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Discussion Starter #1
I've had my "new to me" 05' F250 for a few years now.....and the one thing I'm just not happy about is the braking power. I've went through and put all new calipers and rotors on it, new Wagner HD pads, new rubber lines to the calipers, flushed the brake fluid, and also powersteering/hydroboost fluid.......and although the brakes work ok, they just don't seem all that great. I know it's a 8,000lb truck...but I would have through they should be better than they are.

Could the Hydroboost unit and/or master cylinder need replaced? Or do they just go bad...and not really slowly wear out?

I know it's a 15yr old truck and it's not going to have as good of brakes as a new 2020......but I would just think they would be a little better. The brakes on my 04' Dodge Ram 1500 were much better than this truck.
 

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Master and hydrobooster, no. Power steering pump, can.

The Wagner HD pads are probably going to be a low FF rating on the edge code friction scale if I know my Wagner. Something in the high FF or GG ratings would get you where you want to go. Except, there is no way to tell if an F rating is high or low, so you'd have to hunt for pads that have G in the edge code.

Rotors, no matter the bells and whistles still have a friction coefficient of 0.32 by themselves, which falls into an E rating. You have to establish the transfer layer on to the rotors (all friction material does) to match the pads.
 

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Discussion Starter #3
So the power steering pump can affect braking power?
 

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Since the brake booster is a hyroboost system the power steering pump provides pressure for the steering gear box and the brake booster. I use oem Ford pads but performance truck brake pads from a company like EBC can improve your braking as well. I use the EBC "Greenstuff" pads in my 1969 Cadillac Fleetwood Series 75 which weighs as much as my truck and it improved it greatly over common replacement offerings.
 

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I have replaced all four calipers, all 5 brake lines with stainless braided, im on NAPA and 1AAUTO rotors and OEM pads..again. I have had my hydroboost bled and my braking still sucks. The pedal is now firm w/ the braided lines but honestly, it feels like it could be alot better.

I know Wilwood has a nice 6 piston caliper setup but tis like 2500$. if you figure anything else out, LMK cause i too have been searching for a better solution.
 

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I see a thread merge in your future.

 

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Discussion Starter #7
I see a thread merge in your future.

Yep....same issue I had bad then. The brakes still suck.
 

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So the power steering pump can affect braking power?
Yes, it's basically a hydraulic cylinder, higher pressure, higher force. The hydroboost has priority over the steering, which is why in parking maneuverings it can be hard to turn the steering wheel. But it's not that the stock pump is sub-par, these trucks have a high scrub radius, so the brakes are trying to prevent the wheel from rotating, which it has to do for the turn.

There are three ways to increasing brake output, increase the rotor scrub radius, increase the friction material coefficient of friction or increase the clamping pressure. If you increase the piston size to increase the clamping pressure, that requires more pedal travel due to the increase in fluid volume displaced. You can make up for that with a larger master cylinder, but then the brake pedal force needed is higher. Things get counter-productive real quick.

Some believe if you increase the scrub area of the brake pads, making them larger, increases the friction. It does not because as you increase the contact area you reduce the unit loading (lbs/sq-in) of the pads against the rotor.

So at the end of the day, the consumer is left with two things, buy pads with a high coefficient of friction, or install a setup with larger-diameter rotors. aka install F-450 axles with its brakes.

And if you have a Superduty with vacuum brakes, you are in worse trouble due to the effectiveness of hydro over vacuum at the highest pedal efforts. Data from 2006 Superduty trucks. At maximum pedal effort permissible by NHTSA (150lbs), a vacuum boosted truck attains 500psi less in the hydraulic lines.

767931
 

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Discussion Starter #9
Nope...mine doesn't have vacuum brakes....I didn't know any of the 6.0 diesel trucks did. I think I might try doing the SS lines....see if that firms things up.

As far as brake pads go.....what are the most agressive ones you can get that would work good on a truck? EBC Green stuff? Hawk? Others? Are they worth the extra money over standard pads?
 

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I believe Jack @TooManyToys was trying to illustrate the differences / similarities between vacuum and the hydroboost systems -- he knows his stuff on braking

I guess I do not understand the problem you are having with the brakes
I have owned two '06 F250 now and both will slide the wheels on asphalt and activate the ABS system without excessive pedal pressure
you mentioned using SS lines to "firm things up" -- are you bottoming the pedal out?
 

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It's the gas motors that have the vacuum booster.

I've run both Performance Friction "Z" and Hawk LTS on Superdutys and have been fine with them. The Hawk has a higher metallic content so its cold driving effectiveness is a little low that I notice. Which brings up one issue with the testing that goes into the Edge Code ratings, the first designation, cold, isn't as cold as some people normally drive their vehicles. Plus the temperature bands are too wide. The test was developed when drum/drum vehicles were still predominant.

I've run Power Stop pads on other vehicles and they have been good. The Z36 is touted as being 17% higher in friction then "OE".

Which then brings up many of our choices have to be by subjective ratings of others, along with the Edge Code. And very few companies tell you the Edge Code until you open the box, so I've left pads on the counter in some stores depending on what I'm trying to achieve.
 

