nitros44
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esto es un negocio serio
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Post by nitros44 on Jun 2, 2012 23:47:40 GMT
Not getting the opportunity much these days to fail discs;i was surprised to see this disc on a 2007 Renault Megan cab by. As we can see its off the rear and like most Renault discs are well exposed to the elements. But is it seriously weakened??Attachments:
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alex
Nominated Tester
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Post by alex on Jun 3, 2012 8:05:17 GMT
:)hiya mate that to me looks in pretty poor condition what was the brake performance like and was the disc worn thin,I personally think that this change in failure criteria needs relooking at,common sense is needed if the brake performance test is ok then fine but the condition of the disc itself is clearly corroded pitted,I no its a minimum standard test but no one in there right mind would say that discs is ok maybe I'm wrong in saying that but I would,nt want that disc on my car carry my family around.ive seen in the past testers failing discs on being pitted but they were clearly still serviceable you know what I mean light pitting but in your picture that is to me well past it's best.common sense is needed.i had one in yesterday clearly the pad was worn thin and the disc looked like it had been getting hot no bind and brake performance was fine,so I showed the presenter the issue raised and explained even though it has passed the brake needs looking at and he seemed surprised that we can't remove wheel trims or wheels on test,fortunately he let me have a further look after test was competed when pads removed found that the pad lining was splitting away from the backing, :order pads replaced and one happy customer.
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Daveg
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Post by Daveg on Jun 3, 2012 9:18:20 GMT
Did you carryout the roller brake test? From what I can make out the disc is not cracked and would more than likely fail the brake performance test on rate of increase and decrease not about the same, but thats not a guarrantee as I didn't test it . The actual condition as far as can be seen would be a pass and advise. It looks in poor condition on the face but depends on how thick the material remaining is, and whether it was physically OK for a brake test to be performed. Things are never as bad as they seem , you never bin on a big job LOL ;D Dave
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Post by aylesburyjock on Jun 3, 2012 12:32:14 GMT
Have to agree, the disc does look pretty bad, but if it does not adversely affect the results of the roller brake test, then obviously it's not as bad as it looks. any time I advise on brake discs being in poor condition, my boss always has a look afterwards, hoping to convince the customer they need to be changed, which is never easy, 'cos they must be alright guv they just passed the MOT, and I have regular bollockings along the lines of 'Did you not look at those discs? Youre going to kill somebody one of these days.' I must be wierd though because I'm starting to enjoy them ;D
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Daveg
NT & VTS Council member
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Posts: 1,549
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Post by Daveg on Jun 3, 2012 17:08:53 GMT
What can one say to someone who always believes your decisions taken are wrong when they don't agree with you? From an mot testers point of view, its something in the mind of understanding that is better than somebody who might of been in the trade all their lives, but never lifted a spanner and never really understood but thought their opinion was right over yours? Sometimes it can be a tough call Dave
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phaetonott
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Post by phaetonott on Jun 4, 2012 8:29:16 GMT
I've seen discs nearly as bad as that on a Primera. Rear calipers seized in sliders so only one side if disc was seeing any action. Passed RBT without any problems , but I did notice that when the assistant applied pedal pressure the caliper was bending instead of sliding so I failed calipers on restricted free movement and advised the customer that it would be irresponsible to do the calipers without doing pads and discs.
If he had not had the discs changed I couldn't imagine it passing the RBT on judder, but thats very much a "testers opinion" thing.
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nitros44
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esto es un negocio serio
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Post by nitros44 on Jun 4, 2012 18:02:20 GMT
It has been a few years now since the reasons for rejections were changed with regards to discs and from a personal point of view,the change was a good one,from a presenters point of view that is. If anything it prevented,up to a certain degree the incorrect failures of discs that still had plenty of service life remaining in them. Ive seen it in the past when the old reason for rejection was used "excessive pitting" and one early MONDEO springs to mind. A tester i was working with at the time failed the discs on the front of this Mondeo and the job was passed to me to replace them.The faces of the discs had pitted but very slightly and in my opinion there was nothing wrong them, I don't know how many of you guys have come across the situation were the brake disc has seized on the drive flange and you have to use excessive force to remove them,you know when you have to take a large hammer to them and it ends up when after a lot of hammering the disc shatters and still leaves the centre part of the disc seized on the flange,then you get the heat on it. The only thing that was seriously weakened on this occasion was my arms and shoulders lol. It still happens today were discs are failed unnecessarily;take the one in picture for example,from a service point of view its knacked,but from an mot point of view you have to ask is this disc still capable of doing its job. On inspecting this disc, and a few of us may know that these discs;from new are thin anyway and at first may look extremely worn thin,but even then one still has to ask is it seriously weakened for it fail. To me the disc does look bad but in my opinion is not reduced in its strength therefore not seriously weakened so i pass and advise. A rbt is the last part of my routine so at this stage on moving axle 2 into the rollers i would expect to see some judder when applying the service brake. Excessive judder,increase,decrease and 36% imbalance(advised) was the outcome.But the brake disc is still a pass and advised.
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Daveg
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I believe I am perfect, but others may differ in opinion?
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Post by Daveg on Jun 4, 2012 19:06:34 GMT
I would have thought that what you said here was a fail LOL ;D Excessive judder,increase,decrease and 36% imbalance(advised)Now I am sure you have been drinking LOL ;D Excessive must be excessive , and 36% increase and decrease can't be about the same in proportionality can they Dave ;D
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nitros44
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esto es un negocio serio
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Post by nitros44 on Jun 4, 2012 21:43:36 GMT
I would have thought that what you said here was a fail LOL ;D Excessive judder,increase,decrease and 36% imbalance(advised)Now I am sure you have been drinking LOL ;D Excessive must be excessive , and 36% increase and decrease can't be about the same in proportionality can they Dave ;D You thought correctly ;D The above did fail ;put your glasses on and i will put my glass down Come on Dave keep up I will wright slower next time lol.
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Daveg
NT & VTS Council member
I believe I am perfect, but others may differ in opinion?
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Post by Daveg on Jun 4, 2012 22:08:55 GMT
I would have thought that what you said here was a fail LOL ;D Excessive judder,increase,decrease and 36% imbalance(advised)Now I am sure you have been drinking LOL ;D Excessive must be excessive , and 36% increase and decrease can't be about the same in proportionality can they Dave ;D You thought correctly ;D The above did fail ;put your glasses on and i will put my glass down Come on Dave keep up I will wright slower next time lol. I wonder if I can still read at a distance of 20 metres LOL ;D I was sure I read it right LOL ;D Are you sure LOL Dave
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nitros44
Nominated Tester
esto es un negocio serio
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Post by nitros44 on Jun 4, 2012 23:16:08 GMT
Now thats a good one Why 20 meters? and What is a reasonable distance?
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Daveg
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Post by Daveg on Jun 5, 2012 11:08:03 GMT
Now thats a good one Why 20 meters? and What is a reasonable distance? Its getting better ;D 20 meters from you LOL will probably cost a considerable amount of money ;D, I want FLUKE meters LOL ;D 20 metres in distance is a bit different to your meters LOL ;D The highway code and people who have corrected vision must be able to read a car number plate at a distance of 20 metres to be permitted to drive on UK roads. The mot also states that a number plate must be able to be read from a distance of 20 metres. Somebody decided that 20 metres was reasonable, this actually means that an average person should be able to see a number plate and its characters at 20 metres away from the point of where that person is positioned. That is of course providing that the number plate characters are 79mm high, 50mm wide with a stroke width of 14mm, and a space of 33mm, with margins of a minimum 11mm for a normal car number plate ;D What you have to look the data up to confirm it Dave
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