I'm posting this in the tech forum because I know there are alot of people here who do thier own gears. Sorry, I know it's not turbo related.

Anyway, I'm rebuilding the rear in my car, and am thinking about shimming the pinion gear differently than it came from the factory. I'm wondering if anyone has seen this done before. The typical setup for shimming the pinion to set the pinion depth is in the next two pictures:

As can be seen in the first picture, this is the typical overall assembly for the 8.8 pinion. The pinion shims go behind the pinion, then the inner pinion bearing, then the crush washer, then the outer pinion bearing, then the pinion nut. Obvioulsy there is no driveshaft flange in this picture. Just pretend there is. The second picture is just a closeup of the first picture, showing the pinion and pinion shims and inner pinion bearing. The pinion bearing presses all the way against the shims which sit next to the pinion head. Basically, the shims are between the pinion head and the bearing.





The last pic is what I'm thinking of doing. I'm thinking of removing the inner bearing race from the axle housing, and sandwiching the shims between the inner race and the housing. This basically would do the same thing as the Ford method, it would set pinion depth relative to the differential centerline. The only reason I'm thinking of doing this is because it seems like it would be easier to remove and re-install the pinion bearing race to change shims, than to press the pinion bearing on and off the pinion a bunch of times.

Anyone done this before? Does it work? I don't see why it wouldn't, but maybe there's something I didn't think of, and that's why I'm asking.

 

damn those mechanical engineers. you used to color outside the lines a lot when you were little didn't ya jared?
i don't have any input to the actual scenario you posed but my question is, how often are you pressing new bearings onto the pinion or changing gears, etc back there to want to do this lol? i've always just done it the same way as ford b/c i haven't had to disassemble it enough to have a desire to do it any differently. since it appears that theoretically it would work, how about you just try it out and let us know what you find?

 

Hey Barry, I'm not really going to be pressing the bearing on and off too many times. I could just do it the normal way, but that means I'd have to pull and press the pinion bearing at least twice. And I'm lazy. Really, the only reason I'm thinking about doing this is because the "built" rear end I bought (used) has turned out to be a hack job and it needs to be fixed. I've got all new bearings and seals and gears for the axle housing. All I need now are bearings for the Moser c-clip elims. I know if I set the pinion depth based on the nominal Ford dimensions (4.420" distance from axle center to the pinion mounting surface) I'll be removing the pinion bearing at least once to correct the depth once I torque the pinion nut. Also, this assumes the depth is corrected the second time I press the bearing back on. Just putting the shims behind the bearing race means the race sticks out further, but the pinion is in the same place. I don't see it making a difference sticking the race out further. Seems like a lot less effort to me to shim the race, since every time I re-shimmed I wouldn't have to crawl out from under the car and press a bearing on and off. Maybe I'm wrong though. I'll try it and let everyone know what happens, but I was curious if anyone had already done it.

I see your car has gotten alot faster than the last time I saw you (the dyno day with Chris Johnson at Engineered Performance?). Looks like it's running good.

Jared

 

that will work fine, if you have the correct diameter and thickness shims.. that is how you build a dana 80 is the shims are behind the inner pinion race... no problem will work fine

 

lol, wow, i had forgotten about that. that was a LONG time ago it seems - back when i had the s-trim setup on this car. i since have had the twin turbo 93 gt, sold the s-trim car, bought the s-trim car back, parted out the motor and setup to put my twin turbo 93 motor in it. so it is back to the same car now. it is indeed running good, but not as good as it would if you'd cut me a crazy deal on that a4 block you've got (i know what you paid heheh) .
anyways, i check up on ya every now and then on the corral and all to see where you are and what you've been doing. maybe by the time i ever graduate, you'll have some contacts out there to hook me up with a big money job :bling: (or maybe, just a job)

 

In a way, it's not a great idea, but in another it's OK.

Yes, it should locate the pinion in the same spot. I doubt that you'll have enough shims to make any difference in pinion race support, but it's hard enough to get a pinion bearing race seated correctly without the hassle of shims behind it and you have no guarantee that that pocket is cut evenly (the race is thicker so it doesn't make as big a difference).

As far as I'm concerned, if you can avoid it I'd try not to remove the races that are there to begin with. The only time I bother is if they are actually physically damaged. For that matter, I'm not sure how this makes sense. That race should be much harder to remove then the bearing off the pinion (and I don't even own a press, I've managed to take them off using 2 wood chisels before). For testing pinion depth I usually try not to hurt the bearing that came out of there, grind out the middle of it slightly so it will slide over the shoulder with no pressure and assemble. Once you get the shims right, press the new bearing on and you're good to go.

 

i'm pretty sure this is how the newer DANA rears are set up jared.
i did a rear on a big dodge truck and i think its the one i shimmed like that. it was a few years ago so i'm not positive.
its a good idea though, i think.
good luck
-luke-

 

Your method will work find, although it is a pretty valid point that its hard to get those bearing races/cups/whatever seated properly in the housing. The shims would make it a little more difficult.

For rearend setups, I take the original pinion bearing and hone it out with a cylinder hone so its an easy slip fit over the pinion. That way you can "mock up" your pinion/shim setup 100 times (if need be) easily, then when you have your proper shim pack set up, drop in on the pinion, then press the new pinion bearing on it.

Whoever said they reuse races/cups with new bearings: BIG NO NO!!!

Also, HTF did you get a pinion bearing off the pinion with wood chisels?? Thats some pretty serious determination there!

 

In theory, yes, it's a big no no. In practice, well most people replace those bearings because they're there or they broke them getting them off in the press, and the races are practically virgin. OTOH, I've seen tons of rears put together by "pros" that after a few miles the bearing races do finally end up actually seated and suddenly you've got a whine that wasn't there before (ever wonder why it seems like half the gear installs make some funky noise?). Worse, I've seen a few that had the race pressed in crooked and killed the bearing. Either way you're likely to have already worn a pattern into the gears and they'll be noisy no matter what you do at that point. They could have completely avoided that if they REALLY made sure that they races were seated or just left them alone if they were OK.

Personally, I usually reuse the bearing, since I've never seen one trashed and never tweaked one removing and installing them.

WRT to the wood chisels... they were the right shape so I tried them. I've done 7 sets of gears that way and never had a problem. The one time that I paid someone to do it they trashed all the gears they touched with a press, messed up seating one of the races and I ended up with a noisy rear. I brought it back trying to get them to make it right and after the 3rd time they stamped my receipt warranty void (wasn't about to take it back anyway after all that. Didn't make a difference, I split the pinion in half within about 8K miles, less then a year)