Ex Member Posted June 19, 2018 Share Posted June 19, 2018 I would suspect servo being adjusted incorrectly. Quote Link to comment Share on other sites More sharing options...
xychix Posted June 19, 2018 Author Share Posted June 19, 2018 34 minutes ago, Red90 said: I would suspect servo being adjusted incorrectly. The servo on the rear brakes wasn't touched after placing the disc's How can these servo's being adjusted? (other than the adjustment nobs that determine the distance of the blocks to the drums in 'rest' state? Quote Link to comment Share on other sites More sharing options...
Ex Member Posted June 19, 2018 Share Posted June 19, 2018 Yes. There is adjustment on the servo rod length where it engages the master. If it is too far in, the master will not release. Possibly the addition of the vacuum pump put it over the edge. Back it off and see. 1 Quote Link to comment Share on other sites More sharing options...
Ex Member Posted June 19, 2018 Share Posted June 19, 2018 https://www.jegs.com/installationinstructions/500/555/555-631010-116.pdf 1 Quote Link to comment Share on other sites More sharing options...
Snagger Posted June 20, 2018 Share Posted June 20, 2018 12 hours ago, xychix said: The servo on the rear brakes wasn't touched after placing the disc's How can these servo's being adjusted? (other than the adjustment nobs that determine the distance of the blocks to the drums in 'rest' state? The servo is not on the rear brakes, it is on the whole system. However, if misadjusted, it could be just affecting one circuit. The master cylinder has two pistons, the first pushed directly by the output rod of the servo. This powers the front brakes, but also applies hydraulic pressure to the back of the second piston which applies the rear brakes. If the front circuit develops a leak, the first piston will directly push the second, but there will be a small amount of lag and pedal travel will be longer for the same pressure in the rear circuit. If for any reason one of those pistons isn't fully retracting, then the brakes could be held on to some degree, and from the system description above, you can see that all would be applied if it was the first piston failing to retract (from internal failure or servo issues), so it does suggest that the second piston (nearest the radiator) for the rear lines is at fault if the front brakes are not binding. Similar symptoms could occur for any other failure in the circuit that traps pressure, but I can only think of a degraded flexi hose or a fault in the PWDA valve doing that. Quote Link to comment Share on other sites More sharing options...
xychix Posted June 29, 2018 Author Share Posted June 29, 2018 (edited) any writeups / shopping lists out here for replacing all brakepipes on a 109" s3? also we would I buy T pieces? shoppinglist so far 2x different unions for attaching the brakeline to the defender 90 master cyl. 2x T piece (1x for front left/right split, 1x for rear left/right split. I'm going to leave out this non working sensor unit thats already there but doesn't work) could be NRC4251 6x unions to fit the T pieces (would be the male metric ones to match NRC4251 while the rest is imperial) 4x unions to fit 2x front hoses to wheels and both sides of the flexi hose to read axle. 2x unions to fit to rear drum-backplate. No unions for front part at the wheels as this is just renewed in the zeus kit 2x flexi hose to the front wheels (flexi hose for rear is already bought) Brake pipe cunifer 3/16" 7,62 mtr (will that be enough? is de diameter correct?) .... Edited June 29, 2018 by xychix Quote Link to comment Share on other sites More sharing options...
Snagger Posted June 29, 2018 Share Posted June 29, 2018 You could probably reuse the bulk of the unions and should be able to reuse the brass fittings. Once you remove the pipes, you can cut the ends off to get the unions and if necessary, soak them in vinegar or coke to clean up any corrosion. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted June 29, 2018 Share Posted June 29, 2018 From memory I bought ~10m of pipe when I plumbed my 109 and it was only just enough, although my system layout may be slightly different to yours. I had the "servo ratchet" effect when I fitted an early Defender servo to mine, in my case it was because the adapter plate (pedal box to servo) I'd made was too thin to allow the servo to release properly. Quote Link to comment Share on other sites More sharing options...
xychix Posted June 29, 2018 Author Share Posted June 29, 2018 5 hours ago, FridgeFreezer said: From memory I bought ~10m of pipe when I plumbed my 109 and it was only just enough, although my system layout may be slightly different to yours. I had the "servo ratchet" effect when I fitted an early Defender servo to mine, in my case it was because the adapter plate (pedal box to servo) I'd made was too thin to allow the servo to release properly. I'm about to mount a early def 90 master cyl to my current 109 servo (seemed to match fine...) holding it on it didn't seem to foul anywhere and bolted straight on. Only hope that it will fit under the bonnet with the reservoir on.... Quote Link to comment Share on other sites More sharing options...
