Is My Front Diff Bad?

THIS FORUM IS FOR ANY QUESTIONS ON THE 7.25" IFS FRONT DIFF, CV HALF SHAFTS AND FRONT DRIVE SHAFT.

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Mr Bean
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Is My Front Diff Bad?

Post by Mr Bean » Wed Jan 27, 2010 9:43 pm

Since we've owned the van (for three months) I've changed out the diff fluid front and rear. The van had a pretty noticeable "grinding, whirring" noise around the front end since we purchased it. Changing the diff fluids out didn't change it at all. It's now starting to get worse and I can feel it in the steering wheel and when I let off the gas, it feels very much like the van is dragging its front feet. It has felt like it was dragging its feet for the past few days as the grinding/whirring became slightly louder. Is my diff bad? transfer case fluid also was changed. The old stuff was blue and looked pretty good. When we purchased it, I put new blue stuff in. AWD works wonderfully. But I'm worried about the front diff. No leakage around any seals that I can see under there.
~Scott & Heather
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ihatemybike
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Re: Is My Front Diff Bad?

Post by ihatemybike » Wed Jan 27, 2010 9:58 pm

From personal front diff destruction experience, sounds like it.
Aaron

2005 Astro (Gandalf) - AWD, 4.3L, 3.42, 130k+ miles
1997 Astro (Grumpy - $250 Rally Van) - AWD, 4.3L, 3.42, LSD, 2" lift, 31" tires, 335k+ orig engine, $30 eBay fuel pump
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Re: Is My Front Diff Bad?

Post by Mr Bean » Wed Jan 27, 2010 11:19 pm

ihatemybike wrote:From personal front diff destruction experience, sounds like it.
Ugh. So should I bust it to pieces like you did and put the parts back that hold the bearings in place until I can afford a new one?

More importantly, I have to drive to Michigan's U.P. this weekend...if it goes completely, what happens? Are we stranded in a snow-laden wilderness with nothing but alpine woods and bears for miles?
~Scott & Heather
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Re: Is My Front Diff Bad?

Post by rlsllc » Wed Jan 27, 2010 11:40 pm

Are you sure that it isn't one of the front unit bearings? I had one slowly go from an occasional odd sound to full on grinding over the period of about 2K miles.

It sounded real bad.

When accellerating, the sound would sometimes completely go away. It was odd.

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Re: Is My Front Diff Bad?

Post by Mr Bean » Thu Jan 28, 2010 12:03 am

rlsllc wrote:Are you sure that it isn't one of the front unit bearings? I had one slowly go from an occasional odd sound to full on grinding over the period of about 2K miles.

It sounded real bad.

When accellerating, the sound would sometimes completely go away. It was odd.
Could be. But it doesn't go away when accelerating. Doesn't change at all when I turn the wheels. Doesn't change when I coast in neutral. Doesn't change when I press the brakes except it slows down in pitch of course. I still would like to know if this will strand us or not? :-k
~Scott & Heather
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Re: Is My Front Diff Bad?

Post by LiftedAWDAstro » Thu Jan 28, 2010 12:20 am

I would jack the front end up and check everything out. Check the hub bearings first. Then look to the front diff. Check the pinion for play and check the oil level. Check the u-joints on the front prop (drive) shaft. When my hub bearings went it was a low growl that progressively got worse until there was a lot of noise and vibration.
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Re: Is My Front Diff Bad?

Post by Mr Bean » Thu Jan 28, 2010 3:46 am

LiftedAWDAstro wrote:I would jack the front end up and check everything out. Check the hub bearings first. Then look to the front diff. Check the pinion for play and check the oil level. Check the u-joints on the front prop (drive) shaft. When my hub bearings went it was a low growl that progressively got worse until there was a lot of noise and vibration.
Alrighty. The garage and I will be cozy again tomorrow. Thanks. I'll report back in.
~Scott & Heather
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ihatemybike
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Re: Is My Front Diff Bad?

Post by ihatemybike » Thu Jan 28, 2010 3:55 am

Drain that diff and use a magnet in the fluid to look for fillings from the gears. Hopefully it is the hub bearings, but Grumpy's bearings didn't make much noise or slow the van much when they went and they were very bad.

When the diff goes it's brutal. Loud bangs and the van trying to push itself over the front axle. Towing is what gets you home.
Aaron

2005 Astro (Gandalf) - AWD, 4.3L, 3.42, 130k+ miles
1997 Astro (Grumpy - $250 Rally Van) - AWD, 4.3L, 3.42, LSD, 2" lift, 31" tires, 335k+ orig engine, $30 eBay fuel pump
Prev Astros:99,97,00,94,87,86

Mr Bean
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Re: Is My Front Diff Bad?

