mpbarrett Posted March 30, 2009 Posted March 30, 2009 I know I have asked this before but anyone got the automatic adjusting rear brakes to work properly? My 1973 mk3 gt6 has them and I cant get them to adjust automatically. I have cleaned them so that everything is nice and free to move, dressed the edges of the levels so that it works on the ratchet part of the adjuster. I have set the hand brake cable (where it attaches to the lever arm on the back plate) so that the lever arm is parallel with the back plate when the handbrake is off. If I operate the hand brake I can hear the adjusters moving so the mechanism is working but the brake pedal is moving a long way down before the brakes start to operate. If I pump the brake pedal then the pedal comes up and feels about right which, I think, suggest that the rear brakes need adjusting but they wont adjust automatically.So whats the trick to setting them up correctly? I cant see anything in the manual about them, did they work when they were new? I am almost at the stage of drilling a hole in the back plate so I can get a screwdriver in to manually adjust them or convert them to manual adjustments.... or just adjust the handbrake cable to take up the adjustment on the brakes (but then the auto adjustment will never work).mikeGT6 now with nice new OD gearbox but I cant try it cause the brakes are not working.....
Gt6s Posted March 30, 2009 Posted March 30, 2009 Yeah they are a bit crap !To get them to work properly you need to adjust the shoes out as much as you can before sliding drum on fully home. Look out for a pair of 1500 dolomite drums these have holes in them alowing screwdriver access to adjuster ratchet, makes life a lot easier.
mpbarrett Posted March 31, 2009 Author Posted March 31, 2009 Gt6s wrote:Yeah they are a bit crap !To get them to work properly you need to adjust the shoes out as much as you can before sliding drum on fully home. Look out for a pair of 1500 dolomite drums these have holes in them alowing screwdriver access to adjuster ratchet, makes life a lot easier.Done that, so I think its time for a hole and screwdriver! Maybe they have always been crap even when new!I just want to drive the car, took it off the road at begining of March to do the gearbox and then ended up doing all sorts of other things on it (servo, oil change, rear suspension bushes, U/J's, cleaned some rust and painted, new seat belts, insulated gearbox cover, replaced lots of ify wiring, new fuel pump and filter, lots of interior stuff etc etc), which has meant that its taken ages to get it all back together! I think the moral is just do one thing at a time and finish it before starting on the next bit of tweaking.... they are meant to be driven and not just for sitting in the drive looking pretty!Mike
Velocita Rosso Posted March 31, 2009 Posted March 31, 2009 Hang on , you say you pump the pedal until brake works?Surely then the system needs bleeding ,then they work as they are supposed to and then the adjusters come into play when the shoes wear?
Tim Bancroft Posted March 31, 2009 Posted March 31, 2009 Are the back plates the same as those without auto adjusters-if so retro fit the old type?
mpbarrett Posted March 31, 2009 Author Posted March 31, 2009 michael_charlton wrote:Hang on , you say you pump the pedal until brake works?Surely then the system needs bleeding ,then they work as they are supposed to and then the adjusters come into play when the shoes wear? Ok the brakes have been bleed (Eezibleed and manually) and the pedal is hard, but moves down a long way. I beleive this is due to the clearance between the drums and the shoes, if the clearance was less then less fluid would have to be moved into the system to move the shoes to the drums and therefore the pedal would not need to move so far.If I rapidly 'pump' the pedal then I think what happens is that you add more fluid into the system and move the shoes out before the return springs can act on the cylinder pistons and move the fluid back to the resivour. Once the pedal is released the springs on the rear shoes move the shoes back and the piston in the rear brakes pumps the fluid back to the reservoir.But then again I might be completly wrong!cheersmike
mpbarrett Posted March 31, 2009 Author Posted March 31, 2009 timbancroft61 wrote:Are the back plates the same as those without auto adjusters-if so retro fit the old type?dont think so, pretty sure the shoes and drums are different on the 2 types of rear brakes. On the auto adjust its the same arrangement as used on the dolly (same drums). I guess BL were starting to rationalise there designs.... cheersmike
rotoflex Posted March 31, 2009 Posted March 31, 2009 No air in the lines but must pump the pedal for the rears - usually adjustment, but Is the slave cylinder wobbling a lot on the back plate?Paul Tegler has a page on the late GT6 self-adjusting rear brakes. I know almost nothing about them.http://www.teglerizer.com/triumphstuff/73gt6br_selfadjust.htm
mpbarrett Posted March 31, 2009 Author Posted March 31, 2009 Useful site. I wonder if I could get a pair of original adjusters and fit them in place of the plates at the bottom. Would not be too difficult to machine out the original plate rivets...Actually I now realise that the brakes work and wear slightly differently. With the auto adjust brakes the bottom edge of the shoes always pivot on the bottom plates. As the shoes wear most of the wear is taken by the top of the shoes (near the cylinder) and the bottom part will never wear out as it the pivot point of the shoes is fixed...With the manual adjust then the adjustment is done by increasing the difference between the pivot points on the bottom of the shoes, I would have though this means that the shoes wear more evenly. Maybe this is why the brakes feel much better on the Herald, which has manual adjustment compared to the GT6. Once the pedal starts to drop a quick adjustment of the rear brakes and the pedal is back where it should be!cheersmike
TimW Posted March 31, 2009 Posted March 31, 2009 409 wrote: 8)Yes so crap i converted to rear disc. Very easy conversion if you can make the mounting plates for the calipers!
Paudman Posted March 31, 2009 Posted March 31, 2009 On my late model Mk3 I found that the adjusters had the opposite effect to what they should have had - they actually used to slacken off the brakes when the handbrake was applied instead of tightening them. This meant that every two or three months I had to readjust them manually anyway.
simonjrwinter Posted April 2, 2009 Posted April 2, 2009 Pretty sure those brakes need bleeding again (and maybe again)Simon
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