AWM Posted December 28, 2021 Report Share Posted December 28, 2021 (edited) I went out to my Barn to have a look at the Landrover PDWA installations and they are chassis mounted on substantial brackets. The chassis themselves being of much thicker steel than the Triumph chassis of course. I wonder if the problem of the Switch leaking on the TR6 PDWA is partly related to vibration, as they are only mounted on the thin metal of the footwell? I will look at perhaps spot welding a stiffening plate on the inside of the footwell (where it's less obvious) so that there will then be less vibration. Obviously this doesn't help with the internal corrosion/seal leaking issue but that shouldn't be a problem with Silicone fluid. Andrew Edited December 28, 2021 by AWM Quote Link to post Share on other sites
Luke-Mia Posted December 28, 2021 Author Report Share Posted December 28, 2021 Hi Andrew. I personally can't see my PDWA valve vibrating while bolted down, the 4 brake lines will also add rigidity, and I am sure there are other rubber seals and components under more vibration than the PDWA valve. I think the problem can only be pitted bores, or perished or poor quality rubber seals. but I did not think brass pitted like steel, but I could be wrong. I am going to fit my PDWA replacement tomorrow weather permitting, and will feel safer knowing I am not relying on a rubber seal in a valve known to have problems with age, after all this is over 50 year old technology, in over 50 year old cars, parts are bound to have problems with age. Luke. Quote Link to post Share on other sites
AWM Posted December 29, 2021 Report Share Posted December 29, 2021 There's no doubt you must ensure that your hydraulics are in good order. I completely agree with that. As far as I know, the TR6 PDWA bodies are the brass type, so only the steel shuttle valve can corrode. A stainless version would solve that issue. I'm just wondering why this seems a big issue for TR6's, prompting people to remove the valve, when it's not for other vehicles that the PDWA valve is fitted to. The Switch does seem a weak point but if the seals are in good order then it won't matter. Clearly if the shuttle valve seals fail, then a plastic switch isn't going to resist brake line pressure. I expect renewing all my brake system seals and the change to Silicone fluid will solve this issue. Andrew Quote Link to post Share on other sites
Luke-Mia Posted December 29, 2021 Author Report Share Posted December 29, 2021 (edited) Hi Andrew. I did a quick Landover Spitfire etc PDWA valve internet forum search today and the first posts I read had the same problems I am having so not unique to the TR6. I went to fit my PDWA valve replacement today only to find I need one 3/8 and one 7/16 3 way brake pipe union not the two 3/8 I had but I will get there in the end, even if it kills me. Luke. Edited December 29, 2021 by Luke-Mia Missing words. Quote Link to post Share on other sites
stuart Posted December 29, 2021 Report Share Posted December 29, 2021 15 minutes ago, Luke-Mia said: I went to fit my PDWA valve replacement today only to find I need one 3/8 and one 7/16 3 way brake pipe union not the two 3/8 I had but I will get there in the end, even if it kills me. Luke. Thats to differentiate between front and rear lines as you will notice the same on the master cylinder. Stuart. Quote Link to post Share on other sites
Luke-Mia Posted December 29, 2021 Author Report Share Posted December 29, 2021 Thank you Stuart. Luke. Quote Link to post Share on other sites
AWM Posted December 29, 2021 Report Share Posted December 29, 2021 2 hours ago, Luke-Mia said: Hi Andrew. I did a quick Landover PDWA valve internet forum search and the first post I read had the same problems I am having so not unique to the TR6. I went to fit my PDWA valve replacement today only to find I need one 3/8 and one 7/16 3 way brake pipe union not the two 3/8 I had but I will get there in the end, even if it kills me. Luke. Yes, some mentions of similar problems but definitely not the same level of concern as we see with the TR6 and, as I've said, I've got several of my own with no issues to report over many years experience. Andrew Quote Link to post Share on other sites
Luke-Mia Posted December 29, 2021 Author Report Share Posted December 29, 2021 Hi Andrew. I removed my PDWA valve today, and was very surprised how easy the shuttle came out, so I could have rebuilt in place, but I am sorry to say I have read too many PDWA valve problems so its going, but as I say pays your money takes your choice. Luke. Quote Link to post Share on other sites
AWM Posted December 29, 2021 Report Share Posted December 29, 2021 I went to the US based TR Tech Forum - PDWA issues is near the top of the first page of discussion topics... Andrew Quote Link to post Share on other sites
Luke-Mia Posted December 29, 2021 Author Report Share Posted December 29, 2021 Well Andrew that's the joy of owning old cars I suppose, there's always maintenance to be done. Luke. Quote Link to post Share on other sites
