Help with 4WD

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Apr 27, 2005 | 01:50 PM

lgdb

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Help with 4WD

My son has a 1989 Ford F-150 4WD. When he put the truck in 4WD the back wheels lock up. Any help would be appreciated.

Apr 27, 2005 | 06:39 PM

teds74ford

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As won't turn at all, or bind when taking a corner? Some binding is normal, but to totally lock up isn't. Please describe what is happening a little more.

Apr 27, 2005 | 11:52 PM

lgdb

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They will not turn at all. When he tries to drive forward the wheels just slide.

Apr 28, 2005 | 12:06 AM

aurgathor

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From: Lynnwood, WA

You mean, the front tires will turn, and drag the car and the locked up rear wheels?!?

Apr 28, 2005 | 08:38 AM

teds74ford

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That's what I got out of that. That is weird

Apr 28, 2005 | 05:51 PM

Lou Braun

Fleet Mechanic

Joined: Nov 2003

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From: West Cornwall, CT

If the truck's front or rear end gears were changed and the two ratios are different you will see this behavior.

An easy check is to put the truck on jackstands so that all 4 wheels are off the ground and run it (slowly) in 2WD and 4WD. If everything turns OK you verified that there is no mechanical binding.

Next check the front and rear gear ratios. With the truck off and transmission in neutral turn the rear driveshaft by hand enough to get one complete revolution of one rear wheel (I'm assuming that the rear end has an open differential). Record the number of driveshaft revolutions needed. Do the same with the front driveshaft. Compare the two results and you will have the answer.

Lou Braun

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