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Car Forum / Chevrolet / Chevrolet Trucks / December 2005

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Front Differential Problems

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Big E - 29 Dec 2005 02:01 GMT
In early october, I purchased a brand new 2005 GMC Sierra 2500HD
Duramax pickup.  It's a factory conversion truck with a 4" lift kit,
33" tires and every bell and whistle available.  While driving home in
the snow last week my drive train locked up  ( I was in four wheel
drive ).  I put my truck back into two wheel drive and everything was
fine.  I tried four wheel drive again and the truck would not move at
all.  After returning to two wheel drive I hurried over to my local GMC
dealership.  They told me that the 4"lift kit and tires caused the
front differential to prematurely wear out  ( 4000 miles on my truck  ;
about 5 of those miles are in four wheel drive ) .  Are there any known
problems with GM's front differentials from 2005.  Also, how can a
factory conversion truck cause front differentials to wear out.  Is
this something that I have to worry about?  Any input would be
appreciated
TheSnoMan - 29 Dec 2005 02:09 GMT
> In early october, I purchased a brand new 2005 GMC Sierra 2500HD
> Duramax pickup.  It's a factory conversion truck with a 4" lift kit,
[quoted text clipped - 10 lines]
> this something that I have to worry about?  Any input would be
> appreciated

Not with the problems you describe. I am thinking that maybe your truck
slipped out of the factory with two different axle ratios because of a
assembly line screw up. It would cause what you describe.

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John Craker - 29 Dec 2005 05:51 GMT
>> In early october, I purchased a brand new 2005 GMC Sierra 2500HD
>> Duramax pickup.  It's a factory conversion truck with a 4" lift kit,
[quoted text clipped - 14 lines]
> slipped out of the factory with two different axle ratios because of a
> assembly line screw up. It would cause what you describe.

Not unless it changed during/after the 5 miles he made it!   :)

Get all 4 wheels off the ground firmly & safely (jack stands, etc).
Stick in 4 wheel, and see if you can get the wheels to move.
See if you can rotate each front wheel freely.
TheSnoMan - 29 Dec 2005 11:34 GMT
>>>In early october, I purchased a brand new 2005 GMC Sierra 2500HD
>>>Duramax pickup.  It's a factory conversion truck with a 4" lift kit,
[quoted text clipped - 20 lines]
> Stick in 4 wheel, and see if you can get the wheels to move.
> See if you can rotate each front wheel freely.

If the 5 miles was in slick snow it would have worked and it would have
bound up on dry pavement. THe only other possibbilty here is front diff
has no lube in it or Tcase is dry (not likely either) With GM 4x4, the
driver side front wheel is always engaged to front diff and the ride
front has a disconnect at the axle housing so if thw wheels were binding
it would still bind in 2wd. A thing to note and remeber here though is
that GM can be very fussy about warranty work on drive line problems
with lifted trucks. I have a 2000 K3500 old style with a snow plow and
they have never said a word about that because truck is stock otherwise
including tire size.

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hipcheck - 30 Dec 2005 14:36 GMT
>>>>In early october, I purchased a brand new 2005 GMC Sierra 2500HD
>>>>Duramax pickup.  It's a factory conversion truck with a 4" lift kit,
[quoted text clipped - 31 lines]
> have never said a word about that because truck is stock otherwise
> including tire size.

I have a neighbor that had the gears in his truck changed, he went to 4:11's
or so he thought. They put 4:11's in the back and 4:88's in the front. In a
snow storm he put it in 4hi he drove for about 10 miles then hit one dry
patch in the road... the transfer case was the week point and there he sat.
So it could possibly happen... but there are a few other things it could be
too...
Shep - 29 Dec 2005 14:48 GMT
I don't believe there is a "factory lift kit" other than some dealer
installed sales deal, not factory installed or authorized.
> In early october, I purchased a brand new 2005 GMC Sierra 2500HD
> Duramax pickup.  It's a factory conversion truck with a 4" lift kit,
[quoted text clipped - 10 lines]
> this something that I have to worry about?  Any input would be
> appreciated
Big E - 30 Dec 2005 04:02 GMT
> I don't believe there is a "factory lift kit" other than some dealer
> installed sales deal, not factory installed or authorized.

