Frontt axle won,t engage
#1617951
05/08/14 11:58 PM
05/08/14 11:58 PM
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Joined: May 2009
Posts: 618 Vesper,Wisconsin U.S.A
DusterJeff
OP
mopar
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OP
mopar
Joined: May 2009
Posts: 618
Vesper,Wisconsin U.S.A
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I got a 1990 W-250 pickup.The 4 wheel drive never worked on it when I bought it 2 years ago.I,m getting around to it now,tinkering with it. I suspected the front axle vacuum modulator on it.I took the old one off,put my hand vacuum pump on it and yes it did not work.I went and got a new one and installed it on the truck.Still no front wheels turning.The front shaft on the transfer case spins, but nothing turns on the axle.The truck is on jack stands in my shop. Does the truck have to be on the ground and rolling forward or back in order for the axle to engage once the transfer case lever is thrown in gear???? Or do I have little vacuum at the modulator? I put my finger on the end of the hose,there is some vacuum, but is it enough??? My next step is to pull the front axle cover off and see if the ring gear is stripped of teeth..If so,I have to pull the gits out of the axle.It is a Dana 44 FBJ. I,m havinh a lil hard time tryiong to find the special tool needed to remove the inner axle shaft. Chrysler number D-354-4 the tool and the adapter D-354-3.Any body know where I can get that at a reasonable price?????
Do Something..Lead..Follow..or get the {Beep} out of the way..
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Re: Frontt axle won,t engage
[Re: DusterJeff]
#1617952
05/09/14 12:20 AM
05/09/14 12:20 AM
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Joined: Sep 2003
Posts: 1,295 Hawley, Texas
shinnery
super street
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super street
Joined: Sep 2003
Posts: 1,295
Hawley, Texas
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When you bought the new vacuum unit did you test it before you installed it? Can you use the hand vacuum pump to make the vacuum unit work on the front axle? Can you connect the hand vacuum unit to the line on the truck to read the vacuum available on the truck when it is running and in 4x4? Just some of my first ideas before tearing into the axle. Bryce
Every electronic device is manufactured with smoke stored deep inside...
only a true genius can find a way to set it free.
The most terrifying words in the English language are: "I'm from the government and I am here to help!"
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Re: Frontt axle won,t engage
[Re: DusterJeff]
#1617953
05/09/14 12:35 AM
05/09/14 12:35 AM
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Joined: Jan 2003
Posts: 10,588 Freeport IL USA
poorboy
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 10,588
Freeport IL USA
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The only thing the vacuum modulator does is lock the axle on that side to itself so it will turn in the differential. without it locked in, the wheel end of the axle will freewheel. With both front wheels off the ground, I'm not sure you will be able to tell if the gear is locked in or not.
The vacuum only pulls the sliding gear in or out, depending on which vacuum port has vacuum. Once it is slid in the direction the port dictates, there is no need for the vacuum to hold it in place, but I believe the vacuum remains.
One of the biggest issues with this setup in the vacuum lines. They are thin steel lines with rubber hose ends, and the hoses go bad and the steel lines rot out.
You can manually lock the gear in by removing the vacuum unit, sliding the mechanism into the lock position, and shifting the vacumme lever to the side making it hold the slider in gear, then reinstalling the vacuum mechanism. To disengage the 4x4, you have to remove the vacuum mechanism disengage the slider, center that vacuum mechanism and reinstall it.
Pulling the cover to inspect a differential is never a bad idea, but unless its really broke, your probably not going to gain anything concerning the 4x4 function. Gene
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Re: Frontt axle won,t engage
[Re: DusterJeff]
#1617956
05/09/14 11:00 PM
05/09/14 11:00 PM
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Joined: Apr 2010
Posts: 41 Maryland
regularjay
member
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member
Joined: Apr 2010
Posts: 41
Maryland
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use your hand pump to engage the front axle, spin 1 front tire, if the other tire moves in either direction (likely opposite the one your turning) then the front end is "in gear".
79 Lil Red Express - I'll finish it someday 94 2wd Ram 1500 5.9 Donor for...??? 78 CJ7 4.2 with Clifford Cam, Holley 390, 4" on 33's 1992 W250 Cummins 2013 Ram 4X4 Hemi Crew Express 2005 Ex Cab Dakota 4x4 4.7 Daily Driver 1993 2wd Ramcharger 5.2/auto
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Re: Frontt axle won,t engage
[Re: DusterJeff]
#1617958
05/10/14 03:03 AM
05/10/14 03:03 AM
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Joined: Aug 2005
Posts: 11,543 chicagoland,usa
buildanother
I Live Here
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I Live Here
Joined: Aug 2005
Posts: 11,543
chicagoland,usa
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It's pretty straight forward of a setup. The connecting collar just slides over and engages both splines when locked. You probably already know that though. If I recall, the collar stays on the outer stub of axle when in 2 wheel drive, and then when 4x4 activated, it slides towards right side of truck when activated. The vacuum signal remains for either the 2 wheel position or 4 wheel position. So if you had a live vacuum hose handy, you could slip it on one or the other of the 2 actuator nipples, and the fork will go one way or the other depending on which nip was chosen. I must be the only one who has not had issues with this CAD system, although many here have had rusted lines, cracked hoses, or the switch on transfer case problems.
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