vbMike

iTrader: (2)

So I’ve been reading trying to figure out how to measure for the correct pinion depth. Apparently the measurement is taken from the carrier bearing center line to the head of the pinion after it has been install into the housing. Supposed the ideal pinion depth measurement varies between different gear sets and the depth number is supposed to be stamped on the pinion. After you have an initial measurement you need to add or remove shims from the pinion until the depth is correct.

My question is what happen if the pinion does not have the depth stamped on it???
Do you just use the stock shim and make adjustments based on the pattern? I hear the stock pinion shim will work fine 99% of the time so is it worth spending the money on the special tool to take the measurements with?

Here are the numbers that were stamped on my pinion. Do any of these number indicate the correct pinion depth??? I believe the gear set is made by Yukon Gear.

P01-878370BW-37-10-U.S.A./J-6

Any comments regarding pinion depth or gear setup in general would be appreciated.

1989iroc66

dont know to much about rears but i have a 9 bolt and had to rebuild it so i know how it is. I used white lithium grease and tightened the pinion nut untile the pinion showed a good pattern on the ring gear. U will need a new crush sleve but the 10 bolts use the same one so they are easy to get a hold of.

vbMike

iTrader: (2)

Someone must have some info about setting this up.

My original though was to take a measurement from the bearing cap mating surface to the stock pinion and then install the new pinion to match that measurement. Apparently this is not the correct was to do this. I guess you are supposed to measure from the carrier bearing center line to the head of the pinion to match the measurement etched on the pinion.

Does the number in my first post contain the pinion depth measurement???

If I don’t have a pinion depth measurement to go by should I just use the stock shim, set the backlash and call it good or should I adjust the pinion based on the pattern?

midwest

No it doesnt. If and if it has the number it will look like some one took an engraver and hand wrote the number. Also they may have a polished spot, if it does that where you would take the measurement from.

But all in all dont worry about measureing it. Just take the shim from the original pinion and put it on the new pinion. Tighten the pinion nut untill you have about 25 inch pounds of turning torque. Then put your carrier in, that has to be shimmed to, it should be a tight fit, 3-4 hits of rubber mallet to get it seated should be tight enough. check your back lash. About .008". Then use some grease paint and paint a 6 tooth section on the ring gear. Run the gears forward and back ward a few times over the paint. Then look at the pattern. Dont forget to check both drive and coast sides of the gear. If the pattern is good then awesome, if its not, them compare to diagrams and determin which way you need to move the pinion. But before you go through the trouble of that. try changing the back lash first.

vbMike

iTrader: (2)

Alright, sounds good to me. Looks like the only thing I'll have to go by is the pattern since the pinion depth is not marked. I'll get a dial indicator to measure backlash and an in/lb torque wrench. Thanks for the help.

midwest

the tg wrench must be either an old beam and needle style or a dial indicator type. A click style wont work right.

vbMike

iTrader: (2)

Yea I know. I was thinking about getting this one. Looks like it cost about $40. Not sure if it is any good or not.

http://www.kd-tools.com/29552957.htm

Pat Hall

iTrader: (31)

Yeah, that wrench you posted the link to should do the job. The dial indicator type are even nicer to use, but you probably won't find one for that price. I picked up a very lightly used Snap-On, Dial-a-Torque type one on ebay for about $130. It was over $300 new. Since you're probably not gonna set up too many rears, I'd say go ahead and get the one from KD Tools. Midwest's advice on setting the pinion depth is pretty good. You want to make sure to keep the backlash in the range of .006-.010. Once you get the backlash right, mark the gears and adjust the pinion depth until you get a good pattern on both the drive and coast sides. I also agree that using the original shim would be a good place to start. I'm installing a brand new set of Motive gears in a 12 bolt rear, and they have the pinion depth engraved on the back of the pinion gear. I bought one of those cheap pinion depth checking tools that Ratech sells($29) and it's a total joke. Didn't work worth a damn. According to the tool I only needed a .017 shim. After checking the pattern, it wasn't even close. I ended up with a .034 shim before the contact pattern looked right. So I tossed the measurement on the pinion head out the window, and just shimmed it until the pattern looked right. On that note, I highly recommend taking an inner (large) pinion bearing and honing it out until it's a slip fit, and using that for shim adjustments. Once you get the right shim for the depth setting, then press on a new inner bearing for the final assembly. If you don't use the setup (honed out) bearing for shim adjustment, you'll end up destroying your good bearing after pressing it on and off several times. One last tip on establishing a good contact pattern: You get a far more accurate pattern if you simulate a load on the gears. It also makes it easier to read since it spreads it out more on the tooth. I do this by putting the flat side of a pry bar against the flat side, or edge of the ring gear while rotating the carrier around. The resistance you create with the prybar against the ring gear is similar to the load created when the gears are under power, or the weight of the car when coasting. I usually hold the prybar with one hand while turning the pinion yoke with the other hand. It's easier to do with a helper. On my 12 bolt I could barely see a pattern just spinning it around, but it really came into focus after applying some resistance with the pry bar. Do this in both directions to establish the drive and coast patterns. We used a 1/2 inch drill to do this at the shop I used to work for, but doing it by hand worked good enough here at the house. You'll want between 20-25 inch lbs. of preload for new pinion bearings, and with the pinion seal installed, about 27-28.

vbMike

iTrader: (2)

That’s for the reply Pat. Your tips are appreciated, here are a couple thoughts I had though.

I have a manual for the 9 bolt axel and the spec for the backlash is .004 - .007. Seems tight but that’s what it says.

I’ve heard that tip before about using a setup bearing when adjusting the pinion depth. I don’t think this is need on the 9 bolt since the pinion spacer goes behind the inner bearing race (cone).

There were two dial indicators that I was looking at. The first one is a few dollars more but I like it better because I think it has more adjustability and a bigger range.

http://store.summitracing.com/partde...5&autoview=sku

http://store.summitracing.com/partde...5&autoview=sku

Pat Hall

iTrader: (31)

Yeah, I honestly wouldn't go any tighter than .006, or you might end up with whining gears. The book I've got says .006-.010 on both the 10 bolt and the 9 bolt. Either of those dial indicators should work great. If you happen to have a Harbor Freight in your neck of the woods, you can get one even cheaper, plus you won't have to pay Summit's $11.00 "handling fee". I've heard some guys say the depth shim is behind the inner race, and others have said it's between the bearing and the pinion. I've never gone through a 9 bolt before, so I won't place a bet one way or the other on that.