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Discussion Starter #1
Hi.
The car is:Vauxhall Nova Saloon 1.4S 1990.
I failed the MOT due to imbalance between the rear brakes(which are drum brakes)
one rear brake is weaker than the other.
I would like to mention that i passed the handbrake test,but braking test
with the pedal i didn't pass.This make me think that there is a problem
somewhere in the hydraulic line such as the proportioning valve on the line of the weaker brake,
air in the lines,master cylinder or wheel cylinder failure etc.The problem is that even though
i passed the handbrake test,i have noticed(by looking at the MOT document results)that the rear right brake is still much weaker than the left brake and not just at the braking test by pressing the pedal.
So,it seems that the reason doesn't have to be in the hydraulic line.
My question is:could those symptoms caused by something mechanical
besides glazed brake shoe pads?since Its been a long time that when i pull the handbrake,sometimes it makes 4-5 clicks,while in other time it makes 7-8 clicks so i wonder if this handbrake behavior can be related to the MOT results?
Thanks.
 

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It could be a few things causing the problem,possibly a weeping cylinder one side,
i always found it best to strip the rear brakes out and see what's going on,
if the rear brakes haven't been looked at in a while you may find it needs a combination of parts renewing,freeing off and de glazing
 

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Discussion Starter #4
Hi Valer.
I stripped the rear brakes out last year due to a glazed pad
i installed a new pads,a new wheel cylinder,new set of springs and a brake shoes
automatic adjuster.After that i passed the MOT.
Since then the car made hardly 5000 km(30+ years old car)and now
it failed again on the same wheel.the right brake is weaker,again, than the left one.
Can an handbrake problem cause this issue according to my information that
i detailed on my first post?(numbers of handbrake's clicks changes often),
What this changing of handbrake's clicks can indicate?
 

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Can an handbrake problem cause this issue according to my information that
i detailed on my first post?(numbers of handbrake's clicks changes often),
What this changing of handbrake's clicks can indicate?
This could indicate that the automatic adjuster in the drum is slipping from time to time.
The best thing to do is take both drums off and have a look.
 
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Discussion Starter #6
This could indicate that the automatic adjuster in the drum is slipping from time to time.
The best thing to do is take both drums off and have a look.
Hi Alan.
Yes,it make sense.In fact,as i mentioned before,last year i made a full inspection of the right drum(the weaker one)
and i installed a new automatic adjuster(among other)since it was worn,but it seems that this handbrake behavior persist.Even though i installed a new automatic adjuster,there are several components that are connected to it,which are not new,maybe they somehow related to the slipping issue.
Anyway,could this automatic adjuster slipping cause to one brake be stronger than the other when i press the pedal?and cause imbalance?
 

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How are you adjusting the rear brakes, if your just tightening the handbrake cable then you need to release all tension from the cable, then adjust the rear shoes so they are just biting then tension the cable, if the cable is too tight the auto adjuster wont work properly.
 

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Discussion Starter #8 (Edited)
How are you adjusting the rear brakes, if you just using tightening the handbrake cable then you need to release all tension from the cable, then adjust the rear shoes so they are just biting then tension the cable, if the cable is too tight the auto adjuster wont work properly.
Hi andyl.
Yes,when i assemble the brake-shoes with all the parts,the handbrake is released.And followed
by haynes book,i adjust the cable tension by putting the handbrake in second click and turning a kind
of nut under the car(located between the two rear wheels)until the rear shoes are just lightly rubbing
the drum.The same idea as you mentioned.
But,if that auto adjuster doesn't work properly,could it cause to one brake be stronger than the other when i press the pedal?and cause imbalance?
At the following photo i marked with red arrows the parts that i didn't replaced(15,16,19)the rest of the parts,including the auto adjuster,are new.could one of the three old part make problems(especially number 19)?
brake drum.png
 

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Right that type of adjuster won't slip, I was thinking it was the type with toothed quadrants.
As Andyl says, you need to slacken the handbrake cable off so that the levers on the brake shoes are right back to their stops, turn the adjusters so that the drum will only just go on, then adjust the cable.
You need to remove any wear ridge on the edge of the drum first.
I think you will probably find a leaking wheel cylinder when you take it apart, or a partly seized one.
 
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Discussion Starter #10
Well done on your diagnosis.The wheel cylinder was the defective part indeed.
The first part that i checked when i dismantled the drum was the
wheel cylinder,as you advised,and i found out that the wheel cylinder was partly seized
(one piston was rusted and seized).I installed a new wheel cylinder and i hope i will pass
the MOT now.Refer to the brake cable,i followed your adjusting procedure,but it will take
some time to see if the number of clicks will change.For now it is okay.
I changed the brake fluid and made the air bleeding in the traditional way(two persons),
while i saw that there is a kit which is called:"hand held vaccum bleeder"(pumping the liquid
from the brake's nipples)and one can do the bleeding/changing the brake fluids by himself
without any assistance.
Can i use this kind of tool in vauxhall nova 1.4S 1990 car?
Will this method will do the job as good as the traditional way,without leaving air in the system?
Thanks.
 

