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gritsop |
Posted: Wed Aug 26, 2009 12:52 pm Post subject: |
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Hi Ben.
It may be a long shot but try to blow compressed air all the way from the brake MC to the rear bleeding nipple.
Disconnect the brake line nut from the MC and place a rag on the other end of the line at the wheel cylinder. Compressed air will probably remove any rust bits inside the line and it will clean the inside.
This suggestion was proposed to this very forum when my front right brake were missing 400N force comprared to the other side. I had replaced everything except the metal lines with no obvious remedy. Compressed air removed all debris and the brakes over the front axle were balanced.
Hope this helps |
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Ben_nz |
Posted: Wed Aug 26, 2009 12:02 pm Post subject: |
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Ben_nz wrote: |
So I'm over this issue again until 6 months from now! |
It's 6 months from now, if you know what I mean.
My grey 1.5 strangely got through its WOF with no brake balance problems, but my black 1.7 failed AGAIN with the left rear brake 30% stronger than the right rear brake AGAIN.
I really need to find a WOF testing garage without independent brake-testing roller thingies.
The grey car has had a new brake bias valve put in at great expense, which at the time did nothing to help the balance problem. Both cars have had the flexible brake hoses going to the rear axle replaced, and I've played with adjusting brakes and swapping drums in the past with occasional temporary success. But it's always the right drum that's weaker, and it has happened to both my cars. I want to know what causes it and I want a permanent fix!
Today ALFA stands for "Aggravating Latent Fault Appears!".. "Aww Look, Failed Again!" |
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Ben_nz |
Posted: Sun Mar 22, 2009 1:04 am Post subject: |
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I didn't think adjusting the self-adjuster would make any difference to anything but the pedal travel no matter what the issue was.
WOF inspections are annual on new cars, but not old stuff like 33s. Given how useless the average motorist is though, imagine how many blown bulbs they'd all have if the inspections were less frequent... |
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BigAl |
Posted: Fri Mar 20, 2009 1:04 pm Post subject: |
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coolio
You have your wof every 6 months, unlucky you, ours is yearly but i like to check mine every 6 months when i service my car, doing an oil change ect. I was mistaken, my rear shoes have plenty of meat on them still, they just needed adjusting up again as the self adjuster is obviously not doing what it says on the can!! So i just replaced my front pads and will re-adjust the rears when i get a replacement bearing. I didn't think swapping your drums would make a difference, i would just adjust the "self adjuster" with a long thin screwdriver, we are getting to know our brakes very well |
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Ben_nz |
Posted: Fri Mar 20, 2009 8:24 am Post subject: |
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BigAl wrote: |
how did you get on ben? |
One car was within the acceptable range once the rear flexible brake hoses were replaced (although for a while afterward the rear brakes would drag sometimes and one or both drums would get hot and smell).
I swapped the drums over on the other car and it made no difference, although by this time the WOF inspector guy knew me pretty well and he was sympathetic, letting me pass anyway. He said the brake balance wasn't that far beyond the limits and it would probably improve once the shoes bedded in to the different drums.
So I'm over this issue again until 6 months from now! |
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BigAl |
Posted: Wed Mar 18, 2009 12:51 am Post subject: |
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how did you get on ben?
I just had my brakes tested again and this time the rears locked both sides on the foot brake and one side on hand brake, even though the braking force is the same on both sides.
I don't get this as my shoes need replacing along with my pads, weird. |
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BigAl |
Posted: Sun Feb 08, 2009 7:50 am Post subject: |
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I think that the system is a x split system design so that one side is not dependant on the other side, so that if one side fails the other will continue to work.
I think that the difference in brake force has come from the automatic brake adjuster working/working better on one side.
Over here the nuts are no longer available from Alfa, so its another incentive not to remove anything unless necessary.
I do this just before every mot and when i feel the brake pedal has lots of travel in it before it goes hard, which is now, lol |
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Ben_nz |
Posted: Sun Feb 08, 2009 6:11 am Post subject: |
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I thought that even if the brake shoes were adjusted closer to the drum on one side of the car than the other, the brake system would still apply the same amount of force on each side?
More fluid would have to flow into one side than the other to move the more distant shoe further, but once all shoes have contacted their drums they all have the same system pressure behind them. Is this wrong?
If it's not wrong, why will adjusting the brakes help? |
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BigAl |
Posted: Sat Feb 07, 2009 12:38 am Post subject: |
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ben
before you do that why don't you undo the handbrake cable inside the car and then adjust the rear brakes with everything insitu through one of the wheel bolt holes. |
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Ben_nz |
Posted: Sat Feb 07, 2009 12:04 am Post subject: |
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Well, 6 months later both my cars were due for WOFs again.
And both of them failed because the rear footbrakes are out of balance! Aaargh!
Handbrakes are fine on both cars.
In both cases it's the right rear brake that is the weaker.
I guess to start with I'll swap the drums over on both cars and take them back to try again. |
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Admin |
Posted: Sat Sep 20, 2008 8:43 pm Post subject: |
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Hi
Not sure. On MOTs I am not sure I have locked the wheels on a car.
All the best
Keith |
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BigAl |
Posted: Thu Sep 18, 2008 12:08 pm Post subject: |
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hey keith, i think you mis understood me.
