Offroad Trailblazers and Envoys

Front End "Drive" Questions

Something not working right?

by Trail X » Fri Mar 01, 2013 5:17 pm

I'm saying, follow the flowchart. Then in very detailed terms, tell us exactly what you did and what you observed at each step.

If it is indeed a blown differential, the normal diagnostic routine isn't perfectly set up to diagnose that, so its important that you take detailed notes and articulate it well to us.

Donny, seized spider gears could explain the 'engaging' front driver wheel. But it doesn't explain the non-engaging passenger tire. Yes, both the diff and disconnect could be broken, or there could be some other explanation.

Even without lube, seizing the spider gears would require many one-wheel peels, which would be difficult in 4wd mode.
8-) Build Thread | ExPo Build | YouTube Videos
Not all who wander are lost. -Tolkien
User avatar
Trail X
Founder
 
Posts: 9925
Joined: Mon Sep 07, 2009 10:22 pm
Location: VA, Roanoke
Name: James Downing
Vehicle Year: 2005
Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD w/ Aftermarket Locker
Rank: Expedition Guide

by fishsticks » Fri Mar 01, 2013 8:58 pm

JamesDowning wrote:Donny, seized spider gears could explain the 'engaging' front driver wheel. But it doesn't explain the non-engaging passenger tire. Yes, both the diff and disconnect could be broken, or there could be some other explanation.

Even without lube, seizing the spider gears would require many one-wheel peels, which would be difficult in 4wd mode.



If I read his posts correctly, he's trying to spin the wheels in 2WD. So the disconnect would be disengaged.

I disagree on the one wheel peels for two reasons.

1. 4WD: Since the front wheels articulate for steering, the difference in speed between wheels is much greater. The spiders in front get more of a workout. The problem is exacerbated if he's been driving around in 4HI or A4WD frequently.
2. 2WD: I believe (but I don't have proof) that in many cases the force required to spin the front carrier may be greater than what's required to spin the spiders. I think the spiders spin pretty constantly during cruise.

I think either of these could easily seize the spiders onto the crosspin in a low lube situation. The description of the oil that came out of the front diff ("some of the worst the tech had seen") sounds like someone ran the front diff dry, then tried to add fluid later.


All speculation of course.
11 Silverado LTZ - 6.2L/6l80, 2/3 drop, self tuned
85 Hilux - 3RZ, dual cases, caged, 40s, chromo everything
02 TrailBlazer LTZ - 35s, lockers, balls - Gone but not forgotten - Build
User avatar
fishsticks
Moderator
 
Posts: 4356
Joined: Thu Apr 01, 2010 11:30 pm
Location: WA, Vancouver
Name: Donny
Vehicle Year: Other
Vehicle: Other Vehicle
DriveTrain: 4WD w/ Aftermarket Locker
Rank: Extreme Offroader

by HARDTRAILZ » Fri Mar 01, 2013 9:12 pm

Best bet...




Remove rear driveshaft

Lock in 4lo

Hammer the throttle

Replace what breaks....
I hate to advocate weird chemicals, alcohol, violence or insanity to anyone...but
they've always worked for me.
User avatar
HARDTRAILZ
Moderator
 
Posts: 6342
Joined: Sat Sep 12, 2009 1:49 am
Location: IN, Batesville
Name: Kyle
Vehicle Year: 2006
Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD w/ Aftermarket Locker
Rank: Extreme Offroader

by fishsticks » Fri Mar 01, 2013 9:28 pm

HARDTRAILZ wrote:Best bet...




Remove rear driveshaft

Lock in 4lo

Hammer the throttle

Replace what breaks....



5. Clean up mess of transfer case fluid you just made. :mrgreen:
11 Silverado LTZ - 6.2L/6l80, 2/3 drop, self tuned
85 Hilux - 3RZ, dual cases, caged, 40s, chromo everything
02 TrailBlazer LTZ - 35s, lockers, balls - Gone but not forgotten - Build
User avatar
fishsticks
Moderator
 
Posts: 4356
Joined: Thu Apr 01, 2010 11:30 pm
Location: WA, Vancouver
Name: Donny
Vehicle Year: Other
Vehicle: Other Vehicle
DriveTrain: 4WD w/ Aftermarket Locker
Rank: Extreme Offroader

by Trail X » Sat Mar 02, 2013 10:52 pm

fishsticks wrote:2. 2WD: I believe (but I don't have proof) that in many cases the force required to spin the front carrier may be greater than what's required to spin the spiders. I think the spiders spin pretty constantly during cruise.

