Ok, so I'm starting the install of my 911 front suspension and brakes. I have a 19mm master cylinder in a box, ready to install. So I pull the belly pan, roll under the car and stare up at my current master cylinder. I see an embossed '19' staring me back in the face.

It looks like its been there a while. Am I golden or am I missing something?! Was the 19mm ever an option on the 914? I held my new M/C next to it and they look identical, at least from the firewall out...

Thanks!

The more important question is....

how much do you want for the new one since you already have a 19mm installed?

Someone probably just went with the 19mm unit during a repair since it's such a common upgrade. A 4 cylinder car shouldn't / wouldn't have come with one. I don't know if the /6 cars used the 19mm master cylinder or not. I'm guessing they did since the rest of the suspension is 911.

If the M/C on the car looks old, I'd replace it, cheap insurance

for a while, the 19mm M/C unit cost less than a 17mm M/C, so that was one reason some people used the larger one for repair

Only the front suspension is 911 on the 914-6. The 19mm MC was used on them, though.

The 19mm is a direct bolt-in replacement for the 17mm, though you might have to move one of the brake lines a little? I forget.

Sounds like someone already replaced your MC with a 19mm one.

--DD

Cool, looks like I'm set. I didn't see any leakage around the fittings so I'll leave that one in there and unload the spare.

they don't leak at the fittings (unless improperly installed), the fail internally which you cannot easily see....If you suspect the M/C of being older than 10 years or even just a few years old but not being used (as in car sitting around not running), I'd replace it now.

If I recall correctly.. they dont say 19 on the side that you can see.

FIID. Delete that post. You dont want the hassle of dealing with someones loved ones after they buy a MC from you and they die in a crash. Throw it away.


B

True, the number is on the top when viewed from below. A royal PIA to see, as I recall.

OK, staring up at the think, I see a '19'. However, the replacement I have has a '19' on the portion that is on the backside of the firewall, I believe.... ACK!

Should there be any noticable difference in the external construction (size, shape, layout) of these thigns as they look identical.

Thanks!

Side by side you can't tell the difference. As others have said if you are this far into it just change to the new one and have that piece of mind. Then buy my 320i calipers

HA.. thanks, maybe I will do that.. hopefully without too much aggrevation.

Joe.. I have the 911 calipers so you will have to find another buyer...

Here in Canada we started replacing the original master cylinders when the cars were 7 years old. That means they may be on their fourth master by now. Well, that may be a bit harsh, but I would think not too far off of the mark. I would think that torsion bars were not too far behind the masters in years to replacement. I have also replaced a lot of transmissions over the years. Rebuilding calipers has been quite a business also.

BTW: the cast sizes on the master cylinders are a rough guide to the bore size. For some reason the master cylinders are in "inch" sizes with increments of 1/16"

17 = 17.46 = 11/16
19 = 19.05 = 12/16 = 3/4
20 = 20.64 = 13/16 as used with 69 911S with aluminum "S" caliper

DaveP

What post?

Good point. Thx for the advice.

Here is a post I saved that might shine a little more detail to this issue. I was in the same boat you were in last year........had new m/c in hand and found my car already had a 19mm installed. I would have replaced it at the time but the brakes worked great with the stock 914 calipers and my only reason for upgrading m/c was the installation of 911 calipers.

The brakes continue to work as expected after a year on the street and the new m/c has been added to my parts been for future use.

http://forums.pelicanparts.com/showthread....?threadid=90929

John

Really!?!?!

Oh... and good luck getting those rubber/stopper fittings back in. You'll wish you were never born! That ranks as one of the absolute worst wrenching tasks I've "ever" done on a 914.

If there's any tricks out there I'd be all ears cause I've got the 911 and the Gt project to go. I've resigned to leaving the tank out on the GT until I install the MC so as to make it easier.

That's the way to do it.

Leave the tank out. Stick the hoses in the MC before you install it in the car.

You're right- it could be the #1 PITA 914 job.

Paul

Not only leave the tank out, but loosen the two hoses that attach at the resivour, pull them down a few inches and it'll make life much easier

I put the rubber gromments in first in the M/C, then I push/twist the feed line into the rubber gromment.
(lubed with some brake fluid)

The size of the master cylinder (17 or 19) is viewed on the under side of the master cylinder, but on the part of the master that is in the body work.You can't see what size the master is without pulling it out, or, MAYBE, having a really good set of eyes and a mirror and going in from under the pedal section in the car.(never tried that) Any numbers that you see from under the car can't be a guarantee that the master is that size!

Ladies & Gentlemen....

High Performance House's own Rich Bontempi.

I know, I can read, he joined back in February, but he's only had 12 posts, and this is the
first time I've seen his name.

Welcome Rich, er, Mr Bontempi


914 guru
Multiple time racing champion

Hi Scott, yea I know I should post more often, but somehow I never seem to have enough time to get everything done on my plate as it is. And the times that I do get on the clubsite, there usually isn't too many questions that are not answered correctly! So I try to fill in with help when it's needed!

That never stops Brad from posting here.

We need a "ducking for cover" smilie.

Hi Jon! Yea but I work for a living!!! LOL

Thanks for all of the suggestions.

We decided to pull the old master out and install the new one. As predicted by some, it was a '17mm', not a '19'. Please see the source of my confusion below. Why the hell would Porsche do this?...

well - Porsche doesn't make anything - they just build cars from parts. i haven't seen enough Ate master cylinders to know, but i bet the 'little' number is just the production sequence - and yours happened to be made in the 19th week of the year...

Looks to me to be a casting number. Mold 19 out of? That is ATE's doing, not Porsche. Enjoy the 19. BTW, the 411 got a 19 with the same front calipers as the 914, but used rear drums. Exactly why the 914 did not get the 19 as did the 411 and the 914/6 is not known. No cost savings I can see.

DaveP

/6's were assembled on the 911 line at Zuffenhausen, where there were no 17's stocked.

why the Karmann-assembled cars got 17 if otherwise identical 19's were available, i donno - other than all things being equal, the smallest suitable MC will provide better modulation and lighter pedal (more hydraulic advantage).

/6's had larger front and rear pistons, so my guess is 17mm just wasn't adequate considering racing use - may have been a homologation factor too...

Righto on the Porsche vs. ATE thing.. I was just venting... Regardless, new 19 is installed, new turbo tie-rods, 911 struts ON. Should be back on the ground this week....