The bleeding instruction is found on page L10 of the manual for anyone else looking it up.
Guessing here, and bearing in mind that hydraulic brakes were a new thing for Jaguar mechanics, and manual writers as well. The paragraph is about what happens if you get air in the system, so the writer may have been concerned that the mechanic would either start bleeding before checking the level and allow more air to get in, or fill the system and bleed it when the shoes were mostly worn down, and then later when they were changed to new and the wheel cylinders pushed back in, there would be too much fluid in the reservoir and you might get it overflowing.
Backing off the shoe adjusters before you start bleeding would ensure that you have the correct amount of fluid in the system, after which you can add more.
Either that or the sentence is in reference to the next sentence about filling the reservoir before you start bleeding.
Interesting that yours was built at nearly the tail end of the production run, yet has fixed pivots on the rear. Chassis numbers for DHC brakes are not given in the SPC, but for saloons the fixed pivot type ended in early 1950, before my April '50 car. Makes you wonder what happened there; either your rear axle was changed for an early one at some point, or the factory boys found a leftover axle already set up with fixed and installed it.
Hi Rob
Thank you.
Explanation makes sense.
The question arose when bleeding the system the instruction was followed to the letter, air removed then brake shoes adjusted with good pedal feel, about 2 to 2.5 inch pedal travel.
Just to make sure all air out, then bled the system again with the shoes adjusted up, all pedal feel disappeared and full pedal travel occurred.
Back to the drawing board and back to the WS Manual instruction, result pedal feel and pedal travel back.
Can only guess I allowed some air back in the system somewhere.
Strange!
Regards
David
Just an interesting aside. I had an occasion to assist a colleague with returning a long-time stored near-concour condition Mk V to the road. The brakes pulled to the left severely. Upon removal of the drums we noticed that the linings were fairly worn but still adequate. Looking closer revealed that the linings were de-bonding and it was possible to ease a screwdriver under some of the edges.
This was not the cause of the imbalance of course, but when the new linings were fitted, the drum on the left side could not be fitted. The problem was that one piston was slightly different from the other. It was identical in all aspects except for being a few millimetres longer.
I have no idea if the rogue piston was relevant to any version of Mk V brakes, or even any Jaguar.
Sounds like a mismatch of parts.
There were two types of wheel cylinders in front and two types in the rear, i.e. early fixed pivot and later sliding pivot with steel “boots” on the pistons to keep out dust, and there was even a later variation on the sliding pivot which had rubber boots and different pistons altogether.
With pictures we could help figure it out.
I agree, and someone must have been careless when doing maintenance. The mystery was why this was just one out of the set. They were the steel capped type. I didn’t think to take photos at the time and the car has long gone to a new owner.
Rob and Peter.
A couple of photos here, front left on disassembly, note no steel covers fitted to this set, other side had steel covers fitted, new covers were made to fit this side on re-assembly.
Rear all complete.
Regards
David
I made stainless steel pistons with stainless steel caps.
Front
Rear
Here is one of my rears as originally made with plain steel caps.
Here is a later version rear with rubber caps. You can see the piston is different, probably a bit taller, so would account for Peter’s observation of the shoe not fitting right.
