Diagnosing 4WD problems
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Joined: Nov 2001
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Diagnosing 4WD problems
The 4WD hasn't worked on our 1980 F250 Xcab 4X4 ever since we got it a year ago. When in 4WD with the hubs locked, it makes a crunching noise from around the transfer case. The previous owner told me that he thought the drive chain in the transfer case was stretched, but I am going to try to diagnose it myself before spending $120-$150 for a chain that I may not need. I plan to engage the 4WD with the hubs unlocked and drive it around...if there is no noise and the front driveline is turning, the transfer case should be okay, right? Next, I will lock the hubs, but disengage the 4WD. If there is no noise, the front axles and gears should also be okay, right? Now here's what I think is wrong. I noticed that it has a light-duty rear axle like you would find on a 1/2 ton (on a ~8500 lb. GVWR vehicle), so I suspect that a previous owner swapped the whole rearend and the gear ratios are now different in the front and rear differentials. Where are the numbers/tags located to identify the gear ratios on the front and rear differentials, and is there a website that can decode the numbers to tell me what I have? Is there an easier way to check this?
Elder User
Joined: Feb 2000
Posts: 601
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From: South Sioux City, NE USA
Diagnosing 4WD problems
[font size="1" color="#FF0000"]LAST EDITED ON 01-Nov-01 AT 04:41 PM (EST)[/font][p]What do you mean about the light duty rear-end? Does it look like 9", or maybe an 8.8"? If someone did swap in a different ratio rear-end, then yes, that could have caused enough bind in the xfer case to ruin the chain. (And if you find out who did the swap, slap him silly for me too.)
Look on one of the bolts on the rear-end cover, there should be a tag with the info. If you want to post it here, I'm sure someone would be able to figure it out for you.
HTH
Roger Lane
Test Analyst
Sr. Automated Test Engineer
Look on one of the bolts on the rear-end cover, there should be a tag with the info. If you want to post it here, I'm sure someone would be able to figure it out for you.
HTH
Roger Lane
Test Analyst
Sr. Automated Test Engineer
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