Ya know, I didn't think of the damage occuring in 2wd mode, but you're absolutely right, that could seize them. That might be the answer.

I did think he was doing it in 4wd though, since he couldn't spin the drivers tire at all, if it was in 2wd, he'd just be spinning the front prob shaft if the diff gears were hosed up.
8-) Build Thread | ExPo Build | YouTube Videos
Not all who wander are lost. -Tolkien
User avatar
Trail X
Founder
 
Posts: 9925
Joined: Mon Sep 07, 2009 10:22 pm
Location: VA, Roanoke
Name: James Downing
Vehicle Year: 2005
Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD w/ Aftermarket Locker
Rank: Expedition Guide

by axo488 » Sun Mar 03, 2013 1:01 pm

[quote]
If I read his posts correctly, he's trying to spin the wheels in 2WD. So the disconnect would be disengaged.

I disagree on the one wheel peels for two reasons.

1. 4WD: Since the front wheels articulate for steering, the difference in speed between wheels is much greater. The spiders in front get more of a workout. The problem is exacerbated if he's been driving around in 4HI or A4WD frequently.
2. 2WD: I believe (but I don't have proof) that in many cases the force required to spin the front carrier may be greater than what's required to spin the spiders. I think the spiders spin pretty constantly during cruise.

I think either of these could easily seize the spiders onto the crosspin in a low lube situation. The description of the oil that came out of the front diff ("some of the worst the tech had seen") sounds like someone ran the front diff dry, then tried to add fluid later.


All speculation of course.
/quote]

This is indeed the case. I have only had this vehicle in any 4wd mode when absolutely necessary (snow) since I have owned the vehicle. All tests have been done in 2wd mode. I did test the newest mods in a very low impact situation just before this issue started. The left front is engaged now all the time when driving in 2wd mode. I have looked over the flow chart extensively and didnt really want to mention it but it doesnt seem conducive to diagnosing the particular issue that I have. Again I am new to 4wd problems but I am fairly experienced in most things mechanical (industrial mechanic presently and former motorcycle mechanic by trade) but right now I have no idea where to start. I am also very aware that these issues are difficult to diagnose on the web. If anyone could point me in the direction of where to start disassembling this thing to possibly find the problem then I am all ears! I there a servo that engages the unit? P.S. At this point I am not sure the right front wheel is engaging when in 4wd mode. I will check that today hopefully. Thanks A Ton!
Axo488
Never argue with an idiot, they will bring you down to their level and beat you up with experience!
axo488
Cruiser
 
Posts: 19
Joined: Mon Jan 28, 2013 8:41 pm
Location: TN, Bristol
Name: Paul Allan
Vehicle Year: 2003
Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD

by The Roadie » Sun Mar 03, 2013 2:21 pm

If you have torque of any kind going to the front left wheel in 2HI mode, there's problems in both the front diff and the transfer case. The splined disconnect on the passenger side of the oil pan sounds like it's properly disconnected in 2HI. That item replaces locking hubs (manual or electric) on other vehicles.

Have you read: http://www.offroadtb.com/articles/tech- ... operation/ yet?
User avatar
The Roadie
Founder
 
Posts: 5011
Joined: Mon Sep 07, 2009 11:29 pm
Location: OR, Portland area
Name: Bill Carton
Vehicle Year: 2004
Vehicle: GMC Envoy
DriveTrain: 4WD w/ G80
Rank: Expedition Guide

by Trail X » Sun Mar 03, 2013 9:41 pm

Very odd problem indeed. How does it manifest while you are driving? How did you know there was a problem? Are you positive its not just a sticking brake on that wheel?
8-) Build Thread | ExPo Build | YouTube Videos
Not all who wander are lost. -Tolkien
User avatar
Trail X
Founder
 
Posts: 9925
Joined: Mon Sep 07, 2009 10:22 pm
Location: VA, Roanoke
Name: James Downing
Vehicle Year: 2005
Vehicle: Chevrolet TrailBlazer
DriveTrain: 4WD w/ Aftermarket Locker
Rank: Expedition Guide

Previous

Return to Troubleshooting