Replacing Master Cylinder
Thread Starter
|
Posting Guru
Joined: Dec 2004
Posts: 1,023
Likes: 0
Replacing Master Cylinder
My master cylinder and rear wheel cylinders are leaking, so i'm replacing them this weekend. I have heard (and read) many people having problems with the proportioning valve after doing something like this. My light isn't on, and i'd like to keep it that way. I was just going to list how I plan to do things, and ask if anything raises a red flag.
1. hand pump fluid out of old MC
2. bench bleed new master cylinder
3. install new MC. Use new pushrod? (manual brakes)
4. install new rear cylinders
5. re-bleed MC
6. bleed each wheel starting with the furthest from MC
7. mash brakes to re-center proportioning valve?
8. test drive
1. hand pump fluid out of old MC
2. bench bleed new master cylinder
3. install new MC. Use new pushrod? (manual brakes)
4. install new rear cylinders
5. re-bleed MC
6. bleed each wheel starting with the furthest from MC
7. mash brakes to re-center proportioning valve?
8. test drive
Senior User
Joined: Jun 2007
Posts: 140
Likes: 0
From: Milwaukee, WI
I have replaced just about everything on my brake system EXCEPT the proportioning valve. I have never touched it and (knock on wood) have had no issues while bleeding any part of the system. Usually, the toughest part that you are looking at would be removing the hard brake lines from the wheel cylinders without damaging them. The nut will rust to the line and twist right off. Trust me, I know! 
Good Luck!
Good Luck!
Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
I quite honestly have never touched the proportioning valve when bleeding my brakes but
I decided to look it up in the 1981 factory service manual and, whaddya know, they say it
needs touching while bleeding the brakes.
It doesn't say *only* for the rear brake, and what needs to be done is dependent on vehicle:
I decided to look it up in the 1981 factory service manual and, whaddya know, they say it
needs touching while bleeding the brakes.
It doesn't say *only* for the rear brake, and what needs to be done is dependent on vehicle:
Elder User
Joined: Jun 2010
Posts: 509
Likes: 4
From: Casper, Wyoming
My master cylinder and rear wheel cylinders are leaking, so i'm replacing them this weekend. I have heard (and read) many people having problems with the proportioning valve after doing something like this. My light isn't on, and i'd like to keep it that way. I was just going to list how I plan to do things, and ask if anything raises a red flag.
1. hand pump fluid out of old MC
2. bench bleed new master cylinder
3. install new MC. Use new pushrod? (manual brakes)
4. install new rear cylinders
5. re-bleed MC
6. bleed each wheel starting with the furthest from MC
7. mash brakes to re-center proportioning valve?
8. test drive
1. hand pump fluid out of old MC
2. bench bleed new master cylinder
3. install new MC. Use new pushrod? (manual brakes)
4. install new rear cylinders
5. re-bleed MC
6. bleed each wheel starting with the furthest from MC
7. mash brakes to re-center proportioning valve?
8. test drive
You forgot step 2A- adjust pushrod to spec. (just to make sure it has play at the pedal). I don't remember what the spec is, but you need some play in the pedal for the m/c to work right with the booster.
Power bleeding is the easiest way, and a Motive Power bleeder can be had for less than $50. I fabbed up an adapter in about ten minutes using a scrap of bar stock and a piece of rubber.
Thread Starter
|
Posting Guru
Joined: Dec 2004
Posts: 1,023
Likes: 0
Thats one of the biggest questions I have, I don't have power brakes, so no booster.
Do I still need to adjust the the rod?
The new (rebuilt) MC came with a new rod, should I use it or reuse the old one?
I noticed on the end of the new rod that there is a groove in the round part of the rod, should there be some king of bushing or something in there (it didn't come with one).
Do I still need to adjust the the rod?
The new (rebuilt) MC came with a new rod, should I use it or reuse the old one?
I noticed on the end of the new rod that there is a groove in the round part of the rod, should there be some king of bushing or something in there (it didn't come with one).
Elder User
Joined: Jun 2010
Posts: 509
Likes: 4
From: Casper, Wyoming
Thats one of the biggest questions I have, I don't have power brakes, so no booster.
Do I still need to adjust the the rod?
The new (rebuilt) MC came with a new rod, should I use it or reuse the old one?
I noticed on the end of the new rod that there is a groove in the round part of the rod, should there be some king of bushing or something in there (it didn't come with one).
Do I still need to adjust the the rod?
The new (rebuilt) MC came with a new rod, should I use it or reuse the old one?
I noticed on the end of the new rod that there is a groove in the round part of the rod, should there be some king of bushing or something in there (it didn't come with one).
You still need to check that the pedal has enough play. I doubt the amount is critical so long as it's more than 1/4 inch and less than 3/4 inch, but I'd want you to look up the spec. You just don't want the rod to have NO clearance or too much clearance.
Too much=the brake pedal won't have full travel, Not enough=the master won't push the right amount of fluid.
Neither situation is common, but it pays to check.
Trending Topics
Thread Starter
|
Posting Guru
Joined: Dec 2004
Posts: 1,023
Likes: 0
Thanks, i'll use the old one then. I'll also ignore the proportioning valve, unless I run into one of the situations described. I assume the rod clearance is just how far down the pedal travels before the rod begins to move towards the cab? And power bleeding is just bleeding with the engine running, so that it speeds the proceedure up?
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Moderator
Joined: Nov 2007
Posts: 22,415
Likes: 92
From: Denver Metro Area, CO
Power (AKA pressure) bleeding is a method of forcing fluid through the hydraulic system
under some sort of pressure (generally, air) from the top. I see a Motive product talked
about on here but have no experience with it myself.
Pressure Brake Bleeder
Some people have luck with what's known as vacuum bleeding, where a vacuum is applied
at the bleeder screws to draw fluid through the system. I recently got one from Harbor
Freight based on a recommendation of a friend of a friend but I'm not too awful impressed
by it, the clear tubing connecting the bleeder screws & waste fluid containment vessel
never seems to totally fill with fluid so I never get the warm, fuzzy feeling that there is no
air being let back up into the system.
Brake Fluid Bleeder
under some sort of pressure (generally, air) from the top. I see a Motive product talked
about on here but have no experience with it myself.
Pressure Brake Bleeder
Some people have luck with what's known as vacuum bleeding, where a vacuum is applied
at the bleeder screws to draw fluid through the system. I recently got one from Harbor
Freight based on a recommendation of a friend of a friend but I'm not too awful impressed
by it, the clear tubing connecting the bleeder screws & waste fluid containment vessel
never seems to totally fill with fluid so I never get the warm, fuzzy feeling that there is no
air being let back up into the system.
Brake Fluid Bleeder
Thread
Thread Starter
Forum
Replies
Last Post
rickm15752
1968-Present E-Series Van/Cutaway/Chassis
6
Feb 5, 2018 02:34 AM
BruceF350
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
5
Feb 28, 2010 01:55 PM
RicManSr
1948 - 1956 F1, F100 & Larger F-Series Trucks
14
Jul 21, 2009 11:40 AM
