Suspected transfer case problem

[dyocis]

Hoping someone can help me out.  I have an 03 SS, and I think I have a problem with my transfer case.  I have a sloped driveway, and the first time I jacked up the front end to do brakes, my truck started rolling backwards.   I just thought that was how the AWD system worked. 

After doing some more reading, I see that after a front axle break, you still can still limp it home.  I broke my front axle over the weekend, and lost all motion.  I had to put my emergency brake on in park because the truck rolled backward.

I think my transfer case is only putting power to the front end. 

Can anyone tell me if I am right, or explain this to me.  I'm pretty confused.

 

Thanks  

[DatLiftedSS]

My truck did something similar a while back, shortly after blowing the rear driveshaft out of it and repairing it i parked it in the driveway and when i looked back it was rolling away, hasn't done it since. would be nice knowiing what was going on there.

[IndyNova]

They will roll, you have to chock the rear wheels. Mine seems to always roll if parked on an incline and the front wheels are off the ground. You would think the transmission being in park would prevent this

[dyocis]

@IndyNova thanks for the reply.  I am more concerned that I lose all forward motion when I break a front axle.  That tells me that my transfer case is stuck in front wheel drive.  

Have you ever broken a front axle and been able to still drive? I've read the manual for the t-case and it would make sense that all power is transferred to the rear if the front has a free spinning tire/broken axle.  Unless I am misunderstanding something.   

[dcairns]

I could be wrong, as I am going off vague memories of how the transfer case is built,  but I think the transmission output shaft is a solid piece of metal, from the transmission to the drive shaft u-joint.  The front is driven by a chain drive off a sprocket on that shaft.  If the front works, and the rear does not, it would mean the output shaft is broken after the chain drive sprocket.  Seems an unlikely failure.  Then again, I managed to break the input shaft on my transmission.. 😆

[IndyNova]

3 hours ago, dyocis said:

@IndyNova thanks for the reply.  I am more concerned that I lose all forward motion when I break a front axle.  That tells me that my transfer case is stuck in front wheel drive.  

Have you ever broken a front axle and been able to still drive? I've read the manual for the t-case and it would make sense that all power is transferred to the rear if the front has a free spinning tire/broken axle.  Unless I am misunderstanding something.   

By front axle, I'm assuming you mean the CV joint. If that's the case, yes, you can still drive with a broken axle(wouldn't recommend that) The transfer case is chain driven off the input shaft from the transmission, through a chain and out to the front through a viscous coupling (hence why you never want to drive or dyno with the front driveshaft out.  I actually smoked my output shaft on my transfer case this summer (that clunk everyone said was chain slap, was not..lol) The transfer case in our trucks(AWD) are full time AWD, and doesn't act the same as a normal 4x4 case

Edited May 20, 2021 by IndyNova (see edit history)

[dyocis]

1 minute ago, IndyNova said:

By front axle, I'm assuming you mean the CV joint. If that's the case, yes, you can still drive with a broken axle(wouldn't recommend that) The transfer case is chain driven off the input shaft from the transmission, through a chain and out to the front through a viscous coupling (hence why you never want to drive or dyno with the front driveshaft out.  I actually smoked my output shaft on my transfer case this summer (that clunk everyone said was chain slap, was not..lol)

Yes, cv joint.  Sorry for the sloppy use of axle.  That's the reason I think either my viscous coupler is bad, or there's some other problem with my t-case.  When I broke my cv joint, I rolled down a hill backward while in Drive on throttle.  

Whatever the issue is, I've got my transmission guy pulling it apart today to diagnose.  

[meistro57]

On 5/12/2021 at 5:51 AM, DatLiftedSS said:

My truck did something similar a while back, shortly after blowing the rear driveshaft out of it and repairing it i parked it in the driveway and when i looked back it was rolling away, hasn't done it since. would be nice knowiing what was going on there.

I had the same issue. Turns out it was the viscous coupling in the transfer case being damaged. It would spin freely very slowly between the front and rear axles. I bought a rebuild np149 that stated the viscous coupling had been serviced. It can't be so that was BS. The rebuilt one had a bad coupling that was slipping internally.