test xantia rear brakes

toofargone · Post by **toofargone** » 15 Jul 2010, 16:43

Hello

Rear brakes on 1997 Xantia 1.9td do not seem to be working. (The car has covered 220,000 miles).The discs are rusty. How do I test if they are working or not?--as it seems, from elsewhere on the forum that the suspension has to be under load.

Should a jack under one of the suspension arms be sufficient?

Is it more likely that the calipers are seized? (Though as far I can see the discs are rusty on both sides.

Post by **myglaren** » 15 Jul 2010, 17:58

I found it handy to pile a load of weight in the boot and drive around for a while to keep that back brakes working properly.

Old-Guy · Post by **Old-Guy** » 15 Jul 2010, 18:43

A Xantia's rear brake calipers are powered from the rear suspension hydraulic circuit (which automatically makes them load sensitive. For many owners, the problem is that even estates do most of their miles with the tank less than half full and no load or passengers in the rear. When you brake, even quite hard, under these conditions, weight transfer unloads the rear suspension sufficiently that the front brakes do all the work.

You can put a jack under the rear suspension and to see if the calipers bite when you press the pedal - it's best to put the suspension on HIGH so that the suspension is locked up against the rebound stops and with some weight in the back. SUPPORT THE CAR SECURELY ON THE JACKING POINT

If the calipers seem to be working, put a couple of hundred kilos of weight in the back, find an empty stretch of road and do a series of emergency stops from a low enough speed that you won't have a big moment if the rear brakes misbehave.

Let us know how you get on.

Post by **RichardW** » 15 Jul 2010, 20:38

With the suspension on high you will get full rear brake pressure. Just put it on high, jack one side up, spin the wheel up, run round quick and stamp on the pedal which should bring the wheel to a sudden stop. Chances are though that if the discs are rusty the pads are seized up. A good strip, clean and copperslip should see it right again. Of course, the calipers are probably rusting off the arm, and will need to be removed and cleaned up. Which will probably break the bolts...

toofargone · Post by **toofargone** » 16 Jul 2010, 08:59

Thanks for replies

I tested with a jack under the suspension arm on full height and there is no brake. I think the calipers are seized.

Any tips on getting the calipers sorted?

Thanks again

Homer · Post by **Homer** » 16 Jul 2010, 15:33

Just take the pads out and push the pistons back.

If you are lucky that will free it up.

If you are unlucky it will ruin the seals and you'll have to strip them down.

The moral of the story is to periodically remove the pads and push the pistons back to keep them freed.

At the very least, every week or so put the car on high suspension and press the brake pedal hard to exercise them.

citronut · Post by **citronut** » 16 Jul 2010, 20:40

old guy wrote
"A Xantia's rear brake calipers are powered from the rear suspension hydraulic circuit"

i have always understood the rear suspension just returns throught the brake dosour valve,

regards malcolm

Post by **CitroJim** » 17 Jul 2010, 06:29

Have you tried bleeding them?

The rears seem to get full of air at the drop of a hat. Bleeding will also show if fluid is getting to them.

Do it on high with one wheel off and supported on a jack as already discussed so there is some load on the suspension.

A completely blown anti sink sphere, especially it if has released all its nitrogen into the system, can cause this problem.

It is unusual for the caliper pistons to seize.

toofargone · Post by **toofargone** » 17 Jul 2010, 16:21

Thanks again for replies.
I will not be able to try it until Monday but will try the various things mentioned.

Post by **RichardW** » 17 Jul 2010, 22:09

citronut wrote:old guy wrote
"A Xantia's rear brake calipers are powered from the rear suspension hydraulic circuit"

i have always understood the rear suspension just returns throught the brake dosour valve,

regards malcolm

Old Guy is right, Malcolm, the feed for the rear brakes comes off the rear suspension between he height correctors and the spheres. It's why there are 4 pipes front to rear - Pressure feed o rear; brake feed to doseur; brake feed from doseur to rear brakes; low pressure return. So oil for the brakes goes front, rear, front, rear - no wonder it takes a long time to bleed the rear brakes! At least this way the rear brakes are load compensated without the need for a brake load compensation valve which is prone to seize up (mind you, the height corrector's not exactly immune from this

)