I just installed new (not refurb) front calipers and rotors from Moss Motors, that I recieved over 15 months ago. I also ordered new "Speed Bleeders (Russel brand) so I would not have to occupy my partner with all that "Down/Hold/Up pedal action. So I removed the RH hub, rotor and caliper. Looked at the removed caliper and the brake "feed" line attached to the caliper is towards the floor. Grabbed a new caliper off the shelf, offered it up and it fits perfectly, with no "centering" shims needed. The 5" long original steel line connecting the caliper to the bracket mounted flexible feed hose was a bit off center, but hooked up ok. The LH side was no different, but the steel line there was 3/4" out of whack. I adjusted a few bends in the pipe and it all came together perfectly. Or so I thought!

So today I marched into the Garage, hooked up a bleed bottle, cracked the Speed Bleeder and started pumping. I got nothing! pedal goes to floor, no percedable pedal resistance, checked the bleed bottle - Dry as a bone. Tried with engine running - Nothing but a flat pedal.
Switched out the Speed Bleeders for the standard ones - again either side - nothing.
Gave up. Checked Google for "XJ6 new calipers cannot bleed". Number one hits all said to ensure the calipers are on the correct side and thay the bleed nipple is at the top.
I was lucky that I don't immediately clean up after work like this and picked up the removed RH caliper, compared it to the newly installed one and it's nipple is at the top. My new install has the bleed nipple on the bottom!

Bottom line, either the new "LH hand" or new "RH" will fit almost happily (except for the feed lines) on either side. I was not aware that this was even possible, as everything lined up (except for the feed lines).
Swapped them over today so the Bleed nipples are at the top and reinstalled the Speed Bleeders. Re adjusted the pipes so they fit as they should.

I will venture into the garage tomorrow and hopefully will sucessfully bleed the system. Who would have thought one could swap the calipers around? Nothing on any forum or manual I've searched says any warning about this. I will surely advise on the outcome tomorrow, so no one else has to go thru this.
Ian

 

It looks like you came across that old saying "but they're always fitted that way" ! Common in a lot of places but particularly in car matters ! So always take photos before dismantling so you end up with the new looking like the old. When I rebuilt a Mark 2 I was most careful to take photos of the engine compartment and other places with stuff everywhere that had to go back in the right place.

 

off topic but had a similar experience with the front pads on my Audi Q5. All will fit in any position in the carrier, until you reinstall the caliper (which fits over the pads), at which point i found they fouled. So I took a closer look at the pads. 2 matched (turned out to be the inners) but the two outers were slightly different to the inners and to each other. So 3 types of pad made up the 4. All 4 were shrink wrapped together and there was no notes indicating they were handed and nothing on them to indicate position. I'm convinced Audi do this to discourage home mechanics.

 

So, I switched the newly installed calipers. When I removed a caliper and then turn the caliper upside down and take it over to the opposite side and then rotate it 180 degrees, then it again lines up, but the bleed nipple is now on the TOP! As it should be.

I put back in the speedbleeders and bled perfectly! What a ****-off. Hoping this can be avoided for other members. I should take pictures before, but I dont have a cell phone, sorry. Ian

 

I had never heard of speed bleeder before but from what I read they make a tedious job much easier. I have to replace my master cylinder (again). Can you please tell me what size speed bleeders I need? I assume I need four of them? 1979 XJ6 series III. Thanks.

 

I think my 85 XJ6 would have the same calipers as yours so for the front calipers I used these:

and for the rears I used these:

Both from Amazon. Hope this helps. I won't be going back! Ian