dual master cylinder

[ajwans]

What's the current best practice for converting a 67S to dual master
brake cylinders. I have seen kits like the one on Alter Ego
but exx$$y.

While we're on the topic, do the single master cylinders have a habit
of failing?

Again, please excuse my ignorance.

andy

[obrut]

andy

you may be confusing dual master cylinder with dual circuit?

daul m/c are primarily used in race cars so you can adjust the relative braking force front to rear.

dual circuit is a safety upgrade from single circuit.

[ajwans]

You are right, I am confused. Dual circuit is what I want to know about.
What needs to be done, what are the best bits to get to effect this upgrade?

andy

[ErVikingo]

Andy,

Get a system from a more modern 911 and you have the dual circuit (off the top of my head I can't recall when they started). For track duty though, the (best) way to go is with a dual M/C setup like what I have listed on my website.

Cheers, Juan

[Gearbox]

I agree with Juan, finding a used late model pedal cluster would be the most cost effective way to go. Alter Ego looks like they use the original 901 system and fabricated a new brake pedal and mounts for the second master. Tilton also sells a very nice set up that will also work that is cockpit adjustable. But the bottom line is what are you trying to achieve? Any dual system will require you to drill holes in the floor pan and re route the brake lines. Great for a race car where you can dial in front to rear bias for track conditions, but IMHO a bit overkill for street use. Plus there are other mods that will give you better braking and feel that can be bolted on and off. The early S's are becoming very valuable and rare, cutting holes is probably not a good idea.

[ttweed]

You are right, I am confused. Dual circuit is what I want to know about.
What needs to be done, what are the best bits to get to effect this upgrade?

Andy-
The factory changed to dual circuit MCs in 1968. Conversion kits for the older cars are common, often sold for the 356 cars as well. They are around $300 or so, and include a new 19mm dual circuit MC, new reservoir (with dual feeds to the MC) and hoses, clamps, etc. Some people install the new reservoir on the inner front fender, per the later cars, and some keep it in the smuggler's box, which is where the reservoir was on the '67S originally.

Try NLA Limited or Klasse 356 for the conversion kit, or just buy the later parts separately.

The failure of the single circuit cylinder is no more likely than the dual circuit one, but the downside is that when the single circuit one fails, you have only the E-brake as backup. With the dual circuit, you will likely lose the brakes only at one end of the car, and you will still be able to stop it with the brakes on the other end.

Dual master cylinder setups are an entirely different animal, as people have pointed out, for racing applications only.

TT

[ErVikingo]

The dual m/c assembly used on my race car and featured on my website (www.alteregoracing.com) is a racing or high end track car or DE application.

For clarification, different than other dual m/c applications out there, this unit bolts into the stock location and the master cylinders are inside the driver’s compartment, similar to the factory SC/RS assembly. This kit does not require any modification to the chassis. This pedal assembly is a dual master cylinder unit with adjustable balance bar.

The kit contains all the hoses, fitting and hardware necessary to connect to the stock brake lines. It also incorporates a brake light switch.

I used to use a Tilton proportioning valve with a dual circuit system and this system is night and day.

Cheers, Juan