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Re: [T3] Brakes are done!

On 7 Apr 2006 at 23:27, Constantino Tobio wrote:

> Here's what I'm noticing on my pedal, which is different enough that I
> just want to put my mind at ease.
> It's fairly soft, almost spongy, but I wouldn't go that far. Doesn't
> require a lot of force to get it to close to its stop (though enoguh
> pressure builds up to stop it). On a second pump, travel is about 2/3 of
> what it is on the first pump. I've bled until there was no air coming
> out of the bleeder hose.

As the calipers age and corrode, the first thing that happens is that 
the pistons stop retracting on their own like they are supposed to. 
The mechanism that retracts them is nothing more than the deformation 
of the square cross section seal ring in there, so there's little 
actual force available for pulling the pistons back from the rotors.

The end result is that old rusty calipers give you a very high and 
hard pedal. Blocked hoses make this even worse. At the same time, the 
rotors run extremely hot, the gas mileage goes down a bit, and you'll 
run thru a set of pads in 500  miles.

Everyone's first reaction to getting back in a car that has had its 
system rebuilt is that the pedal is now spongy, but it's actually 
back to the way it felt when it was new.

OTOH, it's also possible that your pedal is too low. If everything 
has been well bled (and there's no trick to this, it's easy) then the 
next thing to check is the rear wheel brake adjustment. These are 
often set too loose, just because they're not centered as the 
adjustment is done.

Centering is done by rotating the wheel while you do the adjustment. 
Rotate it both ways, to push the shoe into it's centered, or minimum, 
position. I will sometimes get in the car, start the engine, and run 
the wheels forward and backwards applying the brakes lightly in each 
direction, then get out and recheck the brake adjustment.

If you've already done all that and the brakes still seem soft, then 
I don't know what else to do. I have to admit that some of my own 
cars seem softer than I'd like. I have one car that seems to lose 
it's rear wheel adjustment almost instantly. It's like someone comes 
around and loosens them up the first night after I tighten them.

One thing you can do is to set the parking brake and then see how the 
pedal feels. That limits the pedal motion to the front circuit only. 
If the pedal feels extra high when you have the parking brake on, 
then the front brakes are probably fine.

If everything seems fine until you actually get out and drive, then 
check the front wheel bearing adjustment, and if your type 3 is 
earlier than mid-68, you might need to make sure you don't have the 
wrong (late) inner wheel bearings installed there. Wobble in the 
front wheels will push the pads out and require more pedal travel to 
bring them back in again.

I've actually also wondered about brake pads and shoes. Does anyone 
know if some brands or materials tend to be "softer" than others, to 
the extent that they'll compress and require more pedal travel?

Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA

List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org

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