ejparrott Posted February 9, 2014 Share Posted February 9, 2014 Spent the afternoon trying to get the brakes sorted on The 109...and failed... I can't get a decent pedal at all, and it feels like there's 2" of free play in the pedal before it does anything, but I cannot for the life of me get rid of it. Its a dual line system, servo, no PDWA valve, and its standard 109 setup with 11" TLS fronts and SLS rears. My 88 has the same setup and there's no free play in that at all. I've replace the fractured pipe that was leaking under pressure...ended up replacing all the pipes on the front n/s so moved the bleed nipple to the top at the same time, and bled it until the fluid was clear. I'm out of fluid now so I need to get another 5l can, but I just can't see what's happening with it. This has plagued me now for about 2 years and I am honestly sick to death of it! Really starting to regret fitting stainless brake hoses too..... Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted February 10, 2014 Share Posted February 10, 2014 I'm not intimately knowledgeable about brake systems but I'll throw some thoughts out to try and jog your grey matter! Is there enough vacuum? Were the brakes ok before the stainless hoses? Perhaps a faulty hose acting as a one way valve? Although I see you have been fighting it for 2 years. Are the hoses the same diameter as the old ones? Working on the principle (this will test my high school physics) that if the diameter is too large, the pressure drop is too much over the run of the pipes...? Hopefully that's right! Pedal adjustment correct? Air trapped in the m/cyl? (Happened to me!) Using the correct rated fluid? Wrong DOT rating will dissolve the seals throughout the system. Sorry it's teaching granny to suck eggs EJ, hope you finally sort it? Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 10, 2014 Author Share Posted February 10, 2014 Not sorted it, gathering suggestions for things to look for on a planned attack next saturday. To answer your suggestions: Vacuum? Symptoms are the same with or without engine running, what feels like 2" of free play before the master cylinder feels like it's pumping fluid. Brakes before? Brakes have been shocking since I got it, a couple of years of standing appear to have done it no good. We replaced the original rubber hoses with Goodrich braided stainless 2 years ago, they are the ones designed for the job, so I hope they're right! They appear to be, so no reason to doubt, however........ Pedal Adjustment? I don't believe there is anything to adjust with this setup, Went through the green bible yesterday, and while there does appear to be adjustment on non-servo systems, there's no mention under servo or dual line servo systems. Air in the master is not something I've ruled out, my drive is on a slope and I'd hope it's enough, but when I take all the wheels off next weekend I'm going to try and get the back end as low as I can and the front as high as I (sensibly) can. Brake fluid is new DOT4. Air in the master is the only thing niggling the ol' grey matter, but like I say, I'd hoped it wouldn't be. Any and all suggestions welcome! Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted February 10, 2014 Share Posted February 10, 2014 Ed, clamp all 3 hoses and see if the pedal is then solid, that will prove one way or another air in the master. Then release 1 clamp at a time to check each front for air/slack and the rears will have to be both together. If the fronts turn out to be trapped air as the problem you did bleed them with the cylinder pistons clamped fully home didnt you?????????????????? Edit. Bugger, i forgot its braided hoses. Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted February 10, 2014 Share Posted February 10, 2014 When mine had air trapped in the master, my friends dad who's an old school guru mechanic just undid the pipe at the master and told me to pump the brakes slowly until the fluid came out. Then he nipped it back up and it was great! Was in a stage 1 v8 too, so same system as yours more or less. Maybe it could be worth blowing the brake lines through with a little compressed air or poking a wire through if they're coming off anytime soon. Persistence will eventually reveal the culprit and I bet it's something so simple you'll smack your forehead! Quote Link to comment Share on other sites More sharing options...
Team Idris Posted February 10, 2014 Share Posted February 10, 2014 Last time it happened to me I'd rotated the adjuster cam right over the top on one wheel. It took a while to drop back to a position where it needed pumping back up to stop. It was a drive along situation and prepare to stop by vigorous pumping. Quote Link to comment Share on other sites More sharing options...
