So, got all the parts off an 89 RR to convert my 93 RR to non-ABS. The 89 master has four lines, two for primary (front calipers top) and two for secondary (front calipers bottom and rear calipers). In modifying the plumbing here's my options:

1. one proportioning valve
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One secondary line directly to front left caliper. Second secondary line to proportioning valve, to front right caliper and to a T connecting the TWO rear lines.

2. two proportioning valves
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EACH secondary line to a proportioning valve, to front and rear caliper.

My goal is to leave the two rear lines in place and modify the plumbing in the engine bay only.

Any thoughts on which setup would be preferred? I have never seen a setup with two proportioning valves so is this even acceptable? Also, which proportioning valves are recommended? Obviously I need one (or two) which are easily and repeatably adjustable.

Hey Art,

The way I did it was to run the front line to both front calipers on one of the inlets only. I capped the other caliper inlet so it was not used at all.

I ran the rear line to the rear caliper but should have put a proportioning valve in-line with the rear calipers.

I have the identical setup on both my Series One and the CrewCab. On each of those trucks I run a Willwood proportioning valve that has a knob. There is a style that has a lever, but I don't think the adjustment is as controlled.

There are others on the list that have the official LR way of doing it, so maybe listening to them is also a good idea.

Do a search and you will dig up a lot of ideas and even some diagrams of the way it's done in the Disco1 (which is probably how it ought to be done to make it perfect).

So, you use only one line for the fronts in the CrewCab? I would think you would benefit from a dual setup, since it is a heavier vehicle. That's why I decided to keep the dual setup since this ia a LWB.

I am surprised you got away without a proportioning valce for the rears. I didn't think any master was so well balanced as to not need one.

Yeah, I've done my reading and realize there's several ways to go. Obviously I'm trying to do as little modification as possible. At this point I'm looking at only fitting some flexible lines in the engine bay and a couple of valves. The tricky part may be fine tuning it if I do go with two valves.

I am surprised you got away without a proportioning valce for the rears. I didn't think any master was so well balanced as to not need one.


I think that I needed a proportioning valve on the '90 RRC I converted to non-ABS. That was the one mistake we made that really could have made a difference.

I'm not sure why we went with the single line to the front of the CrewCab, I just trusted Cooper and Matthew in making that decision. The Hydroboost brake unit I'm running on that truck doesn't seem to have a problem locking up the brakes with it, and it hasn't been a problem even with towing the 80-inch behind it up and down some huge mountain passes.

I'm towing it to Moab twice next month, (well, maybe once, then leave it there until I go back), so the brakes will get a good workout.

I am going to put DBA rotors on the front axle of the CrewCab when I reassemble the axle with some new 2522 CV's.

@ ArtM,

The original configuration as used by LR on the '87 up non ABS RRC's is with one proportionoing valve part # NTC6868 or NTC6868L.

If you have the original factory repair manual for your 1993 RRC look at the pages with the layout of the ABS version and the pages with the non ABS version.
If you want, I can email them to you (my e-address is fal@knology.net)

The proportioning valve you need is all ready under your truck, twice.
You only need one. The MC is designed to work with only one.
Discard one of the two lines going to the back and re-use the T connector on the back above the rear axle, close the second inlet. This is as originally done by LR on the non ABS version.
There is nothing difficult about this conversion.
You don't have to re-ingeneer anything, you can re-use your existing brake lines (exept one you discart) and if you work with the booster and MC from a non ABS RR, this job can easily be done in a day. Just for safety sake, rebuild that MC, the parts are to cheap to cut on this safety item.

With all respect for Mike Slade, but don't cap the second caliper inlet since you wil loose 50% of your brake pressure up front.

fredd

Fredd,

I do have the parts and repair manuals. On my 93 LWB there is only one proportionong valve and it is in front of the ABS booster - not two and not under the truck. The two you refer to are simple adaptors, to connect the rear lines front and back. That's so you can replace them in manageable sections. They're numbered 11 in the diagrams.

I beleive the T in the rear is not a T. It is not connected to both rear lines. The ABS regulates pressure in each rear caliper and it must have a separate line to each. That's why there are two lines going to the rear. They do not mix.

Why take them out at all when I can fit a valve to each and be done with it? I think this is the way to go.

