Brake Caliper Question - 1976 911 2.7

[mikedsilva]

I'm not very experienced with brake calipers and all the various options.. a friend recently bought a 2.7 1976 911.. it pulls to the left under braking suggesting the calipers need an overhaul but I'm not quite sure which rebuild kit I need or indeed which calipers are fitted.. fyi, this car does not have a brake booster (if that means something).

Here is the link to the rebuild kits on PP..
https://www.pelicanparts.com/catalog/SuperCat/0784/POR_0784_BRKCAL_pg2.htm

Could someone kindly let me know what front and rear calipers I have here?

[HarryD]

Sounds like a caliper is sticking. Either the brake hoses have internally swelled or a caliper piston is stuck. If it was me, I would:

1-Remove the jars snd see what the piston boots look like. If they are damaged, it would have PMB rebuild them.

2-I would check the brake hoses snd if they show signs of damage or the date codes are over 15 years I would replace them.

[Bill Verburg]

Originally Posted by mikedsilva

I'm not very experienced with brake calipers and all the various options.. a friend recently bought a 2.7 1976 911.. it pulls to the left under braking suggesting the calipers need an overhaul but I'm not quite sure which rebuild kit I need or indeed which calipers are fitted.. fyi, this car does not have a brake booster (if that means something).

Here is the link to the rebuild kits on PP..
https://www.pelicanparts.com/catalog/SuperCat/0784/POR_0784_BRKCAL_pg2.htm

Could someone kindly let me know what front and rear calipers I have here?

the rear appears to be a regular 911 M rear

The front however is not a Porsche oe, it is an after market ATE 4 piston caliper, you'll have to contact ATE for a rebuild kit

[mikedsilva]

Originally Posted by Bill Verburg

the rear appears to be a regular 911 M rear

The front however is not a Porsche oe, it is an after market ATE 4 piston caliper, you'll have to contact ATE for a rebuild kit

Aftermarket front caliper?
Wow, wasn't expecting that.

Cheers for the info.

[Bill Verburg]

It might be this one which has a 3.5" axial mount and one version is for 20mm rotors




If so I'd be concerned w/ f/r bias unless the rear is at least a wide M from a 3.2 Carrera

[mikedsilva]

Originally Posted by Bill Verburg

It might be this one which has a 3.5" axial mount and one version is for 20mm rotors

If so I'd be concerned w/ f/r bias unless the rear is at least a wide M from a 3.2 Carrera

Cheers for that.
I found a couple of old threads suggesting that a BMW caliper from an E23 series is a direct bolt on to the 911. So I'm wondering if that is what was fitted as an 'upgrade' many years ago.

The car is not with me now, but when it is, I'll take off the caliper off and measure the pistons and mount spacings.

[Walt Fricke]

As I recall, by '76 Porsche had dropped the S/non-S distinction, so your friend's front caliper should have the 3.5" 10mm mounting bolt spacing (interesting that this is an Imperial dimension).

[mikedsilva]

Originally Posted by Walt Fricke

As I recall, by '76 Porsche had dropped the S/non-S distinction, so your friend's front caliper should have the 3.5" 10mm mounting bolt spacing (interesting that this is an Imperial dimension).

Check out this thread I found on a BMW forum.. they are rebuilding his front calipers and they look fairly similar to the ones in my photos.
https://www.bimmerforums.com/forum/showthread.php?2400853-Rebuilding-Front-Brake-Calipers

[Avanti]

I want to reiterate the earlier mention of the brake hoses. They can cause pulling problems and are often the last thing to be considered. Just replace all of them. Also don't overlook the front suspension bushings. Shifting control arms can cause what may be considered a brake pull. You obviously need brake caliper work but check everything.

[eastbay]

You can do a search on 'Alfa' brakes, there has been a few posts on them

[Bill Verburg]

Originally Posted by Walt Fricke

As I recall, by '76 Porsche had dropped the S/non-S distinction, so your friend's front caliper should have the 3.5" 10mm mounting bolt spacing (interesting that this is an Imperial dimension).

I believe that by '76 the only S caliper equipped car was the 2.7RS and 930

My '76 C3 certainly came w/ A/M setup

all A or S caliper cars have 3,5" struts

The base 911 though still came w/ front Ms on 3" struts

[Bill Verburg]

Originally Posted by eastbay

You can do a search on 'Alfa' brakes, there has been a few posts on them

Alfa used 3.5" A calipers, hence the A designation, I had a '69 boat tail w/ them

[Walt Fricke]

Bill - I was referring to the model S, not the caliper S. For '76/77 Porsche had only one base model 911. They had the former "S" model CIS cam and the A front caliper, and were the same, US and ROW. The Carrera 3.0 (not sold in the US) and the 3.0 Turbo were the flagship models for those years.

The '74-5 non-S model, with a detuned cam and an M front caliper, always struck me as a silly attempt at market differentiation. But I suppose that is just the automobile business, which probably is proof of the theory that luxury items can have a negative demand curve. Hard to believe the cost of production differential between those two models justified any price difference.

Since the A caliper was for Alfa, where did the M and S designations come from?

[HarryD]

Originally Posted by Walt Fricke

... snip ....

Since the A caliper was for Alfa, where did the M and S designations come from?

M for mundane

S for super.

[Bill Verburg]

Originally Posted by Walt Fricke

Bill - I was referring to the model S, not the caliper S. For '76/77 Porsche had only one base model 911. They had the former "S" model CIS cam and the A front caliper, and were the same, US and ROW. The Carrera 3.0 (not sold in the US) and the 3.0 Turbo were the flagship models for those years.

The '74-5 non-S model, with a detuned cam and an M front caliper, always struck me as a silly attempt at market differentiation. But I suppose that is just the automobile business, which probably is proof of the theory that luxury items can have a negative demand curve. Hard to believe the cost of production differential between those two models justified any price difference.

Since the A caliper was for Alfa, where did the M and S designations come from?

Right you are, just looked it up

last year for the front M was '75 on a 911
from '76 they all had A, except for the 930 and euro 2.7RS w/ 911/83 motor

no idea except that S was part on the early sport package, norm is Deutsche for standard so maybe idiomatic

[Walt Fricke]

Sport would be a good guess for the S caliper, because Sport is a German word too.

M a bit harder to guess at. Mittel (middle)? Because there was an even smaller caliper at one time, maybe on the 356? Maserati?

[Bill Verburg]

Originally Posted by Walt Fricke

Sport would be a good guess for the S caliper, because Sport is a German word too.

M a bit harder to guess at. Mittel (middle)? Because there was an even smaller caliper at one time, maybe on the 356? Maserati?

There was a smaller L caliper, maybe L for little

M for mittel makes sense

mundane has no German counterpart that I know of

[chrismorse]

66 911 w/stock pads
Speedster w/ SC engine and C discs, slicks.
914/4 w/ S drilled vented fronts and 6 drilled/vented rears
77 308 w/ F50 fronts, (355-32 discs & 44/48 brembo calipers) & 360 rears, (including brembo parking brake),

Now, 74 911 W/ PMB, new discs F/R w/ air to front, SS lines and sport seats :-)

Some have opined that "brakes" are over rated - Having pad fade at a few high speed auto x's, I will say not so. It is comforting to approach a 100 mph corner, knowing that the car that cost 10 times what yours did, is running out of brakes.
Similarly, they are running through an expensive set of pads and discs in a few days and yours are good for several seasons and rock solid.

You don't need high dollar carbon everything, you just need big thick well ventilated discs, good pads and high temp fluid.

+10 to Bill V,
chris