I think the shallower bore is probably where the 2146 was originally used,and sources figured since the bearing stayed the same,the seal must be the same,so some of the info out there is incorrect. Hence,the reason I just use the 712146 seal for everything.
shallow bores were in the late 69 -70 1971 is where the deeper bore was used. Hence the part number 71 2146
Yes,I guess I didn’t explain that correctly. Here’s a Yukon seal on the left,and a .470” seal on the right. I have installed the thinner seal on applications that are getting certain rear disc brakes. You can have the retainer plate directly against the seal. No drum plate or spacer shim)in place of the drum plate). I have also found a variance in the bore depths. They are not exact. I mic the depth,then mic the overall width of the bearing/seal stack(and drum plate if being used). Then I know if I will have preload or excessive play,and can shim it before installation.
Everyone also needs to remember the BEARING itself will have end play and that also can not be changed so a good bearing is also essential to making everything work right. Sooner or later no matter how much preload you use on the seal to try and control AXLE BEARING end play it will fail too. The whole system just stinks totally because of lack or detail to specs on this system. AS I always said ...IF they would have just left the straight NON tapered bearings (basically a c-clip bearing with a press on inner race system all this would be a MOOT point and end play would not even matter. JIm JD Race
Tapered bearing is reliant on weight of gravity of the car and a seal trying to keep the pressure against the inner race... when you have end play the bearing slides to the top of the tube sliding out of the race ...then the axle is no longer centered in the tube and rubs the top of the seal lip away and the harder you turn/ hard drive( burn outs etc. ) the worse this gets.... So all the specs axle bearing end play of bearings riding in the cage race and the seal being too shallow compound all this - Jim JD
When there is excessive end play on the tapered bearing,the axle pulls up on the seal and the oil leaks out the bottom.
What do you consider excessive? To me it makes sense that. 010 isn't. .125 on the other hand is clearly excessive to me. I've not tested endplay to see exactly when a leak starts.
You will almost always have a minimal end play,and not zero,based on the bearing design. Sure,.010”-.020” is very exceptable. .100” is definitely NOT.
iF THE AXLES START TO MOVE ENOUGH to deviate true center that is excessive. you can not have the axle shaft pin the seal lip and over heat it. THIS is hard to tell until you get in the car drive it around and check it to see what is happening with weight on the rear. IT is tough. Some housings are just better than others to help all this too. IF you have a high mileage ragged housing end NOT true that is NOT going to help you out either. If you twist the bearing in your hand uninstalled ....that end play is NOT going to come out...THAT is built into the bearing and race period. So you can see how all this adds up once you add seal housing tube end imperfections depth specs. housing tube straightness. THERE are so many variables against this tapered bearing system it just seems doomed from the get go. If there was a BALL bearing sealed bearing for this rear I would use it. Jim JD
