XK8 / XKR ( X100 ) 1996 - 2006

R & R Brake Master Cylinder Steps?

 
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Old 05-30-2019, 12:34 PM
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Default R & R Brake Master Cylinder Steps?

Have searched Google and other sources and no step by step or video available I can locate. Looks like the LHD cars should all be similar. (2003 XK8) The 2 mounting bolts appear diagonal rather than horizontal mounted to the booster. Appears one would need to empty & remove the reservoir to determine next step.
I do not have JTIS downloaded. Will someone share a link or links to the procedures to perform this operation. Seems the R&R is difficult due to limited space by the enclosure bulkheads. Appears after the electrical connectors are removed, the brake lines and other attaching fasteners should be accessible. Please share any methods that worked for you?.
 
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Old 05-30-2019, 12:56 PM
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Do you mind sharing the diagnostic that leads you to this R&R? Are there easier steps you could take first? The vacuum line to the throttle body is a known spot for air leaks (weird brass setup) and maybe poor vacuum assist.

From memory replacing the brake switch, you might gather more insight by checking the area behind the pedals.

Best of luck, keep us posted.
 
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Old 05-30-2019, 01:41 PM
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The pedal seems to drop excessively once it is pushed. Generally the pedal is at good height when pressed. Have bled the brakes couple of times with the pedal height becoming normal and solid. Indications point to the Master Cylinder perhaps bypassing. Pumping brakes returns the height to normal, but then it acquires more travel over time. No leaks at Calipers or the M/C does not get low. Classic symptoms for internal bypass I think. It does good, but does not seem quite proper. Fluid (Dot 4) is clear at each bleed port and was flushed thru 1.5 years ago.
Guess us Squirrels are too picky. :-)
 
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Old 06-01-2019, 07:19 AM
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I have the same, tried bleeding a few times, I have braided hoses all round, still pedal sinks down slowly when pressed. Maybe we are bleeding wrong.. or.. maybe the seals in our master cylinder are going.. From what I have seen you cannot repair the master cylinder as there are no kits available, you'd have to replace with another one. Unless of course someone knows the seals we can use? Mines a 1999 xkr
 
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Old 06-01-2019, 09:32 AM
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When replacing a master cylinder, remove the electrical connectors, then the brake lines. Unbolt the master cylinder and remove it from the booster.

The next step is to bench bleed the new master cylinder to get the air out. Installing one and then bleeding will not work if the master cylinder is at any angle at all.

You will need a kit to do this which attaches special nipples into the ports where clear tubing is routed from the nipples into the chambers and held in place. The cylinder is held level in a vise where the chambers are filled with fluid and the piston is slowly cycled with a screwdriver until there are no more bubbles showing in the line. Put the caps on and very carefully reinstall the cylinder, being sure not to tilt it.

The bleed the system your usual way. I suggest pressure bleeding.

If this is not done, it is just about impossible to get a firm pedal.
 
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Old 06-01-2019, 09:41 AM
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As further explanation, the booster drive does not produce full excursion of the master cylinder plunger, making the case for bench bleeding. So don't think you can outsmart this procedure, you must bench bleed the master..
 
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Old 06-02-2019, 07:37 PM
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Originally Posted by oldmots View Post
As further explanation, the booster drive does not produce full excursion of the master cylinder plunger, making the case for bench bleeding. So don't think you can outsmart this procedure, you must bench bleed the master..
Interesting info here... Luckily I never have removed the maser cylinder so not had to go through that procedure..

any tips of maximizing the chances of a good firm pedal from a standard bleed? I have a pressure bleeder. If I remember correctly the pedal has never been good since i had to remove and replace the abs unit due to the normal dry solder joint failure.. The code never came back.. neither did the pedal firmness though
 
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Old 06-06-2019, 04:27 PM
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thanks for replies. One could see a need to remove the electrical connections and the brake lines. My request was for someone to share the Jag Tech instructions for the operation of R & R assembly. After looking at the enclosure, it would seem to be best to remover the reservoir prior to attempting any other removal of attached parts. Guess I will keep searching and perhaps i can locate a confirmation of need to remove the reservoir.
 
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Old 06-08-2019, 06:26 AM
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Anyone have experience with a Motive Pressure Bleeder? They use a pressurized tank and cap adapter to push fluid thru system. Since the M/C rod does not fully depress, there must be air at end of travel. i will try this since the pedal is not as I expect. BTY, anyone with a link to the JTIS section requested regarding this R&R operation, please share.
Ok to Mark as RESOLVED or close. Will proceed in another direction.
 
 
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