GM did not physically install the lift kit.  My truck was lifted by A&J
conversions from Valders Wisconsin  ( AJvans.com ).  I called them and
they told me that the lift kit they installed was completely covered by
my GM warranty.  They buy trucks directly from GM at which point they
lift them and so on and so on.  My dealership does now have a new front
differential on order.  They say now that this part never goes out so
GM doesn't make extras.  In 3 weeks it should be at the dealership.
They told me now that they want to sue A&J to cover my warranty.  I
think my dealership is horrible.  I'm currious to see what happens.
One of my friends heard GM has had trouble with the four wheel drive on
new diesels.  Apparently they installed faulty bearings in some of the
front differentials and have had some problems.  Who knows though.
Hopefully they don't find anymore problems when they replace the front
differential.
SuperDave - 29 Dec 2005 19:02 GMT
Those aluminum IFS front diffs are pretty weak, but I don't believe the
dealer is telling you the truth.  Unless they actually took the front
diff out, how do they know it's worn out?  I have an older IFS front
end truck and there is no inspection cover, the diff splits in half
(right and left sides) before you can inspect the ring and pinion.  If
the ring and pinion were bad, it would make a hell of a raquet for some
time before locking up.  You would hear a whine at first, then as the
gears eat each other up the noise would change to grinding and popping.

I've got a 6 inch lift and 35" tires on my truck so I can attest that
the front diff will take some punishment - and 4000 miles is peanuts.

I have heard of the drivetrain completely locking up before one other
time.  A friend of mine was with his father at the dealership test
driving a new Denali and while driving down the street, not too far
from the dealership, the entire thing came to a screaching halt.  After
lots of messing with things, they couldn't get the truck to move at
all, so they walked back to the dealership.

Take John's advice - get all four tires off the ground and try to find
out where things are binding.  With 4wd engaged, disconnect the front
driveshaft and see if the transfercase will turn freely, and that will
tell you if the problem is in the front diff.

One other thing - if the front diff does turn out to be a problem,
consider buying a used one instead of getting that one fixed.  I was
planning on selling mine so I looked for prices on ebay, and found they
were going for around $100 to $150.  That's way cheap compared to
getting it fixed, because it cost me around $700 just to have the front
gears changed from 3.73 to 4.88 (nothing broken, no troubleshooting,
etc).  Keep in mind I'm talking about a little bit older truck, but
unless something changed for 2005, your front diff probably matches
ones from a few other years.

SuperDave
TheSnoMan - 29 Dec 2005 20:55 GMT
Those diffs are not weak and you will tear the half shafts off before
you damage the 9.25 diff in a 2500 truck. It is pretty stout.

> Those aluminum IFS front diffs are pretty weak, but I don't believe the
> dealer is telling you the truth.  Unless they actually took the front
[quoted text clipped - 31 lines]
>
> SuperDave

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SuperDave - 30 Dec 2005 03:26 GMT
SnoMan, you might well be right.  The one in my truck is the aluminum
type that came in the 1/2 ton trucks and it is known to be weak - it's
got an 8.25" ring gear, and simply torquing the case housing bolts down
will distort the case enough to affect the gear meshing pattern.
TheSnoMan - 30 Dec 2005 05:22 GMT
> SnoMan, you might well be right.  The one in my truck is the aluminum
> type that came in the 1/2 ton trucks and it is known to be weak - it's
> got an 8.25" ring gear, and simply torquing the case housing bolts down
> will distort the case enough to affect the gear meshing pattern.

You cannot even fit/mount the 9.25 front diff in the 1500 truck (except
the 1500HD which uses a 2500 chassis) as it is a lot different. Never
seen it done yet either with modification. That same ring and pinion
used in the GM 9.25 IFS is used in the AAM solid front axle that Dodge
has been using since 2003 in its HD trucks.

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Jon Pickens - 29 Dec 2005 21:00 GMT
A friend of mine had a Bronco II that did that... she was driving and
suddenly the whole drivetrain locked up completely.  It was like she'd
slammed on the brakes.

She took it to the dealer, and they basically said they'd heard of it,
but it was a 1 in a million thing, and not to worry, that it wouldn't
happen again...

Unfortunately it did...  Get it looked at ASAP.

~jp
 
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