Ford 8.8 rear end interchanging!


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Joined: Sat Mar 28, 2015 1:17 pm

Location: lloydminster. Alberta

Post Tue May 08, 2018 12:45 pm

Ford 8.8 rear end interchanging!

Hey guys! I got one for yah! I currently have a ford 8.8 open 3.55 rear end in the old boy. I have another 8.8 that is a posi that i want to put in. I would like to keep the 3.55 ratio as well. Is it possible to just change carriers and put the ring gear off the open carrier and throw it on the posi carrier? I really dont want to have to pull the pinion and put a new crush sleeve and have to set up the rear end again. Or is that wishfull thinking. Lol.

Golden Jubilee
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Location: Lyman, IA

Post Tue May 08, 2018 1:39 pm

Re: Ford 8.8 rear end interchanging!

I'm going to say a "qualified yes". You can leave the pinion alone, but there are a coupla things that might require some changing. 1st sometimes the carriers are used on a limited number of ratios, and if you want to change beyond that the carrier itself needs to change so check and see if the posi carrier is right for the 3.55's. Also the 8.8 uses two different axle shaft splines so make sure the Posi matches the axles that you are using. 3rd you are still going to need to check the tooth pattern and set the back lash. You might get lucky and one set of spacers will be right, but you can't count on it. The pinion depth should be right because you are keeping the same ring gear, just mounting it on a different carrier, but where that carrier places the ring gear might not match the old carrier.
Diff's are one of the very few things that are still a "selective fit" part, every one goes together with different settings.
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Pile of Parts
Pile of Parts

Posts: 42

Joined: Sat Mar 28, 2015 1:17 pm

Location: lloydminster. Alberta

Post Tue May 08, 2018 7:57 pm

Re: Ford 8.8 rear end interchanging!

Thanks cornbinder! Thats a handfull of info for sure. I appreciate it. I was going to mention about the axles if the open ones will fit in the posi carrier or not. The ones out of the posi are 31 spline so im assuming the open ones aren't. Ill definately check that first before pulling the carriers out. Lol.

Golden Jubilee
Golden Jubilee

Posts: 5170

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Tue May 08, 2018 8:31 pm

Re: Ford 8.8 rear end interchanging!

They may or may not be, it isn't posi or non posi that determines it, it is what the axle came in originally that makes the difference. I think the wheel end bearing might also be a different size with the different spline count, so it may not be as easy as changing axles, you might need to change the side gears to match the axles you have now.
Its not a deal killer, just more hassle and parts.

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