Question about early ('74) 911 Brake Upgrades

[Tidybuoy]

I just got my '74 911 and I am surprised how lousy the brakes are. It's very possible that the calipers need rebuilding or some other reason but currently, I doubt if I could lock the brakes up if I wanted to.

My 914 originally had similar braking issues and the most often upgrade is to switch to BMW 320i calipers for the front.

I was wondering if there is any common upgrade for the 911. Any other suggestions would be greatly appreciated.

Thanks......Vern

[mspirito]

Rebuild the calipers likely they are rusted and not moving well, mine were the same prior to rebuild. Probably go with new master and new rubber brake lines! It will make a world of difference

[E Sully]

With caliper and master cylinder rebuild, new rubber brake lines and a good bleeding my 73 stops very well.

[Tidybuoy]

Thanks! I have a brand new master cylinder that I was saving for my 914 (the 911 version - I think 19mm). I will try and rebuild the calipers and see what happens.

[fintstone]

My '74 stops well...but without any booster...it takes a bit of getting used to to feel confident. Takes a heavy foot on the brake.

[rfuerst911sc]

Once you know that the master cylinder and calipers are working properly and brake lines have been replaced experiment with brake pads. There are many good pads available that will make a world of difference. Lack of good brake performance is rarely a weakness in a Porsche.

[Driver_X]

The brakes on my '74 are more than sufficient.

Are the brakes firm or soft?

[chrismorse]

Definitely, make sure everything is working freely, is well bled, (with Motul, Castrol LMA or other good fluid), before going the upgrade route.

Is the car really driven hard or tracked?? Or is it just a daily driver??

Hopefully some of the experienced guys will offer advice on the following:

Do any of you guys that drive hard on the street have a particular pad that you recommend???

Are braided stainless lines no longer recommended???

Chris

[Tidybuoy]

The pedal is firm and the car does stop...it just doesn't stop as well as I think I should. I had a similar problem in my 914 and it was solved with the 320i upgrade. I will start here with rebuilding the calipers and changing the master cylinder (only because I have a new one in my garage), and then a good flush. After that, I amd going to change the pads.

This car is in very good condition but one problem is that it has been driven very little over the past 10 years and so brake maintenance was probably not ever done as it wasn't needed.

[Flieger]

A firm pedal on a stock 911 with 19mm master cylinder often means that the inner caliper pistons are frozen. That was my experience. I sent my S calipers in to Eric Shea on exchange for some nice rebuilt ones and the pedal was noticably softer when I got the new ones on. That was because both pistons were now working! The old ones had hardly any wear on the inside pads.

[Fidalgo911S]

If you have the alloy brakes (stock) on your '74S, they are really good calipers. Mine were rebuilt just prior to me buying the car, they are a really good caliper. Talk to Eric at PMB Performance to see about a rebuild. Well worth the $$$. I see you have a 914, you've most likely dealt with Eric before?

[Steve@Rennsport]

Originally Posted by Tidybuoy

The pedal is firm and the car does stop...it just doesn't stop as well as I think I should. I had a similar problem in my 914 and it was solved with the 320i upgrade. I will start here with rebuilding the calipers and changing the master cylinder (only because I have a new one in my garage), and then a good flush. After that, I amd going to change the pads.

This car is in very good condition but one problem is that it has been driven very little over the past 10 years and so brake maintenance was probably not ever done as it wasn't needed.

I'll offer another opinion,....

I'm no fan of the flexible alloy "S" front calipers and I've gotten FAR better brake pedal feel using the later "A" iron calipers (SC).

With the right pads (very critical!), good SS brake lines, and a healthy MC, these non-boosted brakes feel & work very nicely.

A cheap upgrade comprises Carrera front calipers and rotors, but that will cost a bit of $$.

[RWebb]

Originally Posted by Tidybuoy

the car ... just doesn't stop as well as I think I should...

what exactly do you mean?

do the tires skid? how old are the tires?

does it take a lot of pressure on the pedal to make the car slow down?

is there something else you do not like about the "feel" of the pedal?

does the car make noises when braking?

does the car veer to one side or another when braking?

is this on the street or on a race track???

I doubt that your brakes are in good shape, and seriously doubt that you need a different system, like those BMW 320 calipers or others.

No matter what you eventually do, you MUST replace the flex hoses every 20 years or more often. Use new factory rubber hoses, and put in new, high quality fluid then test.

Brake fluid must be replaced every 2 to maybe 3 years no matter the mileage.

[silver911rdb]

I had a 74 911 with lousy brakes as well. You don't mention whether you'll just use it on the street or if some track time is involved. Initially my car was used mostly for street and occasionally on the track. It progressed over to much more track time and the brakes just weren't good enough. One of the best upgrades I did was to convert to the 1984 or later carrera brakes. I needed to replace the strut housings as well to accomodate the longer 3.5" bolt spacing needed for larger carrera calipers. The spacing on these calipers is larger than the approx 3" m-caliper mounting bolt spacing. I'm assuming you have the smaller m-calipers on your 1974. Mine was a 911S and it was fitted with the m-calipers, although I have read in places that some 74 911S's came with the alloy calipers (including the 74 carrera). The nice thing with the 84 carrera brakes is that the rotors are thicker than the a calipers on the SC's and the caliper is spaced accordingly as well. I also changed my 19mm master cylinder over to a 23mm master cylinder from a Mercedes. This gives you a much firmer pedal. For the most part the master cylinder is a bolt in upgrade with the exception of the reservoir line. I needed to add an elbow to the line to make it work. Lastly, one of the most important things you need to consider are the brake pads. I ended up going with performance friction pads. I wasn't sure which one's to use so i called their tech line. They made a recommendation and that's what i went with. I was very happy with the pads they recommended.

So having gone through the same problem you're going through right now, this would be my recommendation. If you only plan on using the car on the street, before considering changing the brakes and master cylinder. Ensure your calipers,master cylinder, & lines are in good condition. Then, invest in a really good set of brake pads. Brake pads make a big difference.
If you plan on doing anything more than street driving then i would think the upgrade I mentioned above would work nicely for your car. Once you compare the size of the brake pads of the m-caliper vs the sc/carrera you'll understand. I hope this was helpful

[RWebb]

see Steve W's post above re 1984 or later carrera brakes

or you can spend more and put 930 brakes on - very pretty

some have had good experiences with Boxster calipers

BUT "better" brakes really means more "thermal mass" - i.e. a heavier rotor. That is only needed if racing and is the last thing to do, not the first.

[Steve@Rennsport]

Originally Posted by RWebb

some have had good experiences with Boxster calipers

Hi Randy,

I didn't mention that since they do not fit inside 15" wheels.

930 brakes are an excellent option, however they are not inexpensive.

[Tidybuoy]

This car is mostly for street use with ocasional auto-x.

The brakes are definatley not working correctly. Although the car will stop and does not veer, I would not be able to lock the brakes up. It currently feels a bit dangerous. I'm a strong guy and pedal pressure is not a problem. I would probably brake the pedal before I could get the car to skid. A volkswagen bug would stop faster than this car - even with drum brakes.

I've got enough info to get started....I will start by rebuilding the calipers (to include new pads as well) and change out the master cylinder. Then a good flush.

Thanks for all the advice.....Vern

[Driver_X]

If you going to go that far, might as well put in new brake lines as well eh?