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Post by CelicaST182 on Nov 23, 2010 4:28:14 GMT
Brake Pipes Excessively Corroded - [3.6.B.2c]
My Celica failed it's test on one item only (see above), had no hydraulic fluid leaks and no problems with the efficiency test.
Is it acceptable to remove the flakey rust, treat with rust inhibitor and apply a topcoat of suitable paint (Hammerite) to stop further rusting, or do i have to replace with new parts ?
The pipes are the main rigid ones and not the flexible ones and the rust is present on only a few inches of pipe where it connects to the 'brake compensator valve' at the rear of the vehicle.
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hayden
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Post by hayden on Nov 23, 2010 8:37:08 GMT
hi, the tester has failed the pipes so they need replacing, if they were a pass and advise then what you suggest would be ok. if you just did a clean up job chances are the tester would fail them again. think "safety" lives could depend on it.
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Daveg
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Post by Daveg on Nov 23, 2010 19:25:30 GMT
Could you post us a picture please Thanks Dave
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Post by CelicaST182 on Nov 24, 2010 2:23:47 GMT
So it's bad news as far as i'm concerned The annoying thing about it all is if i had cleaned/painted the pipes up before the MoT it may well have passed. I also expect that it would be pointless cleaning, painting and taking it to another testing station since the failure is now logged on the computerised system. I can't understand why Toyota didn't cover the entire length of the pipes in plastic instead of stopping a few inches from the end. Thanks for your replies.
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hayden
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Post by hayden on Nov 24, 2010 8:12:55 GMT
hi, the reason pipes are failed if heavily corroded is the wall thickness of the pipe is reduced so could burst under braking, so even if you had cleaned them up before MOT and they passed they would still be potentially dangerous. nice pictures and i would have failed them as well. it is always better to present your vehicle in it's original condition so the tester can give you a better idea of it's road worthiness.
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jimmy
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Post by jimmy on Nov 24, 2010 8:17:55 GMT
Looking at those pipes you should feel lucky he did fail them.
No doubt the next kid who runs out in front of you will also be lucky you were able to stop. Those pipes could have burst under emergency stopping pressure.
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wally
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Post by wally on Nov 24, 2010 15:38:53 GMT
The annoying thing about it all is if i had cleaned/painted the pipes up before the MoT it may well have passed. It may well have passed but - be honest - it would not have made them any safer would it. Wally
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Post by shpauly on Nov 24, 2010 22:26:16 GMT
So it's bad news as far as i'm concerned The annoying thing about it all is if i had cleaned/painted the pipes up before the MoT it may well have passed. I also expect that it would be pointless cleaning, painting and taking it to another testing station since the failure is now logged on the computerised system. I can't understand why Toyota didn't cover the entire length of the pipes in plastic instead of stopping a few inches from the end. Thanks for your replies. FFS
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Daveg
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Post by Daveg on Nov 24, 2010 23:40:08 GMT
So it's bad news as far as i'm concerned The annoying thing about it all is if i had cleaned/painted the pipes up before the MoT it may well have passed. I also expect that it would be pointless cleaning, painting and taking it to another testing station since the failure is now logged on the computerised system. I can't understand why Toyota didn't cover the entire length of the pipes in plastic instead of stopping a few inches from the end. Thanks for your replies. FFS FFS anyone? I assume it's something that shouldn't be said? Reading through the threads I see everyone has judged the pipes as a fail based on the pictures, however for me I would of liked to see the pipes without all the chalk over them, and may be the surface corrosion removed before I made a decision. From what I can see so far the pipes diameter along their lengths don't look as though they have "Thinned" out anywhere, although there is agreed a level of surface corrosion present. While I agree that the brake pipe wall might not be considered too think, and there being surface corrosion present, that part is a visual inspection open to personal opinion, but the roller brake tester used correctly is not a personal decision, and the hydraulic pressures generated are considerably more than probably most people could imagine, and they have not leaked or bursted during their application, which again is considerably more than normally used on the road unless panic braking, are you all sure you made the right decision Dave
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hayden
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Post by hayden on Nov 25, 2010 6:18:22 GMT
i think the jury have already come back with their decision on this one. ;D as for FFS you will find it here dave, do try and keep up now LOL. TTFN ;D www.internetslang.com/default.asp?i=F
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Daveg
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Post by Daveg on Nov 25, 2010 22:18:33 GMT
i think the jury have already come back with their decision on this one. ;D as for FFS you will find it here dave, do try and keep up now LOL. TTFN ;D www.internetslang.com/default.asp?i=FI must of missed that part trying to keep up lol at 06;18am ;D Dave
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Daveg
