A 20.64mm or 22.22mm Master Cylinder Option, ...the "How-to" thread Options

[tomeric914]

My apologies in advance if this has been documented on here before.

Is 19mm too small and the Mercedes 23mm master cylinder too big? Well I've got a solution that is just right.

I was looking for a 20.64mm master cylinder option and stumbled across a thread on Pelican where someone had put a 1990's Corrado master cylinder in a 911 or 914. There was only but one picture and not much of a write-up so I figured I'd try and document what I did.

This master cylinder uses the same pushrod that you already have, though some adjustment will be necessary. You will also need to bend new brake lines if you want to do it right.

As with any brake work. If you don't know what the hell you're doing, don't do this.

Parts:
357 611 019 - this is for the 20.64mm master cylinder

357 611 019 B - this is for the 22.22mm master cylinder

911 355 322 00 - straight reservoir feed fitting

911 355 323 00 - angled reservoir feed fitting

7mm blue braided brake reservoir hose



You'll need to decide which master cylinder is right for your application. For example, my braking system is pretty much all mid-1980's Carrera sized calipers and referencing Bill Verberg's brake page, I found that the mid-1980's Carrera used a 20.64mm master cylinder. I also knew that my pedal travel was more than I liked while on track.

https://members.rennlist.com/1976c38/brakes.htm

I purchased all of the parts through Pelican, the 357 611 019 (20.64mm) is an ATE unit made of aluminum and was only about $100. The 357 611 019 B (22.22mm) is made by a few companies, is a cast iron unit and about $50.

Here's where you are today:



1. Drain your reservoir using a turkey baster so you don't wear the entire contents of the reservoir.

2. Disconnect all brake lines, the reservoir feed lines and unbolt the master cylinder.

3. Loosen the locknut and unthread the master cylinder pushrod from the pedal cluster, then run a tap through the threaded portion still on the pedal cluster to clean it up. Make sure the threads on the pushrod are clean and that the locknut threads all the way down on the pushrod. (I had to find a thinner locknut for my application. You may or may not need to do the same).

4. Unbox your new master cylinder and pop in the fittings as shown in the picture below. Use a dab of brake fluid to help lubricate the fitting where it inserts into the master cylinder. ALSO, you'll need to plug one of the extra ports on the master cylinder that you aren't using as seen below. I placed a piece of tape over all of the openings while fitting the master cylinder to keep dirt out.



5. Grease the tip of the pushrod before installing the master cylinder. Torque the two 8mm nuts to 18 ft-lbs. I left the washers off. VERY IMPORTANT - now adjust the pedal free play to approximately 1mm by turning the pushrod inside the car at the pedal cluster. Once adjusted, tighten down the locknut. Make sure that the brake light switch lever is in the correct position to actuate when the brake pedal is depressed.



6. Back under the vehicle, decide how you will connect the reservoir to the master cylinder. The metal ends of my plastic lines were rusty so I decided to cut them off and use a short length of 7mm blue braided reservoir hose to each line. You could also run the blue braided hose all the way from the reservoir to master cylinder. Use a dab of brake fluid to make it easier to install the hose on the fittings.



7. Next, bend new brake lines for the front brakes and a short piece for the rears.



8. Last, but not least, bleed the brakes reinstall the bottom pan and enjoy your new firmer, but not too firm, pedal feel!