Michele Posted February 10, 2014 Share Posted February 10, 2014 I managed to bleed the brakes on my 109" for the 2nd time due to a wheel cylinder swap, and it was a royal PITA...I have to thank Jamie here for the assistance, and Bill too...they may come up with some useful suggestions for you too...Your setup is different from mine, no dual line and servo here (yet)... Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 11, 2014 Author Share Posted February 11, 2014 I did have the cylinders clamped in, my usual method of using a ratchet strap to hold the shoes in and hence the pistons. It's not perfect, but it's difficult to get a G clamp on the TLS pistons. Job for this week is to make some little perch's out of some scrap to support the clamp at that end, then we'll be well away. I've not tried the unions on the master....did you do it under gravity or with a pressure bleeder? Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted February 11, 2014 Share Posted February 11, 2014 Ah, no really amazing circumstance. I just mentioned it to him one day and he literally just undid the union, told me to press the pedal in slowly and repeat until the fluid came out of the union, then nipped it back up! Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 11, 2014 Share Posted February 11, 2014 The pedal can't be adjusted on the servo system, but the servo's push rod can. The manuals all say don't do it, but I needed to on mine as there was too much free play between the acorn nut and the MC receiver. If you take the MC off, you'll see the acorn nut with a locknut behind it. Just be caue ful not to overdo it or the MC will be stuck on slightly, preventing brake release. Are you sure the shoes are fitting the drums correctly? One well known provider had a reputation for selling shoes with a smaller diameter than the drums, so there was a certain springiness as the shoes distorted under pressure to fill out the drum circumference. If you're confident that the problem is air in the system, then the only way to fully clear it is to remove the front hubs and brake back plates and then bleed the front brakes with the outboard side of the brake assemblies facing down and the pipe side up so the air can get out of the ports. I keep saying it - messing about with the pipe set up to reverse the sequence of fluid flow does nothing, but most of you won't believe me. It's not the flow in the pipes that is the problem but the flow in the cylinders, and messing around with pipe routings doesn't alter the fact. Go back to the standard routing, which is shorter, and bleed the way I outlined above, and you will get a 100% air-free system. Remember to sit the brake assemblies in their drums or in straps when you do it, obviously. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 11, 2014 Author Share Posted February 11, 2014 It does make it a hell of a lot easier to get at the nipples when they're at the top though! Ultimately I want to disk the front axle at least, preferably both, but with pressing jobs on the 88 desperately needing doing now is not the time to be taking on another project, thanks to the weather mostly it's took long enough to get the LT77 installed Quote Link to comment Share on other sites More sharing options...
discomikey Posted February 11, 2014 Share Posted February 11, 2014 you should be able to take the tin cover off the top of the pedal box from the under bonnet side and theres a threaded rod that goes through the pedal, lengthen the rod to reduce pedal freeplay, there should be ~10mm freeplay IIRC. once thats done have you pulled back the rubber covers on the wheel cylinders and checked condition of the bores? any wetness is bad, it will be drawing in air there. also if you can get hold of a pressure bleeding system it helps to push any air in the system out. something like a gunson ezbleed system. i take it you have bled all four corners? i was told when having the same problem as you that pupming the pedal till it went solid then jamming it down overnight this compresses the air and sometimes brings it closer to a bleed nipple. it can be frustrating but sometimes just needs a LOT of bleeding, i.e. emptying a litre of fluid through each corner in extreme cases. i replaced a wheel cylinder 3 times, 2 of the replacements were faulty. it took loads of diagnosing, because i was in the mindset that surely the same replacement part cant be faulty yet again... sometimes it is just that simple Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 11, 2014 Author Share Posted February 11, 2014 Yup, pressure bled with Gunson Eazibleed. All the bores are fine, no leaks from the cylinders. Pumping the pedal and jamming it overnight has been considered - tried it once with the 88 when that was playing up....didn't work then though. Won't work with The 109 though, can't get it to pump up a pedal at all at the moment. Quote Link to comment Share on other sites More sharing options...
