bedford trucker Posted October 25, 2011 Share Posted October 25, 2011 HELLO i need some advice with my bedford mj, failed MOT last week on 37% brake inbalance on rear axle. test values were 1150kg on n/s and 2300kg on o/s. i striped down the n/s and found 1 seized piston in the cylinder so replaced with new. took it today to a local hgv garage for a brake test and found similar results. i adjusted each side while i was there, still no improvement. the o/s was striped down about 4 months ago and cylinder was replaced so i assume that side is ok. feel rather lost now for ideas. brake test results from about 6 months ago read approx 1250kg equally on both rear wheels so could the o/s be to powerfull? thanks paul Quote Link to comment Share on other sites More sharing options...
paulbrook Posted October 25, 2011 Share Posted October 25, 2011 My advice, from bitter experience is that assumption is the mother of all **** ups. Strip the whole lot down, then put it back together exactly like the manual says it should be. Had a very badly running vehicle in the workshop the other week. "It can't be the carb" said the owner "it is brand new". Very shiney it was too. It turned out (because I check everything) that the float was upside down in the float chamber. So assume nothing! Quote Link to comment Share on other sites More sharing options...
Tony B Posted October 25, 2011 Share Posted October 25, 2011 Bear in mind, line of least resistance. You have a brand new cylinder on one side, so the pressure will take the easy way out on the old cylinder. Brakes are like dominos, one goes then the next, then the.... Replace both cylinders., at least. Also how did you bleed it? Most vehicles of that size have equiliser valves bettween front and back brakes, and absoulete mare's nest to bleed. A good pressure bleeder, I personally have no time for the vacum bleeds, will make life a lot easier. They run from about £15. Quote Link to comment Share on other sites More sharing options...
Tony B Posted October 25, 2011 Share Posted October 25, 2011 Bear in mind, line of least resistance. You have a brand new cylinder on one side, so the pressure will take the easy way out on the old cylinder. Brakes are like dominos, one goes then the next, then the.... Replace both cylinders., at least. Also how did you bleed it? Most vehicles of that size have equiliser valves bettween front and back brakes, and absoulete mare's nest to bleed. A good pressure bleeder, I personally have no time for the vacum bleeds, will make life a lot easier. They run from about £15. Check any flexi hoses aren't balloning Quote Link to comment Share on other sites More sharing options...
Tony B Posted October 25, 2011 Share Posted October 25, 2011 (edited) And I have no idea why the forum has posted the answer twice! Oh ! Quick thought, the brake systems and compressors have a habit of filling with a waxy gunge. Paul had similar problems when he first got his MJ, we had to strip the thing in Belgium. Muck out no more problems. Edited October 25, 2011 by Tony B Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted October 25, 2011 Share Posted October 25, 2011 Most vehicles of that size have equiliser valves bettween front and back brakes, and absoulete mare's nest to bleed. Not on a MJ, they have a tandem master cylinder, two separate circuits, front and rear. Any gunge in the air system should removed from the wet tank at the front by the automatic drain valve, unless it is bunged up. Quote Link to comment Share on other sites More sharing options...
Tony B Posted October 25, 2011 Share Posted October 25, 2011 Richard, if it is a dual circuit master. Could the middle piston be the wrong place? Or would that give no brakes at one end? Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted October 25, 2011 Share Posted October 25, 2011 Richard, if it is a dual circuit master. Could the middle piston be the wrong place? Or would that give no brakes at one end? Tony, Paul has an imbalance between the two rear brakes, so unlikely to be a m/cyl problem. No middle piston............. only two pistons, outer and inner. Quote Link to comment Share on other sites More sharing options...
Tony B Posted October 25, 2011 Share Posted October 25, 2011 Thanks Richard. Reading other peoples problems, may well be useful in the future. Quote Link to comment Share on other sites More sharing options...
volvoc303 Posted October 25, 2011 Share Posted October 25, 2011 my mj had in balance couple weeks ago on the mot off side binding replaced both w clinders sanded the shoes both sides to ruff them up and then gave it a good run my problern with the brakes is the lack of use the offer mj had front brakes sticking same problern lack of use strip down same way ok now i bet if left again same problern will happern Quote Link to comment Share on other sites More sharing options...
LoggyDriver Posted October 29, 2011 Share Posted October 29, 2011 I run my MJ every three weeks to keep everything lubricated. All seems fine at the moment. Quote Link to comment Share on other sites More sharing options...
exoduschris Posted November 17, 2011 Share Posted November 17, 2011 Hi Paul. Did you get this sorted yet? I've just today managed to get a (class 4) MOT for my MJ after three test failures for front brake imbalance. In the end I had to replace the hydraulic flexi hoses (although I know there's only one on the back and that won't be causing your problem), both slave cylinders, new linings and a complete strip down and re-grease of pivot points, link-arms etc. For the class 4, brake imbalance only seems to be a fail point on the front (steered) axle. I guess you're getting an HGV MOT? Chris Quote Link to comment Share on other sites More sharing options...
bedford trucker Posted November 17, 2011 Author Share Posted November 17, 2011 hi chris yea managed to sort mine out, stipped both rear brakes down and cleaned/checked everything, and then set up the brakes as per the book of wisdom. i think when i adjusted the shoes up when i changed the slave cyl a few months ago i hadnt adjusted them correctly and that was were my fault was (teach me not to read a manual first) thanks paul Quote Link to comment Share on other sites More sharing options...
27-KF-73 Posted December 26, 2011 Share Posted December 26, 2011 I never leave my mj sitting over the winter months without being moved hence ive never had a problem with the brakes,although like any mj youv'e got to feather the brake pedal for the first few miles otherwise it bucks you out the seat and you end up making love to the windscreen :laugh: Quote Link to comment Share on other sites More sharing options...
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