xychix Posted May 6, 2018 Share Posted May 6, 2018 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? Quote Link to comment Share on other sites More sharing options...
steve b Posted May 6, 2018 Share Posted May 6, 2018 Do the wheel cylinder pistons move freely ? Are the shoes fitted correctly ? it is not hard to get them on wrong so the adjuster pins do not line up with the cams correctly , I've done it myself before Is the pedal clearance to the master cylinder correct ? If too tight it can build pressure in the system pushing the pistons out What happens if you set the adjusters at minimum? What new parts have been fitted ? and what manufacturer's were used ? cheers Steve b Quote Link to comment Share on other sites More sharing options...
Bigj66 Posted May 6, 2018 Share Posted May 6, 2018 If it’s both rear brake drums then I’m suspecting the master cylinder. Have you changed it? Quote Link to comment Share on other sites More sharing options...
secondjeremy Posted May 6, 2018 Share Posted May 6, 2018 Is this a SWB with 10in rears? If so the rear brake is the standard land Rover drum brake which was used from the later 80in vehicles. Originally the thing was self - adjusting with only the bottom spring - but as this caused probelms the post and return spring was fitted to the leading shoe together with an adjuster for the leading shoe. Why all this? The idea is that the leading shoe is drawn to the drum when its applied which gives some servo action. If the drum is dirty or rusty - there's a tendancy for the leading edge to pick up on the rough drum surface and apply itself. In particular this happens in reverse as there's very little restraint for the back shoe - which now becomes the leading shoe. What can you do about it? - the edges of the shoes should be well chamfered (cut back at an angle of 45 degrees or flatter). The sides of the shoes should also be inspected in case they're rubbing on the drum. If it happens when you're reversing out of a parking place - consider parking the other way round. Rust will form in a clean drum surface in a very short time (few hours) in damp conditions and is polished off when the brakes are applied. There were some cylinders around with excessively strong inner springs - which caused problems. I've had to dismantle cylinders and fit springs from old cylinders to solve the problem. Current ones seem OK. its also possible your master cylinder isn't releasing pressure fully - due to restricted pedal travel or something - and whilst you don't notice anything wrong with the discs - the residual pressure is noticeable on the back due to the self-servo effect. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted May 6, 2018 Share Posted May 6, 2018 Do you have a brake bias valve? I have an idea that disc brakes benefit from such things, and master cylinders to suit. Quote Link to comment Share on other sites More sharing options...
xychix Posted May 6, 2018 Author Share Posted May 6, 2018 (edited) @gazzar I guess you are spot on. Forum member Arjan was here today. Seems to much pressure builds up in the system and pedal travel is minimal. Front system was replaced with zeus disk kit other than that nothing was altered (recently) on the brake system. Other only non default item is the electric Hella UP28 giving the vacuum instead of the intake smothering valve, this might give me a fierce vacuum but I don't see how this would shorten travel and create residual pressure in the brake lines.... Arjan opted to research conversion to a defender master cylinder. So its a 1979 SIII 109" station wagon. originally double cilinder front drum brakes and single cyl rear drums. Front was replaced by a full Zeus disc kit, rear remains original. Edited May 6, 2018 by xychix Quote Link to comment Share on other sites More sharing options...
Gazzar Posted May 6, 2018 Share Posted May 6, 2018 As I've a Zeus kit to fit, please keep posting your results Quote Link to comment Share on other sites More sharing options...
xychix Posted May 6, 2018 Author Share Posted May 6, 2018 Gazzar will do. fitting was a breeze after I got the proper kit (first got LaRo discs + Jag calipers and pipework ) While you'r at it overhaul the hubs (so get proper seals and have a tad fluid seal at hand in case you're missing something) , don't forget to order longer studs and make sure you don't have the 'standard series' rims. I've got new Wolf rims fitted. now back to tearing it apart to do swivel bearings by now I can dismantle front hubs with my eyes closed. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted May 6, 2018 Share Posted May 6, 2018 I'm planning a full refurb of the entire axle, no half measures. Should be fun. G. Quote Link to comment Share on other sites More sharing options...
Arjan Posted May 7, 2018 Share Posted May 7, 2018 The system seems to keep the pressure once the brake is applied once. Drove the 109 this weekend. Having front disk and rear drum brakes and a very hard brake pedal without any travel worth mentioning, I think there is way too much back pressure in the system. I recall reading that sometimes you need to replace the Series master brake cylinder with a later Defender type one... Quote Link to comment Share on other sites More sharing options...
Bigj66 Posted May 7, 2018 Share Posted May 7, 2018 I posted in this thread on this subject from Heystee. Quote Link to comment Share on other sites More sharing options...
