Luke-Mia Posted December 22, 2021 Report Share Posted December 22, 2021 Hi my question is, on a 1975 US TR6 can you remove a brake PDWA valve piston on the car. My PDWA valve is leaking through the switch so I need to stop this. My options. 1: do nothing other than cap the switch with a 3/8 UNF bolt and copper washer, my worry about doing this, if one side of the piston rubbers fail completely would this stop the equal pressure keeping the piston central and possible only having either the front or rear brake circuit working, I do not know the travel of the piston left to right. 2: remove the piston and re rubber the piston, this would be the safest option keeping the braking system to US spec. I have read about the problems removing the piston, can this be done on the car, I have not yet lost my brake pedal but it must be drawing in air. I am sure someone must have tried this, if you cap the switch and remove the piston bore cap and press the brake pedal, will this eject the piston. 3: if the piston is removed has anyone not put the piston back in and run the car with one brake circuit like UK cars, I am worried that the 2 circuits could have different pressures from the brake master cylinder and cause all sorts of braking problems. 4: has anyone done away with the 4 way PDWA brass body and used 2 brass straight connectors to create a front and rear brake circuit. Thank you for any help Luke. Quote Link to post Share on other sites
JochemsTR Posted December 23, 2021 Report Share Posted December 23, 2021 Hello Luke, 4. for me. Jochem Quote Link to post Share on other sites
Luke-Mia Posted December 23, 2021 Author Report Share Posted December 23, 2021 JochemsTR Thank you I think that could be the best way to go, if I can't get 2 brass straight connectors, I could always get 2 BTB657 3 way Connectors, bolt them together and just cap the top outlet. Luke. Quote Link to post Share on other sites
John Bracher Posted December 23, 2021 Report Share Posted December 23, 2021 Luke, agreed with # 4. UK and Euro cars manage well enough without the PDWA. Quote Link to post Share on other sites
Luke-Mia Posted December 23, 2021 Author Report Share Posted December 23, 2021 John thank you. Quote Link to post Share on other sites
stuart Posted December 23, 2021 Report Share Posted December 23, 2021 Delete it and run the same way that the UK cars do with separate dual line, these joiners are what you need https://automec.co.uk/collections/fittings/products/brass-inline-connectors-unf Stuart. Quote Link to post Share on other sites
Luke-Mia Posted December 23, 2021 Author Report Share Posted December 23, 2021 Thank you all for your replies. I have decide to go a little rogue. I have read you can’t rely on the PDWA piston to move if you lose either your front or rear brake circuit, and it is basically only a switch with a warning light, as mine is leaking I think this is a weak point in a 50 year old braking system, so I have decided to keep the 2 separate brake circuits which I think is a good idea. I have a very good hydraulic parts supplier near me, I could have gone for straight brake pipe unions, but I liked the 3 way brake pipe union better, because I could use the fixing hole to bolt them together and look more like the originals not that bothers me, I will attach a photo. Luke. Quote Link to post Share on other sites
Kenrow Posted December 23, 2021 Report Share Posted December 23, 2021 12 hours ago, John Bracher said: Luke, agreed with # 4. UK and Euro cars manage well enough without the PDWA. Just wondering, did all LHS TR's have a PDWA installed? Quote Link to post Share on other sites
stuart Posted December 24, 2021 Report Share Posted December 24, 2021 13 hours ago, Kenrow said: Just wondering, did all LHS TR's have a PDWA installed? AFIK yes they did. Stuart. Quote Link to post Share on other sites
Chris59 Posted December 24, 2021 Report Share Posted December 24, 2021 17 hours ago, Kenrow said: Just wondering, did all LHS TR's have a PDWA installed? As Stuart : on the (about) one hundred TR6s, including many PIs, I worked on, ALL were fitted with a pdwa from new. Once removed from the car, rebuilding a pdwa don't take long. I often rebuilt mines with a stainless steel shuttle. Quote Link to post Share on other sites
Kenrow Posted December 24, 2021 Report Share Posted December 24, 2021 thanks for the answer all... Quote Link to post Share on other sites
