Brake pedal hard to push and air\vaccum sound

cleartoy

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Brake pedal hard to push and air\\vaccum sound

Ok, i got a 94 Toy 2wd, recently installed set of wider arms that did not have a provision for steering stops. So when i turn lock to lock in either direction, the calipers hit the lower arms and push the pistons back in the calipers resulting in no brakes till i pump em up.

Welp after having them on for 2 weeks and hitting the calipers several times, sat, the pedal is hard to push(as if no power assist) and when the pedal is depressed, i hear a hissing sound under the dash.

I figure either a piston is stuck in the caliper, and or the brake booster is shot. It also idles funny when the pedal is depressed like vaccum leak.

Any ideas? Thanks again.



85 Toyota xtracab 4x4(for sale)
94 Toyota stdcab 2x4
99 Yamaha YZ250

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GMS739

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Re: Brake pedal hard to push and air\\vaccum sound

its time for a power brake booster.

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phorensic2k

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Re: Brake pedal hard to push and air\\vaccum sound

I have this same problem, but I did not know it was caused by the same situation I have. Funny thing is, I have a '96 GMC Sonoma with 3.5" lift spindles ([censored]). If I lock my wheel in one or the other direction (left is worse) then I have NO brakes until I pump them up again. I too had the hiss-of-death when i stepped on my brakes and idle-hunt (vaccuum leak). But I never thought it was because of the calipers hitting, hmmmm, or is it?

Well, my fix was to take the vaccuum line off the brake booster and plug it up with a lug nut and then put the hose clamp around the lug nut. My right leg is extremely strong now, hehe. My fabricator is going to mount up a linkage system to give me more of a mechanical advatage instead of fixing the brake booster. Why, you ask? Well, let's just say we are doing A LOT more than that to the truck.
 

1992f150

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Re: Brake pedal hard to push and air\\vaccum sound

mind if I ask what kind of arms you put on?

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ntsqd

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Re: Brake pedal hard to push and air\\vaccum sound

If you make brake pedal linkage that gives you a lot of leverage you will have a very long travel pedal. The normal ratio for non power brake pedals range from 6:1 to 7:1. If the existing pedal's ratio is in this range, I would recommend that you try removing the booster. You could simply remove the check valve, the plastic dohickey (that would be a technical brake term) that the vacuum hose used to attach to, to try out what driving with no booster is like. That check valve's removal will let the booster exhaust the compressed air it's building up when you press the brake pedal. Note that this is one way to make bleeding power brakes much easier as well.


Sounds like both of you need steering stops installed/adjusted to keep from hitting the calipers.


TS

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cleartoy

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Re: Brake pedal hard to push and air\\vaccum sound

They are Total Chaos Uniball arms. I have to make stops for them, as the threaded holes in the spindles are too far away for just bolts threaded into them(tried that).

Planning on running 1/2" plate off the front of the arms with bolts out of the spindles.

Is the booster a dealership\junkyard only item, or Pep Boys?

Thanks!

85 Toyota xtracab 4x4(for sale)
94 Toyota stdcab 2x4
99 Yamaha YZ250

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Timmah

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Re: Brake pedal hard to push and air\\vaccum sound

Yup, those are pretty classic failure symptoms of a booster gone south! Now, do yourself a favor and dont start trying to modify your brakes to work without the booster, especially if your truck is street driven.

You can find a booster at a junkyard, but check prices at your local autoparts store first, it might not be that bad. (I like clean parts that come with a warranty).

Oh yea, I almost forgot. When you replace a booster or a master cyl, you also need to check and possibly adjust the booster / pushrod clearance to factory specs. Overlooking this seemingly miner item could result in residual brake pressure / brake drag or too much pedal freeplay.

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ntsqd

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Re: Brake pedal hard to push and air\\vaccum sound

Personally I think boosters are an abomination & should only be used on vehicles that are too heavy to stop otherwise. If you get the overall ratio in the right range on a truck that size you should not need a booster.
My own Toyota still has a booster because I'm too involved in other projects and too lazy to take it off.

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 

Timmah

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Re: Brake pedal hard to push and air\\vaccum sound

Ok, you can take off your booster, but only if you ditch the power steering too. That way you wont be tempted to turn too fast when you are having trouble stopping!

But seriously, I agree that real race cars dont have boosters, but they are designed that way from the get go. I guess I side with the 70 or so new veh manufacturers that currently sell vehs in the US when I say that boosters serve a useful purpose for daily driven street vehicles.

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cleartoy

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Re: Brake pedal hard to push and air\\vaccum sound

Thanks guys. I got work to do. Let you know what happens.

85 Toyota xtracab 4x4(for sale)
94 Toyota stdcab 2x4
99 Yamaha YZ250

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ntsqd

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Re: Brake pedal hard to push and air\\vaccum sound

I think they sell vehicles with power brakes because the 90th percentile have been brainwashed by advertising into thinking they have to have power brakes. If you're willing to do a little homework I say you don't need power brakes on a light duty vehicle. A tow rig is a different story......

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 

Timmah

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Re: Brake pedal hard to push and air\\vaccum sound

Aw c'mon ntsqd, where is your sense of adventure! :)

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ntsqd

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Re: Brake pedal hard to push and air\\vaccum sound

I'm sitting on it and I ate @ Del Taco today........
:)

TS

"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
 
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