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Topic: Mushy Brakes - Again... Any guidance is appreciated (Read 180 times) previous topic - next topic
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Mushy Brakes - Again... Any guidance is appreciated
Hi Everyone,

I am reposing my question in it's own thread, as it was a bit off topic.  Sorry to re-post...

Quote from Larry W;

"When a master cylinder is replaced, there is a rod, between the pedal and the cylinder that must be adjusted so there is a slight amount of clearance, any pressure on the master cylinder, when the pedal is released, will cause problems..
The usual indiction of a mis-adjusted MC is having the brakes slowly apply themself, as the brake fluids heats up and expands.
This can bring you to a stop and/or cause extensive overheating and damage to the brake system.
It's surprising how many 'mechanics' don't know about this adjustment."

My post and questions:

Larry - or anyone else!

Is it possible that the rod that you speak of could come out of adjustment and lead to mushy brakes?

3500 miles ago I had a new master cylinder and other brake work done. 1500 miles later the brakes had become mushy. The shop replaced the cylinder free of charge and problem solved until... 2000 miles later and mushy brakes have returned. The brake system has been inspected multiple times and all issues fixed.

Currently the fluid is full, so no leaks. Any insights I can bring to the shop appreciated!

Any brake shop recs around Las Vegas also appreciated!

Pete
Pete
1994 RB
Re: Mushy Brakes - Again... Any guidance is appreciated
Reply #1 –
No, a mis-adjusted actuating rod can cause the brakes to lock up. Mushy brakes usually means contaminated brake fluid or air bubbles. Do they feel mushy after several pedal pushes with the engine off? If not, it could be a hydroboost issue. I would inspect all caliper seals, brake cylinder seals, master cylinder seals, and all brake line connections for signs of leakage.

Steve
2004 FL
2013 Honda Fit
Re: Mushy Brakes - Again... Any guidance is appreciated
Reply #2 –
Thanks Steve,

Definately firm after a few pumps with the engine turned off.

Pete
Pete
1994 RB
Re: Mushy Brakes - Again... Any guidance is appreciated
Reply #3 –
Quote from: Peter Weisel date=1557188994 link=msg=202719 Definately firm after a few pumps with the engine turned off. [/quote
.

The hydroboost's accumulator allow one or two brake applications, when the engine is off, it should always firm up with the engine off.
I agree with Steve, you have air in the system and it should not be keep occurring, odds are there is something bigger going on with some other part of the brake system.
Go to a brake specialist, many mechanics are not familiar with hydroboost systems. where the boost is provided by the power steering pump, not the engine's vacuum.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Mushy Brakes - Again... Any guidance is appreciated
Reply #4 –
Thank you Larry! We'll take it either to Ford or to a specialist in the next few days. Till then just camping and staying put :-)

Pete
Pete
1994 RB
 
Re: Mushy Brakes - Again... Any guidance is appreciated
Reply #5 –
When we took our first trip in our 1990 we began to get mushy brakes after frequent brake application on a windy forest road.  Eventually the pedal would go almost to the floor. It turned out to be the seals in the master cylinder. The test is  while you are stopped in a safe spot you apply constant firm pressure to the pedal and it slowly sinks lower the longer you stand on it. The fluid is actually seeping past the rubber seals in the piston and allowing the rod to move to the end. O'reilly master cylinder fixed it. The other problem was the rear drum adjustments. They were designed to be self adjusting by braking when you back up.  That might have worked 29 years ago when it was new but these days I adjust them by rotating the brake shoe star every start of travel season. Originally they were barely making contact on braking and made for some long pedal travel. It also put the burden on the front discs which caused a lot of unnecessary over heating and long stopping distances.
1990 26.5 MB