AWM Posted December 25, 2021 Report Share Posted December 25, 2021 You see those PDWA valves on 70's/80's military Landrovers (both LHD and RHD) and when I was in I never heard of any issues with, or instructions to remove, them. I've travelled many tens of thousands of KM's in various Rovers that had them. Properly maintained I see the PDWA valve as a useful safety feature. I have an ex-US TR6 I'm restoring and I've refurbished mine with one of those kits you can get. Don't forget also that if you do remove one and have an accident that could possibly have been mitigated by the warning feature, you may have an insurance issue, or worse... Where did you get the SS Shuttle you mention Chris? Did you make it yourself? That sounds like a useful upgrade. Andrew Quote Link to post Share on other sites
JochemsTR Posted December 26, 2021 Report Share Posted December 26, 2021 (edited) 15 hours ago, AWM said: Properly maintained I see the PDWA valve as a useful safety feature. I agree, but most of the times the owner does not have the wiring and working lightbulb to actually use this feature. The connector and wireloom from the brakepressure switch are NLA...so most owners do not even have the PDWA connected. Edited December 26, 2021 by JochemsTR Quote Link to post Share on other sites
Luke-Mia Posted December 26, 2021 Author Report Share Posted December 26, 2021 My US TR6 was converted to RHD, I needed to rewire it so I rewired It with an Autosparks UK, loom this came with no wiring for a PDWA valve, because as we know UK cars did not have them. Andrew re insurance you are correct, but take brakes for instance I wonder how many people have informed their insurance company that they have upgraded their brakes making them safer, but technically uninsured if not informed. Luke. Quote Link to post Share on other sites
AWM Posted December 26, 2021 Report Share Posted December 26, 2021 I found all the bits I needed, including electrical connections, from the aforementioned Landrovers. In fact, they were fitted to many BL products of the 70's and 80's, so they are not rare in general. Look at ex-military and civillian Landrovers of the 70's/80's and also Range Rovers of the same era, even Stags (if you can find one). They all definitely have them and the Rover products can still be found in older scrap yards, or see the Landrover/Range Rover parts specialists/eBay for NOS parts. The military Landrovers had a dash mounted illuminated Rocker Switch you could press to test. If the shuttle operated in service then it would illuminate. Better than the simple lamp that the US TR6 has. Since I'm making many mods to my car anyway, this what I intend to do, as I have a complete spare Dashboard for one of my military Landrovers with this rocker switch. Worth the effort. Andrew Quote Link to post Share on other sites
AWM Posted December 26, 2021 Report Share Posted December 26, 2021 17 minutes ago, Luke-Mia said: Andrew re insurance you are correct, but take brakes for instance I wonder how many people have informed their insurance company that they have upgraded their brakes making them safer, but technically uninsured if not informed. Luke. I agree but you are supposed to. I think if you are improving things then you are going to be in a much better place than if you are removing safety features and the worst happens and they can point to the lack of a warning as being significant. It's relatively easy to add the wiring and lamp as I mention. I think the Stag I mentioned before used the Oil pressure warning lamp to do double duty. If that came on I suppose it would get the Driver's attention... Easy to run a few additional wires to/from the PDWA and use that lamp for the dash warning. Andrew Quote Link to post Share on other sites
stuart Posted December 26, 2021 Report Share Posted December 26, 2021 13 minutes ago, AWM said: I agree but you are supposed to. I think if you are improving things then you are going to be in a much better place than if you are removing safety features and the worst happens and they can point to the lack of a warning as being significant. It's relatively easy to add the wiring and lamp as I mention. I think the Stag I mentioned before used the Oil pressure warning lamp to do double duty. If that came on I suppose it would get the Driver's attention... Easy to run a few additional wires to/from the PDWA and use that lamp for the dash warning. Andrew All true except when converting a L/hand drive car to R/hand drive spec then the PDWA is not fitted as the entire braking system would be converted to R/hand drive spec where its was never fitted. This is then an un modified car whereas fitting a PDWA to a R/hand drive car would then be classed as "Modified" Semantics I know but there you go. Stuart. Quote Link to post Share on other sites
