Good morning, everyone. I replaced the brake master cylinder on my 1973 S1 with one from the S3. I have read various posts about it, however I am still left with doubts.
As I’ve decided to get custom brake lines to connect the new brake master cylinder to the lower block, I’d like to make sure I order the correct fitting sizes.

I understand that the S3 master cylinder has the following fittings:
M10x1
M12x1
DIN/ISO bubble flare. That should be certain.

The bottom distribution block fittings, on the other hand, I understand that they are both 3/8.
But are they 3/8x24UNF or 3/8x20BSF?
Also they should be SAE/Double flare.

Thanks to those who help me clarify once and for all, so that I can order the right parts…

 

I just did this on my series 2. All fittings were identical ser2 to ser3, straight bolt in. Nice having the attached reservoir. The fittings on the front circuit are smaller than the rears. But I can't remember what sizes. I'd just put it in as is, but if you do make new lines to the proportioning valve or distribution block, I'd make them go straight down directly to the block instead of the long convoluted route Jaguar chose, (they did this on series 3 anyway). For ser3 they also eliminated the pesky proportioning valve which I think mostly activated a warning lite, all the factory did was use an adapter to connect the rear lines together (instead of making a new full length line) and a new short line from the master to a T block for the fronts. Do watch for collapsed flexible hoses, all three were bad since replacement around 20yrs ago. The rear one is fun to replace, and I have a lift...

 

Thorsen, why not just put on a ser3 master cyl with the reservoir on top. I've bought two or three for really cheap money, then you dont have the rubber hoses (leaks) and obsolete separate reservoir to deal with.

 

Sorry post in error... was supposed to be posted to another thread.