Need help diagnosing drive train problem

[vandermp]

Greetings! My first post: Just spent a day replacing a non-existent front drive shaft on my 1997 5.0 AWD Explorer with a rebuilt one. Now, the vehicle rumbles and shudders at anything over a few mph. Without the front drive shaft it is fine. What are the chances I got a bad drive shaft? Or is it more likely the front differential? Or the transfer case? It has been running without a front drive shaft for a year or so... Thanks for any help! I'd hate to put in a used front differential and then find out it was something else.

The rumbling and shuddering is consistent with road speed not engine speed. When I checked the front differential before putting in the rebuilt shaft by turning one wheel while the other was stationary, it seemed smooth... The drive shaft is the kind with a cv joint on one end and u joint on the other.

Any help appreciated!!

 

[RangerX]

Did you remove the shaft originally, or a previous owner?

 

[vandermp]

Thanks for responding! I had it removed by a mechanic when there was a vibration problem about a year ago. The CV joint of the old one was pretty much destroyed. When he put the rebuilt shaft in the shuddering started. He thought it was the front differential but wasn't sure. I didn't feel like like spending the money to replace it so had him take the shaft back out and ran it like that for a year. Now I want to use it as a 4 wheel again so I tried putting the rebuilt shaft back in. The same thing happened... I wish there were a way to definitively check the front differential before replacing it... I worry it might be something else... Thanks for your help!

 

[imp]

Faulty viscous clutch in the transfer case. Without front shaft installed, it does nothing. imp

 

[vandermp]

You have confirmed what I suspected. This is in the transfer case, correct? Are there repair kits? I've seen a thread that does a step by step transfer case rebuild, but I'm not sure if that is just seals and such or if it would also fix the VC... any recommendations? Thanks for your help!

 

[RomeovilleIL]

If in fact the VC is the problem for the time and $, might be best served swapping a used one from a yard.

Other than being a little heavy, the swap is a fairly easy and straight forward afair. Disconnect drive shafts, unhook sensor, unbolt from frame. Drain and fill replacement with new trans fluid, lift into place with jack and reconnect.

 

[jremington59]

Are all of your tires the same size? I'm sure they are but if not it will cause the same symptoms.

 

[RomeovilleIL]

Are all of your tires the same size? I'm sure they are but if not it will cause the same symptoms.

Excellent point. AWD requires all the tires to be within 3/32" of each other (which aint much difference) or you get binding.

 

[imp]

Excellent point. AWD requires all the tires to be within 3/32" of each other (which aint much difference) or you get binding.

And eat up the viscous coupling. imp

Aside: Hey Romeo, is that old drainage canal down there still flowing out of Chicago?

 

[RomeovilleIL]

Aside: Hey Romeo, is that old drainage canal down there still flowing out of Chicago?

Of course it is

County forrest preserves have built some really nice trails that run along the I&M canal. I walk and ride my bike there just about every day.

 

[vandermp]

Yes, they are 4 identical tires bought at the same time - but I've replaced two rims (the front) with rims very different than OE. I didn't think different rims would be a problem as long as the tires are the same?

 

[imp]

Yes, they are 4 identical tires bought at the same time - but I've replaced two rims (the front) with rims very different than OE. I didn't think different rims would be a problem as long as the tires are the same?

The importance is the DIAMETER of the tires: they must all be equal in diameter. Rim design CAN affect the "rolling diameter"; for example, a tpoo-narrow rim "bulges" out the center of the tread, making the tire ride slightly bigger in diameter. imp

 

[Flash]

Faulty viscous clutch in the transfer case. Without front shaft installed, it does nothing. imp

How does the VC fail? I know how a VC works but I'm not familiar with these ones.

 

[vandermp]

I'll check the diameters. How does a VC fail? That's a good question - maybe Imp or Romeo can answer that. As far as I understand, there are no mechanical linkages other than input from the transmission and then two output shafts - front and rear. The slippage is modulated by the heat of the fluid in the VC: the hotter the fluid gets from the (shearing induced friction) the more viscous the fluid becomes thus transferring more power to the front wheels. When there is no front drive shaft the VC reads that as high traction on the front wheels and low traction on the rear - which causes rapid heating of the fluid which transfers the maximum power to the (nonexistent) front wheels. I guess in time the fluid breaks down or hardens and the VC "siezes" - meaning it becomes a mechanical linkage for all practical purposes...

That may be completely wrong... but that's what I'm getting from my research... I'd love to take a class or something because I can't stand not to understand exactly how these things work - I guess that's why I'm willing to screw around under this old piece of junk for an entire Saturday: To beat it at its own game!

 

[imp]

Vc failure

Best we've come up with after quite a bit of haggling is, the fluid in the VC can LEAK OUT of it if it's seals fail, then the VC can no longer transmit any torque. Unclear whether that means vehicle won't move at all, or no torque to front wheels only.

Or, the VC can "SEIZE UP", which means it drives maximum torque at all times, consequences, I'm not sure of. imp

 

[vandermp]

Thanks. I'm looking for a used transfer case now. They are not easy to find and are not cheap! I'll post what happens on the thread...

 

[RomeovilleIL]

Guess it all depends on where you are located. Around here many of the yards have lots of explorers in them so getting parts isnt too much of a hassle. Try checking with the sponsor page. There are guys who regularly part out 2nd gens on there.

Edit: Not sure what kind of pricing you were seeing. Called yard - $150 pick up. Looked at a couple ebay listings, were in same range but with shipping end up around $250. Given a new chain by itself it $100 plus cost of seals and bearings for a rebuild, would still go this route myself.

 

[RomeovilleIL]

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