AWM Posted December 30, 2021 Report Share Posted December 30, 2021 9 hours ago, Luke-Mia said: Well Andrew that's the joy of owning old cars I suppose, there's always maintenance to be done. Luke. Agreed, I think that's how this device should be considered - as something that needs to be maintained. Compared to many TR parts the rebuild kits are cheap and since it seems to be something that only needs to be done every couple of decades, I'll keep on keeping on but each to his own as you say. Andrew Quote Link to post Share on other sites
stuart Posted December 30, 2021 Report Share Posted December 30, 2021 15 hours ago, AWM said: I went to the US based TR Tech Forum - PDWA issues is near the top of the first page of discussion topics... Andrew Thats because they are the only ones to have them and they dont have MOT checks. Stuart. Quote Link to post Share on other sites
AWM Posted January 2, 2022 Report Share Posted January 2, 2022 Same sort of discussions as here anyway... Strange how they weren't fitted to the UK versions of the TR6, given that they are on so many other UK versions of other BL products of the era. Andrew Quote Link to post Share on other sites
YankeeTR5 Posted January 3, 2022 Report Share Posted January 3, 2022 (edited) Strange. Been following this thread from its beginning. When mine leaked out the switch, I pulled out the shuttle, replaced the two O rings and reassembled. No problem since, and given the car is 50 years old at this point....not really that big a deal. And while what I did may be considered "primitive" or the bare minimum, there are complete rebuild "kits" (shuttle plus o rings) readily available....just sayin... Edited January 3, 2022 by YankeeTR5 Quote Link to post Share on other sites
Richard Pope Posted January 3, 2022 Report Share Posted January 3, 2022 Does this switch leak from switch body or the threads. If the latter perhap some PTFE tape would help. There seem to be at least two types of switch as per Moss and LandRover types. Has anyone identified which type leaks or is it both / all types? https://www.moss-europe.co.uk/p-d-w-a-valve-switch-fam7821.html https://www.johnrichardssurplus.co.uk/brake-valve-pdwa-switch-aau1700.html Quote Link to post Share on other sites
poolboy Posted January 3, 2022 Report Share Posted January 3, 2022 The switch is just where the leak from perished shuttle seals show up..The switch is not designed to withstand the hydraulic pressure. Quote Link to post Share on other sites
Kenrow Posted January 3, 2022 Report Share Posted January 3, 2022 149971 6 hours ago, Richard Pope said: Does this switch leak from switch body or the threads. If the latter perhap some PTFE tape would help. There seem to be at least two types of switch as per Moss and LandRover types. Has anyone identified which type leaks or is it both / all types? https://www.moss-europe.co.uk/p-d-w-a-valve-switch-fam7821.html https://www.johnrichardssurplus.co.uk/brake-valve-pdwa-switch-aau1700.html The actual switch is in line with your second one from John Richards. However the stock one is plastic, the one you list is much more substantially manufactured if it fits. Quote Link to post Share on other sites
AWM Posted January 4, 2022 Report Share Posted January 4, 2022 15 hours ago, Kenrow said: 149971 The actual switch is in line with your second one from John Richards. However the stock one is plastic, the one you list is much more substantially manufactured if it fits. I think you will find that's for another version of the Switch fitted to later Landrover vehicles. Andrew Quote Link to post Share on other sites
Luke-Mia Posted January 4, 2022 Author Report Share Posted January 4, 2022 Hi Yankee TR5 How can you call (And while what I did may be considered "primitive" or the bare minimum, there are complete rebuild "kits" (shuttle plus o rings) readily available....just saying) what you have done primitive you have correctly repaired your PDWA. Luke. Quote Link to post Share on other sites
Luke-Mia Posted February 1, 2022 Author Report Share Posted February 1, 2022 The final solution for me, see attached photos. I think the PDWA valve is a poor design, if you only have a leaking shuttle O ring you lose brake fluid through the switch, and eventually either your front or rear brakes, the switch at least should be hydraulic fluid tight. I appreciate you can get fluid leaks elsewhere without any other back up. When I removed the PDWA valve I found I needed 1 x 3/8 UNF brass 3 way brake union and 1 x 7/16 UNF brass 3 way brake union and not the 2 x 3/8 UNF brass 3 way brake unions I first thought, posted before. I thought my first solution looked a bit crude, I was going to either use self-tapping screws or nuts and bolts to hold it in place, but removing the PDWA valve I found it was held in place by a UNF bolt and a captive nut below, so this was a good time to redesign my solution and use the original Triumph fixing point. Luke. Quote Link to post Share on other sites
stuart Posted February 2, 2022 Report Share Posted February 2, 2022 TBH I would still have deleted it and re-piped accordingly. Stuart. Quote Link to post Share on other sites
