brake judder air?

John Plum · Post by **John Plum** » 23 Oct 2009, 23:05

@CitroNut

with a clear tube attatched to one of the bleed kniples and the other end in a container, and with the kniple open,engine running, press and hold the brake pedle

Yes I did that; it was a self-bleed valve on the end of the tube though. I ran the engine, let fluid out, then tightened the bleed valve, and moved to the other side. But I only let out about around 100ml of fluid in each maybe.

@MyGlaren: OK yes I was wondering if its best to now.
Should I replace all spheres now then, or just go the accumulator first, then add hydraflush, run it, and then new spheres all round + a LHM change?

John Plum · Post by **John Plum** » 23 Oct 2009, 23:33

@ SL4er

I'm sure I've read on here before that the back brakes take A LOT of bleeding, since the line goes from the wheel to the doseur valve (at the front!) and back again. Was a figure of 1/2 pint mentioned (from memory)? Might be worth bleeding a bit more until the fluid is the same colour as that in the reservoir. And then topping up.

I 'm glad you said that, because I read posts on the doseur valve, flat accumulator and air in fluid here, and that was nagging me. The next stage is the whole system with hydro-flush, accumulator replacement, and proper system-bleed.

Post by **myglaren** » 24 Oct 2009, 09:50

Re: Hydroflush before or after component replacement.

I can see advantages and disadvantages to both approaches. I think that I would be inclined to replace any failing or suspect spheres and other components and drain the system, clean the reservoir and filters, then fill with Hydroflush.

Probably not the perfect solution and I'm sure that others will have their own preferred methods.

John Plum · Post by **John Plum** » 24 Oct 2009, 09:57

Cheers MYGlaren.
Interesting development. I checked more carefully now rocking the n/s wheel, and discovered definite hub bearing play. No other symptoms when driving, other than when pressing the brake pedal.
I'm going to put a new one in, test drive, and then follow with flush and spheres.

citronut · Post by **citronut** » 24 Oct 2009, 10:05

these cars dont offten show hub to bearing play unless someone has not tightend up the hub nut properly,

regards malcolm

John Plum · Post by **John Plum** » 24 Oct 2009, 10:12

Yeah, that's what I recall. The symptom was there at first when got the car earlier this month, and I have re-tightened the driveshaft nut. But I am going to check again with a different torque wrench, and feel again carefully.

citronut · Post by **citronut** » 24 Oct 2009, 10:33

if the car has been used with a loose hub nut it will almost certainly have caused damage to the bearing

regards malcolm

John Plum · Post by **John Plum** » 24 Oct 2009, 12:15

I spoke too soon: sorry. The bearing play is eliminated. (The driveshaft nut was nice and tight when first undone and when I tightened it, and checked). My mistake was to automatically slacken the roadwheel bolts before lifting up and testing!

The lower suspension bushes seem OK, when tested witht he wheel and a lever. Steering rack OK, and all trackrods and lower ball joints.
Off to get the LHM and accumulator plus a few more.

the_weaver · Post by **the_weaver** » 24 Oct 2009, 12:54

John

You mention seeing grease from a split gaiter. Did you fix the gaiter? Which gaiter are you talking about? If it's one of the gaiters on the caliper slides then that can cause them to seize which will produce braking problems. A split driveshaft gaiter will also lead to a lot of noise and vibration once the grease comes out and the water gets in.

Paul

John Plum · Post by **John Plum** » 24 Oct 2009, 18:50

@ The Weaver: It was the driveshaft gaiter, which appeared to have been disturbed on a recent inspection before I bought it. Not so much split, as a cut across the band where the tie goes. I examined it thoroughly for wear and dirt ingress (There was enough grease and it wasn't dirty), and again on reassembly, and am satisfied.
I remembered the handbrake test!

Braking with the handbrake produces no symptoms, which means likely the remaining problem is exclusively down to air/accumulator. I am surprised at the noise though...nothing like I experienced with a BX.

The job's in the middle: no hydroflush until monday. Broke a chain wrench twice. Two rear spheres on.

As an aid, should I snap the accumulator sphere seal with the engine running and pressurised , or depressurised? Unscrew depressurised, I know.

citronut · Post by **citronut** » 24 Oct 2009, 19:02

John wrote
"should I snap the accumulator sphere seal with the engine running"

no need for that on the acumalator as the regulator it is attatched to is boltted firmly onto the gear box (or at least it should be),

just whatch the chain dose not snag up on the triangular ledge in the cornner of the bottom edge of the engine block (lower cornner gear box end),

as im sure this is what people do and think it is the sphere being very tight,

regards malcolm

John Plum · Post by **John Plum** » 24 Oct 2009, 23:05

just whatch the chain dose not snag up on the triangular ledge

Thanks.

John Plum · Post by **John Plum** » 25 Oct 2009, 18:58

I wonder, what are the main likely spheres which, when defective and dumping air into the system, produce these symptoms. The accumulator, and what about others, like the rear central hydractive/anti-sink?

Post by **CitroJim** » 25 Oct 2009, 19:04

Basically any of them John... The anti-sink is often cited as a culprit as it is so often overlooked/ignored as the failure of it does not have a marked effect on much at all. It's also a bit more difficult to replace than any of the others and there;s another reason why it's often passed by.

John Plum · Post by **John Plum** » 25 Oct 2009, 22:05

Ah ha, Jim. That's useful for me to bear in mind.