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FFCobra Master Craftsman
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Discussion Starter #1
Hello.

Let's see if anyone can help me with my question.

I'm currently rebuilding a 8.8 rear axle with 4.10 gears in it.
I'm replacing ring and pinion and am currently reinstalling and adjusting the pattern.
My specs are .207" shim on pinion and .008-.009" backlash.
Here a pics of my imprint. Not sure how to make better ones.
Can anyone determine if the pattern is good, or if not how it needs to be adjusted?
Thanks a lot,
Olivier

 

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hard to see exactly from the pictures, but I think you are good.
Look for contact in the center of the teeth side to side and not on the tip or all the way down to the root.
David W
 

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FFCobra Master Craftsman
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Discussion Starter #4
Thanks for the feedback.
The more I look at the pattern, the more I think I'll have to change something.
Here are some other pictures I took tonight.



The drive side seems to be close to the toe as if it needs a thinner pinion shim.
The coast side looks something in between of needing a thicker pinion shim, or reducing backlash.
Both really don't make sense to me since I'm at .027 pinion shim and .008 backlash.

Am I interpreting this wrong? :confused1:
Thanks.
 

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1st RFM/FFR Legacy Winner
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You are close to OK. I agree the pinion looks a little deep. What shim came off the old pinion gear? Mine was 0.011" and was perfect for the new pinion too. I went from 3.08 to 3.55.
 

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FFCobra Master Craftsman
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Discussion Starter #6 (Edited)
I measured the original shim at .027 and replaced it with the same thickness.
These are 4.10s.
I read and followed the Ford Performance installation instructions and things confuse me.
Apparently pinion shim and backlash changes can have the same effects.
How do you find the balance?
My thing is that I need to bring the pattern down and towards the heel, but the instructions say that if you bring it down it'll move towards the toe.
That won't work unless I can counter a shim change with backlash change in the other direction. But one would have to influence one directional change more than the other.
Does that make sense?
I'll play a little with the backlash since that's not difficult to do.
I sure hope that I don't have to change the pinion shim, but I'll do it if necessary.
Thanks for the help.
 

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use a very thin coat of light grease, if it is too thick it will be hard to see the contact area.
David W
 

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Pro FFR Builder and Moderator
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The pinion is too deep. I think you will need closer to a .020 shim.
 

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FFCobra Master Craftsman
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Discussion Starter #9
So here we go, round two.

Changed the pinion shim to .020" and reinstalled everything.
Backlash is at .012". Here's the pattern.
Any suggestion?




Thanks for your help.
Olivier
 

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FFCobra Master Craftsman
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Discussion Starter #11
Sweet.
Thank you so much for your help.
Should I try to reduce backlash a little more, or not worth the effort?
 

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FFCobra Craftsman
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.012" is the max spec. I'd try to get closer to the min spec of .008"
 

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FFCobra Master Craftsman
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Discussion Starter #14
Ok.

Thanks to everyone for your help.
I really appreciate the feedback.
 
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