discomikey Posted February 11, 2014 Share Posted February 11, 2014 have you tried lengthening the master cylinder actuator rod to get rid of the freeplay? Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 11, 2014 Author Share Posted February 11, 2014 Not yet, can't really get to work on it in the week, I'm going to try cracking the unions on the master first, if I get home in daylight one day this week....see what happens Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted February 11, 2014 Share Posted February 11, 2014 you should be able to take the tin cover off the top of the pedal box from the under bonnet side and theres a threaded rod that goes through the pedal, lengthen the rod to reduce pedal freeplay, Its a servo unit, as Nick has pointed out the only adjustment is to the push rod is after removing the master cylinder from the servo not under a tin cover. If the adjustment was correct originally just changing hoses will not cause the adjustment to alter. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 11, 2014 Author Share Posted February 11, 2014 I see no reason why this adjustment should have changed...before it's lay-up the brakes worked fine. A couple of years laid up and I ended up with it, brought it home, finished the TDi install and got it back on the road....the brakes were not good. Enough to pass an MoT, but not what I'd expect. I tried and tried, and eventually the plastic reservoir split along it's middle during yet another session of bleeding. I bought a new reservoir, experimented with fitting it to the M/C and broke one of the plastic fixing lugs on the bottom....so bought a new M/C with the res already fitted, bolted it straight on to the servo, as you'd expect, fitted some new pipes, took out the PDWA, fitted new Goodrich Braided Stainless flexi's, and set to bleeding yet again. Couldn't get the brakes to be as good as they had been before. It was out on loan last winter, and behaved itself, so put it down to newish shoes bedding in. Stood for 6 weeks when it came home, at which point I set off to fetch some bits from the other side of town, expecting it to be fine, only to discover at the end of my road that I had almost no brakes at all! That is about the full story....except it's spread out over 2 years! Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted February 12, 2014 Share Posted February 12, 2014 My issue occurred after a m/cyl change. Bolted it straight on without thinking about it. The rest (as you know) is history. Mine made a funny popping noise when I pressed the pedal though. Was your 109 petrol or diesel pre TDI conversion? Diesel IIRC had a vacuum exhauster which supplier vacuum to the brakes via a small unit driven off the exhaust .. Something to investigate in terms of maybe vacuum is lacking? Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 12, 2014 Author Share Posted February 12, 2014 I don't know what it was when built, but to put the TDi in we took a Sherpa 2.5N/A out...struggling to remember now, but I think that had the same style vac pump as the TDi? Quote Link to comment Share on other sites More sharing options...
aaronledwidge Posted February 12, 2014 Share Posted February 12, 2014 I'd try bleeding the master as outlined above buddy, then bleed through. If it still persists clamp the hoses to eliminate parts of the system and find your issue. Quote Link to comment Share on other sites More sharing options...
Serious Series Posted February 12, 2014 Share Posted February 12, 2014 Sherpa vac pump looks very similiar to 200tdi. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 13, 2014 Author Share Posted February 13, 2014 I'd try bleeding the master as outlined above buddy, then bleed through. If it still persists clamp the hoses to eliminate parts of the system and find your issue. As luck would have it I managed to get home with just enough daylight left to get the eazibleed on and crack the unions on the M/C, front first then rear, no idea if it makes a difference, but both saw fluid coming out straight away so I'm guessing that wasn't it. with the Eazibleed on the pedal is very firm, with only about 10mm of free play, so I'm guessing that adjustment also isn't the cause of the problem as expected. With the Eazibleed back off the brakes are still the same, what feels like 2" of free play before it feels like it's doing anything. Hoses can't be clamped, they're braided stainless. Quote Link to comment Share on other sites More sharing options...
aaronledwidge Posted February 13, 2014 Share Posted February 13, 2014 Ah bummer on the hoses mate. What about g clamping both rear cylinders shut, that would let you know if its a front brake related issue. Quote Link to comment Share on other sites More sharing options...
Josh NZ Posted February 13, 2014 Share Posted February 13, 2014 Bugger, atleast it's ok though! If the pressure bleeder makes the pedal nice but when removed makes it poor... Hmm sounds like you're edging towards the problem! Pressurising the system enough to get a good pedal which would indicate a distinct lack of pressure from the m/cyl perhaps? Internal seal failure on the master? Would definitely kill any pressure. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted February 13, 2014 Author Share Posted February 13, 2014 Come the weekend I'm going to strip all the drums off, strip all the shoes off (and check them against the drum diameters) and clamp all 6 cylinder wheel cylinders fully closed. This does mean having to make some false jaws for the front cylinders being TLS and therefore a 40deg back so a clamp won't grip them, but that's a minor detail. I would hope the m/c is fine, its not that old, it didn't arrive in a blue box, but I'm damned if I can remember the make....I'll have to look it up, but I think it was TRW/Lucas. Quote Link to comment Share on other sites More sharing options...
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