rear brake problem

classicalgreen

classicalgreen

Active Member
only just got through last MOT as handbrake is v poor and was borderline. having stripped both callipers ( dropped rear end ..bleeding heavy ) and rebuilt noting cam pins fitted correctly ( seems they are easy to flip over ) as new test is looming I have no doubt it will fail . handbrake is hard to apply and I wouldn't trust it in a small slope let alone a hill.
as its same unit used on Zephy mk4 ( I used to own one) I know these brakes ought to work decently well.
checked pins not seized so calipers swing freely. new pads. discs pretty decent. nothing untowards found. checked cable is only just slack slightly when handbrake is off. and both sides pull when applied . at a loss to where to seek the missing braking power . wondering if the handbrake assembly itself is at fault.
anybody has this issue? seems a shame to have it off road again ( and again ..and again) covered almost 300 miles since last MOT. would liked to double that this year.
 
I think Harvey is right. Can you hear the adjuster clicking up when you manually activate the handbrake cams? Sometimes the ridges on the adjuster wheel or the pawl round off over the years and stop it adjusting correctly.
 
If the adjuster isn't working, the rear brakes should be weak on the pedal too, not just the handbrake. My money is on adjustment being required. The other possibility that comes to mind is if one or both of the tappets have fallen over in the bore the handbrake lever goes into. You say that you checked that, but it is easy to have it happen if you have the lever stop screw out while you are refitting the caliber pivot pin to the rear end on reassembly.

Yours
Vern
 
Vern Klukas said:
If the adjuster isn't working, the rear brakes should be weak on the pedal too, not just the handbrake. My money is on adjustment being required. The other possibility that comes to mind is if one or both of the tappets have fallen over in the bore the handbrake lever goes into. You say that you checked that, but it is easy to have it happen if you have the lever stop screw out while you are refitting the caliber pivot pin to the rear end on reassembly.

Yours
Vern
Click to expand...
Excellent point Vern.
 
One thing i have noticed when testing these callipers for correct opperation is that when you opperate hand brake cam from fully off to fully on ratchet clicks 3/4 times every time.
I check this when pads are removed and you can see/feel piston moving.
You should be able to ratchet piston out at least 3/4 inch 3/4 clicks every time,if not adjusting mech is faulty.
Once working/adjusted correctly when i have tested on my MOT brake roller tester hand brake/foot brake readings almost identical at 270/290kg .
clive.
 
many thanks responses. fairly certain the tappet(s) are ok was was aware of this issue when reading up on brakes. ( common fault apparently ) rear brakes on hydraulics passed Ok so its likely as suggested an set up /linkage issue. no slack in cable and before refitting handbrake cable ( when refurbishing callipers) did check both callipers and all mechanical parts moved fully and back. wound in pistons by hand ( easy peasy job for once) did have a seized pivot bolt before stripping but all working well an both callipers move back and forth easily now. the handbrake itself needs excess force when being applied giving feeling something wrong along the mechanical side. will when i get time ( building a new garage for car so will be few weeks) when fully applied .well as hard as can be pulled... very much doubt car would stay on a gentle slope let alone a hill of any description.
intention then is to disconnect cable .recheck cable movement from caliper to caliper and all mechanical parts. then check the handbrake lever mechanism. just in case that is fouling? refit all and restest. final fix being a large box of matches and 5 gallons of premium lead free ( only kidding but frustration give one an attitude)
 
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