Front two wheels do not engage in 4H or 4L

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04/16/2013, 03:55 PM
Vinnybin

Front two wheels do not engage in 4H or 4L

I'm having trouble diagnosing a 4L and 4H problem with the front two wheels not engaging. A hobby mechanic told me it was the front differential but he doesn't know VX. I seek the pro's.
SYMPTOMS
4L- loud popping in irregular frequency coming from the front end. Wheels don't turn
4H- lighter sounding popping in the front. When AWD puts more torque up there the popping is as loud as 4L. When getting to speeds around thirty, I hear a jingle up there which sounds like a couple of BBs in a tin can shaken quickly.
No increase noise in turns
MODIFICATIONS
Calmini lift and some aftermarket rims and hub covers

WHAT I DID
Changed out the transfer case fluid which looked horrible and tonight ill do the front and rear differential fluids. I'd hear of putting a small magnet in the case, looking for metal shavings so ill give that a try too. Currently, the tires are size 32 inch and I am feeling like new gears would be helpful to keep the engine running in its designed power margin. If the front differential is the problem, should I purchase new gears instead of replacing the pumkin gear in the size I don't want? Thanks for your time if you reply. Ill also take as many pictures as I can to help out others as much as possible.
04/16/2013, 05:05 PM
VXorado

It's most likely the CV joints on the half shafts. Check the CV boots for rips, this is a very typical problem for lifted VXes.

Use the search function for "half shafts", "CV", "popping" and you'll find a 100,000 posts related to this issue, including all of the info you need to fix it.
04/17/2013, 04:41 AM
tom4bren

I agree that the popping sound is probably bad CVs. That wouldn't explain the fact that you are not getting drive to the front wheels though. How do you know that you are not getting power to the front?

Remember that the diff fluid can be a PITA to get it to flow out. Make sure you have a probe handy to keep clearing the drain if the fluid stops coming out. I only got about a cup out of mine when draining but then the rest all over the driveway when I dropped the axle.
04/17/2013, 07:12 AM
vt_maverick

Might also want to look into diff drop brackets (Tom there can help you) to prevent the problem in the future.
04/17/2013, 07:19 AM
Triathlete

If the CVs are completely fubar'd the wheels will not turn and will cause all kinds of noise/popping since the balls will no longer be contained by the cage. Usually doesn't happen with normal use but if it was driven hard of offroaded hard it is possible.
04/17/2013, 07:37 AM
tom4bren

Quote:

Originally Posted by Triathlete

If the CVs are completely fubar'd the wheels will not turn and will cause all kinds of noise/popping since the balls will no longer be contained by the cage. Usually doesn't happen with normal use but if it was driven hard of offroaded hard it is possible.

If the CV were so bad that it couldn't drive the wheel, then wouldn't the half shaft just fall out?

When my outboard CV went FUBAR, the cage desintergrated, all of the bearings fell out, & the splined shaft end was laying on the upper control arm.