Master Cylinder Conversion - Upgrade
Hey Jon, do you want to add this to the manuals section?
Upgrade of Master Cylinder to Dual Cylinder
I know that many of us have done this conversion and fumbled our way thru it. This has been discussed many time but I have never seen any step by step with pictures. (Who needs instructions, just show me a picture)
I have the privilege of being mechanically inclined by learning from my dad many years ago. Wow… it’s been 34 years now, I sure miss him
I read most of the postings about this conversion and understood them but thought others might be confused.
This is not the only way of doing this….your mileage may vary…..
Some of the links on conversions:
http://www.m715zone.com/vb/showthread.php?t=4935
and many more. Just do a search on master cylinder
I chose to use the late 60’s early 70’s master cylinder. Mainly because it was in stock.
Here is my parts list:
Master Cylinder #10-1331 - $16 plus $10 core
Napa 3/16 Union Inverted Flair – Female 3/8”-24 Inverted - BK 641-3290 $1.29 - far left
Weather Head 3/8” Inverted Flair - Plug - #131x3 - $1.79
I used these fittings because I was cutting my line to length and wanted to cut down on connections
Napa Brake Line Fitting 1/2”-20, BK 641-3321 $3.95
Napa Brake Line Fitting 9/16”-18, BK 641-3323 $3.95
.
If you buy ready made lines you will need these adapters. They are pictured on the right
Napa 9/16” Adapter – BK 641-3309 $3.49
Napa 1/2” Adapter – BK 641-3305 $1.99
3/16” steel brake line ~$5
1/4” steel break line. ~$5
(I purchased a 51” line because I was bending my own and I knew I would mess up, which I did. lol)
http://img.photobucket.com/albums/v7.../68M715037.jpg
Remove you old Master Cylinder and mount the new one
http://img.photobucket.com/albums/v7...68M715001a.jpg
Remove the line going to the rear cylinders and the line going to the master cylinder.
http://img.photobucket.com/albums/v7.../68M715040.jpg
Install the plug going to the rear ( I removed the block to clean it and for pictures)
http://img.photobucket.com/albums/v7.../68M715042.jpg
I used a coat hanger to get the general shape of my brake lines. There are many website that talk about making the brake lines. Just Google it.
Here is the end result. I chose to not install a booster at this time.
http://img.photobucket.com/albums/v7.../68M715044.jpg
http://img.photobucket.com/albums/v7.../68M715045.jpg
http://img.photobucket.com/albums/v7.../68M715046.jpg
Notice the single fittings at the master cylinder?
All that is left is to bench bleed the M/C and bleed the system
Until next time
Wart Hog
Testing the output pressure of a Master cylinder
Quote:
Originally Posted by
Roy
Is it new or reman? We quit using remanned m/c entirely due to high failure/poor quality issues.
One day we pressure tested 12 units from 3 suppliers. NONE of them would supply the 900/600 minimum required pressures.
First test on a brand new AC/Delco unit provide the required psi and then some. I think it tested 1100/800.
After reading this thread, I need to bring it back to the top with a few questions. How do you actually test the output pressure to these master cylinders? Is there a "test kit" sold at the auto parts stores that screws into the master cylinder ports to test the output of a master cylinder?
I put a re-manufactured 10-1371 on my M725 last fall, and now I'm seeing that I should have used a 10-1331 which has a 1.125 bore. And, with the 10-1371 with a 1" bore, I do not have aggressive braking that I think I should have. I have HUMMER tires and recentered rims on my truck that I am trying to stop. Am I asking this master cylinder to do too much? Are these two master cylinders inadequate for this larger tire application?
Any advice? Thanks in Advance,
What vacuum booster would you pair with the 10-1331?
This is a great write-up. Thanks for sharing these details. I'm renovating the brake system in my M715 and following your instructions. If you were to add a vacuum booster, is there a booster that would pair nicely with the 10-1331 master cylinder and fit into the M715 without modification?
Any advice is appreciated.