Feedback for gear contact pattern

[Kapteenikosmos]

I'm working with the third member atm. I'm changing the higway gears into 3.23 gears and I'm also installing new yokon clutch limited slip unit. I would appreciate if someone with some knowledge would check out these two pics and give some feedback. This was from the first tryout. My own opinion is that the pattern is already decent but it would get bit better if bit more shims would be used under the piniong bearing. I pulled the bearing and added one about 0.009 inch shim into the pack. I'll get it assembled again tomorrow, but any feedback would be welcome.

I have no clue how much the pattern moves with 0.009 inch shim. Is the shim I used already too much, or way too less?

The contact pattern on the drive side of the teeth is almost as wide as the teeth itself but while I rolled it the contact point started to "emerge" somewhere between the midle point and outer edge of the teeth. After 15 revolutions or so it looked like that. The coast side contact seems to be bit too close to the inner edge, right?

[tactransman]

Here is some good info:
http://www.drivetrain.com/ringpinioninstal.html

[Kapteenikosmos]

Great link! The shim I added moved the contact pattern so that it is very close to the figure C shown in the link you gave. The contact pattern still looks bit thinnish and might be bit too deep? The backlash is set to about the maximum limit given by the shop repair manual (It's at 0.007 inch now while the maximum is 0.008 given from the manual). The backlash for motive gears seems to be significantly higher.

Here are the pics for the second try:

The slightly thin contact pattern might also be because I didn't have much patience to turn it on and on as I was getting ill during last weekend. I wen't to see a doctor today and received antibiotics for a bronchitis.

Actually now when I'm looking at the pics I took it seems that the pattern is really deep atleast on the drive side. I will probably need to add more backlash altough it would go over the factory limits? This is the drive side

EDIT Well, I checked through few other forums for the contact pattern and mine seems to be way off  Well back to the drawing board, it could also be that I did a sloppy job when using the color paste and didn't use enough resistance on the ring gear. I'll recheck it again.



and coast side

[Moparal]

Curious if you tq'ed the ring gear down and if it was pulled down straight, and if you over tq'ed the carrier.

[Kapteenikosmos]

The ring gear is torqued down and should be straight. I did measure it before the final torqueing but not after it. The variation in backlash between the minimum and maximum is less than a 0.0004 inches so I assume that the ring gear went straight. I will recheck it next time I'm going to work with it.

The new yukon carrier had a high runout on the ring gear surface, it was about twice as much as the maximum limit given by repair manual. We (me and my dad)  marked up the position and amount of the maximum runout on the carrier and mounted it on the lathe. It was then adjusted on the lathe so that the amount and the position of the runout was about the same as it was when mounted to the actual case. We didn't get the runout to zero with the first try but it was now easily within the limits so we decided it was good enough.

Here are few pics from the process:

Curious if you tq'ed the ring gear down and if it was pulled down straight, and if you over tq'ed the carrier.

Al, what do you mean by over torquing the carrier? The carrier bearing preload? Everything should be torqued according the specs I had from the repair manual but I will recheck everything next time which is hopefully in few weeks.

I will also first clean up the old color paste from the gears and check the pattern again. I'm bit uncertain how much resistance is needed for the ring gear when the contact pattern is checked? I used my other hand to restrict the ring gear movement while I turned the pinion. Should I just ram a wooden block between the case and the smooth surface of the ring gear to restrict it more?

[Moparal]

The left hand ring gear bolts.  Did you tq them down even?  And the bolts that hold the carrier in (4)  if these bolts are not tq'ed the same, it will distort and give a bad pattern. It can make the gears sing when installed and running.

I'd have to look again, but I think ring rear left hand thread bolts are 45 or 50 ft lbs, and the carrier bolts are 70.

[Kapteenikosmos]

Thanks for the clarification. I used 55 ft lbs for the ring gear bolts and 85-90 ft lbs for the carrier bolts. Those were the numbers that were on my -73 shop repair manual but I will recheck the carrier bolts anyway. Ring gear bolts are loctited into place so I don't like the idea of opening those. I'll check the runout from the ring gear, I suppose that it should confirm if the ring gear bolts are ok or not.