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Rebuilding an 8.8, IRS vs solid axle.


adsm08

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Ok, so I don't really do diffs or gears. I'm not afraid to go into them, but the need to rebuild or replace gears in the dealership has not been high in the last 10 years, and I do mostly drivability stuff.

But the Explorer's rear needs a rebuild. The pinion bearings are loud (no play yet) and I suspect I have a suspect carrier bearing in the diff.

By chance I happen to have a gear set for it, I just need bearings and an install set. My concern is that I have heard horror stories from other otherwise competent mechanics, who can rebuild diffs, that pertain directly to repeated failures at rebuilding the IRS version.

Are they really that bad to do, or is there something that makes it drastically different than doing a solid 8.8?
 


bobbywalter

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explorer....i would pull one at a yard....if its good swap it out. wouldnt even give a thought to fawking with a stock diff for stock stuff in a stock application. .
 

adsm08

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explorer....i would pull one at a yard....if its good swap it out. wouldnt even give a thought to fawking with a stock diff for stock stuff in a stock application. .
That's my preference as well, but there aren't many listed near me, nobody has them listed by gear ratio, and the parts I lack are several hundred dollars less than a junk yard assembly.
 

19Walt93

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The early 02-03 Explorers were prone to rear end problems and Ford originally had us install exchange units. After they stopped the exchange program we were rebuilding them and my rear end guy never said anything bad about doing them. Something changed about 04 and the noises stopped. I wouldn't buy a used 02-03 unit unless you know it was replaced. If you can build an 8.8 live axle, you can build an IRS- you have a used one now.
 

adsm08

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The early 02-03 Explorers were prone to rear end problems and Ford originally had us install exchange units. After they stopped the exchange program we were rebuilding them and my rear end guy never said anything bad about doing them. Something changed about 04 and the noises stopped. I wouldn't buy a used 02-03 unit unless you know it was replaced. If you can build an 8.8 live axle, you can build an IRS- you have a used one now.
See that was my thought as well, but like I said, I'm not a rear end guy.

What I'd like to do is try to pick up a cheap housing from a part out and rebuild that so I can just do a quick exchange and not have a bunch of down time.
 

bobbywalter

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sawzall?
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I get them 75 or so at u pull and shelf yards have pulled units for 150 bux 355 or 373 gears at home
 

19Walt93

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Rebuilding a used one and swapping it in to save down time makes sense. The worst part about rear end work is the smell of friction modifier, it reeks and it lingers. I use only Ford Racing modifier which is the old non ecofriendly stuff because it works better but it also stinks worse.
 

adsm08

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31X10.50X15
I get them 75 or so at u pull and shelf yards have pulled units for 150 bux 355 or 373 gears at home
Harry's in Hazelton has a few Explorers in the age range I need, if I read their price schedule correctly I'd be looking at $60 out the door, plus my time.

It was also suggested to me today, by one of our older techs, to have the parts guys call a local salvage yard that we have bought a bunch of these from in the past. Apparently the dealership's price on them wasn't hateful and they used to have them on the shelf ready to go.

Rebuilding a used one and swapping it in to save down time makes sense. The worst part about rear end work is the smell of friction modifier, it reeks and it lingers. I use only Ford Racing modifier which is the old non ecofriendly stuff because it works better but it also stinks worse.
Friction modifier doesn't bother me like it does most people. I have known a lot of people that gag at the smell of it. I can sniff it and say "yeah, it stinks," and just go on with life.

If you really want a smell...… When I was in college my room mate rebuilt his 5R55 during transmissions class, but the dealership sold him a case of misbottled fluid. The case and bottles said Merc V, but it was actually transfer case fluid. I commented that it smelled off while he was filling the transmission up, but you couldn't tell this guy anything, so he went whole hog and filled her up with it. That transmission made it about 100 miles and came back in on a roll back. We tore the transmission down again to do a post-mortem and find out what he did wrong, and oh the smell!

After I finished ASSET in 2008 I was at that school for two more years. Then three years after that, in 2013, I went back for a FoMoCo special event celebrating Ford's 110th and the school's auto program's 100th anniversaries. I walked into the building, five years and a major renovation after this disaster, and I could still smell that transmission.
 

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