As to Mike's thing, he's using a Hydraboost which provides plenty of pressure. I think with a regular master two lines to the front is nice for a heavy vehicle. You're not losing 50% by undoing one - IF you compensate with a more capable pressure source, e.g. a Hydraboost.

in Mike's defense, he may have needed some reduction after bolting on that massive hydroboost MC ;)

FAL thanks for the tech - i'm in the middle of the same thing as Art, but have been half skeered / busy with other stuff to dig into the brakes, yet.

does anyone have a p/n for the t-fittings that run into the master cylinder? The mc/booster I have appears to be the right one, but I'm missing the fittings.

cheers,

isaac

ArtM

>> I do have the parts and repair manuals.

So, you can see under group 70 the layout of the non ABS and from the ABS version.
Then I don't see why your initial question, unless you want to re-invent the system.
As I said before, the factory designed and tested it and I prefer to follow their system.

>> On my 93 LWB there is only one proportionong valve and it is in front of the ABS booster - not two and not under the truck. <<

Some have two, in front of the connectors. Seen this on 2 that I converted.

>> I beleive the T in the rear is not a T.

Here you are correct, I used the T from the non ABS version, my mistake in previous mail.

>> I think with a regular master two lines to the front is nice for a heavy vehicle.

So why re-engineer ?
Use as the factory did.
Even with the higher presssure only on one side of the pad, you will have less efficient brakes and more as allowed pressure on the working part of the caliper.
I've designed brakes systems for a living and that solution is a big no no.

fredd

Isaac,

Does your mc have four outputs or two? I went with the 89 to have the four outputs without needing T's. Just a cleaner setup.

Also, regarding keeping the two circuits - obviously if one fails you have the backup. I don't think I want to abandon that safety factor.

I think a proportioning valve is always required to fine tune the system.I cannot imagine designing a mc that doesn't need one.

I considered the Hydraboost but I think it's not advisable without a ps pump upgrade. That's more work than I'd like to tackle. Sure it's a nice system but I want things simple.

I really don't care about ABS, certainly not on a truck where it's NOT reliable and expensive to fix. I certainly do not care about ETC! If I can do without all the ABS problems and get fine braking with a vacuum system I am there. Heck, once I unload all the ABS parts I should make some money on this upgrade!

Fredd,

>>Then I don't see why your initial question, unless you want to re-invent the system. As I said before, the factory designed and tested it and I prefer to follow their system.<<

If you are saying I should use the same proportioning valve (pv) from my 93 and a T for the two rear lines then, sure, I would if that solves the problem. I don't know if it will so I thought I'd prepare for that by going with an aftermarket, adjustable pv. The Rover is not. Going with two pv's is not really drastic. It allows me to fine tune, or make work, the system if need be.

I think I fail to mention sometimes that I have modified the front calipers to provide fluid to all 4 of the cylinders, hence the need to only run one line to it and cap off the other inlet.

I think I've written up something pretty detailed in one of my posts if you guys search under ABS or caliper or something like that.

Art - mine just has the two outputs, and is missing the t-fittings for the dual lines. did you fab new lines from the MC to the flex lines, or did you attempt to bolt in the existing ABS lines? i'm torn on which way I want to go. I'd rather bend up new lines to all 4 corners but am out of time :(

ArtM,

I'm like you, I like to keep things simple.
I've had several RR's with the non ABS system, and still have a nice '73 also, perfect reliable, and always good brakes.
I have no use for a system I can't trust.
And yes, you can make money of the ABS parts, I've sold some sets for $300.00

fredd

Isaac,

I can't attach the existing lines to the new mc. They just don't have enough length.

So, I will plumb new short lines from the mc to the existing lines. I'll just move the existing lines out of the way a bit.

If you want to redo your entire lines look into Kuniform. They make lines with Rover fittings and you don't need any special flaring tool. They are very flexible and can be formed by hand. I may even use them for my setup.

got it - thought you may have found something obvious that I had overlooked ;)

kuniform - where to buy? I've been looking all over for copper-nickel lines and haven't found a supplier in the states. i have word that only the kuniform lines are DOT approved, and only recently. this was the explanation I have recieved from most about the absence of copper-nickel (also referred to as cupro-nickel, or just cu-ni ) lines.

I plan on going to a local shop to purchase them:

http://www.citysidegarage.com

Ask for Alan Eliott, he is one of the premier Rover guys around.