23mm Master Cylinder from ??

[billjam]

If I want to convert an '87 Carrera or an '86 930 to a 23mm master cylinder as part of a caliper upgrade, what am I actually looking for?
Will parts from another model do the job or are the 23mm m/cylinders an after-market part?
Let me know if you've got what I need.
Email is easier than PM ... jamesx6@iinet.net.au

[wildcat077]

Hi Bill,

The 23mm master cylinder you will need is an OEM Porsche part.They were stock on the 930 Turbo and you can pick them up from Pelican and other parts vendors.
I will have to install one as well due to the 996TT brake upgrade i'm performing on my car.
An 86 930 already has the 23mm master cylinder !

By the way,you will also need one with the Boxster conversion,although some people seem to think you can get away with the stock one ...

Cheers !
Phil

[billjam]

Originally Posted by wildcat077

Hi Bill,

The 23mm master cylinder you will need is an OEM Porsche part.They were stock on the 930 Turbo and you can pick them up from Pelican and other parts vendors.
I will have to install one as well due to the 996TT brake upgrade i'm performing on my car.
An 86 930 already has the 23mm master cylinder !

By the way,you will also need one with the Boxster conversion,although some people seem to think you can get away with the stock one ...

Cheers !
Phil

Thanks Phil. Useful info.

Can someone confirm that the 23mm cylinder bolts up in place of the original Carrera part without any other mods?

[JeremyD]

it does - may need to switch out the brake light switches (2) to 2 pole from three - otherwise it bolts right up

[gtc]

There is a Mercedes 23mm master cylinder that works just fine, and is supposedly cheaper than the Porsche part.

[Bill Verburg]

Originally Posted by gtc

There is a Mercedes 23mm master cylinder that works just fine, and is supposedly cheaper than the Porsche part.

the part that is needed for a 911 w/ power brakes is the ATE 23.8mm oe 930 m/c from a '78-89 930, part# 930.355.011.03

the ATE 23.8mm that was also used on a Mercedes truck is only used for 911 w/o power brakes. This one does not have Porsche part #. ATE (ports face left) # 03-2123-3402.3. There is also a right port version. It's best to buy this in a kit w/ the correct actuating rod and bent feed adaptors

[pmason]

Just ordered mine this morning from our sponsor, heres my parts list.
Putting on 993TT brakes this weekend.

930-355-011-03-M4 Turbo Master Cylinder, 911 (1978-89), Brand: Ate
911-355-922-00-M4 Master Cylinder Reservoir Grommet (sold per each, 2 req.), 911/911
Turbo (1977-89), Brand: Ate
999-181-021-50-M107 Brake Reservoir to Feed Line Braided Hose, blue, (priced/sold per
meter, cut to size), Brand: Meteor
911-355-322-00-M136 Brake Hose Fitting on Master Cylinder (Straight), 911 (1977-89), 911
Turbo (1977-89), Each Brand: OEM
911-355-323-00-M100 Brake Hose Fitting on Master Cylinder (Angled), 911 (1977-89), 911
Turbo (1977-89), Each

[spuggy]

The 3.2/930 vacuum boosters are also 8" instead of 7" (as used on the SC), and were available in a couple of different ratios as well.

According to Bill V's brake page... Brakes

That page also states that the 930 (a) used a prop valve and (b) used two different types (33 bar and 55 bar). Interesting...

[911pcars]

As an alternative, use a 22.4mm MC for a VW Corrado. Andy ("Hassad") ended up using this unit due to insufficient room to house the 23mm MB unit. Fluid delivery should be just a little less than the slightly larger MB unit. In addition, pedal force will also be slightly less.

Bigger master cylinder problems - Pelican Parts Technical BBS

In a follow-up correspondence, Andy responded:
"It worked out just fine thanks. I had to sleeve some remote reservoir connection tails with tight fitting grommets to allow them to connect to the cylinder. I blanked one rear wheel output in the VW part with a 10mm blank. Each front wheel is fed separately. The rears are on a single line through an adjustable pressure limiter. I have fitted a hydraulic pressure switch for the brake lights it then tee's off to feed both rears as standard. I haven't driven it yet but don't anticipate any problems.

It all fitted really easily the pedal stroke is fine but a little higher than standard , I had to modify the stop on the pedal box but real simple."

FWIW,
Sherwood

[Bill Verburg]

Originally Posted by spuggy

The 3.2/930 vacuum boosters are also 8" instead of 7" (as used on the SC), and were available in a couple of different ratios as well.

According to Bill V's brake page... Brakes

That page also states that the 930 (a) used a prop valve and (b) used two different types (33 bar and 55 bar). Interesting...

That's an old page wich hasn't been maintained and is full of typos.

here is the updated brake info

930s don't use any p/v

[billjam]

Originally Posted by Bill Verburg

That's an old page wich hasn't been maintained and is full of typos.

here is the updated brake info

930s don't use any p/v

Thanks for all the great info, especially pmason's shopping list and the link to Bill's brake details.
The only thing missing is part numbers of rotors and calipers.
I had started to do something similar for the various cars and brakes that I have, but my effort pales to insignificance compared to Bill's list.

