Sticking booster

[shawnvan]

Hello,
I'm running a 7 inch duel diaphragm booster and have gone thru 3 different units all with the same result, they work great for 2 months and then they get sticky and won't release the pedal the last 1 inch or so. I believe they are all coming out of China, has anyone bought a USA unit if so any ideas who sells a good one.
Thanks in advance

[Apogee]

Can we assume a rather lumpy cam and a normally aspirated carbed engine? The air valve in the booster doesn't like gas and alcohol, so that could be a possible cause of your booster failures given the symptoms described and time frame given.

Courtesy of another smart brake guy from this forum, you could install a GM style vapor trap (http://www.posiesrodsandcustoms.com/.../pages4858.pdf) in the vacuum line and see if that solves your problem with a new booster, otherwise I don't see how American seals are going to like gas any more than Chinese ones do ;)

Tobin
KORE3

[shawnvan]

No it did this with my stock LS1 twice, the third one was with my cammed LS but not to lumpy and still fuel injected.

[Apogee]

What is the application?

Would it be correct to assume that your MC is functioning properly and dry where the piston seats against the snap ring? Brake fluid in the booster is generally not a good thing.

As for boosters, you have a few domestic options and most if not all of the remanufactured units are remanufactured domestically. I've had decent luck with the Tuff Stuff Performance brand boosters lately.

Not that it should have any effect on the air valve, but is there any reason you aren't running a dual-8" or dual-9" unit? Is it because you've been warrantying the 7" units? If so, it can't hurt to ask if you or the distributor can contact the booster supplier/manufacturer directly, as I would hope they're evaluating these units back through their quality departments? Maybe there's something about the design of that particular unit that's an issue...if so, swapping it out for an 8" or 9" unit might not only solve the early failure issue, but also provide a little more boost in the process.

Tobin
KORE3