grinding noise only after bump
 

OK, I have a 96 Ram 4x. There is a grinding noise coming from the front end after I hit a bump. The noise is coming from the passanger side near the centerline. It does not do it every bump, sometimes it lasts 1-2 seconds and other times I nearly have to stop for the noise to stop. Along with the noise I get a vibration I can feel through the pedals. I have read that many people having a similar noise had bad t-case snap rings but noone has described the noise only occuring after bumps.

I had the wheel bearings and brakes checked. No other noticeable problems.

could this be the t-case? where can i get a good master rebuild kit?

Does your 4wheel light on the dash come on when it does it? It might not. My first guess is that your CAD is not fully disengaged or is moving some. When you hit the bump, the collar is barely moving over where the splines are rubbing but it is not over far enough to fully engage.
Being a 96, I'd be more inclined that it is the diaphram going out and not something in the t-case.

No the light does not come on.

This is my first 4x so forgive me. What is the CAD? and is there any way to check the diaphram?

i also think the cad is not fully disengaged, and the axle halves/coupler is rubbing.

here's a good article on how it works.
the main thing to understand is that there are 2 vac lines from t-case to cad. vac on one should couple, vac on the other should uncouple.
sounds like you have in-between, which is probably due to a rusty/sticky shaft inside the cad. take it off, connect vac, and test it. then take it apart and clean/fix it, or replace it with a posi-lok (manual cable).

http://www.dodgeram.org/tech/repair/..._engagment.htm

dhvaughan, thanks for that info, exactly what I was looking for.

checked 4 wheel drive today and still works perfectly with no grinding noise, so I think I ruled out the t-case.

I will be checking this next.

+1 on the CAD engagement/dis-engagement suspect. I know on my truck that it takes my truck about 10 seconds to fully disengage from 4X4 after I shift it back to 2WD. My CAD or T-Case is probably on the way out. But if you are hearing a noise near the center of your truck but more towards the passenger side then that sounds like the culprit!

Good Luck!

thanks for the help, I will be pulling the vacuum motor off in the next few days to check it (truck is not a daily driver).

If it is beyond repair, would it be worth the extra $80 or so for the posi-lock conversion?

the cad is actually very simple with only a couple of moving parts. the most common problem is a rusty shaft or fallen off e-clip. but, i just thought the whole contraption was too unreliable, subject to a broken vac line or indicator light when you really needed it. so i replaced mine with a posilok. i like pulling the cable and feeling it engage.

Hey I had the exact same problem and it was the transfer case snap ring. When my suspension flexed the drive shaft would push the transfer case gears together causing that grinding noise. An easy way to check is to pull the 4x4 shifter towards the seat and see if it stops. Don't drive it too long like this if it is the problem. you dont need a rebuiild kit, if it is you just need the new ring or an after market repair thingy that stops it from happening again.

So I pulled the vacuum motor off today just to have a look. Either the previous owner would grind the mess out of it every time he put it in 4x, or this is where the noise is coming from.
There are very fine metal shavings in the tube and the edge of the collar is chewed a bit (the shaft must be much harder than the collar, cause not a scratch on it).

This also leads to another quest. The vacuum motor seems to be functioning. there is no rust on the shaft, no missing e-clip, and it moves freely when I blow/suck the vacuum ports.

Off to auto store tomorrow to get a vacuum tester, maybe the vacuum is off in the t-case or maybe the diaphram in the motor is just worn allowing it to move the collar just enough under the right conditions. ANY THOUGHTS?

-Bonecracker, I don't think it is the t-case because it only does it when the front passanger tire hits a bump and even then not on every bump. I have hit some good holes with the driver side and rear and nothing.