Adjusting SPF wheel bearings Part 2

I call this part 2 because it's about adjusting the wheel bearing preload which Steve C asked some time ago an after almost 100 posts we ended up not answering. I have to admit I'm as guilty as anyone for the thread drift from Steve's original question of how to adjust the wheel bearing preload on our 40's. I bring it up again because I'm faced with doing it on a new set or rear bearings and seals.

I think we need to answer question.

It's my opinion that because of the seals we can't use the normal wheel preload. I was hoping maybe we could get the factory to speak up on this issue. Anybody got a phone number?
 
It would be simple to make a solid spacer to fit between the inner & outer cones, it could be made to a few thousandths over reqd length and machined to the reqd size for each hub, since its length wont be affected by seals a few trial assy's without them to get the reqd preload and correct spacer length is all it would take then the seals can be fitted and the axle nut really tightened to a higher torque figure that simply will not come loose. Anyone who has set up a 9" ford diff pinion with solid spacer should know whats reqd- as long as he is not a credit card builder. There must be at least one guy in every established hot rod shop in the USA who could do that.
 
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Jac mac I remember you talked about this in the last thread. I think it's a great idea and I might end up making those for my car but I guess the real question is not so much bearing preload but seal preload. How much load do I put on new seals so they seat properly?
 
Richard from the info IIRC that Alan Watkins posted at the time the seals have dimensions that are built into the design of your SPF uprights/bearings etc. Part of the bearing problems that your cars seem to be having is that in virtually every photo Ive seen posted by SPF owners of the used seals they show evidence that they are turning against the bearing cones and any abutments on the shaft, In doing so they must wear and erode any bearing preload that might have been adjusted at initial assy. Given the seal info this seems wrong to me and converting to the solid spacer will eliminate that wear as with the seals/brgs/spacers clamped tight by the now properly tightened axle nut it simply wont occur and the seal will turn against the bearing cups in the manner intended.
 
Richard I usually tighten the bearings as much as I can with a 9" standard ratchet handle. I back that off slightly if I can't turn the wheel. I know this is unscientific, but it seems to keep the seals tighter against the bearing cones. I've had less need for readjustment this way. Jac Mac's spacer idea would help a lot, but I don't have access to a lathe.
 
I do have a lath and can make the spacers if it comes down to the bearing preload issue. Jac Mac the seals are designed to wear a groove in the bearing race. As you can see from the pictures the seals get sandwiched in the stack of bearings etc. so they have to turn with the hub. Considering how hard the bearing cone material is I have to assume the seal material is very hard also seeing as how it wears a groove in the race. The groove isn't very deep maybe no more than maybe .010".
 

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Yes, Im aware the seals are made to work with the dimensions of the bearings, therefore for the purpose of making and fitting a solid spacer to fit between the inner and outer bearing cones inner races the seals do not need to be in place while you fit and check the spacer length, gradually reducing that length until you arrive at the desired preload. ( this might be easier to do with a 'dummy' shaft with same dimensions as the hub, but machined for light push fit of bearings is used since it will take a few steps to arrive at correct length ). Once that has been done you can fit seals, bearings, & spacer to actual hub and tighten retaining nut to a suitable high torque figure knowing you have have suitable pre load regardless of extra load applied by seals.
 
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