Snagger Posted June 30, 2018 Share Posted June 30, 2018 10 hours ago, xychix said: I'm about to mount a early def 90 master cyl to my current 109 servo (seemed to match fine...) holding it on it didn't seem to foul anywhere and bolted straight on. Only hope that it will fit under the bonnet with the reservoir on.... I have a Discovery servo on mine and the adaptor plate needed to be quite thick (8 or 10mm, IIRC) as the input rod and fork are so much longer than on a SIII servo. It sounds like John had a similar experience in his conversion with the Defender servo. It's not just the mounting studs that have to fit exactly - the smallest push on the operating rod might be enough to prevent the brake pressure being fully released. The same would apply to the servo output rod being even a fraction of a mm too long. Mixing and matching parts from different spec vehicles is a minefield of potential clashes, some quite subtle but with big consequences. Quote Link to comment Share on other sites More sharing options...
xychix Posted June 30, 2018 Author Share Posted June 30, 2018 (edited) 5 hours ago, Snagger said: I have a Discovery servo on mine and the adaptor plate needed to be quite thick (8 or 10mm, IIRC) as the input rod and fork are so much longer than on a SIII servo. It sounds like John had a similar experience in his conversion with the Defender servo. It's not just the mounting studs that have to fit exactly - the smallest push on the operating rod might be enough to prevent the brake pressure being fully released. The same would apply to the servo output rod being even a fraction of a mm too long. Mixing and matching parts from different spec vehicles is a minefield of potential clashes, some quite subtle but with big consequences. I see 1 other solution. plumbing BOTH lines to 1 block dividing to front and rear (so essentially going back to a single pipe system)with my old 109 master cylinder and place a pressure limiter in the line to the back. Edited June 30, 2018 by xychix Quote Link to comment Share on other sites More sharing options...
Snagger Posted July 1, 2018 Share Posted July 1, 2018 Disc brakes typically use less fluid transfer but higher pressures than drums. Unless you fit a very powerful booster, you will have a hard pedal and will find it hard to get the best performance out of your brakes. That's why the master cylinder on Discovery, RRC and Defenders with discs all round have such skinny master cylinders - the piston needs to be small in area to generate the hydraulic pressure without massive pedal forces. Quote Link to comment Share on other sites More sharing options...
xychix Posted July 1, 2018 Author Share Posted July 1, 2018 Yeah, Given all I've learned over the last weeks on brake circuits here's my hypothese on what is gone wrong. 1. fitted discs on front (zeus kit) that need far less displacement compared to the original drums 2. rotten pressure difference sensor in between front and rear circuit on the left front chassis bar (inside) allowing some leakage when there's a big pressure difference 3. did fit a strong hella UP28 vaccum pump in the past so I do have proper aid. 4. I pump the brakes and all the pressure is on the front circuit due to the difference in displacements needs, and some fluid gets sqeezed trough the rotten sensor membrane (or whatever it is) into the rear circuit. 5. pedal is released and the 109 master cilinder takes back the amounts it pushed in the circuits but as there's more fluid now in the rear as was pushed in we've got residual pressure binding the rear brakes. might even mean the master doesn't come al the way back as there is a slight vaccuum on the front circuit due to the 'missing' fluid that moved to the rear circuit.... questions on my mind; IF the master cilinder is at rest is there an 'open' connection from the reservoir to the circuits?? (should be I assume...) well that's just some Sunday morning thinking Quote Link to comment Share on other sites More sharing options...
xychix Posted July 1, 2018 Author Share Posted July 1, 2018 (edited) 6 hours ago, Snagger said: Disc brakes typically use less fluid transfer but higher pressures than drums. Unless you fit a very powerful booster, you will have a hard pedal and will find it hard to get the best performance out of your brakes. That's why the master cylinder on Discovery, RRC and Defenders with discs all round have such skinny master cylinders - the piston needs to be small in area to generate the hydraulic pressure without massive pedal forces. That's what I hoped to solve with replacing my 109 master with the old def 90 master. (assuming that is the one that had disks in the front and drums in the rear.) Waiting to get my hands on new brakelines (as I broke them) and the proper reservoir to test this setup (and try and create a few shims / adapter plates of needed) Edited July 1, 2018 by xychix Quote Link to comment Share on other sites More sharing options...
Bigj66 Posted July 1, 2018 Share Posted July 1, 2018 On 06/05/2018 at 8:56 AM, xychix said: Just lifted my landy 'cold' and the rear wheels turn freely as they should. Once I brake a bit (engine not running but I've got an UP28 hella vacuum pump so I do have pressure) the car breaks as expected. After releasing the pedal the rear brakes bind (despite adjusting the shoes). Any hints? replacing the springs that pull back the shoes (despite them being good before conversion?) fitting a (non LR) adjustable break pressure separator? How easy was the UP28 to fit? Thinking of getting an electric vacuum pump for my Capri. Quote Link to comment Share on other sites More sharing options...
xychix Posted July 2, 2018 Author Share Posted July 2, 2018 18 hours ago, Bigj66 said: How easy was the UP28 to fit? Thinking of getting an electric vacuum pump for my Capri. piece of cake. connected it to the rear light wired (so it runs when you hit the brakes) and folded a bracket from a piece of sheet metal. pull the hose from the air inlet and connect it to the up28. Then properly open the butterfly valve in the inlet and close the opening with a cap or something similar (i used a thick bolt and duct-tape for now) Quote Link to comment Share on other sites More sharing options...
