Gear pattern ?

fasteddieyj

fasteddieyj

NAXJA Forum User
Location
Hanover, PA
Got some work done today on my gear install. Got pinion preload and backlash set to 30 in/lbs and .007 respectively, both within spec. Also checked the gear pattern and "think" it looks ok although I'm not sure about the coast side.
Drive side, not the best pic
011.jpg
011.jpg
[/img]
coast side, not sure about this one
009.jpg
009.jpg
[/img]
 
If you're talking about a D30 the bottom pic is the drive side and your pinion is a bit too deep. Try removing about .005" from behind the inner pinion bearing cup and see what that does for you.
 
If that is a dana 30 the 30inch lbs of pinion pre-load is about 2 times what you need and that's if you have new bearings. It should be around 6-8inch lbs with used bearings and 12-15inch lbs with new.

Jeeperjon the Pinion on the bottom picture is too far away. The flat line is at the face and the radius is at the flank. Face being the top part of the tooth and the Flank being at the bottom of the tooth.
 
jeeperjohn, your right I spaced that one, I dont know what I was thinking. I must have thought about the wrong pattern. It is too close.

A little more help on setting the best pattern up. I set it up with the stock stuff, then record it and write everything down including the backlash and pinion preload. if its too close or too far away I try to judge how much would put me past where I need to be. This way I know the perfect pattern is in the middle somewhere. I write all this info down as well. Then I can drop it in the middle and write it all down. I can then fine tune as I go. That might help ya a bit.
 
Ok, maybe not a moron, although I guess the verdict is still out on that one, but definitely confused. I'm using the Billa Vista article on Pirate, which is telling me this pattern is no good, and a book called "Differentials" by Jim Allen and Randy Lyman, which seems to indicate that the pattern is ok. HELP!!
007.jpg
[/img]
006.jpg
[/img]
 
fasteddieyj said:
Ok, maybe not a moron, although I guess the verdict is still out on that one, but definitely confused. I'm using the Billa Vista article on Pirate, which is telling me this pattern is no good, and a book called "Differentials" by Jim Allen and Randy Lyman, which seems to indicate that the pattern is ok. HELP!!
007.jpg
[/img]
006.jpg
[/img]
Click to expand...
I have not encountered a pattern like that before. I will take a guess that the pinion is too close but I suggest you do a good bit of research and see if you can find some info on that kind of pattern. I think the pinion is way too close.
 
Put more pressure on it next time you run your pattern so you can see it better.

How'd you have it set up when you run that pattern?

I'm by far not a pro at this. Just finished my 3rd set-up, I'll help as much as I can.
 
That may or may not be OK, you need to put more pressure on the gears to get a better reading. I like the yellow gear paint with a slight amount of oil mixed in.
 
Thanks for all the input guys. One thing I did forget to mention in my original post is that these are used gears. Not sure if that will make a difference or not but thought I would mention it.
 
How much shim do you have behind the inner pinion bearing cup? The fact that the gears are used should not result in a crazy looking pattern but it might be a bit different than a new set.
 
When used make sure there a matched set.
 
So............
Went to remeasure everything before I posted and found that my backlash was only .003. So I adjusted that an here's what I have now along with a few more shitful pics (gotta work on that)
Backlash: .009
Pinion shims: .023 shim stack plus .013 pinion baffle
005.jpg
[/img]
003.jpg
[/img]
I guess where i"m most confused is that I expected both sides would show the same thing and that doesn't appear to be the case.
 
What the hell are you using for marking compound? The pattern still looks weird(better pics would help),also you need to put more "load" on the ring gear when pulling a pattern.Thats also to much backlash for "used" gears in a D30.You should have pulled a pattern and checked the backlash while the gears were installed in the old axle and matched those numbers(used gears dont like a change in the wear pattern).
 
Got the compound from Summit Racing. didn't realize it was gonna be white. So how much backlash should I be shooting for? When making a pattern I've been stuffing a couple rags between the ring rear and case and jamming them in their with a small pry bar. It certainly isn't easy to turn. Any other methods I should be trying? Pretty sure I figured out the camera thing, was using the wrong mode, so should be able to take a few better pics this evening.
 
Last edited:
Turning the cam to macro should help if that's what ya found out. On the pattern I have never messed with used gears so I have no clue what backlash should be....new however is 6-10 thousandths per Yukons info. Get those new pics up!
 
Ok, first off thanks for being so patient with me guys.
Secondly, I now understand why guys that do this get paid what they do for what they do.
Thirdly, I hopefully figured out the pic thing.
So I ended up removing .014 from the pinion stack (.006 backlash) and came up with this:
006.jpg
[/img]
009.jpg
[/img]
A very noticable difference. Then added .002 (.005 backlash)and got this:
014-1.jpg
[/img]
016-1.jpg
[/img]
 
I sure am glad I had new gears to work with. Used gears throw some strange looking patterns. Once I had the initial starting shims it took me 12 attempts and about 3 hours to get a good pattern, press all the bearings on and stick it back in the axle. My patterns were also very clear.
 
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