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View Full Version : PDWL Shuttle Valve bracket ?



vlad_d
04-27-2021, 04:44 PM
Hi folks,
I have a question for the group. I am in the middle of upgrading my 1973 Series 3 109(LWB) from single line brakes to Vacuum Power Assisted dual line brakes. Mostly for safety and increased pedal pressure, but also with a mind towards a front Disc brake conversion later. I'm tracking all the parts down from part numbers in the Parts Catalog (awesome resource, btw)., which is fun. But I can't seem to find the bracket that holds the PDWL shuttle valve. They don't make it anymore. Part numbers are either NRC4286, or NRC7409. I've attached a picture from the Parts Catalog, for reference. The car is a RHD, by the way.

Does anyone have one of these they can sell or trade?

Has anyone tried fabricating one? Seems a simple angled piece of steel plate with three holes. I think the fit is not critical either, since brake lines are custom fit anyway ( I will be installing new brake lines, and probably have to manually route them anyway, so some variation might be accounted by the lines routing). Still, I'd like to go with something close to factory. So, anyone have measurements? Can anyone measure theirs and do a back-of-the-napkin drawing for me? Hell, if you can bend a piece of cardboard over yours and trace it out with a sharpie, you'd be my new best friend!

vlad_d
04-27-2021, 04:55 PM
Here is a pic from the Parts Catalog (sorry, I couldn't attach an image from the mobile forum site).
13601

cedryck
04-28-2021, 01:05 PM
Make one, using the appropriate thickness metal and a vise to accommodate the bend, drill holes.

vlad_d
05-29-2021, 04:04 AM
Good point. I was waiting to reply until I fabricated one, but other projects took focus.

Another (related) question for the forum:
The shuttle valve/PDWL thing I got has 5 holes (two in top, two in bottom and one going out the front). I've seen there are 4 hole versions(omitting the front hole).

I asked the very helpful guy at Pangolin4x4(forgot his name, sorry) about it, and he said it was for the front two lines. He said he kind of remember it being that way.

I confirmed somewhat in the Green Bible manual. The official parts manual shows something different. I think I figured it out, but now I am torn by which better?

Basically, when you use the "4 hole" PDLA valve, it's just two lines in-out. So, you have a "T" piece that splits the front line to go to both front brakes. This is how the single circuit works and is how the dual circuit is shown in the Series 3 parts manual.

When you use the "5 hole" PDWL valve, the extra hole out the front is a duplicate of the bottom front hole, so you have two lines coming out for front brakes (right and left). This gets rid of the "T" piece and makes for dedicated brake lines going to each front brake.

Okay, I get it now. I already bought brake lines and T piece for the original. But the amateur plumber in me thinks maybe "the less fittings, the less places to leak"? So, which is better?

1) "5 hole" PDWL valve, separate dedicated front brake lines. Less junctions for less leaks potential.

2) "4 hole" PDWL valve, One front pipe split by "T" into two lines at front. More junctions, but shorter runs of pipe, and maybe more "original".

I can attach images if I'm not makings sense. I highlighted the parts in the same colors...
First one is from the "Green Bible" (Land Rover Official Repair Operations Manual). Shows the "5 hole" PDWL and two lines coming out the front.
13629
The second on is from Haynes (Owners Workshop Manual). It seems to agree with the Green Bible.
13630
The third is from the Land Rover Official Parts Catalog. It has the "4 hole" PDWL and the single line coming out and split with a "T" piece (in orange).
13631

jimrr
05-30-2021, 10:38 AM
hopefully you'll figure this out shortly but none of my series 3 look like the diagrams you've posted. are you sure the system on your rover hasn't been changed somewhere along the line? that there is no evidence of another system from prior installation(s)?
I have the original factory manuals from 1974 (not sure of the print date) but will look this up and take a pic of my series 3 if needed.

vlad_d
05-31-2021, 01:42 PM
Well, my system NOW is the single-line system with no servo. So, I'm trying to upgrade. But I trust the engineers to have figured stuff out after making 1 million of these - so, I'm trying to basically rebuild whatever was available as an option from the factory. They seem to have come with the servo and dual line systems as an option in the Series 3 run. So, instead of re-engineering it all and finding out that it all fails because of a custom part I put in that wasn't the right pressure, or whatever - I'm just looking at the diagrams and ordering part-for-part what's in the Official Land Rover parts catalogs and Service Manuals. I'm making the (100% reasonable) assumption that Land Rover knows what's in the cars they made. Please - dear lord - please tell me that's a safe assumption or I'm selling this car. :P

All jokes aside, this is what the manual shows. So there must be cars that have this setup. In fact, if this is what the manual shows, then this must be THE MOST COMMON way that the dual-line + servo system is set up. Otherwise, why print a book that only affects a rare custom setup?

