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9 inch gear pattern paranoia

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Old 02-11-2016, 10:02 AM
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Car: 89' Sunset Metallic Orange Iroc-Z
Engine: Forged 383
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Axle/Gears: 4.11 9 inch
9 inch gear pattern paranoia

This is my fourth gear-set I set up, and have always been a little shaky on the gear patterns. This is a new Motive set that I would like to make my long term gear-set so I want it to be right.

I went through about every one of the shims checking gear patterns, from the 002 all the way to the unlabeled thick one and the 010 combined (final). The main differences I saw were that the Drive and Coast sides moved towards the middle with every shim I added. As the pattern got towards the middle it seamed to get wider. I stopped when both coast and driver were right in the middle as relation to toe and heel. I installed it and put a few miles on them.

They are dead quiet until about 50 then there is a slight wine on load. On coast I have no noise whatsoever.

To all the gear experts what is your opinion on the gear pattern I ended up with? It looks flat towards the root of the gear, but doesn't go all the way down the root.
Attached Thumbnails 9 inch gear pattern paranoia-imag1012.jpg   9 inch gear pattern paranoia-imag1013.jpg  
Old 02-11-2016, 12:58 PM
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Re: 9 inch gear pattern paranoia

Pinion is too deep. You need to add some more shim.
Old 02-11-2016, 01:01 PM
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Re: 9 inch gear pattern paranoia

I am learning, so don't think I am trying to be a jerk or anything, but how did you determine this?

This process is so subjective, the instructions that came with the gears basically made it sound like the only thing that mattered was centering it between the toe and heal (obviously this is not correct).
Old 02-11-2016, 01:08 PM
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Re: 9 inch gear pattern paranoia

Don't get caught up in toe and heel patterns. The important thing is root to face. Look at the sharp line at the root of the tooth. Then notice how it tapers off to nothing at the face. This means that the pinion is too deep. You want the root and face to be equal.
Old 02-11-2016, 01:18 PM
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Re: 9 inch gear pattern paranoia

Originally Posted by big gear head
Don't get caught up in toe and heel patterns. The important thing is root to face. Look at the sharp line at the root of the tooth. Then notice how it tapers off to nothing at the face. This means that the pinion is too deep. You want the root and face to be equal.
So more of a symmetrical heal to toe, like a smooth arc, ignoring where it is located heal to toe, the same amount of curves on both sides. Pulling the pinion away from the gear (adding shims) will bring the pattern further away from the root?

Am I also shooting for a curve on the bottom and top? Basically a big oval?
Old 02-11-2016, 01:20 PM
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Re: 9 inch gear pattern paranoia

Yes and yes. You may see a straight line at the root and face with curves at both ends, or it could be an oval.


You can adjust heel to toe some by changing the backlash, after the pinion depth is correct.
Old 02-15-2016, 12:14 PM
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Re: 9 inch gear pattern paranoia

Originally Posted by big gear head
Yes and yes. You may see a straight line at the root and face with curves at both ends, or it could be an oval.


You can adjust heel to toe some by changing the backlash, after the pinion depth is correct.
Hows this look, it is about .035 worth of shims. The coast covers about all parts of the tooth, I tried twice to get a better read to no avail.




Old 02-15-2016, 01:11 PM
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Re: 9 inch gear pattern paranoia

Couple of others on the opposite ends





Old 02-15-2016, 01:12 PM
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Re: 9 inch gear pattern paranoia

Old 02-15-2016, 01:15 PM
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Re: 9 inch gear pattern paranoia

Old 02-15-2016, 08:27 PM
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Re: 9 inch gear pattern paranoia

.032 isn't too bad. Looks like this is one of those gears that doesn't want to make a good pattern on both drive and coast sides. The drive side looks pretty good with .032, so I'd go with that. Might not be quiet.
Old 02-15-2016, 11:00 PM
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Re: 9 inch gear pattern paranoia

Originally Posted by big gear head
.032 isn't too bad. Looks like this is one of those gears that doesn't want to make a good pattern on both drive and coast sides. The drive side looks pretty good with .032, so I'd go with that. Might not be quiet.
I was hoping you would check back with me, I really appreciate your help. You think .032 was better than .035? I was worried about the sharp edge toward the root.

Good thing is .032 and .035 have the same backlash so I can swap out the shims while in the car
Old 02-16-2016, 07:11 AM
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Re: 9 inch gear pattern paranoia

The drive side pattern on the .035 was farther out toward the heel and the root to face was about the same for the .035 and .032, so the .032 would be better. Sometimes gears just don't want to make good contact, which is why the coast side doesn't look great. Motive hasn't been doing too well lately from what I have seen.
Old 02-16-2016, 09:58 AM
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Re: 9 inch gear pattern paranoia

It just occurred to me that I had drive and coast mixed up, the pattern on the drive really concerns me. I didn't mind getting a better read on what I thought was the drive side. You seem to see something difference than I see, so I am going go with the .032.

These are Motives, which from what everything I read are supposed to be one of the better brands. Would you try to return them, and get another set? I am going to email them today with the pictures and see what they say.
Attached Thumbnails 9 inch gear pattern paranoia-.032coast.jpg   9 inch gear pattern paranoia-.032drive.jpg  
Old 02-16-2016, 11:17 AM
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Re: 9 inch gear pattern paranoia

Yea, I'd like to know what their opinion is. I doubt that they will exchange them. Most gear companies almost always blame the installer for any noise. I have been doing this for 34 years and had been dealing with the same companies for 15 years and they always blamed me when I told them I had a bad gear.
Old 02-16-2016, 11:20 AM
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Axle/Gears: 4.11 9 inch
Re: 9 inch gear pattern paranoia

Originally Posted by big gear head
Yea, I'd like to know what their opinion is. I doubt that they will exchange them. Most gear companies almost always blame the installer for any noise. I have been doing this for 34 years and had been dealing with the same companies for 15 years and they always blamed me when I told them I had a bad gear.
We will see, I bought them from National Drivetrain. I sent emails to Motive and National Drivetrain. National Drivetrain is looking at the pics.
Old 02-16-2016, 02:54 PM
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Re: 9 inch gear pattern paranoia

So I went back and forth with National Drivetrain. His opinion was the .026 was the right pattern (first set). I told him I thought it was to close on the root, and the .032 was better. He told me to run it and let him know how it feels. I am putting fluid in tonight and see how she runs.
Old 02-16-2016, 05:19 PM
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Re: 9 inch gear pattern paranoia

Which shims are you going to try?
Old 02-16-2016, 07:03 PM
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Re: 9 inch gear pattern paranoia

Originally Posted by big gear head
Which shims are you going to try?
Got a reply from Motive who told me I should run at most .021 worth of shims because 90 percent of their gears work with .019 to .021 worth of shims. He stated I was "too deep" in the gear and needed to take out shims to bring the pattern closer to the heel(backwards). You can see how this whole process is subjective.

Well I ignored both of the experts and went with the .032 as you recommended, just took her for a spin. Totally silent on coast. Silent on drive until about 65 where I hear a slight wine, about 50 percent quieter than the .026 shims.

I think this is it, thanks for your help, now onto other issues.
Old 02-16-2016, 08:11 PM
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Re: 9 inch gear pattern paranoia

Great. I'm glad it was an improvement.
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