Amazon: 1966 Girling Front Rotors

[Splinelube]

Hello,
Can I assume that my 1966 122S has the three pot "piston" Girling brake rotors and single brake fluid lines?
Am having a devil of a time finding a rebuild shop stateside and the new ones ordered were machined poorly and could not be installed.
This is a real pain in the neck as a few years past this was never an issue. The rotors were purchased from a well known international source and apparently not an unusual/unheard of problem.
FINALLY: if one rotors is bad is it really necessary to replace both as I have been informed more than once. Appreciate your help.

[Volvo_133]

I had a 66 122S and can confirm it had single circuit, 3 piston calipers.
Changing 1 disc/rotor only, may cause the car to pull to 1 side when braking. This is the reasoning behind replacing them in pairs. Also fit new pads.
If you replace 1 only, Be aware the pads will not be "bedded in".

[Ron Kwas]

SL;

I agree if nothing has been been changed, a '66 122 likely has 3 Piston Girling Calipers, but assuming is never a good way to proceed, especially on a half century old car where one is not certain about previous work, and when verifying what you have is as simple as a glance under the hood (to see and check that you still have the oe single braking sys and that it hasn't been changed), then by also having a glance under the front wheels (or even simply through the holes in the wheels) to see the Calipers...OK...I can identify them with a quick glance, where others may not be able to, but have a look at them pictured at link below, and you will be able too also...there they are shown dirty, and clean...take your pick...!

If quality rebuilt Girling Calipers are no longer available (and I recommend staying away from the chinas**t nonames, see link!), and you were a capable mechanic, you could rebuild them yourself, prerequisite being the Pistons are free to move (and therefore able to be removed to allow the process!)...

Tip: Do not remove Calipers from the car thinking that you will apply the common tip of "using shop-air will push pistons out"...if pistons are at all sluggish or worse, the measly ~100PSI of shop air will likely be insufficient to move them! Instead, use the significantly higher and almost irresistible force of the car's hydraulic braking system to get them moving in preparation for rebuilding...remove Pads and substitute strategic sized wooden blocks to allow this...and remember, the first piston to fully come out, and this process is DONE, as you will no longer be able to make pressure in the system to move the others, which are even more difficult to move...BEWARE!

I have recently added a detailed documentation of such a process (the reassembly is not yet added) but I suggest you have a look...I will be using 316SS 54 and 38mm pistons at time of reassembly, and I feel pretty good about it...! The system will subsequently be filled and operated with DOT5 fluid.

See: http://www.sw-em.com/Girling%203%20P...%20Rebuild.htm

Cheers

[Splinelube]

Thanks Volvo 123 And Ron for the fast response. Your comments echo what I have been told as "replace one or both". Trying to save a buck. Ron I would never attempt to do a rebuild but will check your site, you do not say what the difference between a one line and dual line brake system looks like or what to look for but my masrer cylinder looks to be pretty simple so assume it is a one line system Regards, Russ

[Volvo_133]

Hi Russ,
If your brake master cylinder has only 1 pipe leaving and is mounted alongside your clutch master cylinder it is a fairly safe bet it is single circuit only.
If the brake master cylinder is mounted on the other side of the engine bay, a 2 circuit system.

[Ron Kwas]

Russ;

Earlier chassis had a single hydraulic brake system, easily identified by the single line departing Master Cyl. Later dual systems in Amazons had two lines departing MC, additional plumbing, but still only 3 piston Calipers as an interim front/rear split systems on some late 122s. True 4 piston, dual sys Calipers, I believe were never fitted to Amazons by the factory AFAIK.

Cheers

[classicswede]

69-70 131's had the 4 pot calipers as a true dual line system like the 140 and 240

[Splinelube]

Thanks Ron, That clears any doubts I had. Russ

[Derek UK]

As said your '66 should be single circuit with 3 pot calipers. Not to confuse things, The very last B18 Amazons imported to the USA had a hybrid single/dual brake system with a hard to find dual master cylinder. No servo. This was USA market only to get round the regulations.
I'd suggest someone like Mike Dudek of iRoll motors for your brake parts. Calipers are available new now rather than exchange and discs are much cheaper now they are available as 1 piece items rather than the original ones where the disc was shrunk to the hub. Saving is around 50% so 2 for the price of one.
https://www.irollmotors.com/