Front Differential...What did it eat?

THIS FORUM IS FOR ANY QUESTIONS ON THE 7.25" IFS FRONT DIFF, CV HALF SHAFTS AND FRONT DRIVE SHAFT.
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Longhair
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Front Differential...What did it eat?

Post by Longhair »

First, I want to say that I'm a total newb to AWD.
New to me AWD made absolutely no noise until the passenger side front wheel locked up at low speed turning into a driveway. I stopped and got out to see if there was a visible reason. Nope. No leaks/drips, no CV boot tears. Got back in and it was fine going the rest of the way up the driveway. Left to go home, and again w/o any prior noise about ½mi down the road (seemed like both) fronts locked (on gravel road) @ about 25mph. Again I got out to look and there was no obvious reason, but after that there was a horrible grinding noise going down the road. Got home (less than 10mi), jacked it up and checked for hub bearing noise or play. Nope. Checked front diff fluid AND IT WAS DRY!! Put a quart in and still couldn't touch the surface with my finger through the fill hole.

So the questions are;
1) What fried? Differential axle bearings? Pinion/carrier bearings?
2) What are my easiest and cheapest options?

If a whole new diff is the answer, what models/years will work on my 2002?
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doyoulikeithere
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Re: Front Differential...What did it eat?

Post by doyoulikeithere »

Sounds ugly. too bad.
Probably the easiest job is to change out the whole front diff assy with a used one from the P&P.
I'm not sure about interchangeability of Gen 2 years as I'm a gen 1 guy. but they seem to be pretty universal on the gen 1's so I would hope the Gen 2 might be also.
2002 uses 6 bolt wheels doesnt it? I dont know if that effects the front diff assy, but, I doubt it.
Some of the more modern guys will know for sure :muhaha:
2021 Yamaha Tenere 700 - Blue.
2016 Yamaha XSR900 - Silver.
1990 Astro - AWD - Brown.
1987 Astro - With 5 Speed & 4wd - Silver & Blue.
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Re: Front Differential...What did it eat?

Post by mdmead »

Plug your van into car-part.com and you can see what interchanges. (Not only that, you can buy one if you want!)
Matt
Selah, WA
-96 GMC Safari AWD Hi-Top Conversion -->Stalled 5.3L swap & 5" lift
-74 Ford Bronco -->Far from perfect but mine!
-99 V-10 Ford Super Duty Super Cab 4x4 -->Stock with 285 Cooper ATs
-00 Ford Focus Wagon -->The Red Turd
-95 Ford 24' Class C Motorhome -->My big block sleeper
-07 Can-Am Outlander XT -->My yellow 4x4 quad for work & play
-04 Ski Doo REV Summit -->Still several chassis behind!


No new projects until the current ones are done!

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Re: Front Differential...What did it eat?

Post by LiftedAWDAstro »

A front diff from 97 - 05 will fit. Best bet is to swap it out. You would need a complete rebuild kit, probably new ring and pinion and then a setup of the gears...way more cost than a used diff. Lots of them in the P&P as Matt said.
Current rides:
2013 Toyota Tundra DC 4x4
2008 Dodge Nitro 4x4
2005 Nissan Sentra 1.8S Special Edition

Mileage spreadsheet

Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy
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Longhair
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Re: Front Differential...What did it eat?

Post by Longhair »

Thanks guys!
Pretty much what I figured. Image
With wind chills below 0°f and no garage to work in, I've decided to shelve the project 'til spring. Picked up a cheap '97 Jimmy to get through winter.
Image
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Re: Front Differential...What did it eat?

Post by doyoulikeithere »

That works too !
Come springtime, The front diff from A blazer or S10 will fit an astro as well.
2021 Yamaha Tenere 700 - Blue.
2016 Yamaha XSR900 - Silver.
1990 Astro - AWD - Brown.
1987 Astro - With 5 Speed & 4wd - Silver & Blue.
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Longhair
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Re: Front Differential...What did it eat?

Post by Longhair »

Bummer! Checked the RPO codes and my Astro has 342 gears......the Jimmy is 373. I was kind of hoping it would have the differential that I need, but I guess I'm just not that lucky.

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Re: Front Differential...What did it eat?

Post by LiftedAWDAstro »

That's not such a bad thing. swap the rear gears into the van. They are a direct swap. The rear axle housing won't work but the carrier and ring/pinion will.
Current rides:
2013 Toyota Tundra DC 4x4
2008 Dodge Nitro 4x4
2005 Nissan Sentra 1.8S Special Edition

Mileage spreadsheet

Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy
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Longhair
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Re: Front Differential...What did it eat?

Post by Longhair »

I thought about that, but I really prefer the 20.4mpg that I got with the 342 gear in my van to the 17.1mpg that I'm getting with the Jimmy.
There's a p&p nearby that typically has several Astros and Blazers, so come spring I'll go check what they have and make an executive decision.
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Re: Front Differential...What did it eat?

Post by doyoulikeithere »

Eeeks, I'm getting 15.6L/100KM in my 90 awd with 3.73 , this week.
2021 Yamaha Tenere 700 - Blue.
2016 Yamaha XSR900 - Silver.
1990 Astro - AWD - Brown.
1987 Astro - With 5 Speed & 4wd - Silver & Blue.
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Longhair
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Re: Front Differential...What did it eat?

Post by Longhair »

Well, I finally got the time, weather, and a second pair of hands, so this week I had to get back to my Astro. It took two old men one afternoon to get the old differential out (about 4hrs). We figured that taking the old one out first would establish a tool list, so going to the p&p we would be prepared......which wasn't exactly how it worked out.

The next afternoon we were off to get the replacement
First issue that arose was the castle nuts on the ball joints. At home I was able to get on them enough with a 1" wrench, but at the p&p it wasn't going to happen. Went to a nearby Nappa to buy a 26mm wrench, but they didn't have one. Closest that they had was a 1-1/16". It worked, but I was holding my breath and praying that it wouldn't just round off the corners (whew!). Pretty much everything else went well, that is until we got to the driveshaft bolts. My '02 has nice simple straight forward bolts with 10mm heads, but the '97 we were taking the differential out of had those nasty little Torx heads, which I had sockets for in my tool box, but we sweated getting those buggers out w/o rounding them off (one in particular...of course). Almost gave up on it but persevered.
Finally got back home with it about 6:30pm and got busy on the install. Finished it up in the dark and took it off the stands @ 10:30pm.
I still have to fill it with 75-90 synthetic this morning, but the hard part is out of the way.

Thanks for all the technical info/help A/S Forum!
I've lived my whole life w/o having to do one of these, and I'm glad that I won't live long enough to ever have to do another one.
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