The Ruckstell in my 26 Coupe started slipping and clattering in Hi and upon tear down the rollers on the shifter fork were found to be nearly worn away and the sliding clutch splines had been worn back ~ 1/4". Undoubtedly, this amount of latitude allowed a false neutral to develop. The puzzling problem is there was no oil in that part of the differential housing. Oil (85W90 NAPA) had recently been checked at plug level but was all confined to the gear side .
After repairs/replacements the rear end was blocked level and plumb on the floor and oil was squirted in through the open drive shaft port until it dripped at the filler plug. It only held 1-1/2 pints. The axles were spun by hand to disperse the oil, but the capacity didn't change. Tilting the axle about 20 degrees did not result in any oil moving into the shifter section after half a day, and it wasn't until the angle rose to 45 degrees that oil started seeping along the sliding shifter. After the tilt was reversed, that oil that could access this same seam flowed back, but left behind about a 2 oz that didn't reach the level of the clutch channel and remained even after leaving the axle tilted this way overnight.
I'm apprehensive about installing the rear end again until I get a handle on this lack of lubrication. It seems the bell housing of the Ruckstell seals to the inside of the differential case and there are no ports to allow routine oil flow from side to side. What little diffuses along the slider clutch during operation doesn't appear to be enough to keep the rollers and their channel lubricated adequately. Do these rollers and the channel need to be lubricated by hand?
Don, Stan Howe adds a grease fitting to the shifter housing. I don't pack that whole cavity with grease, but I slather everything in there with grease. Then add a bunch of pumps to the fitting on the housing, and give it a few pumps any time I'm greasing the car.
You're supposed to occasionally remove the shift lock and pack it and the area around the sliding clutch gear with grease. If you have not do it already it would be a good idea to open the Ruckstell up and check it's condition. Wear in the internal parts can result in a neutral.
I've added the grease fittings and know about packing the shifter housing which will keep the spring roller and shaft lubricated, but grease in there wouldn't appear to reach the rollers on the shifting fork unless it was really greased, and that's the area that concerns me.
Don, which is why you pack grease in around the sliding clutch gear. I put a couple large globs in mine.
Every T I own has a Ruckstell. I use straight 140 in it, Haven't ever had a problem.
How about a photo of the grease fitting location? Thanks.