Soft Brakes
Thread Starter
|
Elder User
Joined: Oct 2009
Posts: 871
Likes: 1
From: New Albany, MS
Soft Brakes
Hello folks,
Let me give you the low down,
I have a unique brake system on my 79 as it is not your typical setup (one tons, 44 inch tires, Yada yada). These are the components:
92 F350 twin piston disc brakes, single piston rear disc brakes
Bronco Grave yard disc-disc proportioning valve
2002 F350 master cylinder (1-3/8 bore)
Hydro boost unit
brand new stainless flex lines in place of the rubber.
Everything is new. The brakes stop the truck pretty good, but even with the new proportioning valve (designed for discs all around) the rears still slide before the fronts. Also it feels like the system still has air (despite two different bleeding methods: vacuum, and traditional two man pumping and bleeding inserting plug to keep the proportioning valve pressure switch from moving ). The brake pedal is not firm until the second stroke.
I thought the master cylinder may have been defective, so I replaced it, and after meticulously bench bleeding it and bleeding my brakes again I still have the same problem, front brakes that do not seem as powerful as the rears and a soft pedal.
What is going on?
Let me give you the low down,
I have a unique brake system on my 79 as it is not your typical setup (one tons, 44 inch tires, Yada yada). These are the components:
92 F350 twin piston disc brakes, single piston rear disc brakes
Bronco Grave yard disc-disc proportioning valve
2002 F350 master cylinder (1-3/8 bore)
Hydro boost unit
brand new stainless flex lines in place of the rubber.
Everything is new. The brakes stop the truck pretty good, but even with the new proportioning valve (designed for discs all around) the rears still slide before the fronts. Also it feels like the system still has air (despite two different bleeding methods: vacuum, and traditional two man pumping and bleeding inserting plug to keep the proportioning valve pressure switch from moving ). The brake pedal is not firm until the second stroke.
I thought the master cylinder may have been defective, so I replaced it, and after meticulously bench bleeding it and bleeding my brakes again I still have the same problem, front brakes that do not seem as powerful as the rears and a soft pedal.
What is going on?
Tuned
Joined: Oct 2010
Posts: 357
Likes: 11
From: Roanoke, VA
Have they always acted this way since the build? Have you checked the length of travel of the pushrods between the Booster and Master Cylinder, compared to length of travel of the pistion inside the master cylinder?
As for rear's locking up first, not really sure what to say there. I assume any factory brake components are long gone or bypassed? Have you tried something along lines of a Wildwood adjustable proportioning valve? I've used them on a couple projects with disc/disc
As for rear's locking up first, not really sure what to say there. I assume any factory brake components are long gone or bypassed? Have you tried something along lines of a Wildwood adjustable proportioning valve? I've used them on a couple projects with disc/disc
Logistics Pro
Joined: Jul 2005
Posts: 4,217
Likes: 154
Ar you sure that the front brakes are plumbed to the front circuit on the combo valve? And that that is plumbed the the proper port for front brakes on the master cylinder?
Never thought about the calipers being too wide. Are your rotors thinner than a '90s F350?
Only other thing I can think of is the not having proper leverage.
Never thought about the calipers being too wide. Are your rotors thinner than a '90s F350?
Only other thing I can think of is the not having proper leverage.
Thread Starter
|
Elder User
Joined: Oct 2009
Posts: 871
Likes: 1
From: New Albany, MS
I will check again, but I'm pretty certain that the primary port (front brakes, rearward port on master cylinder) goes to the front port on the combo valve. I know for a fact they are oriented correctly on the combo valve.
Leverage isn't the problem, a soft pedal is.
Leverage isn't the problem, a soft pedal is.
Trending Topics
Laughing Gas
Joined: Mar 2016
Posts: 757
Likes: 43
From: Cheyenne, Wy
"Thekingofcows"
In your video, when showing the prop valve, you have a white cap on it. What is the white cap for and what is it called? Thanks
In your video, when showing the prop valve, you have a white cap on it. What is the white cap for and what is it called? Thanks
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
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
Senior User
Joined: Dec 2009
Posts: 176
Likes: 1
From: Spring Hill
Could the soft brakes not just be normal for the newer master cylinder and hydro boost? Reason i ask is my '06 ram has always had a soft pedal when stopping and stops easily and if i lift up and hit it again it will be hard. So could this just be how the newer system is?
Postmaster
Joined: Nov 2011
Posts: 2,553
Likes: 10
Some brake systems are hard to bleed. ABS and maybe hydroboost. One time I had your situation - stops but soft pedal - that no amount of conventional bleeding would solve. I paid a shop to pressure bleed the brakes and fixed. Since then, fine. May be worth a try.
Thread
Thread Starter
Forum
Replies
Last Post
jrockdiddy
1948 - 1956 F1, F100 & Larger F-Series Trucks
11
Nov 15, 2015 11:12 PM