The Stovebolt Site Forums The Parking Lot Big Bolts speed axle

Hi all,
I have been off line for quite a while but I am gradually getting back to my 48 Loadmaster. The rotary valve that operates the two speed is shot(leaking)and caused my engine to idle rough (vacuum leak). Is there any aftermarket valves that can be used?
Thanks,
JHolland
Middle Ga.

I didn't have any luck with my local driveline specialty shop,here in Iowa. I remembered someone re-building a 2-speed vac-operated system back in the '80's. It looked simple enough,so I removed the 3, 9/16" bolts (on my '55 6500 T.F.). I noticed that the vacuum lines were dis-connected for a reason. the "pancake" had a hole DRILLED through the top of it,with what appeared to be a coat hanger attached to the rod that actuates the 2-speed! I removed all the screws attaching the "pancake" together,since the diaphram is sandwiched between the 2 pieces. AS I suspected,it was dry-rotted badly.I cleaned the mating surfaces with gasoline,as well as 2 layers of truck (20") inner-tube.I then cut the inner tube to fit the outline of the pancake,then I cut one duplicate,to form a double layer.I then "Permatexed" the mating-surfaces on the "pancake, and put the two halves together,to set-up over-night. The next day,I used an awl,to form the holes,so I could screw the "pancake" back together. I used J.B. weld to block-off the hole drilled for the clothes-hanger. I tightened down the 3,9/16" bolts,started "Mater" up,and WOW!! no vac.leak! Then I took "her" out on the road...Low and High side...Works Great!! Mine didn't have a rotary valve. the rod is attached directly to the diaphram. The two hoses are on opposite sides of the rod.Let air in chamber"1" (button "down"),you're on the "low' side. Let the air in chamber#2,(button "up"),you're on the "high" side. I had fun rebuilding this thing, and it's really easy to do! Hope this helps.

Gasoline, even if used for cleaning purposes only, and oil will eat rubber, if it expires someday, might look for neoprene to replace the inner tube.

Last summer I found a replacement diaphragm from Chevrolet. The part no escapes me but mine too was dry rotted. That sealed up the unit on the axle and I have traced the leak to the rotary valve. I removed it and cleaned it and found some sealing surfaces inside but couldn't come up with a material to fix it with.I used to drive an old IH that had a two way valve for the power divider and I wonder if one of these will work.
JHolland
Middle Ga

On my 46 I disassembled and cleaned the pan cake at the diff. and it was fine,(shifted diff with a vise grip a few times to loosen it up after many years) . Then I installed all new vac.lines. My vac. rotary valve is a sealed unit and was leaking also. Then while the engine was runing I kept shooting WD-40 in the line and let the vac. suck it up to the valve while fliping the lever around. It stoped leaking bad and now stoped leaking completely! That WD-40 is great stuff!

Thanks for the tip. I am an aerospace machinist by trade and I work with some pretty good engineers. I am thinking of asking one of them to design me a simple valve and see if I can build it. Gonna try the WD40 first!

Thanks
JHolland

Funny: I've been a machinist for 35 years. There's still a few of us, The computers can't do it all!

Sorry! I mis-understood that you were actually speaking of the vacuum-switch. Mine was completely missing from the transmission,where it is usually located,(at least on the T.F.-style-trucks.) I have a couple of late-'40's Studebaker 2-tons,that have been sitting for years,and decided to mount one of the units to the fire-wall,which makes it super-easy to "plumb-into the vac-line from the intake manifold. I have a spare vac. switch from a '49 Stude,if you're interested. I've tested it ,and it DOES WORK!! I'm not posting it for sale,as it is my spare,but if you want it,send me a P.M. B.T.W... I was a rubber-roofer for 15-years,and Goodyear,Carlisle,and several other manufacturers RECOMMEND cleaning mating surfaces with gasoline! This is the only solvent they recommend. Since "gas" evaporates almost as soon as you apply it,I don't see how this would damage the rubber,in any way. The diaphragm is in an air-chamber,also free of any gear-oil contamination,unless you have a serious vent issue in the axle-housing.