Thanks all for your input!  I was going to wait until Jan to dive into this project, but I went ahead and ordered the fronts from Lone Star via eBay.  I figured that I need brakes for inspection, and the fluid in the lines is pretty much already drained from the prior owner, so why not just do it now...

There are many on the market now. Go with the Stock castings that have been machined out and sleeved with stainless steel.

Additionally ask for the pistons to have o-ring seals not the lip seals. These work the best.

Make sure you clean out any and all old brake in the lines and master cylinder. Then flush again prior to installing the new items.  Your break pedal will thank you for this extra task. 

(click to see a larger image)


"It Takes A Little Longer To Do It Right"
"It Takes A Lot Longer To Do It Again"

Thank you for your feedback- yep, those are exactly what I ordered from Lone Star.

I also learned something very interesting today about the whole situation: the previous owner shared with me that while the car was at the mechanic's during its time to be troubleshot for brakes, the mechanic told the person that it looked like "a different kind of fluid had been used at some point".  Of course, to hear that, I thought maybe that meant that someone had dumped DOT 5 fluid in there.  That would help to further substantiate seal failure and all kinds of weird stuff happening to the already-tired calipers and equipment.

I ended up calling that mechanic today after work, as they know our family, and I asked if they recalled what the issue had been with the fluid mixup.  I specifically asked if they thought maybe DOT 5 had been introduced into the system.  They responded that they did not believe it to be DOT 5, however, possibly hydraulic fluid or something to that effect.   I know the prior owner, and unfortunately, I could totally see them dumping ATF into the master cylinder if brake fluid was not readily available.  Whatever the mystery fluid was that had been used, however, I'm sure it was enough to finish taking out the last of the retention ability of the seals in the OEM calipers.  :(

The new calipers are supposed to be here by Monday.  Hopefully I can get through the swaps with little grief and get the brake pressure back!!

I have used DOT 5 (silicone brake fluid) since I rebuilt my calipers back in the late 70s when they became pitted. While I was able to salvage the rear calipers with some mild honing, the front calipers were beyond salvaging. I replaced them with stainless steel lined calipers. While there are some known disadvantages for silicone brake fluid, I've never experienced them.  Positive aspects of silicone brake fluid are that it does not harm your paint, it's not hygroscopic, and it has a higher boiling point than DOT 3.

I used lip seals since O-ring seals were not available back then but I would be open to a discussion of why O-ring seals are considered better.

Edit: Forgot to mention that I have read in the past that Chinese-sourced calipers are notably bad.

1973 L-82 4 spd

Hello, In my opinion,  ANYTHING that is an export from the chinese, and that includes R.O.C. Auto, Should be left on the container in the port. 

Click on image for full view

O-ring seals are not better than lip seals unless you are racing your car.

These guys know what they are talking about.

http://www.duntovmotors.com/tech-calipers.php

http://www.duntovmotors.com/tech-caliper-seal.php

Lots of good info on their website.

Not knowing all the information just presented in the Duntov Motors technical notes, I always figured the lip seals would be better because of the design which would tend to seal tighter as the pressure was increased.

I guess we would have never had the leaking caliper problem if the outer seal had been watertight.  🤔

1973 L-82 4 spd

Hi, I replaced all my calipers & master cylinder with stainless steel from Lone Star Caliper.

Lone Star has a lifetime replacement warranty.

I have had the L/S front leak twice along with the master recently going bad.

I called the sales office where I purchased them from and they sent replacements along with return shipping label.

Other than my labor & time there was no other cost.

Hope this helps

Alex

Happy Holidays

Where was the leak occurring?

1973 L-82 4 spd

Leaking from one of the 4 pistons, the master was not holding pressure when brakes were applied.

Depending on the depth of the rust pits in the bores of the calipers, it may be time to replace the caliper with one that has stainless steel liners. If the pits aren't too deep, it is possible to hone it and still maintain piston seal.

1973 L-82 4 spd