VC = Viscous Coupler Caused Damage

[7schulz]

So when I bought my truck I was a newbie and not knowing a lot I bought one with the VC that was seized. There has been talk on Mud about it not causing damage and I want to show all that it can and does cause damage. I had typical tire scrub/skip/chirp on the front wheels when I made a tight turn in a parking lot.(due to the seized VC). I also had a pretty bad whine above 20mph. It eventually broke teeth off my ring and pinion. Here are some pics. I also have the bad VC if anyone wants to dissect it and see the failure mode, total failure or partial failure etc.

 

[7schulz]

Second tooth missing


VC

 

[OGBeno]

Ouch.

That is going to be a pricey fix.

Good luck.

 

[7schulz]

Beno, you sent me the new VC and the 4.88's are already in.

 

[OGBeno]

Beno, you sent me the new VC and the 4.88's are already in.

Oh ok, this is a post hoc thread.



Glad you got this taken care of.

 

[7schulz]

Yea I wanted save people the trouble/damage if their VC goes bad so they know what can happen and to not drive to much with a seized VC.

 

[e9999]

interesting and perhaps surprising.
I would think that most people would not think that the VC being locked would result in such dramatic effects since it's often assumed that the difference in speed between front and rear average tire speed is not as much as that between left and right sides, when turning. But presumably if you keep on driving and turning and the tires don't slip much the stress may end up increasing to objectionable levels.

You didn't have the front/rear lockers on, did you?


good to know anyway, thanks.

 

[7schulz]

NO, I did not have the lockers on. And I did NOT have the center diff locked. It acted the same as if the center diff was locked though. Center diff locked or not it drove very similar. I don't know how long the previous owner drove it this way.
I didn't drive it very long this way either. During my first few weeks of ownership I changed the diff fluid to see what condition it was(Black) I then a few weeks later tried the Heavy Oil Stabilizer from Lucas Oil to see if that helped the nasty wine I had. During that second change of front diff fluid is when I found the first gear tooth. I then took it somewhere to be looked at and quoted for new gears and the second large tooth was found. You could feel the gap where the teeth missed and I was sure I would snap a few more so I stopped driving it, and now I have 4.88's

 

[Higgin]

I am totally jealous of your 4.88's! What size tire do you have on there? I have 35's and stock gears, but I don't find it that bad to drive on/offroad with the stock gears, so I haven't dropped the cash to change em. I figured I'd wait till I wear though this set of tires, and then probably go to 37's next and put in 5.29's since I will hopefully have a 2nd car to drive around then. Glad to see that your cruiser is all fixed up now! We'll have to hit the badlands as soon as I can figure out why mine isn't starting

 

[Wrench]

I doubt the VC caused this damage. Seems like something more extreme happened here. People drive all the time with the center diff locked with no damage.

 

[7schulz]

I am totally jealous of your 4.88's! What size tire do you have on there? I have 35's and stock gears, but I don't find it that bad to drive on/offroad with the stock gears, so I haven't dropped the cash to change em. I figured I'd wait till I wear though this set of tires, and then probably go to 37's next and put in 5.29's since I will hopefully have a 2nd car to drive around then. Glad to see that your cruiser is all fixed up now! We'll have to hit the badlands as soon as I can figure out why mine isn't starting

No tires yet got a set of used OME mediums comming soon and I will go with 35 inch duratrac.

I doubt the VC caused this damage. Seems like something more extreme happened here. People drive all the time with the center diff locked with no damage.

There is/was nothing else wrong with the truck it was 100% stock, running boards and no rust or dents nice leather etc. I don't know what else it could be. Plenty of oil in the diff too. The new VC completely stopped the binding.

 

[OGBeno]

I doubt the VC caused this damage. Seems like something more extreme happened here. People drive all the time with the center diff locked with no damage.

Incorrect Chris.

On a HF2AV xfer case, a binded or seized VC will transmit (or lack thereof) to the rest of the driveline and cause damaged.

 

[Wrench]

Incorrect Chris.

On a HF2AV xfer case, a binded or seized VC will transmit (or lack thereof) to the rest of the driveline and cause damaged.

Not that much force! Are you kidding me? We put these trucks through far worse and not break a ring and pinion. Just driving around a parking lot did that damage? Come on. Be real. Sell your junk if it's that weak.

 

[Wrench]

There is/was nothing else wrong with the truck it was 100% stock, running boards and no rust or dents nice leather etc. I don't know what else it could be. Plenty of oil in the diff too. The new VC completely stopped the binding.

You said the oil was black and there was a nasty gear whine at 20mph when you bought it. Plus you said you where a newbie not knowing what to look for.

 

[7schulz]

Black as in wasn't changed recently, but was still gear oil and the correct ammount
Newbie as I didn't know what a seized VC was when I bought it.
Gear whine caused by the VC. I ended up needing a new carrier too.
Now it's 100% with a gear change and new VC
Draw your own conclustion but with the change everything works as it should.

 

[Brian894X4]

When you turn a vehicle on pavement, even if it's just a shallow turn, all four wheels need to be able to turn at different speeds. So the differential side to side is not enough. You HAVE to have a differential front to rear or it will bind, when all four wheels have equal traction on the same type of surface.

Pavement is one of the highest forms of traction short of getting a tire wedged in a rock, so I can possibly see breaking parts in a tight turn. When you're off road, in dirt, gravel, or whatever, the tires have a lot more give to slip, even if the center diff locked.

However, that said, the gear whine does lead me to wonder if there was other major issues going on with the diff and I do wonder if the locked up VSC was more of an aggravator rather than the root cause of the failure.
.

 

[7schulz]

I think the VC binding up caused enough fource/pressure/binding, through the drive train to damage something in the front diff which in turn damaged the gears and carrier or maybe through the gear engagement offset off? Still the VC caused all the damage. As far as I can tell. Nothing else has been changed and the problem is gone.

 

[OGBeno]

Not that much force! Are you kidding me? We put these trucks through far worse and not break a ring and pinion. Just driving around a parking lot did that damage? Come on. Be real. Sell your junk if it's that weak.

Ok Chris. I will send you a seized VC--I'll even pay for the shipping.

Put it in your rig and see how far down the road you get.

Report back.

 

[silverhorse]

Yet another reason to remove the VC and go part time!

 

[Ebag333]

I doubt the VC caused this damage. Seems like something more extreme happened here. People drive all the time with the center diff locked with no damage.

This is not the first thread that's reported damage in the front end due to a seized VC.

You may get away with driving with your CDL locked or VC locked up, and you can probably get away with it for a loooong time. But not forever.