Not trying to be argumentative or anything, but that's not how it works. The pistons in the calipers are provided a pressure that forces the pads into contact with the rotors. The amount of pressure determines the amount of braking force.

If you apply more pressure there would be more braking force, and thus more heat generated. Either system modulates pressure in relation to how hard you press on the pedal. The calipers and rotors(the stuff that heats up) could care less whether the pressure is boosted with hydraulic pressure or vacuum.

 

Hydrolic fluid is more accurate than vaccum and when boosted can produce more pressure. Even Chevy uses hydro boost standard on both gas and diesel in 3/4 and 1 ton trucks.

 

Buy whichever truck you like, but I can tell you with certainty that the rotors, pads, and calipers will overheat every bit as fast with hydroboost as they will with vacuum assist. I've driven both and each system performs excellently. Once you lock the wheels any additional pressure is meaningless, and each system is capable of doing just that.

 

Even my Touaeg TDI uses hydro boost. Granted vacuum assist will work, but it will require more force on the brakes down hill under load, especially when its hot. I would love to hear Ford's reason why they went back to vacuum assist.

 

I'll chime in with Crazy here. Applying more pressure does not mean less heat. The heat generated has nothing to do with the boost system used. The heat geterated is a result of converting the kinetic energy of the moving truck into heat. The kinetic energy is a function of the mass and speed of the moving truck. When stopping the truck, the kinetec energy is converted to a specific amount of heat, regardless of which boost system is used. If the vacuum and hydro system are both capable of locking the wheels with the same or similar amount of applied pedal pressure, then they are both equivalent in terms of function.

I suspect the reason vacuum brake boost is not used on large vehicles is because the diaphragm diameter would have to increase in order to deal with the increased brake fluid displacement volume. You may have noticed that as the vehicle weight increases, so does the diaphraghm diameter. The diameter of a F250 brake diaphragm is as large as is practically possible.

-Carl

 

This is not something that i would worry about one way or the other. As an exsample I work on Sprinter vans as part of my job. Hydroboost has never appeared on any Benz designed, hydraulic brake system for unknown reasons. Sprinters are all diesel powered(no gas option), available up to GVWs of 13,000lbs, and stop just fine with vaccum boosted brakes. IMHO, vaccum brake systems have less problems over the life of the vehicle as well!

 

Pulling my 13K 5er out of the storage lot 1.5 miles home for preseason tuneup. Im going down the steep hill midpoint to my house and stop at the light. For some reason my eye noticed my brake controller wasnt lit up. Yep, for got to plug her in, but soon turned into the hood where I could pull over. Braking down that hill and stopping without trailer brakes was not even noticed. The massive brakes covered my lack of attention to detail (gotta start using that trailer checklist in the dash computer). Vacuumn on my 2012 born on Dec 14th. The brakes are like the rest of the truck, awesome...stopped 21K pounds from 40mph and I didnt notice. Speaking of stopping things, Love your sig chad149!

 

The systems do feel different when you are operating them. As I've said before in another thread with the same topic, the vacuum assist brakes seem to be dependent on the amount of pedal travel versus the amount of force applied - the hydraulic system offers some resistance to pedal application.
I personally feel that I can apply braking force more precisely with the hydroboost system, which is nice when bringing the vehicle to a soft, controlled stop. With the vacuum system I feel that the first bit of pedal application doesn't do much, and then it grabs - with no real difference in pedal feel, it doesn't work against you, you can push the pedal all the way to the floor without feeling much resistance. That's what I mean by 'pedal travel' - how far you push the pedal vs. 'applied force' - how hard you step on it. Also, the 'breathing' noise is another difference.
You could flip that around and say that means the vacuum power brake system works really well - the power assist helps to the point where you don't feel anything. It's like those new power assist steering systems in cars that make the steering so lightweight you could do parking lot maneuvers with one finger.

Yes, they both do the job. They have to. If it doesn't, you have reasonable grounds to complain about it. The power assist is not the weak link in the vehicle braking system though.
It's just "different" and therefore weird when you're using to driving your truck all the time and then you switch to a newer model with completely different brake pedal feel. If you drive the same truck all the time it is likely not an issue. I'm comparing F-350s to F-350s here. I can say I don't "like" it but there is no technical reason why it's actually BAD though. If it's better for business that's all the reason they need to switch.