Why do we run vacuum brakes as oppose to hydraulic brakes on our TJs?

Goatman

Goatman

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Question; why do we all run around on vacuum brakes instead of hydraulic? Every vehicle now has power steering so hyd power is already built in. I get why we used to use a vacuum system 50 yes ago. But a good hyd brake has sooo much more stopping power. The big rigs have run them for years. And with more and more (hopefully) diesel engines on the road it would be a good time to develop a good hyd brake system for lighter vehicles.
 
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Great question, I'm curious too. Figured this made more sense as a standalone topic, since it's a good topic of discussion (y)
 
Goatman said:
Question; why do we all run around on vacuum brakes instead of hydraulic? Every vehicle now has power steering so hyd power is already built in. I get why we used to use a vacuum system 50 yes ago. But a good hyd brake has sooo much more stopping power. The big rigs have run them for years. And with more and more (hopefully) diesel engines on the road it would be a good time to develop a good hyd brake system for lighter vehicles.
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We don't run vacuum brakes. We run vacuum boosters to supply additional leverage to increase the force output of the master to increase the pressure into the wheel cylinders.

All of the brake wheel cylinders for our service brakes are hydraulic.

If you are referencing hydraulic boosters, they are in use on lots of small vehicles unless you consider the Mustang to be a large vehicle.
 
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So, still why don't we run more hydraulic 'booster' systems instead of vacuum 'booster' brake system? The added power would be ideal (in my mind) to go with the larger tires and reduction of brake performance.
I did not know the new mustang was running hyd 'booster' brake system. But it shows all the more reason why more vehicles should. Even aftermarket brake upgrades don't seem to ever include going to a hyd 'booster's system. This is why I am asking you specifically. I highly doubt anyone else here has a better understanding of this. We easily (relatively) add hydraulic steering upgrades so powering a brake system should be on the easier side of things. And they are able to provide a considerable upgrade in braking force.
 
I would assume that the oems still use vacuum boosters the majority of the time because it's easy ,cheap, and proven.

Think of it this way, if you were in it to make money, which would you pick:

Routing another high pressure hydraulic circuit around the engine compartment to a hydroboost to increase brake performance when a 10 cent chunk of vacuum hose and a cheap tin can with a diaphragm in it does the trick.

I would pick the cheaper option .
 
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mrblaine said:
We don't run vacuum brakes.
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But why not? Everyone knows that they would work much better (like early windshield wipers) when we let off the gas pedal.:sneaky: Oh forget it, I just realized holding the brakes while flooring the gas to do a burnout at the stop light probably led us away from both the vacuum brakes and that stop light.:p
 
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Paul Ruggles said:
I would assume that the oems still use vacuum boosters the majority of the time because it's easy ,cheap, and proven.
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For at least 15 years or so brake boosters are electric. I can't say for certain that NOBODY uses vacuum any more, but it's rare. My '02 4Runner has an electric booster.

*Edit* I may have misunderstood what part of the system you're talking about. Not really sure what problem is solved by making the booster itself hydraulic.
 
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WallyWest said:
For at least 15 years or so brake boosters are electric. I can't say for certain that NOBODY uses vacuum any more, but it's rare. My '02 4Runner has an electric booster.
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All three of my cars including my wife's 2014 Lexus have vacuum powered power brake boosters.
 
Goatman said:
So, still why don't we run more hydraulic 'booster' systems instead of vacuum 'booster' brake system? The added power would be ideal (in my mind) to go with the larger tires and reduction of brake performance.
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There again though, you are assuming that the OEM knows you will be adding larger tires. They don't assume that and don't build for it. No reason to burden 90% of their customer base with cost that don't pencil out.

I did not know the new mustang was running hyd 'booster' brake system. But it shows all the more reason why more vehicles should.
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I suspect it was done for space, not performance.

Even aftermarket brake upgrades don't seem to ever include going to a hyd 'booster's system. This is why I am asking you specifically. I highly doubt anyone else here has a better understanding of this.
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I personally love hydroboost and if I could, I would include it with every big brake kit. It is fantastic.

We easily (relatively) add hydraulic steering upgrades so powering a brake system should be on the easier side of things. And they are able to provide a considerable upgrade in braking force.
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A larger vacuum booster works just as well and is much cheaper. I have a Dakota booster in Kat's TJ. With the 1" master on it, I got it up to 2700 psi on the gauge at the caliper. That's a bit much.
 
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Jerry Bransford said:
All three of my cars including my wife's 2014 Lexus have vacuum powered power brake boosters.
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Ok then, I guess it's a luxury feature now, lol.

I haven't worked on every car/truck out there of course, but everything I've owned since the late 90's seemed to be eliminating vacuum powered anything.
 
I bet it has a bit to do with vacuum power being free as opposed to hydro boost costing a bit of horsepower which in turn uses more fuel. I know the power loss is minimal but when the manufacturer is trying to squeeze every bit of fuel economy out of every vehicle built it adds up.
 
WallyWest said:
Ok then, I guess it's a luxury feature now, lol.

I haven't worked on every car/truck out there of course, but everything I've owned since the late 90's seemed to be eliminating vacuum powered anything.
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I dunno but like my '04 TJ, Wrangler JKs use vacuum powered power brake boosters too. I dunno about the newer Wrangler JL brake booster.
 
mrblaine said:
There again though, you are assuming that the OEM knows you will be adding larger tires. They don't assume that and don't build for it. No reason to burden 90% of their customer base with cost that don't pencil out.



I suspect it was done for space, not performance.



I personally love hydroboost and if I could, I would include it with every big brake kit. It is fantastic.


A larger vacuum booster works just as well and is much cheaper. I have a Dakota booster in Kat's TJ. With the 1" master on it, I got it up to 2700 psi on the gauge at the caliper. That's a bit much.
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I’m interested in this Dakota booster - how much custom massaging did you need to make it work?
 
BuildBreakRepeat said:
I’m interested in this Dakota booster - how much custom massaging did you need to make it work?
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I have to think Jeep might have suspected I might add bigger tires when they built the Rubicon. Upgrades to make it for hard offroad use without thinking larger tires might be involved is unlikely.

A hyrdoboost would be placed in the same spot as a vacuum boost. So the odds of leaking into the cabin is low. Brake fluid is more likely to do that.

Do they at least offer it as an option on those house sized 1 ton pickups? They keep bragging about tow capacity numbers going up every year. The hydroboost would be ideal for them. Plus adding a component on the front of their diesel engines just to produce usable vacuum would save $$. The amount of h.p. vacuum brakes saves compared to the load put on the engine by adding a port on the power steering system would be (in my little brain) minimal. I would think the OEMs would jump on the idea to offer such an upgrade. Adding 10 more cup holders is getting ridiculous.
 
why ?

I'd say the big reason for vacuum brakes being the standard is vendor supply inventory and cost management by continuing to use what works and what the public is used to. Status quo. If it doesn't break, keep using it. KISS
 
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