Hello

1999 ZR2

I have a constant whirring sound coming from the front end somewhere (I believe) It gets louder with speed, not engine revs. Same thing in 2 or 4 wheel dr.

I did find that my front hubs were locked even though I was in 2wd. weird.. I release the vacuum to the diaphram below the battery and they unlock.. they will lock when I press 4x4 again, but will not unlock on their own (when I change back to 2wd) without me releasing the vacuum line (My diaphram is actuated by an electronic valve for vacuum mounted on the firewall.. not vacuum line from tcase.) So I have no idea how long they were locked for and am wondering if maybe I have worn out where they connect into the front diff??

My main question is this. I notice that my front driveshaft is always spinning whether in 2 or 4wd. Is this normal? I would assume that the Tcase would only engage the front drive shaft if 4wd was pushed, or does the shaft always spin and engage at the front diff? Same thing goes for the CV shafts.... they always spin whether in 2 or 4 wheel... but I think this is a little more normal as they would engage at the side of the diff?

Or am I out to lunch??


Thanks for the help in advance!!!

Bryce

 

Oops... guess this should be in the driveline forum.. my bad, but I dont know how to move it :0

 

Don't worry about it, I'll take care of it for ya! If you ever think that you have put something in the wrong section, just PM one of the Mods/Admins and we'll move it right away.

Anyway, to your problem...

If your front axle is engaged, then the front driveshaft will turn. With the t-case in 2wd and the front axle disengaged, the front axle should not turn. It sounds like something is not working properly in the front axle engagement mechanism. It almost sounds like the return spring in the vacuum diagram is broken, not keeping tension on the engagement lever at the front axle...

 

After some more messin around....

Ok.. even with vacuum disconnected to diaphram (and visually inspected that diaphram is released) I put the truck on jack stands and in 2WD the front drive shaft still spins while in drive. If I put it in neutral I find:

1. If I spin the back tires both front & rear drive shafts turn.
2. If I spin th front tires.. they spin freely, neither drive shaft turns.
3. Visual inspection of the diaphram shows it is not contracted (Hence free spinning front wheels.)

Would this not indicate that the front DS is engaged in the TC and not as a result of the front axle engaged?

Thanks for the reply

B

 

Yeah, that's what it sounds like... Will the truck go into 4LO? If not, it sounds like you have a problem with the encoder motor in the transfer case.

 

Yup... Shifts into 4 lo no problem.. seems weird

 

Still could be a problem with the encoder... But it sounds like the front axle is just always engaged... That's a new one.