car failed mot on retest after replacing master cylinder + all 4 calipers discs and pads.
reason for failure : insufficent reserve pedal travel.
car is not equipped with abs
would this point to either air still in the system or a faulty servo?.
the pedal is slightly spongy when brakes are applied still.
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I would guess some air in there still. Wedge the pedal down overnight and then re-bleed. Never failed for me.
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One of the odd things that I have seen when a braking system has been rebuilt is the calipers put on the wrong side - with the bleed nipples at the lowest part of the caliper instead of the highest - unsurprisingly, the owner couldn't get a good pedal, despite having bled over a gallon of brake fluid through the system!
Number_Cruncher
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Faulty servo (or any leak) can sometimes mean pedal gradually going down when engine on, going down fast when engine off. Often you may hear hissing or high pitched noise due to losing vacuum through faulty servo seal.
Air if the system is air tight, then some air would gradually be absorbed by the brake fluid.
Who did the brake replacement? Sometimes only a pressurised fluid change will get all the air out.
I sometimes wonder whether servos go after someone spills brake fluid on them (without wiping it up) and they corrode years later.
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If a garage did it, get them to redo it. After all an MOT failure on brake work, is just about as condeming as it can get.
If it is you, pressure bleed with an Eazibleed kit. Just changed my fluid. I always do it twice, out of habit really, and got a rock solid peddle, on easily a litre of fluid. Best £10 I ever spent 15 years ago. The machine still works perfectly. Only put 18 lbs of pressure in to be on the safe side.
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i bought the car a few weeks ago from ebay, link to the sale here for anyone interested
cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=1301...9
the item description gives more info on the brake problem, and when i went to pick it up from the garage (yes he was an under the arches garage trader) he said he'd replaced the master cylinder also but still couldnt get a firm enough pedal for an mot although when the brakes bit they are perfect and i cant fault them?.
so conclusions i draw are the garage i got it from is rubbish and cant even bleed brakes properly or the 2nd hand servo he put on it is also duff (unlikely but possible?)
other than that im stumped ....which is why i though servo??.
any simple tests i can do to try to diagnose further guys??.
ps: the car (as you can see from the ebay link) is a 1996 p reg swindon built accord 1.8i without (SURPRISINGLY) abs, it is the type that is essentially the same as a rover 600 and is a damn good car brakes aside :¬)
Edited by castlet5 on 10/12/2007 at 16:29
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I'd wonder why it doesn't have ABS? The Honda ALB system was very prone to expensive faults - has it been removed and a mismatched master cyl grafted on?
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screwloose, i checked as i thought the same, but apparently and quite disgustingly for such an expensive car new at the time this base model accord was not available until 97 r with abs as standard and on n+p reg base model cars it never even had it as standard only as option!!!
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If the car has a direct acting servo (as opposed to a remote one), then it's extremely unlikely for the servo to cause a poor pedal fault. In effect, this type of servo has an (almost!) solid link between the pedal and master cylinder, and as such would be at the very bottom of my list of potential suspect items.
The only non-solid portion of the link which runs through a direct acting servo is the so-called reaction disc, which is a small rubber disc which allows the pedal force to be converted into a tiny relative movement that allows the switching of the vacuum and atmospheric air which allows the servo to work.
Faced with this type of fault, I would begin by obtaining a number of ** bleed screws. Take the brake pipes out of the master cylinder, and fit the bleed valves. Then, bleed the master cylinder, and check that you get a good pedal. If so, the master cylinder and pedal and servo are completely cleared off the list of possible suspects, and your problem lies downstream.
one at a time, connect your brake pipes up to the master cylinder, bleed through, and check the pedal. When you find one that makes the pedal go bad, that's the circuit with the problem.
** If you have them, you can also use tools which clamp up the flexi-pipes to aid in fault diagnosis. Some people don't like the idea of clamping flexible hoses though, because they fear unseen damage within the pipe. It's up to you, but if you do clamp a flexi, make sure you use a correct tool with a decent radius, and not just a pair of mole grips!
Number_Cruncher
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Pair of mole grips and some thick cardboard will do the trick.
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£3.95 on e bay for the clamping tool "DON'T USE MOLE GRIPS" they damage the pipe.
Stick to what nc said above you won't go wrong with that. good luck
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