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Post by Daveg on Nov 26, 2010 22:32:41 GMT
Can I appeal against the juries decision ;D, I heard a rumour that they had all been paid off to say guilty LOL ;D Dave
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hayden
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Post by hayden on Nov 27, 2010 0:39:15 GMT
NO, 10 years hard labour on bread and water, and the only luxury, a copy of the TESTERS MANUAL. LOL ;D ;D
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Daveg
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Post by Daveg on Nov 27, 2010 15:39:44 GMT
NO, 10 years hard labour on bread and water, and the only luxury, a copy of the TESTERS MANUAL. LOL ;D ;D 10 years LOL, that's not so long it's took VOSA since 1960 to produce the right standards, and where brake pipes assessment is concerned, some may agree that they are still not right ;D Dave
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prb5244
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Post by prb5244 on Nov 27, 2010 19:08:38 GMT
i agree they have corrosion but are allowed to remove to inspect with say corrosion tool and they have thinned more than a 1/3 or 1/4 mill in most times with that level of corrosion a pass and advise would be the case i use one of the brake pie tolls it raps round pies more easily to excess how much pipe has thinned proberly the most difficult to judge
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Daveg
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Post by Daveg on Dec 15, 2010 20:06:06 GMT
Interesting how the TM is worded with regards brake pipe assessment advising of 0.25mm, does anyone know how to correctly assess that amount of loss from a brake pipe ;D Surprising the amount of deterioration there to occur for a failure criteria may not look very much, but it is a lot when worked out Dave
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hayden
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Post by hayden on Dec 15, 2010 22:07:31 GMT
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Daveg
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Post by Daveg on Dec 22, 2010 21:45:51 GMT
looks like you are getting quite good at surfing the net and relying on "others" information to guide you lol ;D I have been taking another look at the TM section 3.6 with regards VOSA's rfr on brake pipes. Looking at the manufacturing of brake pipes for "automotive" use I have found five manufacturers who specialise in autmotive manufacturing of brake pipes. First let's look at VOSA's failure criteria for a brake pipe, which reads; Excessively chafed, corroded or damaged. Note; Chafing, corrosion of, or damage to, a rigid brake pipe so that it's wall thickness is reduced by 1/3 (e.g. approximately 0.25mm for a typical hydraulic brake pipe) is a reason for rejection. The first point I would like to make is that (1/3) is not the same as 0.25mm, i.e. (1/3) = 33% and 0.25 = 1/4 (25%) Looking at typical brake pipes; 3/16 = (0.20mm) 1/4 = (0.25mm) 5/16 = (0.31mm) With regards the above I am understanding that VOSA are using these types of figure as a general guide for failure criteria, where these standards do not originate from VOSA but the manufacturer of the brake pipes. So if using the rule of (1/3) to assess brake pipe corrosion then this rule would probably be used with a (5/16) pipe diameter, and the others as above being the 0.25mm limit. When assessing brake pipe corrosion and the limit of VOSA with regards above are looking at failing a pipe when the corrosion has deteriorated the pipe by as much as 25% of it's external diameter, i.e. (1/4) 0.25mm. So how does one know when this limit has been reached, and is the brake pipe in a dangerous condition? ? If we take a brake pipe from above, say (3/16) - 4.75mm OD, then we can calculate both the internal diameter and the wall thickness of the pipe. d^2 = 4.75^2 - ( 22.56 x 4 ) 28.73 3.141 d = sqrt 6.17 d = 2.50mm (This is the internal diameter and not the wall thickness) Wall thickness of the brake pipe is found from; (OD - id) = 4.75 - 2.50 = 2.25 The wall thickness is 2.25mm If one now subtracts VOSA's limit from this figure we get; 2.25 - 0.25 = 2.0mm Is the brake pipe in a safe condition to still be used on the road? Dave
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wally
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Post by wally on Dec 23, 2010 0:36:50 GMT
1) The first point I would like to make is that (1/3) is not the same as 0.25mm, i.e. (1/3) = 33% and 0.25 = 1/4 (25%) 2) Wall thickness of the brake pipe is found from; (OD - id) = 4.75 - 2.50 = 2.25 The wall thickness is 2.25mm Dave I know it's late and I might not be thinking straight as I have had a few but 1) Depends if you are adding or taking away eg, 9 plus a third is 12 but 12 less a quarter is 9. So you add a third to get a quarter!!! 2) Wall thickness of the brake pipe is found from; (OD - id) = 4.75 - 2.50 = 2.25 = Correct BUT, The 2.25mm is for both sides of the pipe, so the pipe wall thickness is actually 2.25/2 = 1.125 Wally
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Daveg
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Post by Daveg on Dec 23, 2010 0:44:01 GMT
1) The first point I would like to make is that (1/3) is not the same as 0.25mm, i.e. (1/3) = 33% and 0.25 = 1/4 (25%) 2) Wall thickness of the brake pipe is found from; (OD - id) = 4.75 - 2.50 = 2.25 The wall thickness is 2.25mm Dave I know it's late and I might not be thinking straight as I have had a few but 1) Depends if you are adding or taking away eg, 9 plus a third is 12 but 12 less a quarter is 9. So you add a third to get a quarter!!! 2) Wall thickness of the brake pipe is found from; (OD - id) = 4.75 - 2.50 = 2.25 = Correct BUT, The 2.25mm is for both sides of the pipe, so the pipe wall thickness is actually 2.25/2 = 1.125 Wally Hi Wally, It's not normal practice is engineering science to mix up diameters of circle geometry with areas of cuboids, with this in mind you can't divide by 2. Dave
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