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GRUNT

Master Cylinders & Brake Boosters

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Greetings all,

I am curious if there is a general rule of thumb for the life span of a master cylinder and brake booster. Especially if it had sat for, oh I don't know, 10 years. Had the Jeep out around town today and then after looking under the hood, I noticed some weeping. It appears to originate from around the lid of the master cylinder, continuing down onto the booster. I cleaned it up and plan I driving the Jeep all this week to check if the condition will duplicate. Also, the fitting around the brake booster vacuum hole(not the elbow, but where the elbow enters the booster) looked cracked.

 

  1. Does anyone know the part for that rubber ring/fitting the elbow slides into?
  2. Can a MC and/or booster "go bad" from sitting around? The Jeep seems to stop around town just fine, but will not stop while in 4-Lo. That specific condition might be related to R&P gearing and T-case low gearing, combined with the V8 power.

 

The Jeep originally came with drum brakes in the rear but has since had read disc breaks installed. Some articles I have read state you can get a master cylinder designed for disc all corners that evens the braking power without changing the proportioning valve. This might be an option later down the road, but I am just trying to improve the condition of what I have.

 

You know, in case I find myself on a "forest road." 😉🤣

 

YJ Brake Booster.jpg

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The seals in the master have failed, time for a new one. You could possibly find a rebuild kit, its easy enough to do, but with the lifetime warranties and the low cost of replacements, it doesn't seem worth it to me.  That rubber grommet is available at any parts house in the "Help" section.

That master and prop valve were designed for a Disc/Drum set up.  You will have much better braking response with the correct Master.  Disc brakes require more fluid to operate (larger piston) and the prop valve will limit fluid psi to the rear to prevent drum lock up.

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1 hour ago, Curly said:

The seals in the master have failed, time for a new one. You could possibly find a rebuild kit, its easy enough to do, but with the lifetime warranties and the low cost of replacements, it doesn't seem worth it to me.  That rubber grommet is available at any parts house in the "Help" section.

That master and prop valve were designed for a Disc/Drum set up.  You will have much better braking response with the correct Master.  Disc brakes require more fluid to operate (larger piston) and the prop valve will limit fluid psi to the rear to prevent drum lock up.

 

Okay. Thank you, sir! I will look at my bookmarked articles to find a suitable replacement. At first glance there were a few that people stated were for a all disc vehicle and a matching mounting pattern.

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