Brake Booster (Page 2/6)
Dennis LaGrua MAY 14, 02:30 PM

quote
Originally posted by olejoedad:

The area to be moved with the hammer is the top of the lower frame rail, isn't it?



I've done three of these installs and should know the answer to that question but not sure. If you remove the brake booster you will see a step down area that I assume may be where the wheel well attaches to the lower frame rail. This is the area that needs to be tapped down just a little bit to clear the booster. Some guys tend to beat the crap out of this area but if you measure correctly only a very slight amount of bending is needed. The modification is really worth doing. The braking pedal response is very much improved.

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olejoedad MAY 14, 02:34 PM
Yeah, that's the lower frame rail/wheel well interface.

We've done several of those in the shop.

Every car I've driven with the S-10 booster seems over boosted to me.

And I'm curious as to what happens in a panic stop situation on damp or slick roads.
pmbrunelle MAY 14, 03:14 PM

quote
Originally posted by Dennis LaGrua:
The braking pedal response is very much improved.




quote
Originally posted by olejoedad:
Every car I've driven with the S-10 booster seems over boosted to me.



One person's improved response is another's overboosted.

How do you guys push on a brake pedal?

I find it hard to control a brake with too much gain, because I place the arch of my foot on the brake pedal, flexing my quadriceps to develop the braking force. I'm using gross motor skills, not fine motor skills, so the brake pedal can't be too sensitive. My heel is in the air, so I can swing it over to stab the throttle if necessary.

I think that many folks place their heel on the floor of the car (acting as a pivot), and then use their calf muscles to extend the ball of the foot. You can't push as hard on the brake pedal this way. I do it this way for light braking, if no downshift is expected.
hunter29 MAY 14, 05:24 PM
Thanks guys, yes the rest of my system is good, the hammer scares me thou.. lol
Spoon MAY 14, 11:18 PM

quote
Originally posted by hunter29:

Thanks guys, yes the rest of my system is good, the hammer scares me thou.. lol



When I did mine I drew a circle on the interfering area and used a ball-peen hammer to make a big dimple. Painted the area and it looks nearly factory.
Like mentioned above once the booster is in place you won't see the modification.

Spoon

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theogre MAY 15, 01:13 AM
Most claim the "big booster" is best are comparing to old booster, worse whole brake system w/ problems.
Many also claim OE booster "Fails" during "Racing..." Then push BS to use "Big Booster" when real answer is fixing vacuum problems.
Do Not Compare to ABS vehicles. Many are Way "Over Boosted" because makers expect ABS "Box" to prevent 1 or more wheel to lock. ABS often eliminates the Proportion Valve too for same reason but still have Natural Brake Bias w/ "weak" rear brakes.

On top of "normal" brake problems like worm out pads etc...
1. Most Vac Boosters are "Dual Diaphragm" That can Partly Fail causing high pedal effort.
2. All Vac Boosters can have problems w/ control valve, check valve or both causing "low vacuum" w/o obvious Vac Leaks causing same.
3. 84-86 Fiero has vac filter in engine bay that can plug up and small line that restrict air flow with long line. The small size (3/8") work w/ front engine vehicles because only 1 to 2 feet to reach the booster. GM "fix" this for 87-88 Fiero w/ 1/2" vac line and related fitting and deleted the filter. (Warning: FSM and 22P has no data for this and many parts stores don't list correct booster vac parts for 87/88 Fiero.)

GM and others Expect you to push brake pedal w/ ball of foot and even toes by people w/ small feet w/ foot on floor or near so because they done ergonomic work to know how people use whatever.
And make PB Boosters for this type of use even Before ABS. Even Non PB cars are made around same low effort pedal designs.
If you push brake or clutch w/ lower part of foot, worse heel, can cause wire and other problems as foot often hit pedal switches etc.

IF "Racing" or just driving hard and brake "fail" then have 1 or more of these...
Brake Fade because pads etc get overheated.
Low or No Vac because you keep engine RPM Too High for Too Long. Fix here is add big Vac Tank or even an Electric Vac Pump.
Brake Fluid Boiling because Wet Fluid, Brake Problems, Exhaust Problems or all 3.

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pmbrunelle MAY 15, 04:46 PM

quote
Originally posted by theogre:
GM and others Expect you to push brake pedal w/ ball of foot and even toes by people w/ small feet w/ foot on floor or near so because they done ergonomic work to know how people use whatever.
And make PB Boosters for this type of use even Before ABS. Even Non PB cars are made around same low effort pedal designs.
If you push brake or clutch w/ lower part of foot, worse heel, can cause wire and other problems as foot often hit pedal switches etc.



My dad has a K13 Nissan Micra, and you're clearly meant to keep your heel on the floor.

When I drive that car, my knee hits the plastic underneath the steering column. It is the sort of issue that would be discovered during a test drive though.

I'm fine in a Fiero, and in my Ford Ranger. Saturn S-series was good too.
longjonsilver MAY 15, 07:07 PM
One of the best mods i have done to my Fiero is the S10 booster. You don't need to tap much with a hammer. Its not easy to get the 4 bolts in tho with the bigger diameter booster. However i CAN be done.

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hunter29 MAY 15, 07:33 PM
So you don’t have to tap much, how much do you have to move the metal? 1/8 inch 1/4, 1/2 ?
olejoedad MAY 15, 10:56 PM
Somewhere in that range....