Brakes need work, dealership tells
me a piston on the L/F caliper is sticking. Also, sometimes the brakes go from feeling just fine to sinking almost to the floor before I get a little stopping action.
I am going to rebuild both front calipers, remove all
fluid from the reservoir and flush using the motive power brake bleeder system. I have the 99-03 service manual from this site (thanks!)
I would also like to rebuild the master cylinder (as this seems to be a more likely culprit) but I can’t seem
to find a rebuild kit for this part.

I looked through the stickies, and found a couple possible junkyard part options. But I really only need the rubber. Any ideas?

 

It would help if you include your cars details in your forum signature so we all know what year/model etc. your car is. (See my signature below for an example)
From your post I would guess your car dates from sometime between 99 and 03.

Your car's model year is the 10th digit in the VIN number:
X 1999
Y 2000
1 2001
2 2002
3 2003 (2002.5)

The 11th digit is the model:
J 2.5
F 3.0
G 4.0
H 4.2
1 4.2 S/C
7 2.7 D

2003 Model Year cars finished at VIN M94764.
The master cylinder changed part number at: VIN M45254 This is the start of the 2003 (2002.5) Model Year cars.
It is also a diferent part number if you have DSC or no DSC.

If it is any help here is a link to the official Jaguar on-line parts catalogue:

https://www.jaguarclassicparts.com/uk/s-type-parts

However Jaguar did not produce a rubber kit for the master cylinder and changing the rubbers was not a recomended repair procedure.
You may be better finding a second hand master cylinder that is know to be good and fitting that, as although they are still available new from Jaguar the price is prohibitive on an older car.

Mellow

 

Hi Mellow,
Yes, my vehicle is a ‘03 STR. I have found some available master cylinders from junkyards using info found in the stickies, and $100 for a used master cylinder is better than $650 for a new one from the dealership. So I suppose I will look in that direction.

Regarding the signature, thanks for the vin info. I am not sure why it isn’t displaying.
Here is a screen shot on my profile info:

As you can see, I have a signature with my car info. I realize how helpful
that can be.

I should also note that Your posts do not seem to show a signature with your car info:


Mobile page

After requesting desktop

Perhaps there is a setting somewhere, I’m not sure.

But thank you again for the info

 

OH! And using the link You provided I see the MC costs $280 dollars. Dealership quoted me over $650 for this part! In previous dealership visits that quoted me over $700 for the parking brake motor. I spent 30min online and found three sources for new OEM parts for half that. I called them and told them, saying if they couldn’t come down on the price for the part they could not do the work. They came down $200 immediately, so the parking brake motor was replaced
Note to self: Dealers mark up is insane!

 

Both my 1998 XJR and my 1999 XKR convertible both have German ATE master cylinders as have most Mercedes Benz cars. The XJR m/cylinder JLM20266 is one inch bore and I plan to rebuild it with Frenkit " part number 125077 ( D1848 125077 ) which is also from a 1999 M/Benz . The trick is in removing the hardened steel cross pin that passes through the front piston. The blind circlip can be cut out as the replacement in this kit is a normal type.
The pin is 5/32 in dia and 40mm long . Have yet to dismantle the XKR m/cyl JLM21164 . " An update ; After considerable research it appears that ATE only ever manufactured one Tandem master cylinder between the years 1996 through to 2006 and that the bore size was one inch . What this means is that all the internal seals etc are the same but different outer body styles ( Castings ) were manufactured. If you look at the Jaguar master cylinder bodies you will see they all have ATE cast into them. Unlike Mercedes Benz that made their version serviceable , Jaguar have made it almost impossible for the average person to dismantle their versions. BUT where there is a will there are relations.

Cheers John