Brake master cylinder overhaul

Jon Weywadt · August 31, 2010, 08:12:22 PM

When applying the brakes the car always stopped on a dime, as they say "over there". But holding the pedal down I noticed that after a few minutes I could push it down further. Leting go and applying it again brought the pedal bck up.

Conclusion, worn piston seals.

So I got a new set from Simons (partnumber 13019A at 20€) and installed them this past weekend. In the process I overhauled the cylinder itself. Cleaned off all paint, brushed away all rust, honed the inside, rinsed, painted with 99,9% zink, followed by a rally black coat. Cut away old seals and installed new ones (eased by the supplied mounting fluid in the kit)

The result is a firm pedal, that stays where it is at, once applied.

A note of interest for you who are faced with this job.
When disassembling the master cylinder, you have to remove 2 cotter pins that hold the two pistons in place. It turns out that there is a hole in each end of the pin. this is handy, as you can insert a small hook and just pull them out. They are not seated very firmly.

davidewanprice · August 31, 2010, 08:45:38 PM

As allways, very nice to see, this will be a job for me over the winter so all the advise would be greatly appreciated

Jon Weywadt · August 31, 2010, 09:02:02 PM

Quote from: davidewanprice on August 31, 2010, 08:45:38 PM
As allways, very nice to see, this will be a job for me over the winter so all the advise would be greatly appreciated

Hi david.
I just modified my post to include the Simons partnumber for the repair kit.
Best regards.
Jon.

Oetker · September 01, 2010, 07:53:40 AM

I am not a big fan of reviving brake master cylinders this way.
My experiences are not so good, and with my mini's in the past it didn't last very long.
Most of the time the water in the brakefluid pitted the cylinders to much.
With a bit of searching you can find brake master cylinders for low prices.
This one I bought for €38.-

It is already fitted.
At the same time I revised the booster and made a new vacuum system.

System from a Volvo.

Jon Weywadt · September 01, 2010, 08:07:39 AM

Quote from: Oetker on September 01, 2010, 07:53:40 AM
I am not a big fan of reviving brake master cylinders this way.
My experiences are not so good, and with my mini's in the past it didn't last very long.
Most of the time the water in the brakefluid pitted the cylinders to much.
---

I inspected the inside pretty carefully after honing it. I saw no pitting, so hopefully it will last. Like I wrote, the pedal is firm and stays in place when brakes are applied.

I am curious about your vacuum booster. It looks like you have added an electric pump and a valve to prevent back-flow

Oetker · September 01, 2010, 01:35:51 PM

This is a vac-pump from a Volvo V40-60 diesel and it give a lot more vacuum then the engine.

This is the vacuum the engine delivers.

And this is the vacuum the Volvo pump delivers.

At first I only mounted the pump.
Pointing at the brake was enough to block all wheels so I took a regulator from the same car.
It regulates a little weaker then the Murena standard, but you can adjust the spring in the regulator to what you need.
Also it cut off the pump when under pressure is build up.

The regulator is used to switch a relays, because motor ask 4 Amp, and it is to much for the regulator.
Every now and then the pump makes a few turns to keep under pressure on specs.
It works OK and no more vacuum lurking on the engine.
Of course the vac system needs to be in shape.
During the build a vacuum leak was found on the switch for the headlights wich was there for a longer time making the engine cripple on 1 cilinder.

Jon Weywadt · September 01, 2010, 06:54:00 PM

Quote from: Oetker on September 01, 2010, 01:35:51 PM
---
At first I only mounted the pump.
Pointing at the brake was enough to block all wheels so I took a regulator from the same car.
---

I bet the headlights snapped up and nearly flipped over backwards

closing them must have been a "snap" too.

If you put skirts around the car, I bet you could suck it down to the road for some serious speed in turns.

Nice job though. I actually like the idea.

Oetker · September 01, 2010, 07:26:55 PM

One of the reasons to do this was to get rid of the long vacuum route, and I didn't like the the way it was mounted on the inlet.
One cylinder had a lean burn as I noticed at the spark plugs.
I couldn't find the leak, but this system made me clear that the vac.switch was the problem.
Also I need the space to place a vaporizer for LPG.
Extra advantage is when towing the brake booster works and the the engine doesn't need running to get the lights up/down.

RazorbackNOR · June 16, 2011, 09:33:05 PM

Is there a special trick for removing the brakemaster from the brakebooster, or is mine THAT rusted....?

Oetker · June 16, 2011, 10:36:33 PM

No tricks, remove the 2 nuts and seperate.

RazorbackNOR · June 16, 2011, 10:57:07 PM

Quote from: Oetker on June 16, 2011, 10:36:33 PM
No tricks, remove the 2 nuts and seperate.

Ergo rusted solid....
Seems like I have to secure it in a vice and give IT a few whacks with something heavy....

RazorbackNOR · June 17, 2011, 08:28:29 AM

Problem fixed. A little tapping with a hammer on the studs made it give. But damn, it was rusted solid!

klumzer · December 04, 2011, 08:32:43 PM

Quote from: Oetker on September 01, 2010, 07:53:40 AM

Oetker, there is an outlet on the brake master cylinder at the left bottom of it (refer to photo) for a wire in your car. What is it for? Originally it does not have.

Another question: Which cars use the same brake power controller as Murena? Are there any alternative part to install or a repair kit?

Oetker · December 04, 2011, 10:18:27 PM

Normaly the master is from Bendix and the M10 connection is not there, however I found around 10 different manufacturers that made the Murena master cylinder.
Some have it and some don't.
Mine is from Lockheed an has the connection.
I presume it is for connecting a switch for the brake lights maybe used on the Talbot Horizon.
The Horizon use the same Brake master cylinder .
Also some Simca 1510 and 1307/8 and 1609/10

Concerning the brakebooster I did not have found a replacement yet.

klumzer · December 05, 2011, 07:29:50 PM

Thanks.
I have a new master which is used in Horizon and it has the extra outlet. Some weeks ago I saw the photo of your car in a topic and I remembered that you have an extra wire from it. I just wanted to know what it is for. Probably I will close it with a blind cap. Maybe in the future if I would be bored...

I did not mean the brake booster. Sorry, maybe 'brake power controller' is not the right English name. I mean the item number 13056 in the illustrated parts catalog. Mine looks not so good...