They crack between the vanes and the shroud on the exit side.  Mostly from hydraulic shock when the pump loads.  If you let it go unchecked long enough, chunks of the vanes could break off and damage the bowl.  When the pump unloads, you have to take your foot out of it before it takes a gulp.  Driving style plays a big part.  If you baby it, it will never break.  If you beat on it, it will eventually give it up.

My stock 304 shaft twisted the splines before my MPD detailed Berkeley B+ gave up.

When you upgrade to a SS impeller, you will want to upgrade your shaft to 17-4.

Thanks for the info guys. Looks like I'll end up having to go stainless. My impeller is already pretty beat as well.

What's the pro's and cons for
 bronze vs S.S? They seem pretty close in price.


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I've got a Berk JE with a new 17-4 shaft and inducer and am looking for an SS "A" impeller.  You say B-1 racing?  Do they have a website or phone #?  I couldn't fine them on the web, but probably just me.