Soft left brake pedal

Darren S · #1 03-13-2011, 06:27 PM

On the first flight of the day the left brake pedal depresses quite a bit. When I release the pedal and then step on it again, it is much firmer. The right pedal doesn't do this so something is leaking somewhere.

I didn't build the plane so I'm looking for a little guidance before I hit the hanger tomorrow.

Is regular automotive brake fluid usually used ?
I suspect the left caliper. I think I'll look there first rather than the brake reservoir.

Thanks,

Darren

Mel · #2 03-13-2011, 06:30 PM

Sounds like you have air in the left circuit somewhere.

Geico266 · #3 03-13-2011, 06:57 PM

If you can ask the old owner what fluid he used. Most aircraft do not use car brake fluid because it will harm paint, and absorb moisture. It would not be a good idea to mix them.

You will need to bleed the brakes from the bottom up using a pressurized system of some kind. (see link below) I made one using a 1 gallon garden sprayer filled will the red Mil Spec 5606. This of course is a subject of hot debate.

Brake Fluid Wars --------------> http://www.vansairforce.com/communit...highlight=5606

Brake Bleeder ------------------>http://www.aircraftspruce.com/catalo...leedertank.php

Darren S · #4 03-13-2011, 07:43 PM

Thanks for the help.

Bleeding the brakes is a two man job. I will try to find out what the previous owner used. If not I may have to drain out all of the fluid and start over.......... sheesh........I think I may wait till the annual in May since there isn't really a safety issue.

Darren

alpinelakespilot2000 · #5 03-13-2011, 08:12 PM

Quote:

Originally Posted by Darren S

Bleeding the brakes is a two man job.

Actually it's quite easy to do as a one-man job. If you read one the threads posted above you'll see how.

LifeofReiley · #6 03-13-2011, 08:17 PM

Easy one man job from the top, takes about 15 minutes even with dual brakes.

chrispratt · #7 03-15-2011, 08:11 PM

Is it a Matco master cylinder unit? After you bleed the brakes, if the problem recurs you may need to use an overhaul kit to make sure the O-rings are okay (available from Van's). if that doesn't solve the problem then consider an alternative such as the Grove units. I switched years ago after having a similar experience, and have had no problems since.

Chris