My Cherokee was built in the last three weeks by transplanting all the running gear from a 98 into the body of a 93 - fortunately not by me! - and there were a couple of challenges along the way. The one major unsolved problem is the brakes. Despite having been bled, they're very spongy, and don't engage at all until the pedal is almost to the floor; it'll stop, but not in a hurry, and not with any kind of confidence.

The builder replaced the booster and master cylinder with junkyard parts after some problem with the 98 parts. I'm not sure if he bench-bled it [I'm checking with him] but he's nobody's fool and I can't imagine he'd have forgotten to do that. I checked the calipers, and they're right-side-up. [Yay for Search!] The system holds pressure, and there don't appear to be any leaks.

Any suggestions?

 

Purely my opinion, I won't trust my life or those around me to any brake parts sourced from a bone yard. The cost of new is much less than a funeral.

 

x2

 

Yeah, my next stop - unless somebody's got a better suggestion - will be a factory-new master cylinder. It's probably not the booster, right? It's more likely to be the master cylinder, or calipers?

 

With the two boosters I've had go bad on me,not on Jeeps,one was the bladder inside which gave me a vacuum leak (affected engine idle) and a hard brake peddle. The other was a fluid leak between the booster and master cylinder.

 

One note: the guy who built it pointed out that the older-style booster might have a shorter rod: could this cause the brakes to not engage until the brakes are almost to the floor?

 

What kind of symptoms did you have when the booster was bad? Someone mentioned that it'd make the pedal more firm, as I wouldn't be getting as much assist, but brakes aren't really my thing.

 

Symptoms were that I had to push the brake pedal HARD to stop and the engine idle increased some due to the vacuum leak.

Your guy is right about the rod. You need the correct length. Some vehicles were adjustable some.

 

I wonder if I can just put a post-98 booster in, so the rod is the right length. Probably won't fit in the body correctly, though, right?

 

Turned out to be the booster rod length [for those who search this out later], which is different on different years.

 

Thx for the update!