Author Topic: Brake master cylinder  (Read 175 times)

Offline Dmulder

Brake master cylinder
« on: September 14, 2018, 08:54:59 AM »
So last weekend was my annual Press On Regardless TSD rally in Northern Michigan. I ran it in my mini again this year and took a first time co-driver with me. It took the first leg of the rally for us to iron out the kinks and for me to trust him 100%.
The second, third, and fourth legs of the rally went very well for us and we were zeroing most of the controls. We weee having a blast running many of the old Stage Rally roads. We crossed the Mackinac Bridge and ran over 200 miles of two track and logging dirt roads in the beautiful UP. The weather was perfect.
Coming into the last service/fueling stop of the night with about 60 miles left to run we realized we had no to very little rear brake and the peddle went all the way to the floor.
We have fluid in the master cylinder, checked for obvious visual leaks (none).  Since we wanted to be safe we decided to drop out and head back to the hotel, load up and drive home. We arrived home at 4:30 am.
My question is this - I have front brakes, I have hand brake, I have minimal rear brake and fluid in the master cylinder. I've checked the rear drums. Everything looks fine. Could there be a problem with my master cylinder?  Are they worth rebuilding?  Does anybody know of interchangeable master break cylinders off of a car that my local parts store might have instead of ordering and having it shipped across the pond?

Thanks in advance
Devin
"In like a lamb, Out like a lion."

Offline tsumini

Re: Brake master cylinder
« Reply #1 on: September 16, 2018, 03:06:22 AM »
Are you single pipe system or split sytem?  If single my first guess would be to adjust rear brakes.
« Last Edit: September 16, 2018, 03:12:31 AM by tsumini »

Offline Dmulder

Re: Brake master cylinder
« Reply #2 on: September 16, 2018, 01:22:53 PM »
How would I know if it is a split or single system?
"In like a lamb, Out like a lion."

Offline MPlayle

Re: Brake master cylinder
« Reply #3 on: September 16, 2018, 01:52:29 PM »
The 'single line' systems have only one line connecting to the master cylinder.

The 'split' systems has two lines connected to the master cylinder.
(NOTE: There are three types of 'split' systems: two are front/rear split and the third is diagonal split.  The MiniSpares page for master cylinders has good descriptive titles and pictures for identifying your type.)

http://www.minispares.com/shop/classic/Brakes/Hydraulics/Master~Cylinders.aspx?041001


Offline Dmulder

Re: Brake master cylinder
« Reply #4 on: September 16, 2018, 03:13:11 PM »
It is definitely a split system. Any other suggestions before I spend the money to replace the master?
"In like a lamb, Out like a lion."

Offline 94touring

Re: Brake master cylinder
« Reply #5 on: September 16, 2018, 03:46:24 PM »
Tighten the drums till they won't spin, then back it off so they spin but drag enough to stop after about a rotation if you were to spin it like you're on the price is right.  You could of course bleed for good measure, but if that doesn't solve it and you still have a soft pedal, I'd turn toward the master as well.   I've replaced more masters on minis that have turned soft than I've owned cars.   I don't know why we can't just have parts that last nearly forever.

Offline tsumini

Re: Brake master cylinder
« Reply #6 on: September 18, 2018, 12:53:51 PM »
Agree with Dan.
It did sound like split sytem. Notb sure you can have good fronts and no rear brakes unless reaars are realy out of adjustment.