71 911 master cylinder/Brake system upgrade?

[jrsully]

going through the complete brake system on a stock 71 911 T and have heard the ides of upgrading the orig 19mm MC to a bigger bore.? wondering if this is a good idea.? Just doing a basically stock rebuild of the car, nothing crazy. What I am replacing (or will try to replace)
1. M/C,
2. Resourvoir lines/cap/filter
3. F/R stainless braided flex lines
4. rebuilt M calipers /cut rotors/bearings etc.
5. as many pre bent hard lines as I can get ahold of. The original lines are in very good shape, no rust on this car at all. Cannot seem to locate anybody (incl host here) that has a "kit" available.?

If I am missing anything, let me know and thx in advance for the help.! JIM

[Bill Verburg]

Originally Posted by jrsully

going through the complete brake system on a stock 71 911 T and have heard the ides of upgrading the orig 19mm MC to a bigger bore.? wondering if this is a good idea.? Just doing a basically stock rebuild of the car, nothing crazy. What I am replacing (or will try to replace)
1. M/C,
2. Resourvoir lines/cap/filter
3. F/R stainless braided flex lines
4. rebuilt M calipers /cut rotors/bearings etc.
5. as many pre bent hard lines as I can get ahold of. The original lines are in very good shape, no rust on this car at all. Cannot seem to locate anybody (incl host here) that has a "kit" available.?

If I am missing anything, let me know and thx in advance for the help.! JIM

a bigger m/c cylinder increases the amount of leg needed and reduces the pedal travel, the brake gets higher and harder, some like it most don't, even the ones that like it have to spend a lot of time getting used to it, at first it feel like no brakes at all(think modern ABS car on slick ice)

there was a 20.5 used in '69 Porsche # 901.355.012.04, ATE # 3.2120 - 3901.3 that would be nice on a track car(this one may or may not be available, I haven't seen one in 30yrs). This one is a small increase in piston size and so only a small change in pedal

the ones I see these days are the 23.8mm ATE (ports face left)# 03-2123-3402.3, there is another one w/ right facing ports that you don't want. I always advise buying a kit which includes the correct piston and some hydraulic parts that make the installation easier. This one is a large increase in piston size so is a large change in pedal feel. Again some like it most don't

[bobolsn]

Jim,

I have read and believe what Bill says about the larger MC and the harder it would be to depress the pedal.

As for the "kit". I am not sure what would be included in the "kit". Of course, there are kits for the calipers (host). PMB does offer all the brake lines and I believe they are prebent (as illustrated on their web site). Also, Stoddard's provides a kit of all 10 components of the brake lines, but you will have to bend them.

Hope this helps, cause I am about to embark on the same journey for my 71T.

Bob

[burtm5]

I also have a 71 T with M brakes. As long as you change/flush the lines on a regular basis, these brakes work well. I would not change m/c cylinder just as others have said. also would go to stock new rubber brake lines have heard that ss brake line covering obscures any problems underneath. Rubber lines last 10 years plus and you can see when they are getting old. Flush and reuse your metal lines. Unless you have a much higher hp car, I wouldn't spend the extra money for little or no benefit. best Henry

[roblav]

Agree with leave the M/C. M brakes are just fine. Hawk pads are really good.

[Bill Verburg]

Originally Posted by bobolsn

Jim,

I have read and believe what Bill says about the larger MC and the harder it would be to depress the pedal.

As for the "kit". I am not sure what would be included in the "kit". Of course, there are kits for the calipers (host). PMB does offer all the brake lines and I believe they are prebent (as illustrated on their web site). Also, Stoddard's provides a kit of all 10 components of the brake lines, but you will have to bend them.

Hope this helps, cause I am about to embark on the same journey for my 71T.

Bob

The 23.8mm m/c kit includes all the parts seen here, the plastic 45s and the new rod are the important pieces. The old 19mm rod is too short


you could make your own rod

[Trackrash]

HBTDT I found a good deal on some S calipers and upgraded from the Ms. Regardless of what some will say, I fell they gave me a noticeable improvement in my braking. I regularly autocross and DE, however. On a purely street driven car you may or may not think it is a worthwhile upgrade.

