.

So the logic of fitting braided lines because they keep their shape and do not swell, are more resilient to tearing and having a teflon liner rather than rubber and being in use in just about every class of racing known and on performance cars from factory is bunk? Given that rubber is massively cheaper than stainless braid, it's a performance consideration over financial but if they were cheaper and better...

Just about all rubber hose has some sort of embeded reinforcement. But I'd still dispute that a factory hose doesn't swell, especially at 25 years.

Originally Posted by clubagreenie

So the logic of fitting braided lines because they keep their shape and do not swell, are more resilient to tearing and having a teflon liner rather than rubber and being in use in just about every class of racing known and on performance cars from factory is bunk? Given that rubber is massively cheaper than stainless braid, it's a performance consideration over financial but if they were cheaper and better...

Just about all rubber hose has some sort of embeded reinforcement. But I'd still dispute that a factory hose doesn't swell, especially at 25 years.

All brake lines are braided. All lines also swell under pressure (basic physics). Lines with stainless external braiding are just for looks and are less damage tolerant than lines with internal braiding and a tough rubberised outer.
Any line can have a teflon liner regardless of it's exterior.

Where do I find these factory performance cars with stainless braided lines? Race cars are not a good measuring stick for recreational 4wd's.

Well they made a massive difference to the braking when I put 'braided' brake lines on the wife's disco over the factory rubber ones

Thank You. You're not the first to report a better pedal feel post upgrade, even though I'm sure they were replacing old hoses not brand new.

As for manufacturers running std braided hoses: Konneisigg, Mc Laren, Aston Martin, Porsche, Ferrari... They can be speced as options on many lower level cars in brake upgrade packages as well.