Brake MOT fail- Why?

rbruce1314 · Unread post by **rbruce1314** » 01 Aug 2005, 20:12

My vehicle has just failed MOT on rear brakes. When pedal is pushed Dials on tester come up immed. on fronts but on rear it takes a full 1/2 sec (nearer 1 sec) before gauge registers. Same for both sides. Nothing done recently (no fluid change etc.) so what is up?

citronut · Unread post by **citronut** » 01 Aug 2005, 20:39

what car is it
regards malcolm

Kowalski · Unread post by **Kowalski** » 01 Aug 2005, 20:46

http://www.andyspares.com/discussionfor ... C_ID=15317
This seems to be the same problem.

Rostami · Unread post by **Rostami** » 01 Aug 2005, 20:49

Which car are you writing about?
If it has drum breaks on rear, then its usually one of the rear "pumps" that is failing. They are quite easy to replace, so it is a simples DIY job.

rbruce1314 · Unread post by **rbruce1314** » 01 Aug 2005, 20:56

Sorry folks- I thought you could all read. Car is as in my signature [:)][:)][:)]
Thanks Kowalski for the link- seems exactly the same problem.

Unread post by **RichardW** » 01 Aug 2005, 21:38

Bleeding the rear brakes should get you a ticket in the short term, but the problem will reappear. The gas is actually nitrogen and not air, and it's coming from a leaking sphere membrane - probably the anti-sink sphere, as this is most closely connected to the brake system. You'll probably need to consider changing some rear spheres sooner rather than later!

rbruce1314 · Unread post by **rbruce1314** » 01 Aug 2005, 23:14

Main spheres changed 3 months ago!

Mandrake · Unread post by **Mandrake** » 02 Aug 2005, 01:32

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by rbruce1314

Main spheres changed 3 months ago!
<hr height="1" noshade id="quote"></blockquote id="quote">
The very act of CHANGING any of the rear spheres will most likely let some air (real air, not nitrogen) into the rear brake lines, as the rear brakes run off the rear suspension.
Most of the trapped air should bubble out through the height corrector back to the tank if you do plenty of Citrobics after changing the spheres, but some may find its way into the brake lines and get trapped there. Because of this its good practice to bleed the rear brakes after changing any of the rear spheres...was this done at the time the spheres were changed ? (I'm betting not)
Regards,
Simon

Mandrake · Unread post by **Mandrake** » 02 Aug 2005, 01:34

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by rbruce1314

Sorry folks- I thought you could all read. Car is as in my signature [:)][:)][:)]
<hr height="1" noshade id="quote"></blockquote id="quote">
Some people, like me, have displaying of signatures turned off on the forum and wouldn't see it.... it wasn't until a few weeks ago that people were refering to pictures of their cars that I couldn't see that I turned it back on and discovered they were in the signatures [:)]
Regards,
Simon

citronut · Unread post by **citronut** » 02 Aug 2005, 03:28

how dose one see ones signiture,i must be dafter than i first thought because i canay see what jaloppy you drive when it has an MOT
regards malcolm

Mandrake · Unread post by **Mandrake** » 02 Aug 2005, 04:11

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by citronut

how dose one see ones signiture,i must be dafter than i first thought because i canay see what jaloppy you drive when it has an MOT
regards malcolm
<hr height="1" noshade id="quote"></blockquote id="quote">
Click on Profile then after logging in set "View Signatures in Posts" to "Yes."
Regards,
Simon

NiSk · Unread post by **NiSk** » 02 Aug 2005, 12:46

The rear suspension units are self-venting, replacing a sphere does not trap any air.
//NiSk

ActivaV6uk · Unread post by **ActivaV6uk** » 02 Aug 2005, 15:28

But the rear breaks are not, the problem is it only takes a very small bit of air in the lines to have an effect, however this could just as easly be furred up calipers.
The trick that myself and my dad do is just to put 2-3 large slabs in the back of the car and this will make the rear breaks work harder (suspension and breaks are lined at the back incase you didnt know), put them in 2 weeks every 6 months and your rear breaks will be fine.
Andy

jeremy · Unread post by **jeremy** » 02 Aug 2005, 15:58

Or keep your tools in it!
Jeremy

Kowalski · Unread post by **Kowalski** » 02 Aug 2005, 16:58

Taking your tools to a garage is asking them to disappear.