[easelboy1]

Arrived late for comments - but I can supply some eye candy for the weekend project:



I opted to buy a new Reservoir 911-355-013-13-M100 as well for the SC I installed this in.

[pmason]

billjam, received my parts today and just finished putting it all in, need to bleed the brakes yet but everything else is done.
Just a note on my shopping list, the MC came with the 2 grommets.
911-355-922-00-M4 Master Cylinder Reservoir Grommet (sold per each, 2 req.), 911/911
Turbo (1977-89), Brand: Ate
But it was cheap insurance if it didn't, would of been kicking myself.
Phil

[cooperk]

Hi all, First restoration so please go easy. I have 00-04 boxster calipers on all four corners, and Zimmerman cross drilled Carrera rotors, and Textar pads.

I have been looking for some instructions or parts diagrams for the ATE 23mm master cylinder conversion on a non boosted 911 and have came up empty, or at least a little vague at my skill level.

I wanting advice on if the below and pictured will work.

The old pic with red labels is of my now removed 19mm M/C:
A) was a T hard brake line connection to the front brakes. B) was the rear hard brake line C) was the brake light single pole switch. D) reservoir in and out ports.


The (bottom) pic of the new labeled M/C 23MM is the best configuration i have come up with. ATE shipped it originally with two -three pole brake light switches and plugs where the reservoir gaskets go(middle pic pulled from web). I received none of that. SO. I am thinking the following:
A) front brake like in the original t configuration using the T B) hard brake line to rear brakes C) two pole brake light switch??? (is this necessary to have this switch, the old single pole doesn't fit, (should i adapt the size to fit the old single pole or use a jumper the new two pole, i am at a loss.) then D) plug this hole as i pictured where the second switch would go.

Thanks in advance.

[Bill Verburg]

here's what a typical non boosted 23.8mm ATE looks like when installed in a '76 or earlier 911



When purchased as a kit you get the angled fill fitting, fill hole and a correct length actuating rod

[cooperk]

Thanks Bill. On the picture you sent I do not see the brake light sensor Is than not needed? Second, I see that three of the ports are running hard lines to brakes, and only one reservoir port is being used is this correct? I feel like your provided photo only has one less threaded port than the pic I provided. Mine has two threaded ports near the firewall.
I really appreciate the help.

Originally Posted by Bill Verburg

here's what a typical non boosted 23.8mm ATE looks like when installed in a '76 or earlier 911



When purchased as a kit you get the angled fill fitting, fill hole and a correct length actuating rod

[Bill Verburg]

Originally Posted by cooperk

Thanks Bill. On the picture you sent I do not see the brake light sensor Is than not needed? Second, I see that three of the ports are running hard lines to brakes, and only one reservoir port is being used is this correct? I feel like your provided photo only has one less threaded port than the pic I provided. Mine has two threaded ports near the firewall.
I really appreciate the help.

I put a mechanical one on the brake pedal on mine

[PS930]

Hi guys,
I have a 1976 early 3.0 turbo which a previous owner fitted the later 930 Porsche 4 pot calipers 917 type if I recall.i have fitted a URO 23 mm m/c , but the brakes don't inspire any confidence and very hard pedal with no real feedback.You have to really jump on them to have any stopping effect.
I have been worried about this setup and wondering what is the significance of the push rod as Bill described as part of "kit"?
I see it is 150mm long by 7mm diameter. Would a standard push rod give the issue that I am experiencing as I am not sure if the rod was as per the rod that
Bill described ?
Any help /advice appreciated!
Thanks Paul

[911tracker85]

resurrecting an 84 944 and surprised it has a 23mm MC.

[UROParts]

Originally Posted by PS930

but the brakes don't inspire any confidence and very hard pedal with no real feedback.You have to really jump on them to have any stopping effect.

Hi Paul, barring seized caliper pistons or line obstruction, an overly-firm pedal means one of two things:

• The master cylinder piston diameter is too large relative to the piston surface area in the calipers. Remedy with either a smaller master cylinder, or calipers with larger pistons.
• The pedal ratio (the brake lever's mechanical advantage) is too small. Remedy by moving the pushrod pivot on the lever closer to the pivot at the end of the lever.

Rather than mess with trying to change the pedal ratio, most folks change MC and/or caliper piston diameters to get the pedal feel and braking performance desired. Here's a good article on how it all works: https://www.onallcylinders.com/2014/08/07/pedal-pushers-figure-pedal-ratio-master-cylinder-bore-size/

Race cars are set up with a very firm pedal and require a LOT of muscle to engage, but this gives a skilled driver a tremendous range of pedal pressure and modulation. Grandma's Oldsmobile is set up the opposite, with a very soft pedal and on-off braking performance. Pick your poison, or find a happy medium.