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The vacuum method relies on a really good seal around the bleed nipple into the caliper otherwise it is too easy to be fooled by air being drawn in around the nipple. One trick is to put red rubber grease around it to stop air from being drawn in.
Personally I prefer to use the traditional method you have used.
 
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Had the same problem on my wife’s 1.2 nova many years ago weak rear drivers side drum brake failed MOT, my fault turned out to be that the flexible pipe to that brake drum had failed internally no sign on the outside of pipe. Replaced the pipe brake back to normal passed its MOT.
 

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Discussion Starter #13 (Edited)
Had the same problem on my wife’s 1.2 nova many years ago weak rear drivers side drum brake failed MOT, my fault turned out to be that the flexible pipe to that brake drum had failed internally no sign on the outside of pipe. Replaced the pipe brake back to normal passed its MOT.
Thanks,radman66,for that information.If i won't pass the MOT again for the same result,
it is good to know that a flexible pipe may cause the same imbalance symptom.
Anyway,I hope that,for the current MOT,the failed brake cylinder was the only failed part.
The vacuum method relies on a really good seal around the bleed nipple into the caliper otherwise it is too easy to be fooled by air being drawn in around the nipple. One trick is to put red rubber grease around it to stop air from being drawn in.
Personally I prefer to use the traditional method you have used.
Hi Koicarpkeeper.
I,also,prefer to use the traditional method,but sometimes you can't find an assistance
at your convenience time,so the vacuum method can help at those occasions.
When you said to apply red rubber grease around the bleed nipple,did you mean to
the place that i marked in the following photo?
wheel cylinder nipple.jpeg
And if yes,isn't there a risk that somehow the grease will find a way inside the liquid brake
system and will contaminate the liquid?doesn't the vacuumed air can easily pull the grease inside
the wheel cylinder?
 

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That is the right place.
Red rubber grease is perfectly safe with brake fluid. If the nipple is a good fit then no air should be drawn in anyway.
You can still do the brake bleed in the traditional way on your own with a "One Man Bleed Kit" which has a one way valve in the pipe you put onto the nipple.
 
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Discussion Starter #15
That is the right place.
Red rubber grease is perfectly safe with brake fluid. If the nipple is a good fit then no air should be drawn in anyway.
You can still do the brake bleed in the traditional way on your own with a "One Man Bleed Kit" which has a one way valve in the pipe you put onto the nipple.
Yes,i familiar with"One Men Bleed Kit",but the vacuum method seems to be more simple,
for the reason that you don't need to get inside the car each time and press/release the pedal.
If,according to your answer,the vacuum method will do,indeed,the same good job as the traditional one,
i assume that i will use this method as a second option when i won't find an assistance.
Thank you all for your help:)(y)
 

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Although i have a vacuum bleed kit my preferred method is a pressure bleeder (eezibleed)
combined with the one way bleeder pipe if you're doing it on your own.
 

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I misplaced my Eezi Bleed many years ago but it was very useful when I built my kit car and you have to fill a completely empty system.
 

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Discussion Starter #18
Bad news,the car didn't pass the MOT,even though,i replaced the partly seized wheel cylinder.
Same result: pressing the pedal→failed(right wheel weaker).pulling the handbrake→passed.
radman66,mentioned something about the flexible pipe.From outside it looks fine.
How can i verify/check if the flexible pipe is really the problem?
 

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I'm trying to remember the sequence of events now over 20 years ago but this is what I think I did.
Car failed MOT same fault as yours. Took the car home after a drive the faulty rear drum was noticeably cooler than the other drum. Changed brake shoes and right hand cylinder brake still noticeable cooler the only other thing I could see that was in that line was the flexible pipe to that brake so changed that. Both drums now the same temperature car passed MOT.
Hope this is helpful.
 

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Bad news,the car didn't pass the MOT,even though,i replaced the partly seized wheel cylinder.
Same result: pressing the pedal→failed(right wheel weaker).pulling the handbrake→passed.
radman66,mentioned something about the flexible pipe.From outside it looks fine.
How can i verify/check if the flexible pipe is really the problem?
If the handbrake is working ok, then the linings & drum ought to be good, and you have fitted a new cylinder, so it shouldn't be that.
The only thing left would seem to be the flexible hose, they are cheap enough, so get one & fit it.
 
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