MOT and brake force

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c.morewood
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MOT and brake force

Post by c.morewood »

Just had my MOT at a new garage with the all singing new fangled vibrating test bed.
It failed on rear brake imbalance and not enough reserve movement in the brake pedal.
The rear brake imbalance as caused by me not nipping up one of the nipples when I replaced the rear brake pipes a couple of months ago.. fairly easily fixed.. but the not enough reserve movement..I've had the mod on my Xantia for about12 years, because I nearly ran in to the back of another car with the old system. She's never failed on that before..I've always warned testers about the brakes .. but never a failure. How do I get past that one? Take a couple of washers out?
The test sheet also included a braking efficiency and force results sheet.
What should the braking efficiency be?
What sort of force are they expecting to find when applying the brakes?

As usual just a couple of questions that someone might know the answer to and a lot of us will be grateful for.
Thanks
Chris
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Re: MOT and brake force

Post by superloopy »

I'd not be too quick to think you've fixed the 'rear brake imbalance' failure until she's had her retest.

The new requirements whereby they are now testing for imbalance across ALL axles (hence the rear now) and not just 'sterred' axles (front) as previously caused me a lot of grief recently.

I read that some cars are going in and failing only to be failed by an even greater 'imbalance' on retest following a cleanup.

I was advised (citronut) to ensure that on retest they test that all is well with the brakes BEFORE logging the retest on VOSA otherwise you'll be hit for another test-fee when it fails a second time.

Makings of a quick buck for the government eh at the little man's expense methinks.
Last edited by superloopy on 17 May 2015, 16:56, edited 1 time in total.
Mike

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c.morewood
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Re: MOT and brake force

Post by c.morewood »

I've only cleaned up the messy side Mike.. but there's no way of knowing, is there?
Chris
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Re: MOT and brake force

Post by superloopy »

c.morewood wrote:I've only cleaned up the messy side Mike.. but there's no way of knowing, is there?
That's the problem.

You should have the figures from the test and be able to identify which wheels are giving the imbalance?

If, as you say, you had a leaking bleed nipple then maybe you'll get by on a retest, all i'm saying is dont bank on it.

My garage had to cleanup the rear brakes and present TWICE before the machine gave an acceptable reading of less than 30% imbalnace between wheels.

Now .... was that down to them not doing their job first time around (they say not, they would wouldn't they) or, as is being mentioned, the quirks of the testing environment.

I'm no MOT man but even the testers on a forum, (can't remember which now, i checked around for 'rear imbalance' across a good few sites) were having doubts about the procedures being used at one point, not good.

Best of luck.
Mike

Xantia Activa Dante Red MK1 (96) 121k - SORN, to be broken
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Re: MOT and brake force

Post by MikeT »

What is this "reserve travel" business? The pug 106 we worked on got that listed as a failure - never heard of it before. And although I'm not qualified, imho, the brakes were close to perfect when presented. After the garage "fixed" the handbrake failure, (nothing was charged for fixing the reserve travel) the brake pedal is scarily spongey I kid you not, when I moved the car 10yds from one parking bay to another I nearly went through a hedge due to how much brake travel there is before friction occurs (and bear in mind, I'm used to such brake surprises with Xantia's that are driven before the hydraulics are up to pressure). How can this be?
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Re: MOT and brake force

Post by citronut »

go to a garage that is well versed in hydraulic citroens, as there are quite a few garages out there that aint got a clue when it comes to proper brakes
( hydraulic powered ), and not just the brakes either,

Mike do you have a ministry test staion local to you, if so pop by and ask them what they think on you brake pedal travel, obviously pointing out to them as it is a hydraulic citroen and all that
Regards, malcolm.

current ride a BX 1.7 TZD estate
1986 MK1 BX 1.9na D Auto(in Mothman Andy's stable )
layed up roppy 1.9TD XANT estate, now gone to meet her maker
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Re: MOT and brake force

Post by chinkostu »

