It just landed on me that the brake lines from the master cylinder to the PDWA on the LHD SII take a very long scenic route and I wonder why that is.
Anyone knows the rationale?
Or I can safely modify them to shorter more direct ones (I have a reason for considering this, obvious from the photo).
Thank you.
Eric,
we sometimes wonder why the consequences of any design issues seems to have gone unnoticed … this time Jaguar engineers might have had a concern about keeping the brake lines “out of the way” … for whatever reason!
Then again, it might have been just that design started on RHD cars where the brake main cylinder as well as the booster is in in the way of the carbs, the oil filter and the air filter housing - they may also just have translated RHD to LHD and transferred all the well-advised routing of the brake lines from right to left … who knows?
Good luck
Jochen
75 XJ6L 4.2 auto (UK spec9
Odd. Are you sure they are the original lines?
Mine go straight down to the pressure differential switch.
David
PS Pardon my filthy engine bay!
Thanks Dwomby, I don’t know which configuration was original. Looking at the pipes, now that they are clean and zinc plated, there is no sign of them being any different from the rest of the lines. But, thanks to your picture, I am going modify the lines and make them go straight down!
I have a 1985 xj6 and the brake lines run straight down from the M/C just as David’s do. They are original.
Dave
So, the next question of course, with a view to make brake pipes, straight from the MC to the PDWA, is… Single flares, double flares, bubble flares? …
Me think double flare. Right?
A whole new can of worms 
The originals are the bubble flares and the seats in the M/C and PD switch are fixed, I believe.
Dave
Bringing this topic back to life. I am still looking for a definitive answer to the flare question.
It seems established that there are 4 types of flares:
Tribal beliefs seem to go towards: “Jaguar used bubble flares on the XJ”.
Cross referencing this with the elimination of unsuitable options in the list above, the conclusion is that the 1970’s Jaguar XJ is fitted with Bubble (DIN-F/ISO) flares:
Are we good? 
Now I need to find fittings, tool, etc
References:
http://www.fedhillusa.com/webnuts/common%20flares6.pdf
http://www.christian-merten.de/DAF/Bremsleitungen/Artikel1.html
Eric, you will find both bubble flares and double flares on an XJ depending on what is being connected. For example you’ll find a double flare with a female nut where a hard line enters a flexible line to the front caliper.
The modern DIN/ISO bubble flares (with the 90° back side) are interchangeable with the old style bubble flares that are original (with the 45° back side). That early style was eventually superceded with the modern style because the angled back style will flare out the nut if overtightened - which they often were. If you’ve ever tried to remove old-style bubble flared lines from say… a master cylinder and found it hard to get out the nuts even though they were loose, that is the reason.
The common thing you’ll find is that the brake lines are all 3/16" The differences are in the type and size of the nut - metric or SAE - the lines and flares are the same. I’ve found the quality of Fedhill’s copper-nickle lines to be far superior to no-name stuff you’ll find on Amazon. Definitely spend the extra money and get the supplies from them.
I think you mentioned you were working on a PDWA. Not sure which of the two types of flares you’ll need and if the threads are metric or SAE in that device but I’ve found the Eastwood vice mounted tool invaluable for this kind of thing, except it can’t be easily used with lines on the car. Other than that though, one of the best $200 I’ve spent.
Yep,
3/16" Cunifer lines
SAE thread fittings
Bubble flares.
Thanks.