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Idk about the OP but after calipers , pads n rotors , stainless lines and a re bleed I press the pedal , it goes about 2-3 inches before I feel it forming up. Then I need to press more to get a feeling of it actually slowing the truck down. It just feels like the pads aren’t doing anything lol


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As hydro mentioned, we never had an issue sliding tires either with all the Superduty vehicle tests we ran. A little harder with the '99-04 trucks, but the friction material was chosen was not my ideal.

For those that don't know, after working as a friction material compounder for the first 5 years, I was in charge of all development and prove-out testing of friction materials for my company, both OE and Aftermarket. We were the supplier to a very large amount of Ford vehicles for the three decades I had worked for the company, and I also had the designation of being the project leader for the prove-out of the P131 launch, Superduty trucks. The company did away with vehicle testing in 2008.

Adding less expansive hose to the brake system can firm up the pedal travel, but no energy is lost to the clamping force of a caliper. There are three levels of brake hose available to the auto manufacturers depending on the expansion rate. Ford chose the least expansive for the Superduty, mostly due to the length of the front brake lines. In some cases, the aftermarket rubber lines are not as good, level 2, so you have to be careful. Many times the shorter pedal travel noted is due to the re-bleeding of the brakes, a minuscule amount of air does accumulate and it does not take much to alter the pedal travel. It's not necessarily the braided lines.

Those two charts are from actual vehicles we had under test. At the beginning of every FMVSS 105 stopping distance test we ran, I had added another sequence where we would check pedal travel at the beginning. That wasn't a pedal effort check, it was a pedal travel test. There were two aspects to that. One is that some friction materials are more compliant/compressive than others. The second is to know if we had bled out all the air as every test (500 miles) had new calipers installed. During the fade sequences of the FMVSS 105 tests, an important aspect to analyzing the test is how long of pedal travel you have. You can't do that effectively if you have air in the hydraulics.

Pedal travel has an important role in the subjective rating of brakes' effectiveness, so it should never be underrated. Kelsey-Hayes did a study decades ago where they had a group of people comment on the effectiveness of two vehicles. The only thing that was different was the pedal travel, and it was 100% that pedal travel was the declaration of good brakes.

The other thing that travel will affect is the runout of the booster, which also has an important aspect of the "effectiveness" of the brakes under high deceleration. In the vacuum boosted chart you see a knee in the curves at about 60lbs Pedal Effort, with the Hydro at ~705lbs PE. That's the runout of the boosters, the point where there is no longer booster assistance to the hydraulic pressure, you are now in manual brake mode. That point has a dramatic feel in brake effectiveness, you are pushing much harder to increase braking.

So anything that causes longer travel will make the brakes feel like they are not as good. It can be hoses that are expanding more, usually, it's that accumulated air has not been bled out over time (we used to bleed brakes every few years), and it can be tapering off the brake pads from wear. That will be worse when one piston of a dual piston caliper hangs, or slide pins, not that Superdutys have that issue often. So during accelerated wear/durability tests one of the things I looked for was taper in the brake pads. More so due to the tangential forces as you'd not see piston or pin issues in such short of time.

767939



And that brings up another cause of excessive travel, rotor runout. I guarantee 99% of you guys never check that installed rotors meet the service specification of below 0.0015" rotor runout. In the above of an OE test, you'll see the front rotors are checked for TIR at the start and end of every test, and that includes the FMVSS 105 tests. You'll notice it didn't move, and despite the short duration of the test in miles, it dissapated enough energy during that time to project wearing out the pads around 30k miles. How many of you have worn out the OE brakes in 30k?

A high runout of the rotors widens the distance between the pads, knocking back the pistons into the caliper deeper. The extra piston travel takes up brake fluid volume, pedal travel, and in the end, during a hard stop, you can get into the area of booster runout. The brake don't work as well.

From my perspective, anything about brakes becomes a deep rabbit hole.
 

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Discussion Starter #14
Is that right?? .0015" run-out? Only one thousandth run-out is the limit? Or did you mean to say .015" .....15 thousandths?
 

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You guys have me on a rare day, I usually don't talk brakes much anymore.

Yep. It's in the service manuals. At the assembly line build, the standard was 0.0010". It's damn hard to find aftermarket rotors that meet the spec. Every time I install rotors I check runout and clock the rotor to achieve the lowest runout.

You guys develop pulsation and declare it warped rotors. The issue is not the rotors moved around with heat (some can, depending on design and casting issues) but millions of dollars of testing show its rotor runout and brake pad abrasiveness, which wears the rotors to have thickness variation (DTV) between the rubbing surfaces. Pad abrasiveness can solve or worsen the issue. In my world, we look at pad abrasiveness during brake-on and brake-off usage. Brake-off abrasiveness has a huge impact, the wearing of the rotor at the highest runout. Brake-on abrasiveness is a truing effect.

The same exact vehicle I showed above. This time the durability test used an aftermarket candidate (I said we did test for both OE and aftermarket sides of our company) on the front brakes which were more rotor abrasive, and in fact, had a higher coefficient in friction.

