Brake ??? on 1973 911T

[bluesky]

My 1973 911T came factory equipped with the S-calipers.

What is the correct brake master cylinder to use for these S-calipers?

The brake master cylinder was changed years ago.....I know it wasn't replaced with the correct one because the top light in the Temp/Gauge that indicates E-brake engagement or Brake system issues didn't light up after the replcaement. I was told that the correct cylinder wasn't available so a different one with a incorrect sensor was install. I want to change it back to correct now.

[Bill Verburg]

1) 1973 T came w/ M front & M rear calipers. Even when the optional S appearance group was used.

2) If you have S front calipers, someone changed the struts and callipers after the car left Stuttgart

3) ALL* 911 from MY69 to MY 76 used a 19.05mm m/c part # for MY73 is 901.355.012.02 the current part # is 911.355.012.02 and can be found here

*there was one exception, in early 1969 a 20.5mm was used for some cars, Porsche # 901.355.012.04, ATE # 3.2120-3901.3

[bluesky]

Thanks Bill.

Wow, I know the car has things like S gauges set up, Koni adjustable shocks, the thru the trunk sway, as well as the S-calipers. I always thought that it came from the factory equipped this way.

I learned something new today.

So the 19mm is the one to get and not the 23mm ones that I see for sale out there.

Well, my real goal is to get the brake warning light to work again....my current master cylinder is stopping the car fine....it is just that the brake warning light is not working in the dash gauge..

This is because the mechanic who installed this master cylinder said the "old" style with the correct warning switch wasn't available so he installed a "newer" cylinder. He said that the switch didn't have the correct ends to plug the wiring harness lead up to it.....so if i want to get the warning light to work, can I just swap out warning light switches?...is there a correct warning switch to buy?

I looked at the link you provided and saw switch #901-613-115-00-M14 here
.....would this switch have the correct ends that my 911T harness leads would plug into and would the threads on this switch work in any/my master cylinder?

I know asking these questions without seeing the car is like asking a Doctor to make a diagnosis over the phone but I thought I'd ask them and see. Thanks

[Bill Verburg]

You mechanic is probably correct, it seems that the early style switches may be NLA. You should be able to use the later style w/ a little rewiring, it's just a +12v and a ground. Check your wire though, see what it wants

the factory S appearance group was just trim, gauges and the front S spoiler. Roll bars and brakes would have been added afterward.

m/c need to be matched to the calipers
A, S, & M all want 19.05 or 20.5mm
930 & the later Brembos want 23.8

[bluesky]

Perfect!!! Thanks as always for the sage advice!

[billwagnon]

Is it true the M calipers were iron and thus magnetic, but the S calipers were alloy?

[djpateman]

That is correct. The S calipers were an aluminum alloy.

[Bill Verburg]

Originally Posted by billwagnon

Is it true the M calipers were iron and thus magnetic, but the S calipers were alloy?

All the A's and M's(there are several versions of each) are iron

S's and later Brembo and '78 up 930 are aluminum

[evilfij]

Can't you just short the switch to make the light go out?

[Jim Sims]

Alloy front S-calipers were available as a factory option on the 1972 911T; I owned one so equipped. The '72-73 911 factory parts manual shows them available as an option both years for the "T" model.

[Bill Verburg]

The option list also includes titanium connecting rods @$903, that doesn't mean that they were regularly produced

[DinFtown]

Nice titanium for $903.... sign me up for a set... lol

[Bill Verburg]

Originally Posted by Dinkytown

Nice titanium for $903.... sign me up for a set... lol

remember this was 1972, base was $7645 WestCoast PoE
other options
am/fm radio(mono) $87-226 depended on which one
retractable antenna $63
S front spoiler $210
appearance group(front spoiler, gauges, trim) $183
tinted glass $81
6x15 Fuchs &n185/70 tires(5.5x15 steel standard w/165HR 15) $473
5 spd trans $162
f/r sway bars $87
tow hook $16
Recaro seats dual or drivers side only
bumper overriders
transmission coolers
optional gear ratios
leather wrapped steering wheel
koni shocks
fog lights, several varieties
rear window wiper
sunroof
paint
LSD
leather seats & interior
electric widows
85 liter fuel tank

note that many of these were aimed for race and rally use, it was just like today's special wishes program


In '73 even the front oil cooler was an option on all models including the S but not RS

[Jim Sims]

Well the '72 911T had the S-calipers with matching struts and other than the gage package, an S-front metal valence and it being originally painted a dark purple there was nothing special about the car.

[Jim Sims]

Aubergine, the hot race and rally car color of 1972:

[Bill Verburg]

Got the Monroney Sticker?

[rfn026]

My '73 T came with the S package but no alloy calipers or sway bars. I later converted it to the alloy calipers but I had to change the struts as well. I also added the S sway bars.

Richard Newton

Autocross Performance Handbook

Ultimate Garage Handbook

[bluesky]

Originally Posted by Jim Sims

Aubergine, the hot race and rally car color of 1972:

Jim, The pic of your car is exactly how my car apparently looked when new. It was Aubergine with the S-goodies and no sunroof!

It spent some of its new life in Los Angeles since I found a parking garage stub with that year date stamped on it that had fallen down into the front defroster vent plumbing.

[Jim Sims]

The picture posted is not of the '72 911T I owned, just an example of the aubergine original color - a standard factory paint color - 025?). No window sticker but I recall the front top strut sealant was in place covered by the original purple (aubergine) paint which was under a white repaint. Front brake calipers were silver and non-magnetic. Engine had been crudely converted to carbs but remains of the MFI system were evident. I do not recall it having a front sway bar. I bought it for a parts car ($500) but before I could remove many parts from it a friend bought it from me to rescue it (he rebuilt the engine and we went through the transmission) and now a second friend has it and is converting it into a track car.

[kilodawg]

My '73 T came with S calipers and sway bars as well.