Jaguar S-TYPE Brakes Bleed

Posted by XJK Ltd on 04/07/2016 14:48


Morning gents, I have a few classic jags of which I am usually able to maintain and repair myself, however the wife and I have an S type each, and I have a problem with mine that just baffles me, it had the usual servo leak, I did buy a new from jaguar with identical part number etc, I was able to fit it without disturbing thaw master cylinder, brakes were spot on, however I then discovered corrosion on the near side front brake pipe, so changed it with a genuine jaguar pipe, Now the pedal is perfect until the car is started, it then travels 2/3 rds of the way down before the brakes work, I have bleed them a number of times and all air has been removed, I have taken it to a friends MOT station he has also bleed the car and it is still the same, however on the stations brake tester the breaks are perfect it's just the pedal travel that seems to be the problem, I have tried to read up on it but the internet seems to have lots of theorists and not experts, would really appreciate any advice, no doubt you will have come across this before, Kind regards

Answer ;

; Hi Mike, The first thing I would ask you to do is to check the pedal feel without the engine running, pump the pedal until the vacuum is lost from the brake booster and reassess the feel of the pedal. If the pedal still has a lot of travel then there is and issue with ether air in the system or possible master cylinder seal fault. In the workshop we can run the ABS modulator to move any air which could be trapped in the modulator/valve body. You can do this on the road by getting the ABS active by locking a wheel. If the pedal goes hard when the engine is not running and no vacuum in the booster I would have to say the system is bleed correctly. The booster on these cars is very powerful and if the brake pedal is pressed with the engine running but standing still you can push the pedal down a long way which is just increasing the pressure on the pads to a level which exceeds the amount need to stop the car. You can also run the same tests on your other car as a cross reference. Regards Ian Kelsall Technical Adviser


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