Post by Mr Bean » Thu Jan 28, 2010 2:46 pm

Aaron and Dean...thanks for your much-needed help. The van is up...turning the tires...nothing appears to make noise or be very wrong. It doesn't even feel like there's much drag on them. of course they are turning in opposite directions. Aaron, haven't yet drained the diff to check for metal filings because I forgot to buy more gear oil before putting it on blocks...I'll leave that for last since the garage is heated up finally. Dean, not exactly sure where to look for play...the front U joints seem to be tight. I've had U joints fail, so I kind of know what to look for. The only thing I notice is that when I turn the tires back and forth, there is somewhat of a delay before it actually turns the prop shaft. i can grap the tire and turn it back and forth a bit without even moving the front prop shaft. How can I know if it is a hub bearing? would the tire be loose on the hub? I'd hate to take this van on the round trip of 1000 miles to the U.P. and back and have something fail. I should have looked at this sooner. If I can't be sure what it is, we'll borrow another vehicle.
~Scott & Heather
2001 Astro AWD LT
All about me, my girl, & our van with loads of pics:
viewtopic.php?f=20&t=5281
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ihatemybike
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Re: Is My Front Diff Bad?

Post by ihatemybike » Thu Jan 28, 2010 5:37 pm

For the hub bearings

Remove the wheel
Grab the flange that the wheel studs are in
Try to move it around - up, down, left, right

If it moves without moving the steering knuckle then it is bad.
Aaron

2005 Astro (Gandalf) - AWD, 4.3L, 3.42, 130k+ miles
1997 Astro (Grumpy - $250 Rally Van) - AWD, 4.3L, 3.42, LSD, 2" lift, 31" tires, 335k+ orig engine, $30 eBay fuel pump
Prev Astros:99,97,00,94,87,86

rlsllc
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Re: Is My Front Diff Bad?

Post by rlsllc » Thu Jan 28, 2010 10:17 pm

If the wheels are turning quietly in opposite directions, then your hub bearings and spider gears are okay. Your ring and pinion, driveshaft, etc are not turning when this is happening.

I'm guessing it's the pinion bearing or side bearings on the dif. Could be the gears themselves, but I'm thinking bearings. Hard to say without disassembly.

Either way, I'd look for a used front end. Cash-for-clunkers has flooded the market with cheap used parts, most are cheaper than doing the repairs. R&R of and axle is easier than a rebuild, IMHO.

Mr Bean
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Re: Is My Front Diff Bad?

Post by Mr Bean » Fri Jan 29, 2010 2:10 pm

Bearings seem to be just fine. I will drain the diff fluid today and check for metal filings. Leaving for Traverse City, then on to Escanaba for the rest of the weekend. So I won't be able to perform a diffdecomty as Aaron calls it (lol) until next week. Wish me luck. Thanks for the help. I'll be crying for more next week. Aaron, trying to sort through your very thorough cardomain blog to help make the diff replacement process easier...any tips or how-to's would go a long way with me! Thanks!
~Scott & Heather
2001 Astro AWD LT
All about me, my girl, & our van with loads of pics:
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Re: Is My Front Diff Bad?

Post by astroturf » Fri Jan 29, 2010 2:16 pm

Good Luck with your trip. Jim

ihatemybike
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Re: Is My Front Diff Bad?

Post by ihatemybike » Fri Jan 29, 2010 4:39 pm

Mr Bean wrote:Aaron, trying to sort through your very thorough cardomain blog to help make the diff replacement process easier...any tips or how-to's would go a long way with me! Thanks!
Wait.




Somebody actually reads that?

Now I feel like I need to do a better job of updating it.
Aaron

2005 Astro (Gandalf) - AWD, 4.3L, 3.42, 130k+ miles
1997 Astro (Grumpy - $250 Rally Van) - AWD, 4.3L, 3.42, LSD, 2" lift, 31" tires, 335k+ orig engine, $30 eBay fuel pump
Prev Astros:99,97,00,94,87,86

Mr Bean
I finally get the smurf thing
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Re: Is My Front Diff Bad?

Post by Mr Bean » Mon Feb 01, 2010 10:57 pm

ihatemybike wrote:
Mr Bean wrote:Aaron, trying to sort through your very thorough cardomain blog to help make the diff replacement process easier...any tips or how-to's would go a long way with me! Thanks!
Wait.




Somebody actually reads that?

Now I feel like I need to do a better job of updating it.
Um...yeah. read practically the whole thing. ahah. So, here's the deal, a used diff around here is $400. Not gonna happen right this second. We just bought an MCI-9 charter bus to conver to a tour-bus. So the van gets back-seat. Going to pull the diff and take the half shafts apart and do what you did...drive without the diff for now...can you outline how we need to do this? Doing the whole thing tomorrow night (Tuesday night the 2nd of Feb) Help me out Aaron!!!
~Scott & Heather
2001 Astro AWD LT
All about me, my girl, & our van with loads of pics:
viewtopic.php?f=20&t=5281
Image

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