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Discussion Starter · #1 ·
4.56 gear ground down to accept cross pin in carrier (no notched cross pin)

Disclaimer: I am in no way suggesting this mod just suppling pictures to help you make a decision for yourself should you decide you would like to make this mod yourself.

There are pros and cons from what I have learned:
Some say that the notched cross pin is not strong enough.
Others say that grinding the gear will cause a vibration.

I do not know the answers, but I will post further results when the Bronco is back on the road.

Grinding the ring gear in an 8.8 rear end to accept the stock cross pin.


In order to use the stock cross pin when installing 4.56 gears in an 8.8 rear you must grind down the tip of one tooth on the ring gear. I could not find pictures of this so I decided to do this and post the pictures.

Here is a picture of the carrier with the cross pin installed and the 4.56 ring gear on the carrier. From this angle you can see that only a small portion of one tooth needs to be grinded in order to slide the cross pin in and out.


Another angle:


Carefully, using a grinder, I was able to grind the one tooth that was interfering with the cross pin. The shiny steel you see on left and right teeth next to the grinded tooth was incidental contact and in no way was it necessary to grind these teeth in order to remove the cross pin.

*NOTE: I covered the center section of the carrier with a shop towel and wrapped a piece of duct tape around it so that I would not contact the center section of the carrier itself.


Another angle:


Another angle:


Another angle:


I only grinded the tooth necessary to remove the cross pin on the side where the retaining bolt goes through the pin. You may also want to note that if you have to remove the ring gear after grinding and then replace it, make sure you line up the ground gear in the correct manner as to allow the cross pin to be inserted and removed. If the pin is in the carrier when you install the gear, make sure it will come out should you need to remove the axles, regardless, you will have to remove the pin in order to insert the C clips.

One last picture, here I have tried to show the amount of material removed from the tooth on the ring gear by placing a piece of metal across the teeth. You can see a void where the metal has been removed. I wish it were a better picture, but I could not the lighting just right.
 

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Satyr of the Midwest
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As long as the contact pattern doesn't come too close, that's more than half all-right in my book! :thumbup
 

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Discussion Starter · #7 ·
Thanks for the info.

Has anyone used a ground ring gear on the road? Any real world results?
 

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Never noticed it on mine after several thousand miles. When I did mine I accidentally ground off a little more than what was necessary. Still didn't have any issues.
 

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Side step it
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1,841 Posts
456 gear pin

I just had West Coast Diff replace front & rear 355 gears with 456's & they ground the gear a little less in length but deeper. Eithor way I've had it off road on a three day trip, came home changed the fluid, inspected it, & had it on the road for the last month with no problems as my DD. That's how they did it & they do installs everyday! I'd just break it in like normal & wouldn't give it another thought...they did say don't use synthetic fluid if you have a limited slip because you'll get about 25k+ on your clutches because it lets them slip instead of grab even with friction modifier.:thumbup-Kevin-
Edit: Just so I don't start a debate. The clutches still grab but also slip a little causing added wear & less life by about 50% or more. But I'm going to put a locker in sooner or later so I wasn't too concerned & used Royal Purple anyhow which they said would be fine then since the limited would be removed to install the locker.
 
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