MikeT wrote:What is this "reserve travel" business? The pug 106 we worked on got that listed as a failure - never heard of it before. And although I'm not qualified, imho, the brakes were close to perfect when presented. After the garage "fixed" the handbrake failure, (nothing was charged for fixing the reserve travel) the brake pedal is scarily spongey I kid you not, when I moved the car 10yds from one parking bay to another I nearly went through a hedge due to how much brake travel there is before friction occurs (and bear in mind, I'm used to such brake surprises with Xantia's that are driven before the hydraulics are up to pressure). How can this be?
if you ever need to work on that car again, take a look at the bar that runs from the back of the booster to the pedal (across the top of the bulkhead)

theres a 13mm locknut that you can use to adjust the pedal travel. chances are they've nipped it out so theres a bit of free play in the brakes. Both my Saxo's had iffy feeling brakes until I adjusted them.

word of warning: leave the cover off and adjust them in a carpark or a wide open area incase you adjust it the wrong way like i did once :shock:
Stu

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Re: MOT and brake force

Post by RichardW »

Check:

Depress the pedal fully and check the position of the pad relative to the floor.

RforR:

When the pedal is fully depressed, there is not enough reserve pedal movement. Note: This does not apply to power operated braking systems, providing the foot valve is fully open before the pedal is fully depressed.

This should make a modified Xantia less likely to fail as there will be less pedal travel - unless they do it with engine off :-D Arguably doesn't apply to Xantias anyway given the note in the RfroR.
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Re: MOT and brake force

Post by citronut »

chinkostu wrote:
if you ever need to work on that car again, take a look at the bar that runs from the back of the booster to the pedal (across the top of the bulkhead)

theres a 13mm locknut that you can use to adjust the pedal travel. chances are they've nipped it out so theres a bit of free play in the brakes. Both my Saxo's had iffy feeling brakes until I adjusted them.

this is a Xantia we are talking her Mr chinkostu,
they do not have servo assisted brakes like the Saxo does, and the usual fault on the Saxo is the linkage at the bulkhead seizes up
Regards, malcolm.

current ride a BX 1.7 TZD estate
1986 MK1 BX 1.9na D Auto(in Mothman Andy's stable )
layed up roppy 1.9TD XANT estate, now gone to meet her maker
purple and lilac metalic 2CV(VIOLET)registered to her in doors
1972 DS special been layed up aprox 31 years
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Re: MOT and brake force

Post by Gibbo2286 »

What they're talking about is simply the brake pedal goes too low, in the case of the leaky bleed nipple possibly just air in the system and needs bleeding.
Man is, by nature, a lazy beast, he does not need twice encouraging to do nothing.
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Re: MOT and brake force

Post by Stickyfinger »

mine does not go to low....tester happy the other day.....why is this a problem and what causes it ??
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Re: MOT and brake force

Post by Gibbo2286 »

Stickyfinger wrote:mine does not go to low....tester happy the other day.....why is this a problem and what causes it ??

It's a problem because it indicates that there is a fault in the system, maybe maladjusted, worn parts, air in the fluid lines, etc.

Ever driven a BX or Xantia then another make with conventional brakes and a low brake pedal, quite a shock when you first have to stop
Man is, by nature, a lazy beast, he does not need twice encouraging to do nothing.
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Re: MOT and brake force

Post by citronut »

Gibbo2286 wrote:What they're talking about is simply the brake pedal goes too low, in the case of the leaky bleed nipple possibly just air in the system and needs bleeding.
Mr Gibbo
i think its quite the opposite in no/not much travel,
it sounds to me the tester is not familiar with hydraulic citroen brakes, or there is air in the system so the first pedal pressure is not doing anything, so it nout or full on brakes
Regards, malcolm.

current ride a BX 1.7 TZD estate
1986 MK1 BX 1.9na D Auto(in Mothman Andy's stable )
layed up roppy 1.9TD XANT estate, now gone to meet her maker
purple and lilac metalic 2CV(VIOLET)registered to her in doors
1972 DS special been layed up aprox 31 years
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Re: MOT and brake force

Post by citronut »

Stickyfinger wrote: and what causes it ??
maybe an uninitiated MOT
Regards, malcolm.

current ride a BX 1.7 TZD estate
1986 MK1 BX 1.9na D Auto(in Mothman Andy's stable )
layed up roppy 1.9TD XANT estate, now gone to meet her maker
purple and lilac metalic 2CV(VIOLET)registered to her in doors
1972 DS special been layed up aprox 31 years
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Re: MOT and brake force

Post by Stickyfinger »

citronut wrote:
Stickyfinger wrote: and what causes it ??
maybe an uninitiated MOT
LOL...I LOVE my tester :)
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