740 GL: How to adjust brake booster?

#11

"Geronimo" <someone (AT) somewhere (DOT) net> wrote

Quote:

Its a 740 GL, 1989, brakes are non-ABS.

The brake padal doesn't feel spongy like air but you have to go all
the way to the floor, or nearly, before the car will stop. I assume
the brake pads are still good, there are no tell-tale metallic noises.
When bleeding the brakes estensively did not help, I changed the brake
booster; then when that did not fix the problem, I changed the master
cylinder. Bled the brakes extensively again....same thing!

It was this way when I first got it, but I am thinking that it is
like my 85 mercedes...you shouldn't have to go more than a quarter
inch even, before you begin to brake the car.

IT looks like the only thing left is the adjustment of the booster.
Don't have any manual to explain how to adjust it. To get it to brake
earlier (with less travel). I would think it has to start from a more
forward position. Do I turn the pushrod, or the clevis connected to
the brake pedal? IN what direction?
Before I atttached the new master cylinder, I had someone push on
the brake pedal with engine running while I watched to see how much
the pushrod was moving. It moved forward about an inch or inch and a
quarter, I would estimate.
Thanks for your help.

After the booster is adjusted, you can expect the original problem to
remain.

A "sleeper" is the lubrication of the front calipers. I let mine go too long
(on an '85) and the brake pedal kept going lower. In addition, the car
pulled to the left when I put on the brakes. With the front wheels off the
ground I found the right wheel could still be turned freely when the pedal
was floored - not a good sign. The slide pin had seized and would not let
the caliper float, so one pad was several mm away from the rotor. The rear
brakes (at least on mine) are dual piston and don't have that issue.

Others have reported the brake hoses (going to the calipers) deteriorating
and causing symptoms like this, but probably with more gradual onset.

Mike

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740 GL: How to adjust brake booster?

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Re: 740 GL: How to adjust brake booster? - 07-16-2005 , 12:08 AM