Gazzar Posted May 7, 2018 Share Posted May 7, 2018 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. Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 8, 2018 Share Posted May 8, 2018 The servo might be staying on a little with the greater vacuum, preventing the master cylinder from fully returning to rest and preventing the rear line fluid from fully depressurising. If you move the master cylinder to one side, you'll see an acorn nut in the recess of the servo which pushes on the first master cylinder piston. You could try adjusting that a little to reduce its length, or you could try a thin shim between servo and master cylinder. A stronger pedal return spring may also help. Check the clevis pin between pedal and servo input fork to make sure it isn't worn, as any play could cause this problem too. Quote Link to comment Share on other sites More sharing options...
xychix Posted May 21, 2018 Author Share Posted May 21, 2018 (edited) On 07/05/2018 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. Did not but have these wheels still around and can give it a try. Still unsure which part to buy or how to proceed (have one week near the 109 mid-june). For now I'm considering to order a NRC9529 (early 110/90 master cilinder) and hope this is a bolt in job. (choice based on Googling... real experience is always more valuable so still open for other ideas!!!) Likely only to find: - The part's isn't matching the servo. - The brakeline connectors are sized differently - After all is fitted the problem is still there Suggestions more than welcome. Edited May 21, 2018 by xychix Quote Link to comment Share on other sites More sharing options...
Gazzar Posted May 21, 2018 Share Posted May 21, 2018 Try an extra Spring on the pedal as well. Quote Link to comment Share on other sites More sharing options...
xychix Posted May 21, 2018 Author Share Posted May 21, 2018 1 minute ago, Gazzar said: Try an extra Spring on the pedal as well. Will do, actually need that as the current one is bad. BUT as my UP28 pump was connected to the brake-light switch I already trained myself to lift the pedal back with my toes so this spring won't solve my original problem it might help my schizophrenic right foot to become normal again Other 1st thing to check is the brake-lines. As I'v worked on the rear half of the chassis I hope I didn't dent the line placing the tub back on which would restrict return flow (also unlikely but still). Quote Link to comment Share on other sites More sharing options...
Gazzar Posted May 21, 2018 Share Posted May 21, 2018 I'd order a new good brand hose for the back, if you are bleeding the system anyway. 1 Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 21, 2018 Share Posted May 21, 2018 Yep, could be the hose. It's not unheard of them to perish internally and act like a non-return valve. Quote Link to comment Share on other sites More sharing options...
xychix Posted June 16, 2018 Author Share Posted June 16, 2018 Well, back onsite only to be finished (the bad way) in less than 30 minutes. Removed enough fluid, removed master cylinder only to find that the reservoir of the 109 master doesn't fit on my new NRC952... Other stuff I figured out. The screw in holes for the 952 are different in size, little wider on the front hole. Seems the same size as the 2 on the old master, however the other way around!!! on the 109 the wider one is closer to the firewall. As I'll be going nowhere with my new cylinder before I find a 90 reservoir I'll try something else: place the dual servo brake (came of the front) to the rear. It might be that 2*2 servo's can handle more fluid than 2*1 2-sided servo. (not sure of this can even work but I really want the 109 to be somewhat drive-able to keep the spirits up). Also replacing the flex hose is on the list. Quote Link to comment Share on other sites More sharing options...
xychix Posted June 17, 2018 Author Share Posted June 17, 2018 had a bad day on what ever I did today, decided to at-least replace the flex hose to the rear axle in the brake lines. Somehow that went south as well, broke the steel line just above the steel connector.... Is that repairable or do I need to strip the body again to replace the complete line?????? Quote Link to comment Share on other sites More sharing options...
Gazzar Posted June 18, 2018 Share Posted June 18, 2018 Do you have a pipe flare tool? Put a joiner on it. Replace with cupronickel. It was probably on the way out anyway. G. Quote Link to comment Share on other sites More sharing options...
lo-fi Posted June 18, 2018 Share Posted June 18, 2018 As a Gazza says, if you broke the steel line it was well past it anyway. Just pull the drivers side floor panel up, you can get to the rest easily enough without taking anything off. Steel requires quite a flaring tool, so tricky to put a joiner on, and you're better off knowing the line isn't going to fracture somewhere at the worst moment! Quote Link to comment Share on other sites More sharing options...
xychix Posted June 19, 2018 Author Share Posted June 19, 2018 ordered flare tools and will order a decent amount of pipe. What thickness is used on the series? 3/16" ? "CuNiFer" is likely what gazzer called cupronickel right? Also: hopw can I find out if my joints are metric or imperial (1979 SIII 109) I'd expect atleast 2 sizes of male units as the master cylinder has 2 different sizes on it. I've also found this 'brake failure warning switch' on the frame, no wires to it so the warning light would never work, is that an item I should reuse / remove / replace / refurbish?? Quote Link to comment Share on other sites More sharing options...
Snagger Posted June 19, 2018 Share Posted June 19, 2018 I would remove it and fit the level sensing reservoir cap from a Discovery/RRC late Defender instead. Those PDWA valves tend to rust and seize, and usually don't work anyway, but the also make bleeding a pig - I think most of the trouble associated with bleeding the twin leading shoe systems on 109s is actually from this, based on my experience after fitting coiler axles with discs all round. Quote Link to comment Share on other sites More sharing options...
xychix Posted June 19, 2018 Author Share Posted June 19, 2018 wellll, had binding rear brakes and now it looks like this: Quote Link to comment Share on other sites More sharing options...
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