1973 front caliper piston has a nick
 

All,

I am in the process of rebuilding the breaks on my 1973 911T.
I removed the pistons from the calipers and noted that one of them has a nick on the "O" ring mating surface.
The deformity is located on the bottom 1/3 of the piston and is apporximately 3/16 inch long. It runs from the inside (lower) to the outside (upper) of the piston.

It appears that someone had worked on this once before, as there seemed to be some marks caused by very fine sanding.

My question is simple.
Can I run with this piston?
Can I just smooth sand it by hand?
Do I have to get another Piston?
If so where?

Thanks for any help.

Mark Kozikowski
Can I get it reground?

I just rebuilt the calipers on my 78. I also found a nik. It was discussed that with a light sandpaper it could possibly be smoothed over. With the thoughts that this was one of the major components that could save a life at any one point (mine or thiers) I opted to purchase all new pistons. Cheap enough, if you are doing the install.

If if rubs the O-ring, it will cause a leak sooner or later. If it is somehow in an area that doesn't move dirextly across the ring, then it will be OK as long as the ridges of the nick are level with the piston surface. Water get in there and rusts/eats away at the piston and the caliper bore. Many times this rust is back in an area that can be cleaned up and reused with the new O-ring. But if it is right there where the ring is, throw it away.

I've never taken a Pcar caliper apart, but most calipers get their seal between the O ring and the wall of the cylinder, the piston is just along for the ride (notwithsanding the previous post about whether it will wear on the O ring).

I've been wrong many times before, but my S calipers have the O-ring in the caliper bore. The piston is smooth. I assumed all ATE calipers were like that.

RCM,

Where would one get new pistons for the brakes?

Is this something you have to go to the dealer for?

What type of calipers do you have - I have several spare pistons from A-type calipers. If you want them let me know by messaging me...

I have the 'M' calipers

The pistons might be the same..? They look pretty similar but that's from memory as I've rebuilt each type a while back. What diameter are your's? I can check mine and these might work for you!

Whynot just upgrade calipers?

Not to sound cheap, but that is about $6000 per wheel new, and about $2000 per wheel rebuilt.

Just a little out of my league for now.

Maybe later.

Are you high? You could upgrade the fronts to nice four piston calipers for probably less than 500-600 bucks with new pads, liner, and fluid.

Oh you could spend a lot if you want to stop the world, but you can make your breaks a lot better than they are now for a lot less money than you seem to think!

I am all ears.

Where can I find this upgrade.

PP doesn't have anything this cheap, as far as I have seen.

Another thought.
Do I need to upgrade my rotors with the
'S' caliper?

4-piston calipers for $500?? I am listening, too!! What are they, and where do you get them?

mkozikowski!

I did purchase my pistons at a dealership locally.

Hmmm... I see your into looking from escort stock pricing to ferrari expensive pricing.

If you must have new, You can buy big reds from our host for 1795 (set of two). I suppose if you must have some one install them for you, you will pay a good deal more(sorry, I don't have people install things for me and so don't worry about that associated cost.) You can buy boxter calipers for300 bucks, they are 4 piston and would be an upgrade from your stock M calipers (are they a direct bolt on, NO).

Now my suggestion would be to follow the masses and upgrade to a set of 944 turbo or 928s-4 brembos up front. They should fit into my six hundred dollar range.

Sorry if I was terse, but you don't need to spend 6k per wheel unless you are serious about racing, real serious. And even then you probably won't need it.

Whoa,

I am, for the most part, ignorant about my choices. I am new to the car, and am doing everything I can myself.

I am just looking for options. I am perfectly fine using alternatives, I just don't know what they are.

I am not a 'label' user. Don't care about big bucks. But I looked at our host's site and saw the type "S" for 2500 and figured this was all there is.

That is why I am here.
To find the alteratives.

I will look into the 944/928 options.

You'll be fine, I guess the important message is to do some research, which you are!, and then do what serves you best. These guys know alot about the different choices one can make. Seriously, there are some that take their car to the shop for every little thing (and thats OK for them) and there are some that do everything on their cars and some in between. This board is great at getting the betweeners to be the all doer's. Many times you can find "S" calipers on ebay, or here, for a few hundred bucks a pair. They will serve you very well. There were standard on the early S and options on the T and E. I belive they were also on the later 74-77 cars and maybe the SC's.

There are many different combo's one can try and many of these guys have tried each. Do a search under brakes and calipers and see what you find and hopefully some of these guys will chime in about their own experiences.
Oh and welcome to the board ;)

Mark,
Dennis mentions some good options but with a 73T & M-calipers, none of those options will work directly. Unfortunately, your front strut will NOT fit any of those options. You will need an entire front suspension of a later car (like Dennis' car) that has a 3.5" caliper bolt spacing. You're stuck with M-calipers unless you want to re-weld the strut (not a great idea) or replace the suspension with an SC or Carrera setup which would allow you to use better brakes (A-calipers) if that's what you are searching for. Hope that helps the confusion.