qwiketz

Hi guys. I'm in the process of trying to adjust the brake pedal position. It's currently too close to the floor before the brakes kick in. My question has to deal with the plunger on the power brake booster.

I replaced mine a while back. The box said that it was more than likely adjusted to the right spec. However, I need to adjust it toward the brake master cylinder more. To do this, how are you guys doing this? The plunger spins so it's not easy to adjust. In addition, it's tight in that area. I'm guessing I need to hold the base of the plunger and use a 8mm wrench to untighten it. Any advice or tricks would be great. Thanks!

oldalaskaman

is it possible you got the wrong plunger rod installed with your new pb booster and possibly needed to re-use the one off the original? or possibly even the wrong part? There's sometime a little adjustment involved but not usually that much. You might also remove it from the brake pedal, make the adjustment and reinstall it.

tpi 421 vette

There is an adjustment on the rod from the brake booster that contacts the master cylinder. I had to do the same thing when changing brake boosters. I ended up using vise grips and twisting the rod outward. My pedal was also low like you are saying. I can't remember if there is a jam nut behind it, but some vise grips will work. I would try to match it to the length of the old one, if you still have it. But you can just unbolt the two bolts that attach the master to the brake booster without having to undo brake lines. So adjust it out more and try it. If you a have to do it a couple times, it's not that bad.

samsonb

Unbolt the master. Push down on the brake pedal and have have someone hold it. That way the push rod is sticking out of the booster so you can get a vice grip to hold the rod while you unscrew the screw. Then it is trial and error if you have the rod out enough but not too far. You can put some grease on the end of the rod. Then bolt the master down, unbolt to see how close the rod is to the master. I think there is an actual gauge you are supposed to use for adjustment. But I think you just want to get the rod close to the master with just a small gap between.

kimmer

Dumb question but did you bleed your lines?

ddahlgren

What year is your car would be my first question if a 90-91 they use a different booster than other years. I have been all through this a while back. The earlier cars did not have the ecu mounted under the hood with a bracket bolted between the master and booster so everything at that end needs to be about 1/4 inch longer than 89 and earlier.
Dave

C409

You say you replaced the booster a while back ... was this a problem right away ? If not , try retightening the attaching nuts under the dash ... I had some that came loose just slightly and snugging them up made a WORLD of difference ... I actually double-nutted them and havent had a problem since ..........

Blue95C4

I just replaced the brake booster and the clutch and brake petal lined up, but The switch that turns on/off the brake lights is a good half inch away from the tab on the brake petal. Did I do something wrong ?

This is a 95 six speed and I don't see any gap between the firewall and the booster.

Thanks

Don in Huntsville

C409

The brake light and cruise switches are push / pull to adjust ... you probably moved it inadvertently while working under the dash .......

Blue95C4

Dave, You hit it.

The Advance Auto Parts / CARDONE ( 54-71405 ) Booster is 1/4 inch shorter than my stock booster. At the switch, that is over 1/2 inch difference.

This time I unhooked the hydraulic lines and moved the master cylinder out of the way, and it's much much easier this way.

Don in Huntsville

Blue95C4

How hard are these things to push/pull ? Do you turn them 90 degrees or what ?

Don in Huntsville

Blue95C4

Advance Auto said that 54-71405 was the right part #.

After looking at everything, I decided that it should work.

I reinstalled the booster and reset the cruise and brake switches and
all is well again. When I moved the switches forward I recalled hearing the same sound the day before when I was upside down under the dash. I had moved the switches without realizing it.

I removed the brake lines, but after hooking everything up again, the petal got hard at about the right place. I think any air in the lines will work itself out after sitting a few hours.

I appreciate everyone's help.


Don in Huntsville

samsonb

What you do is push the switches towards the front of the car. Then you pull back on the brake pedal till the clicking sound quits. That should reset the cruise and brake light switch.

tequilaboy

When adjusting the output pushrod for length via the vice-grip method, be sure to keep the booster applied until after the vice grips are released.

The output rod is only retained in its bore by this radial spring clip, and it is very easy to separate from the diaphragm, if the booster is allowed to return.

C409

....... Push down on the brake pedal and push the stoplight switch toward the pedal ... you will hear it click as the threaded portion passes through the switch mounting clip ... its not an easy push ... then pull the brake pedal back ( up ) against the switch til it stops clicking ... not too much force , might damage the booster .............

pcolt94

The actuator rod from the booster might be out of adjustment. If to short will cause excess brake travel. If it is to long it will depress the masters piston and activate the brakes. Unbolt and pull back the master. Check the length of the rod. It should be approximately just below the imaginary surface line of the booster. It needs approximately 1/8 inch of clearance to the master due to heat expansion of the parts.

When adjusting the rod end bolt, the rod had to be held and the nut turned, in to shorten. I clamp the rod with thin vice grips VERY LIGHTLY and adjust nut. Depress the brake pedal half way down to get the rod out in the open so it can be worked on easily.

Jack the front up before you start. Then unbolt the master and make adjustments. After adjusting (if necessary) the rod, re-check brakes pedal and wheel rotation for dragging. Might take a few tries

qwiketz

Thanks for the advice everyone. Depressing the pedal half way is the trick I was looking for. I was able to do it a little yesterday on my own, but with the girlfriend pushing on the pedal, it should be much easier.