Teves ABS - Project Refurb

Keep looking at those diagrams until you understand why there are no rear brakes if the pump isn’t running. Only the front brakes can be “manually” actuated by the master cylinder.

Yes Kirbert, that’s constructive…

I will keep on looking as so far it looks like you will have rear circuit until pressure in accumulator is depleted (isn’t that the reason why it’s there? also know as design safety factor…)

So, if the front brake hose bursts and the brake accumulator assembly doesn’t work (pump isn’t running) - then you have no brakes.
Quite unusual scenario in the brake system which is not totally neglected by pensioner or stereotypes…

Definitely, this device is soo dangerous - it must be removed, once and for all :wink:

If the front brake hose bursts and the brake accumulator is still working fine, you have no brakes. You must have front brakes to have rear brakes.

Kirbert,

You don’t know or trying to patronise?

The movement of booster piston is LIMITED, it won’t drop all the way in.

Now as description goes both circuits are not mixing fluid with each other.



Also, it is funny that brake accumulators are srill being used in critical safety systems, more in aerospace…

Just asking, does the action of a front brake hose bursting deplete the accumulator hence no pressure remaining to drive the rear brakes?

On the drawings and from description - it looks like accumulator pressure is retained in rear circuit only, there are seals between both pistons isolating it from each other.
Booster piston can apply few milimeters of pressure on the back of master piston to support operation of front brakes, it cannot drop any further forward.

So, no - it doesn’t look like burst of front brake hose would drain the accumulator. It would cause loss of pressure in accumulator and would trigger pump operation (pump fed from separate section of the tank)

Now.it is time to wait for Kirbert and his keen eye for details to confirm/deny it :wink:

I am told that the Teves MK 111 unit on an XJ6 is almost identical to that on the XJS and in the case of sticking solenoids (my problem!) you can use the ABS block and replace the cover plate with old one as the plates are a slightly different thickness.

Rich,

The ATE mk3 was used in many cars, including Ferrari and Volvo. The solenoid issue simply requires replacement solenoid. These may be adopted from any model, some of these however - works other way around and will require simple relay to function.
Prior to replacing “sticky” solenoid - make sure it’s actually the issue - never heard about stickness before, issues with accumulator sphere or air in the system may give you “sticky” response I assume…

Hi Janusz - There was no fluid coming out of the one leg of the ABS block and when the solenoids were checked, one of the six simply hummed, others clicked, so seems v likely that the solenoid is stuck - it is not open circuit.

Rich, can you describe how the solenoids were checked???

I checked my solenoids using a 12v probe. Disconnected the solenoid plug and applied the probe to each pin in sequence (I think pin 1 is common and the rest belong to individual solenoid windings. You can hear them click as you apply voltage (or not).

Good morning Janusz, How did this thread end up in your quest for seals etc. I am embarking on an identical quest, in fact I have inadvertantly opened a new thread on the topic. I have read through your thread, and that of Orange Blossom in the other Jaguar Forum, but there hasn’t been a definitive answer to the quest for parts.
I have disassembled my acuator block, and cleaned out the solenoids (full of sludge), but my symptoms (spongy brake pedal) would suggest the master cylinder is leaking. Do you have any details on dissassembly of the master cylinder, or point me to a referemnce document. There certainly isn’t much in the workshop manual. Many thanks, and kind regards, Chris

Chris,
My project is still pending/on ToDo list of things before I’ll reach 30.

Never check solenoids with with 12v. Guessing you know what you’re doing - otherwise you may end up with compound problem…

Spongy Xjs brake pedal in 95% of cases - is caused by air in the system - taken for failing master cylinder. Maybe 98%…
Out of curiosity - how did ypu managed to strip down solenoids / any specific gaskets required on assembly? I am expecting master cylinder’s piston to have some seals available - dedicated kit may be rare and expensive, after stripping down you need to measure it. The greatest risk is the wear of cylinder walls causing a step that may mess up your new seals. There are companies remanufacturing / honing these. Returning to strip down, I would expect same disassembly as typical master cylinder (probably locking ring of some sort, after removal you can release the pre-tension and pull out the internals)