By expectation, the higher friction rating shifted the work bias to the front brake so the front pad life went down while the rear OE life went up. But look at the rotor runout. More abraded to running more true. Pad taper wear mostly unchanged, but that's caliper design, not pad composition. I'd rather have the first situation.

767940
 

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I always learn something useful on this forum. Thanks for the info.

So could it be that I’m cheap n choosing sub par rotors , pads ? By not getting the OE rotors ?


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I have a different perspective then most will have. I still have OE "Blue Box" rotors stored for my truck, so I'm partial. The Motorcraft rotors made by Federal_mogul for Ford (the OE were TRW) should have the same finish and runout spec as OE. The company spent $10 mil to upgrade the plant back in 2001 to improve the rotors sold to Ford over what they sold as Wagner. I bought a set of rotors from Raybestos and they were double the runout of what OE was on that vehicle, despite the literature stating they met OE standards. They went back.

There's an accumulation of things that can contribute to a longer travel or performance less than expected. I mentioned the lower colder performance of Hawk LTS. But I bought them for the better bad trailer brake situation I might encounter. Brake decisions are always a compromise.

But to the intent of the question, I don't buy rotors that have slots or holes, I buy solid rotors that are more expensive and check the runout on install. I wrote close to 5,000 vehicle test reports on vehicle brakes, worked with guys from TRW, Bosch, Kelsey-Hays, Ford, etc. Next to the friction material choice, rotors that run true are the most important thing to me. The only times I have ever had pulsation from rotor thickness variation is when the tighter rotor manufacturing specs were adopted (~1998) or when I get the ba corrosion-erosion of rotors due to our region road de-icing salts.

Hydro mentioned he's always been able to skid a Superduty. When we ran the ABS Failure sections of the FMVSS 105 which are run at GVW weight, the test drivers typically were at wheel skid by 50-60lbs pedal effort. The Pedal Effort/Travel graphs above show that at about 3.5" for the vacuum boosted Superduty and 4" for the hydro boosted Superduty. While the hydroboost gets you more hydraulic pressure, it does sacrifice a little travel. Now those charts are done at a static, parked state, in movtion there is some rotation of the calipers that causes a higher fluid volume, slightly longer pedal travel, 3/8 to 1/2".

In normal braking on the highway, we tend to brake at about 200-250 hydraulic psi, which in our test trucks would be about 1.75" ideal. I say ideally because I know we had all the air out, the hoses were in excellent shape, no rotor knockback, and there was no taper wear to the pads at that point. Unfortunately, I don't have the data graphs from the individual stops where we would have the pedal travel documented. We rand with travel transducers along with the pressure transducers and all the other instrumentation, including pedal effort sensors. If you are close to 3" of travel, that's a little long.
 

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Discussion Starter #18
Is there one brand/type of pad that delivers more friction than the others? I would think that having a nice aggressive pad would work wonders......I don't really care if it eats up rotors, or makes lots of brake dust. I mostly tow on the highway...so I'm not using the brakes a lot, but when I need them...I need them.

It sounds like that better pads are my only option, unless I want to swap all of the knuckles/hubs/brakes over from a 14' or newer truck....which sounds pricey, and a pain in the butt.

I'm running heavy 10-ply Nitto Terra Grappler 305/55/20 tires on aftermarket wheels. The wheels are lighter than oem, but the tires are much heavier...I'm sure that extra rotational mass doesn't help with braking. The overall diameter is very close to the oem size, so that's good I guess.

Thanks for all the great info TMT!
 

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I've been out of the industry for 12 years. We used to also run tests on competitors' products so I had a good understanding of the product out there at that timeframe despite the edge codes back then. But most aftermarket formulations are only out there for 3 to 5 years before they get replaced by something new. And in the last decade, that means cheaper to make. This far out, I can't give you a definitive answer.

The PS Z36, aggressive EBC versions or PFC "Z" may be more in your liking in that order. The Hawk severe-duty pads probably would to incorrect as that is more heat-activated then the LTS pads are, and in highway driving, if you are not making many stops the brakes will be cool when you really need them.

Rotational centrifugal force does play a role, but it's good that your diameter is close to OE. Tire leverage over brakes is often unappreciated. I'll use my 2003 as an example.

The front rotors had a brake scrub centerline radius of about 11", the tire rolling radius under a load of about 14.5". So the tires had leverage over the brake of about 2.64 to 1. If someone went to 35" tires the ratio changes to 3.00 to 1, so a reduction in brake leverage by 13.8%, that's a lot of braking to lose. Just by upping the diameter of the tires.

And with the higher GVW rating and increases in tire size availability from the factory, why the brake calipers and larger diameter rotors were needed. It doesn't take much of a rotor diameter change to have an effect, but when you are limited to caliper to wheel clearance, you have to up the pistons, then master, then pedal ratio......

1999-2004 rotor on top of 2005 rotor, by full diameter. The other side of the rotors at 180º is even, half of what is shown is the radius change.

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another thing to possibly help would be steel brake lines. Rubber lines will expand under pressure which can reduce the brakes effectiveness. Steel braided lines do not expand when pressure is put on them.

Just a thought to help.
 
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