I imagine not many people opted for the servo and dual-line system here in the states in 1973. You import a British tractor for the farm, and you don't expect it to go that fast. Hell, the thing doesn't drive above 60mph. So people probably said, why pay for the extra cost? But safety in cars has evolved a bit, and what was acceptable in 1973 is a deal-breaker(deal "brake"-er?) today. I see a lot of people on this and other forums doing this upgrade. And there's some great links with parts lists out there (focused on the pedal box, master cylinder and servo and discs, mostly) and they all say these were an option and point us to get these parts. So, they exist. That's not in question.

mearstrae
06-01-2021, 01:36 AM
I don't know how far you've gotten on this project, but... My '76 S3 109 came with power brake booster and single pot master cylinder. I've since added a dual master without any frills (no shuttle valve or brake failure switch) several years ago, I had to get it from England, just for the 109. Be aware (if you aren't already) that you my have to notch the wing top to fit this all in. Sorry, for the late reply, just haven't been keeping up with posts. Oh, just whip up a bracket and stick it on, it's not a critical part. Unless everything has to be Land Rover stamped for a 100 point restoration.

jimrr
06-01-2021, 10:27 AM
if you did that drawing yourself on the keyboard it's fantastic !! Maybe american imports had the dual line shuttle for series 3 mandated at a certain point? mine is certainly original as was my other series 3, not so the series 2A and yes, i see the fender has to be altered but i'm not changing it.

vlad_d
06-02-2021, 02:22 AM
@Jimmrr: Thanks! I always liked ASCII characters art, and I needed a proper signature. Looks a bit funny on mobile, I just realized. It might be fun to start a thread on those...see how creative we can get.

@Mearstrae: You know what? You have a point. I always thought that a brake failure light was a kind of useless feature. If your brakes are out YOU KNOW IT! There's no ambiguity. You notice immediately...as in right when you try to turn off your front street or pull out of a parking lot. Or, on the road, you would probably notice as soon as you try to brake. I can't think of one case where I looked at my dash to tell me something about the driving characteristics you usually just feel. ("Interesting! This light is telling me my steering wheel is missing!")

I guess I'm just trying to be thorough. Somehow, I assumed the shuttle valve was like a pressure maintainer thing. Like if one side went out, it blocked the pipe. But I guess you're right - the plumbing is two separate systems(nice). I was going to wire up the light later. The parts manual has a wire loom listed, and it has a similar light for vacuum booster pressure, etc. All look like simple 2-wire jobs...so I was going to just wire it myself. But I wanted to put it in there and get the plumbing done, then come back to the wiring.

I'm sort of doing this as a rolling restoration out front of my house. So, I have to kind of do it one weekend at a time. I try to plan whatever I cam do in 1-2 days before I have to button it up and let it lie for another week. Last thing I want is to get 50% in and find I need to order a part and wait 2 weeks with all my pipes and greasy bits open to the elements. So, I'm kind of exhausting myself trying to get everything right before I start. I guess that's a fool's errand with Land Rovers, because I'm finding no matter how much planning and research, it always throws me for a loop ("I swear this is the right part number! What the...?!")

vlad_d
06-02-2021, 02:36 AM
Oh, also, I'm hoping to avoid cutting the wing/fender. Been following the great threads on here about Disc conversion:

Credit to TerriAnn (these posts are amazingly useful):
http://www.expeditionlandrover.info/dual_brake_conv.htm

...and per those recommendations, the 8" Servo and stock Pedal Tower "should" fit in the space. I guess the bigger 10" Servo from the later Defenders causes you to cut the wing. The 8" Servo gives 2:1 pedal pressure advantage, and the 10" gives like 2.4:1 or something like that. And people on the thread complained of the brakes locking up and a pit touchy with the 10" Servo and discs.

My plan is to do it in stages: first the Servo and dual line set up. Try it out. See if the increased vacuum assist makes braking easier. Then decide if I want to spend the $2,000 discs.

I hope I don't have any suprises when I get to installing the servo. Don't really want to cut my wings/fenders as the original aluminum ones are getting harder to find(all I see is plastic fenders for sale now!?)

jimrr
06-03-2021, 10:10 AM
it's been a while since i looked at shuttle or ''tipping'' valves but since the wheel cylinders are all the same size what should happen when one side has a significant leak: when unequal flow happens between two systems the system drawing the "extra" flow creates a low pressure area which would attract the "blocking device" hence blocking flow to that portion of the system.

vlad_d
06-09-2021, 03:52 AM
Great link on that valve and servicing it below, if anyone's interested. I'm a little nervous about bleeding it correctly, but I'll cross that bridge when I get there. Also some close up pictures of that bracket. Looks home made as well!! Does anyone have the nice bracket in the Parts Book, or was that a draftsman's fantasy compared to what actually went in these Rovers?

www.autoexpress.co.uk/land-rover/100803/pdwa-valve-rebuild-on-a-series-iii%3famp

vlad_d
07-18-2021, 07:13 PM
Make one, using the appropriate thickness metal and a vise to accommodate the bend, drill holes.

Alright. I was stuck waiting for parts this weekend, so I took your advice (see animated GIF image link, since our hosts' forum, doesn't support them):
https://drive.google.com/file/d/1Ks9Zbtlzw9y7VgZiJ2KP3l4Qavj_RTeF/view?usp=sharing

[Edit] Dang it...the internet is conspiring to not show the animated GIF animating. You can save the image to see the slides how, but that's dumb. Sorry.