I had a leaking axle seal on my 70 skylark after a 500 mile round trip to the goodguys nationals in Columbus last week. I bought the rear end used off a board member. It is a 69 b.o.p 8.2 with 2.93 posi. It has the SET9 taper roller axle bearings in it. So I disassembled and replaced the seals and bearings today, I just don’t quite understand how this set up holds bearing preload and how it actually retains this taper bearing? Maybe I’m missing something obvious but the bolt on plate presses the axle seal in, then there is the taper roller bearings. Surely the plate against the seal is not what they are relying on to hold bearing preload? Can someone explain this setup to me?
The race goes into the tube and seats against the shoulder inside. The bearing cone seats into the race. The seal goes up against the ring on the bearing cone. When everything installed and torqued down,the retainer plate pushes everything together to make a preload. This is why the thickness of the seal is important. If the thinner seal is used,you won’t get the proper preload. The bearing will seat from the race and the weight of the car will push down of the housing,leaving the axle shaft to pull up on the seal and let oil out.
It is a ENGINEERING BLUNDER in my opinion. The original GM axle bearings for this rear were straight roller bearing NOT tapered. IF they would have just keptthe old system bearing the seal thickness would not be an issue. as the axle will never deviate up and down enough to mess up the seal. The seal from the factory in the 1971 -1976 should be .490... There were late 69 and all of 1970 oiled bearing rears that had the 2146 seal and the depth of the tube housing end had less depth to use the 2146 and oiled axle bearing ... THEN in 1971 GM increased the depth of the bearing into the tube and also increased the seal thickness to make up the depth increase into the housing tube. I just try to avoid playing with the 1969 -1976 BOP bolt in axle rears. I have even gone to the extreme of making these rear into c-clip rears by changing the ends...Or go with a after market 7900 Moser end and use a sealed ford bearing instead. Just another day in the life of next generation of BAD PARTS! Jim JD Race
I just can’t imagine relying on an oil seal to keep your bearing preload. I’m no engineer but this seems like a bad design to me….
The moser ends are weld on correct? How do you make sure they are true before welding. I ,at go with this option if it fails another seal.
I put the 7900 ends on the 12-bolt Chevy rears. I do everything in a jig. Sometimes they “look” like they are crooked,but now they are straight. As Jim mentioned,the original bearings were a straight roller. They all had endplay,but didn’t matter because nothing was unseating or pulling on the seal. I have no used why they stopped making that bearing. There was a new version of that on eBay lately,but the few people that tried them said they were junk. I need to try them on something local or one of my own. I’m not installing something like that without testing it,then shipping it across the planet.