Luke-Mia Posted December 26, 2021 Author Report Share Posted December 26, 2021 Hi Andrew I actually did rewire it, but when it comes to insurance and the law, there are really no real grey areas it is either correct or not, personally I think it safer without the PDWA piston seals to fail. All you need to do is to inform your insurance company of any changes they will almost certainly not object, we are talking about 50 year old technology not trying to break the world speed record. Luke. Quote Link to post Share on other sites
Luke-Mia Posted December 26, 2021 Author Report Share Posted December 26, 2021 Hi Stuart your reply came in when typing. Quote Link to post Share on other sites
Luke-Mia Posted December 26, 2021 Author Report Share Posted December 26, 2021 Hi Stuart my car was converted before I purchased it so have no idea how it was done, but it seems more US than UK. Luke. Quote Link to post Share on other sites
AWM Posted December 26, 2021 Report Share Posted December 26, 2021 Each to his own. My decade plus professional operating experience with that feature in place suggests to me it was worth having. Why wouldn't anyone want to know they have a problem with their brakes? And by the way, the shuttle or related switch never failed on any vehicle I was in, professionally then, or privately since. I do agree it needs to be refurbished after fourty or fifty years in service but that applies to most parts, so why single that one out for criticism? With modern non-hygroscopic brake fluid it's now going to last practically for ever, ss shuttle or not.. As to insurance, I think converting a LHD to a RHD TR6, even if you really have slavishly followed the exact RHD spec. in every regard, is definitely something that any insurance company would want to know along with details of all the modifications. Andrew Quote Link to post Share on other sites
Luke-Mia Posted December 26, 2021 Author Report Share Posted December 26, 2021 Hi Andrew when reading US forums it seems they leak a lot, and some were dubious the piston would actually move if required, in a perfect world they would be serviced regularly, but in the real world, only when someone like me finds it leaking. Luke. Quote Link to post Share on other sites
Waldi Posted December 26, 2021 Report Share Posted December 26, 2021 I agree with Andrew above. During my restoration (LHD 1970 PI) I considered eliminating it, but given the many issues reported on this forum with the MC (luckily not personal) and leaking rear wheel cylinders on old english cars (own experience), I decided to renovate my PDWA system; new shuttle and O-rings and new switch. And it works, I found out during bleeding after the initial fill. Not so much because of “originality”, but for the additional safety it provides, which should not be over-rated btw). Waldi Quote Link to post Share on other sites
Kenrow Posted December 26, 2021 Report Share Posted December 26, 2021 On 12/25/2021 at 9:21 AM, AWM said: "Where did you get the SS Shuttle you mention Chris? Did you make it yourself? That sounds like a useful upgrade" Andrew I would like to know this also. I have delt with my PDWA leaking numerous times. Add the fact that the kit for 5 washers is ridiculously expensive for what you get... Quote Link to post Share on other sites
AWM Posted December 28, 2021 Report Share Posted December 28, 2021 I wonder why there's such an issue with leaking PDWA valves on TR6's? I've got four Landrover/Range Rover vehicles with this feature and I can honestly say I've never had a failure in twenty plus years of ownership. Also not when I was travelling around in MOD Landrover vehicles back in the day that had these valves, as I mentioned previously. I've just gone into my workshop to check and it's exactly the same valve and switch assembly on both Triumph and Rovers, as you would expect. I imagine if you change to silicon brake fluid, then you are going to be OK with this valve for a long time into the future. I recently got several gallon cans of surplus US Army silicon brake fluid from an old mate of mine and so I will find out if that's true in the next year (or so) when I get the TR back on the road... Andrew Quote Link to post Share on other sites
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