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Proper pinion bearing preload

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Old 01-05-2010, 08:12 AM
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Default Proper pinion bearing preload

I took the 3.42 gears out of my 8.5 diff and started to install 4.10's. I reused the pinion shim and pinion bearrings. The install kit came with a new pinion seal, nut and crush collar. I placed the new crush collar on the pinion and installed it in the housing. I tried crushing the collar by hand with two breaker bars but couldnt get the leverage I needed under the truck so I used im impact gun on the pinion nut until the slop in the pinion went away. I spun the yoke around by hand and there was almost no resistance so I used my impact to tightern the nut another 1/4 a turn and spun the yoke ariound and it was pretty tight. I know I couldnt back off the collar once its collapsed and the kit only came with one. I squirted some more oil onto the bearings and it was a little easier to turn. I borrowed a beam style in/lbs tourque wrench and found an adaptor to get it on the pinion nut and I spun it around. It took almost 60 inch pounds to get it to spin and around 45-50 to keep it spinning. For used bearings it reccomends 8-12 inch pounds. I knew that wasnt ideal but I assembled it anyway and drove it last weekend, no noises or anything but I am wondering how long it will take for the brearings to seat if they are overtightened? Does anyone know how long I should baby it for?
 
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Old 01-05-2010, 08:32 AM
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That is quite a bit of additional torque... But I would just drive it like you normally would and see what happens.

You really should check your contact patch on the ring gear though. New gears should be setup each time, not just reuse the old shim arrangement. The overall shim stack on the diff housing will stay the same, but the amount that goes on either side of the diff to set the tooth engagement won't necessarily remain the same, nor will the pinion depth shim setting.
 
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Old 01-05-2010, 08:54 AM
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I didnt reuse the carrier shims, I had to play withe their stack ups, I had the carrier in and out 4 times to get a good contact patch using the yellow marking compound. No gear whine or anything. The only thing that concerns me is the pinion preload. Im sure bearing manufacturers reccomend a specific preload range for a reason. I know the pinion would walk up the ring gear if it is too loose but I dont see the disavantage of making it too tight. I cant see the bearings buring up if they are submergerd in oil. The only few times I have ever seen a burn pinion bearing it was due to lack of lube. I suspect that they will eventually break in to where they want to be. But I am not sure. I guess only time will tell I suppose. I was just looking for anyone with personal experiances similar to mine to chime in.
 
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Old 01-05-2010, 08:59 AM
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Ok, just making sure.

As far as too much preload, it will cause the bearings to wear out faster. It can actually cause the rollers to make impact craters in the races that will get worse over time. It will likely loosen back up, but it is difficult to say if it will damage things enough before hand to cause a bearing failure.
 
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Old 01-05-2010, 09:37 AM
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Makes sence about the craters, but what do you mean when you say "wear out" wouldnt they ware to the point they want to be. When i think of the term wear out, I think of the rollers disinagrating to the point they are unusable. Im thinking they may only wear a couple thousandths of an inch. So much emphasis is placed on preload at the point of set up, making sure that there isnt too much pressure on the rollers, but when you tromp on the gas pedal that pinion is trying to climb up the ring gear, the rollers are what keep it in place. There has got to be a lot more pressure on the rollers at that point than anyone could torque on the pinion nut. Its a cross between me justifying my mistake and also getting an understanding of why a preload range is specified by the manufacturer and what the results are if the bearings are used outside their range.
 
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