First things first, we refitted the rear wheels. All punctures & leaks had been sorted so they were good to go back on. Although I noted yesterday the rear pads and discs are worn out, they still work, and are going to have to keep on working until mid next week when I can get hold of replacements. New parts are out of the budget range so hopefully the bent 4.0 Sport that donated its front components will also donate its rears. And bumpstops too. Maybe.
Once the rears were refitted we moved onto the front of the Jag and focused out attention back on the brakes to remove the old callipers. I had been down in the workshop earlier in the day so that I could spray even more WD40 on everything which meant that dismantling the old gear was a lot easier. Their flexi's needed to come away and we aimed to cannibalise any good parts from them, like unchewed bleed nipples and rubber covers.
Incidentally, here's a top tip I learned while disconnecting the flexi's - have a set of blank ends you can screw onto any brake pipes you cannot clamp, so that fluid loss is minimised. To make them, simply create one end of a replacement brakepipe as you normally would, but instead of putting a union at the other end, hammer it flat and fold it over. Cheers to Billy for that one! As we didn't have any of those to hand, the new flexi's were temporarily fitted then clamped while we tested the new callipers before they were bolted on.
While one team got on with that, I set about putting new ends on the ABS earth wire for the OSF which had come adrift at the calliper. I had hoped to re-crimp the original ends of the wire however there wasn't enough time, so non-original generic ones were used. The attachment bolt was pretty rounded but I was able to shift it using an Imperial socket ever so slightly smaller than the 8mm Metric socket that should have fitted. To make sure it was securely on I gave it a wee tap with a hammer - which can also serve to 'shock' the threads a bit, releasing the hold any corrosion might have on the part. This is also a good way to free up stubborn brake nipples too. A golden rule there though is simply never force it and don't get angry - that's when you break stuff or inadvertently punch something hard, like a subframe, when the threads finally release. Just soak it in penetrating fluid & try again in a bit.
Moving back to the replacement callipers, they were confirmed as good. We later found out the brake circuit rig was filled with green LHM instead of Dot 4 fluid which would mean a really, REALLY thorough bleeding after fitting the callipers as the LHM is not good for their seals so needed to be flushed out. All the parts went back together, torqued up to the settings from Autodata, then we bled the front brakes, making sure that the fluid coming through was clear and free of bubbles. The brake fluid reservoir was filled up to 'MAX' then it was simply a case of refitting the front roadwheels and torqueing them up too. The Jag came down off the ramps and it was time for a road test.
Now I must admit, 1st impressions were not good. The pedal went almost all the way to the floor and the brakes felt horrible. Before the job I would say they had a typical Ford feeling, in that there was a positive action, a firm pedal, and a 'bite' point probably halfway up. As I backed out of the workshop though they were just 'mushy'. However, as I drove the car the action of the brakes improved. The pedal movement was still odd but the pulsing, juddering, pulling to the left, drone when coming to a halt from high speeds, and the high speed wheel-wobble, had gone. A quick visual check confirmed no brake fluid leaks so there must be some air still in the circuit somewhere. I would like to re-bleed the entire system, rather than just the front callipers, and triple check that all unions and hoses are tight. That's a job for Monday lunchtime at Mulsanne.
So, mission accomplished for the brakes. If the re-bleed doesn't cure the softness I may have to live with it. The brakes do work and the spongy feeling may just be down to the new flexi hoses having a bit more 'give' under pressure than the original (and expensive) Jag bits after all. And anyway, the new brakes still need to 'bed in' a bit.
The next job - before anything else - has to be the upper timing chain tensioner. To do that I will need a few hours to remove the cam cover and replace some of the guides (if accessible) as well as the tensioner itself. I'd rather fit a Type 2 one but in the absence of that a Type 1 will do. The latter are easy to swap out at a later date. This forum post covers the whole procedure and the details exactly the symptoms I've been experiencing. http://www.jaguarforums.com/forum/xj-x300-xjr-26/note-redesigned-upper-tensioner-x300-can-also-fail-61698/
That's for another day though. Tonight I'm celebrating another job done in the restoration of this fantastic car and I'd like to thank, again, everyone who has done anything to help out with the project! :-)
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