The Stovebolt Site Forums The Parking Lot Big Bolts Two speed rear end splitter.

I've got a 57 Chevy 2-Ton with a two speed rear end. The way you shift the rear end is a splitter selector mounted on the gear shifter. A cable runs from this splitter selector to a splitter control valve mounted on top of the tranny. It has five hoses running to it. One small one, about 1/4 I.D. and four larger ones with about a 3/8 I.D. When the selector is in high I can hear a vacuum leak and it is affecting the engine performance and it even kills the engine every now and then. Are these splitter control valves still available or what is a good replacement?

They likely are but my guess is a hose leaking or a hose fitting. The control valve would be available thru heavy duty parts suppliers or HD truck dealers.

It's got new hoses and clamps, so I don't think that's the problem. Plus the vacuum leak can be heard in the area of the control valve.

Have you tried your local Napa auto parts house?
Bring that valve in and set it on the counter.

It could be the diaphragm & you hear it in going through the valve. Hold you hand or a shop towel around the valve & see if you can locate the leak.

ratru,There are two valve "stoppers", in the control valve. To gain access,loosen the hose clamps,and remove all 5. Remove the two bolts that secure it to the SM420. You'll need to split the casing to access the cable-anchor point,to remove the unit.Once you have the unit on the bench,inspect the bores for dust/debris,that may be causing the problem. My "stoppers" were fine,but enough "junk got into the bore,to cause a leak. You may be able to replace just the "stoppers", (if worn),which would be much cheaper than buying a new unit. Be careful when splitting the housing,to try and save the gasket. I had to use "Permatex. It split in 3 places. L.o.L. Hope this helps.

Vacuum 2 speed diaphragms are notorious for going bad. I usually start at the other end and apply vacuum to the chamber, then check the lines. If that is good, I tackle the selector valve.