4wd rumble

[rkneeshaw]

I'm hoping you guys can help me diagnose a rumble in my 4wd system.

94 4.0L, manual hubs, electric t-case (1354)
New U-joints throughout the front end (3 in the axles, 1 in the front driveshaft)

With hubs locked and in 2wd mode, truck drives fine, can't really tell the hubs are locked at all.

With hubs locked and 4wd engaged, there is a fairly noisy rumble whenever I accelerate or decelerate by engine-braking. The rumble almost disappears if there is no torque on the driveline (for example, when I'm cruising at a steady speed).

Any thoughts as to where my problem might be?

 

[fourwheelford]

im dealing with the same thing and im in the process of trying to figure it out.

 

[rkneeshaw]

im dealing with the same thing and im in the process of trying to figure it out.

You have a 2000 it looks like, so you have IFS. My truck is the older TTB style 4wd setup. Same transfer case though.

My first hunch was that it was some bearings or something in the transfer case, but I wasn't sure if there is something else in the front driveline that could also cause these symptoms (besides u-joints in the axles and driveshafts, which I've already replaced). Could a problem in the d35 differential cause this?

 

[Explorin94]

Probably going to find it in your front pumpkin. More than likely a pinion bearing. The problem lies with not using or putting it in 4x4 from time to time. The upper pinion bearing sits idles for so long and then it spins creating a stiff spot. Sometimes it goes away but not likely.

 

[fourwheelford]

Yeah I bought a pinion bearing for mine but i don't know if I can change it myself, my rumble really feels like its coming from the passenger side more than anything so maybe the u-joints in the cv joints plus I read that those bearings don't seem to go out very often. The boots seem fine on the cv joints no visible tearing but I guess thery could be a bit dry it happens not to mention it gets worse with more driving where as a bearing would make noise regardless. To the op im gonna change the seals in the axle and if I find anything I will let you know it may help.

 

[Explorin94]

Yeah I bought a pinion bearing for mine but i don't know if I can change it myself, my rumble really feels like its coming from the passenger side more than anything so maybe the u-joints in the cv joints plus I read that those bearings don't seem to go out very often. The boots seem fine on the cv joints no visible tearing but I guess thery could be a bit dry it happens not to mention it gets worse with more driving where as a bearing would make noise regardless. To the op im gonna change the seals in the axle and if I find anything I will let you know it may help.

Yours is easy enough....just pull the front cover and see what you find. Look for metal in the gear oil and go from there.

 

[rkneeshaw]

...To the op im gonna change the seals in the axle and if I find anything I will let you know it may help.

That would be great, I'm interested to see what you find.

I did just think of something: as far as I know the shop only replaced 1 u-joint in the front driveshaft... I'm guessing they left the double-cardon joint up by the transfer case alone. That may be the source of my problem, what do you guys think?

 

[fourwheelford]

I had my step dad drive it tonight on the slick roads he is an ASE certified mechanic and is pretty much the only guy I trust to touch any of my vehicles. He heard what I hear and told me a few things

1. It could be the pinion bearing he said to drive it for a bit then get it somewhere you can get under the truck right away and touch the top of the housing behind the pinion yolk if its hot theres a problem. Then he said to wiggle the yolk if there is any movement there is a problem.

2. It could be the output shaft bearing on the front of the TC wiggle the same way.

3. Could be my CV joints I have a lift on the truck and they are at a different angle than they are supposed to be.

4. It was stated above but he also told me to check the diff fluid suck a bit out and see if there is any metal in it if so there is a problem.

He told me mine doesn't sound as bad as most he has heard so thats an upside I guess, I will update tomorrow night after I spend the day under her.(thats what she said)

 

[fourwheelford]

Ok heres my update, I spent 3 hours checking things and found nothing at all. I checked my differential for excessive heat nothing cold as ice. Checked my pinion shaft, no wiggle at all, sucked out two samples of gear oil from the front diff and it was clean as the day it went in 6 months ago. Also checked the one wheel bearing I didn't change and its fine also the TC output shaft is solid, its safe to say that im stumped so I guess I just drive it until it takes a hike completely or I just sell it and be done with it.

 

[rkneeshaw]

That sucks.

I crawled under my truck and felt around. Most everything felt pretty solid except my forward drive shaft. If i push up on it there is a little play in it, not a lot, but noticeable. It didn't look like the TC output shaft was moving at all so I'm kind of thinking this might mean a problem with the double carden joint? I'm not sure any movement is normal or not, this is my first 4x4

 

[fourwheelford]

I had to put a 500 dollar superlift drive shaft on mine because the guy that did the lift cheaped out and left the original one and the angle on it just destroyed the joint and I had to replace it. It seems alot of people have this problem with fords crap ass drivelines thats probably the source of your problem change it out or at very least take it off and open er up and seewhat it looks like mine was dry as a bone and making bad noises.

 

[feellnfroggy]

It sounds like it is the pinion bearing. Especially with the shaft play. It shouldnt wiggle at all I dont believe. Just like a wheel bearing. I would prolly opt to swap out hte bearings and seals anyways. Most likely you have the short vent tube on yours and have had the front axle under water at least once.

 

[rkneeshaw]

How much work is involved in replacing the pinion bearings in the d35? Does the whole pig have to be removed or can it be completed by removing the front drive shaft?

Felt like the play was towards the double carden joint side of the front drive shaft, I wonder if those u-joints are bad?

I'll have to get under there and feel around again and see if I can tell if the play is towards the front or rear of the driveshaft

 

[fourwheelford]

You will be able to grab down at the base of driveshaft right where it bolts to the yolk and see if it moves there watch it very closely to see if it moves at all. And yes its best to take the whole thing out and take it to a gear guy and just have the seals and bearings done at the same time if everything doesn't go back together right it will be bad. That is of course if your bearings are bad.

 

[rkneeshaw]

Fixed!

I rebuilt the double cardan joint in the front drive shaft with a new ball and 2 new u-joints and the 4wd runs as quiet as can be, can only tell your in 4x4 because of how she grips like a raped ape! Just in time for a blizzard!