Problem is S calipers will require a strut upgrade to 3.5" bolt spacing. It is a slippery slope. The advantage of upgrading the struts is you can get rid of the problematic pinch clamp on the balljoint and have a greater choice of shocks.

Regardless, unless you are going to change to something like boxter calipers, stay with the stock MC, they work great with the stock calipers.

[jrsully]

Thanks for all the replies, lots of informative information to say the least. The car will be a basic rebuilt 911 with basically stock drivetrain, so I don't know if a heavy duty upgrade (any.?) is necessary. If the stock M calipers (stock M/C, brake lines etc.) is sufficient (and easier to replace/maintain) that is my goal. Again, thanks for all the replies, Used to doing 69, 70 Chevy musclecars, excited about going overseas.! Thx again. JIM

[Dodge Man]

Originally Posted by Trackrash

HBTDT I found a good deal on some S calipers and upgraded from the Ms. Regardless of what some will say, I fell they gave me a noticeable improvement in my braking. I regularly autocross and DE, however. On a purely street driven car you may or may not think it is a worthwhile upgrade.

Problem is S calipers will require a strut upgrade to 3.5" bolt spacing. It is a slippery slope. The advantage of upgrading the struts is you can get rid of the problematic pinch clamp on the balljoint and have a greater choice of shocks.

Regardless, unless you are going to change to something like boxter calipers, stay with the stock MC, they work great with the stock calipers.

I had replaced struts & ball joints so new spindles were out of the question. I kept the stock MC size and just got the Brembo upgrade from PMB to run "S" pads on a "T" spindle on my 73T. The piston diameters & MC diameter are STILL MATCHED AS PORSCHE FACTORY SIZES(no balance changes). I run an uncorked 1983 930-10 with 225HP at the crank so I was running out of "M" brakes in a hurry. I do not believe that the "M" calipers are good for a 3.2 conversion with a pad change like numerous posters. The PMB upgrade is a true bolt on upgrade and the Brembo calipers are more robust than the "S" calipers. My canyon runner buddy runs Carrera power brakes but that is probably too much conversion work for most people. The PMB upgrade is not for a track car but better brakes on a vintage 911 are always better(just store your old "M" calipers). Call Eric for the calipers & hard line extensions and be happy without changing your front suspension. Just my 2CW but I have to run with the 70 hot rod with a built 3.0 and Carrera brakes on fun runs in the unforgiving canyons. Cornering times are the deal breaker.

[bobolsn]

JR,

Just ran across this upgrade. I had read about it several years ago, but had no documentation. The upgrade is to use BMW 320 (1978 to 1983) calipers to replace the 911 calipers. There is an article posted on the 914 forum "Technical Articles" that discusses this upgrade in detail. Since we have the 3" spacing on our spindles, the upgrade is almost a bolt on. You get more area on your brake pads that tranlates into more braking power.

Let us know what you decide.

Good luck

Bob

[Dodge Man]

Originally Posted by bobolsn

JR,

Just ran across this upgrade. I had read about it several years ago, but had no documentation. The upgrade is to use BMW 320 (1978 to 1983) calipers to replace the 911 calipers. There is an article posted on the 914 forum "Technical Articles" that discusses this upgrade in detail. Since we have the 3" spacing on our spindles, the upgrade is almost a bolt on. You get more area on your brake pads that tranlates into more braking power.

Let us know what you decide.

Good luck

Bob

Right Bob. However, PMB has the anodized rebuilt calipers, extension lines, and selection of pads. The extension lines allow the OEM brake lines to stay in factory position because the Brembos inlet connection is in a different location. M/C is another choice.

[bobolsn]

Dodge Man,

I didn't mean to refute anything you said. PMB provides excellent cost competive products and Brembo is one of the best. I was just providing alternatives.

Also, I have to say I am not sure of the years for the 320 calipers. BMW changed rotors over the years from vented rotors to solid and then back to vented. You would have to make sure that the calipers are for vented rotors and have 3" bolt spacing.

Again good luck

[jpnovak]

Tracked a 71T targa with stock M brakes for years. Baseline to stock operation, add some good fluid and some brake cooling and have fun.

You do not need more brake on a T. Spend your money elsewhere - like on decent seats instead of the stock bench seats. Much more value and fun to drive.