Luke-Mia Posted February 2, 2022 Author Report Share Posted February 2, 2022 (edited) Hi Stuart. I am not sure how you would have re-piped it, but I know you are a professional with the correct tools, I am only asking out of curiosity, thank you. My brake lines meander from the offside B/M/C, up and above the battery, down to the nearside where they drop down to the chassis, the front brakes go into a three way brass brake union, and the rear brakes head to the rear of the car and into a straight connector. Luke. Edited February 2, 2022 by Luke-Mia Missing word Quote Link to post Share on other sites
BlueTR3A-5EKT Posted February 2, 2022 Report Share Posted February 2, 2022 (edited) 15 hours ago, Luke-Mia said: The final solution for me, see attached photos. I think the PDWA valve is a poor design, if you only have a leaking shuttle O ring you lose brake fluid through the switch, and eventually either your front or rear brakes, the switch at least should be hydraulic fluid tight. I appreciate you can get fluid leaks elsewhere without any other back up. When I removed the PDWA valve I found I needed 1 x 3/8 UNF brass 3 way brake union and 1 x 7/16 UNF brass 3 way brake union and not the 2 x 3/8 UNF brass 3 way brake unions I first thought, posted before. I thought my first solution looked a bit crude, I was going to either use self-tapping screws or nuts and bolts to hold it in place, but removing the PDWA valve I found it was held in place by a UNF bolt and a captive nut below, so this was a good time to redesign my solution and use the original Triumph fixing point. Luke. Yep, that'll work. I agree with Stuart that re piping would have done the job too but if you do not have brake pipe making equipment it is a challenge. I guess you had the two 3 way connectors in the garage as they are 3 times the price of the 2 way item Stuart suggested. Admittedly you have made an incredibly tidy job too, using the existing mounting hole. You could have put bleed nipples in the holes to blank them instead of hex head screws and copper washers. Now that would confuse a future owner attempting to bleed the brakes! Cheers Peter W Edited February 2, 2022 by BlueTR3A-5EKT Quote Link to post Share on other sites
stuart Posted February 2, 2022 Report Share Posted February 2, 2022 11 minutes ago, Luke-Mia said: Hi Stuart. I am not sure how you would have re-piped it, but I know you are a professional with the correct tools, I am only asking out of curiosity, thank you. My brake lines meander from the offside B/M/C, up and above the battery, down to the nearside where they drop down to the chassis, the front brakes go into a three way brass brake union, and the rear brakes head to the rear of the car and into a straight connector. Luke. Its not an easy pair of pipes to fabricate but as per R/hand drive factory issue its a one piece pipe from the M/Cylinder up and across the bulkhead and then down across the left hand footwell top and then down the toe board and on down to the 3 way on the chassis. The rear follows the same way and goes down to a joiner at the chassis top to join the line direct to the rear brakes. Stuart. Quote Link to post Share on other sites
Luke-Mia Posted February 3, 2022 Author Report Share Posted February 3, 2022 Thank you Stuart. I could not justify the cost of 2 new brake lines, just to avoid an extra connector like the ones you suggested https://automec.co.uk/collections/fittings/products/brass-inline-connectors-unf I already had new brake lines from the B/M/C to the PDWA valve, can you please confirm if the UK TR6 has a single brake circuit thank you. I worked with what I had, and think it is better that I have a dual braking system. Luke. Hi Peter You are to smart for your own good I never even thought about using bleed nipples, but I think mine looks cleaner and would have not used them, because my 3 way brake unions did not have machined faces I added hydraulic lock and sealer, although I was happy tightening a copper washer in my engineers vice would have made them hydraulic tight, I would have also been worried a younger MOT tester could get confused and worry why they were there. No I did not have any brake components in stock, it would have been cheaper and easier to go with Stuart's suggestion, I think I may have already written I liked the 3 way brake unions because they came with a fixing hole and I could make them look a little more professional and a little like a PDWA valve, as I wrote above I had already 2 x 3/8 UNF 3 way brake unions purchased, only to find I needed 1 x 7/16 UNF 3 way brake unions, it was then I went for the original fixing point. I had at first order a Moss PDWA rebuild kit, but before I went to Moss I did more research and found some people in he US had rebuilt them many times, so I thought for a car hardly ever used why bother with the PDWA. I will add I advised my insurance broker about the change and he was very happy of why I did it and noted it on my file. I wonder how many of you have uprated your braking system and not advised your insurance company which you legally must. Luke. Quote Link to post Share on other sites
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