When the brakes are working as they should, are they good enough to lock the rears when using the foot brake and the handbkare on the brake tester? |
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Admin |
Posted: Wed Sep 17, 2008 10:54 pm Post subject: |
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Hi
Never had any issues with a 33 locking the rear up first. Fronts manage to lock up first (not that the brakes are that good).
All the best
Keith |
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BigAl |
Posted: Wed Sep 17, 2008 2:04 pm Post subject: |
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Is it normal for our brakes to be pants? Should they lock the rear with foot brake or handbrake when being tested, as they are put under much higher load? |
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BigAl |
Posted: Thu Sep 04, 2008 12:15 pm Post subject: |
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Quote: |
actually I have no idea what I'm talking about. |
lol, neither do i, brakes were bled when the rear axle was changed, fronts have 100% on brakes tester, not going to flat spot my tyres on the road, there is just next to no effort on the rears. |
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Ben_nz |
Posted: Thu Sep 04, 2008 2:13 am Post subject: |
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The brake bias valve didn't change the left/right balance problem on the rear footbrake; that was cured by swapping the outer drums over.
But in hindsight the bias valve did seem to achieve a bit of an Alfa miracle - the car can now lock its front wheels under hard braking instead of one or both rear wheels.
I never checked whether it was seized myself, because I thought I'd have to disconnect the panhard rod (?) and I couldn't be bothered.
I'd say your problem is more likely than mine to be related to the bias valve thingy.. unless maybe one of your brake lines is crushed or full of bubbles.. actually I have no idea what I'm talking about. |
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BigAl |
Posted: Thu Sep 04, 2008 12:58 am Post subject: |
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well i had mine retested and the hand brake is more powerful than the foot brake, balance is ok! What do i do now? Changing the rear brake bias valve made no change for you Ben, did the bit on the compensator, that rested on the sprung load rotate? I might try and see if it has seized but im not sure if it only goes in and out. i dont want to waste my time changing it if it made no change for you i am now stumped as the shoes have pleanty of meat on them?
suggestions anyone? |
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BigAl |
Posted: Tue Aug 19, 2008 2:27 pm Post subject: |
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sweet, well done, wish me luck lol |
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Ben_nz |
Posted: Tue Aug 19, 2008 2:08 am Post subject: |
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That's the first thing I did on the weaker side, and I couldn't see any problems.
Latest news though, swapping the drums reduced the imbalance from 27% to about 13% and I passed!
If only I had known to try that first. |
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BigAl |
Posted: Mon Aug 18, 2008 10:04 pm Post subject: |
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Ben, check both the pistons on both cylinders.
Remove 1 drum and get a friend to slowly press on the brake pedal, both pistons should move out, you should be able to see if the self adjustment is working. If the pistons don’t move, or one is stiff, see if you can remove the rubber cover and clean / lubricate, failing that replace the cylinder. Check the other side in the same way. I had an imbalance due to a brand new cylinder on one side and a sticking one on the other side. Paul.H and I noticed that my old one had rust coming out of the seal, so we used the other from his axle and now both are equal albeit not good enough. |
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Ben_nz |
Posted: Mon Aug 18, 2008 9:46 am Post subject: |
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All the shoes and front brake pads were replaced about 7 months ago.
Today I got the car back from having the brake bias valve replaced ($$$) and it didn't have any effect on the rear footbrake balance! Infact the imbalance was slightly worse than last time - 27% difference.
The guy at the testing station suggested swapping the drums left to right, so I did that tonight and I'll go back tomorrow to try again. |
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BigAl |
Posted: Sat Aug 16, 2008 5:24 pm Post subject: |
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Hey Ben, sorry to hear that, were your shoes in good condition?
If your rears are working but not well enough I would check the cylinders are lubricated and not stiff. If they are ok I would then check the compensator by cable tying the sprung load away from the compensator, if it is working you should get less brakes on the rear if there is no change then I guess it’s seized, can these be lubricated?
I now have 1 more brake test to see if they will pass if not then I will try new shoes and if it fails again then I will have to get new drums I guess. |
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Ben_nz |
Posted: Sat Aug 16, 2008 12:28 pm Post subject: |
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You're doing better than me then.
I opened up the weaker brake drum to sand / lubricate / adjust, and I finally worked out how the brake adjusters are supposed to work and why they don't.
Then I reassembled it, went and did a lot of hard stops in forwards and reverse, loaded up the boot with batteries and went for my retest. The strength of the rear foot brakes was more even but not enough to pass.
Now the car has gone to the mechanic, who says the problem will probably either be a brake hose or that trusty brake bias valve. |
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BigAl |
Posted: Fri Aug 15, 2008 12:48 am Post subject: |
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Well I swapped over the drums after measuring and there was a difference.
I looked into the hand brake unevenness and found that the shorter cable side needed fixing.
On the lever that the cable attaches to on the shoe, there is a pressed out part that acts as the stop. The arm was loose at the pivot point at the top and the pressed out part was resting past the correct resting point. With the aid of my wingman Paul.H we swapped over this lever and the cables are once again even. |
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BigAl |
Posted: Thu Aug 07, 2008 2:44 pm Post subject: |
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Oh yes, i figured out how it actually works form one of pauls that we made a good set. I have never had a working adjuster, now i have 2 but it probably wont work in situ. Someone had actually put one of my cogs adjusters the wrong way on. |
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