xychix Posted July 20, 2018 Author Share Posted July 20, 2018 ok the story continues I've gotten my 90 defender master cylinder and 12mm an 10mm brake pipe fittings that should do the trick. I've gotten my 2nd 90 defender master cylinder (cheap ass brand) just to salvage the plastic fluid container..... 👻🤕 I've got 10meters of 3/16" pipe (CuNiFer) 2 flare tools (the china one was 'lost' in transport but did arrive the day before we drove to our location where my series lives.) mixed set of fittings (metric and imperial) ... thank god for that as I just discovered my new SIII 109 brake hoses to the rear axle are imperial (likely same for my 2 hoses to the front wheels) I've got 2 T-splitters so I can have a front and rear seperated circuit and get rid of the sensor / valve / whatever that's in between the cricuits. I've also got my hands on a pressure reduction valve so I can dial down the pressure on the rear pipes if that would be needed (however I hope the defender 90 master will already differentiate for the front discs and rear drums). only 1 question at the moment... which hole on the master cilinder for a defender 90 is for the front circuit and which is for the rear... Quote Link to comment Share on other sites More sharing options...
Ex Member Posted July 20, 2018 Share Posted July 20, 2018 3 hours ago, xychix said: I've gotten my 2nd 90 defender master cylinder (cheap ass brand) just to salvage the plastic fluid container..... 👻🤕 only 1 question at the moment... which hole on the master cilinder for a defender 90 is for the front circuit and which is for the rear... You do know, that you can buy the plastic reservoir on its own, right? Front is farthest from the servo. Quote Link to comment Share on other sites More sharing options...
xychix Posted July 20, 2018 Author Share Posted July 20, 2018 32 minutes ago, Red90 said: You do know, that you can buy the plastic reservoir on its own, right? Front is farthest from the servo. couldn't find them for the defender 90. Well past that point now Once this is all up and running I hope I don't need those parts ever again Ah clear, front = front, rear = rear. I believe it's the same on the 109 master. Reason for asking, on the 109 the 'rear' hole is a bigger size while on de defender 90 the front is a 12mm (10mm for the rear, or closest to the servo). Quote Link to comment Share on other sites More sharing options...
Snagger Posted July 23, 2018 Share Posted July 23, 2018 109 master has the servo end for the front brakes and the "front" end of the cylinder for the rear brakes. The lines normally cross over beneath the PDWA shuttle unit. Quote Link to comment Share on other sites More sharing options...
xychix Posted July 24, 2018 Author Share Posted July 24, 2018 22 hours ago, Snagger said: 109 master has the servo end for the front brakes and the "front" end of the cylinder for the rear brakes. The lines normally cross over beneath the PDWA shuttle unit. Thanks! that clarifies the 'bigger hole' on the servo side. As I'm switching to an early defender 90 with the bigger hole further from the servo my current observation is that the 'bigger hole' is ment to pressurize the front brakes. Quote Link to comment Share on other sites More sharing options...
Snagger Posted July 24, 2018 Share Posted July 24, 2018 Just now, xychix said: Thanks! that clarifies the 'bigger hole' on the servo side. As I'm switching to an early defender 90 with the bigger hole further from the servo my current observation is that the 'bigger hole' is ment to pressurize the front brakes. I can't remember how I did my conversion. I used a whole 300Tdi Discovery brake system (except the rear discs, which were Defender rear or Discovery front discs). I seem to recall having to cross the pipes between master and PDWA unit over, counteracting the crossover below the PDWA, so the front brakes would be from the front end of the master and the rear brakes from the rear (servo) end, but I can't be 100% certain I did that. I'd have to look in the engine bay, and I'm planning to go to the storage unit and fire it up on the 1st of August, so I can tell you when I get home if that is any use. Quote Link to comment Share on other sites More sharing options...
xychix Posted July 24, 2018 Author Share Posted July 24, 2018 Well most important for me is my new defender 90 master... I'll dig around on google images to find some more intel. But if you're there anyways its always welkom. (which reminds me that someone asked how much an original rim would foul the zeus kit... thats an easy check right now to do for me) Quote Link to comment Share on other sites More sharing options...
xychix Posted July 24, 2018 Author Share Posted July 24, 2018 On 5/7/2018 at 6:17 PM, Gazzar said: Out of curiosity, did you try a standard wheel on after the conversion? I'm curious as to how much it would foul by. G. it fools, big-time! You'd have to grind ~1 cm of the back of the calliper to make it fit over which leaves essentially no calliper! Quote Link to comment Share on other sites More sharing options...
Gazzar Posted July 25, 2018 Share Posted July 25, 2018 One cm. Bugger. I may have to re think the use of standard rims. I will try a spacer first, then go down the wolf route, I suppose. Thank you for testing this for me. I appreciate it. G. Quote Link to comment Share on other sites More sharing options...
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