Grinding/Rubbing Sound 1st, 2nd, kinda 3rd

[favord]

I have been trying to track down a grinding or rubbing sound that in my mind sounds driveline. Two different shops test drove it and told me it was in the transmission (NV 5600) so I bit the bullet, had the transmission pulled and it all checked out fine so they buttoned it up, put it back in and charged me 500 bucks. Still grinds. Shop guy told me today when I picked it up to bring it back on Monday to talk with the head honcho about the cost, etc. and see what they could do - think he felt a bit embarrassed to hand me back a truck with a big bill and no fix, we'll get that straightened out.



In the interim, thought I'd see if can come up with some other possiblities - My best description would be a rhythmic grind/rub/friction sound that is very audible and increases in speed/rhythm as I go up thru the gears then dies away or becomes less noticeable when I get up to speed in 3rd gear. I can't feel anything in 4th, 5th, and 6th. I can kind of feel it thru the shifter a little bit. For some reason it feels like it's in the front, or at least not the very rear if that makes sense. Thru the years I've had about every U-joint on the thing replaced, probably multiple times. It has a new custom front driveshaft with about 20-30K miles on it. The joints all "feel good" when I get under there and give the a look over. Transfer case seems to work fine and I don't notice any change when I ran it in 4-hi today briefly to see if it did anything. Anyone have any other thoughts on which link in the system to check next. . ?? It's obviously got a problem that's no doubt going to get worse until it fails but I'd rather not be out on the road somewhere pulling horse trailers/traveling/etc. Thanks for any ideas - I know these kinda problems are tough to figure out over the WWW, especially when you can't figure 'em out in real life!

 

[macdaddy]

How long have you had the 04. 5?. What your describing sounds like normal gear lash. The NV 56 honey is known for this. Especially when you said first through third.



Mac

 

[favord]

Thanks for the suggestion. I subsequently did a search on gear lash and found lots of similar descriptions and threads so guess I'll go with that and drive the helloutta her... funny I never came across gear lash in my searches before I took it to the shop... all I could find was threads by folks that actually had something break in the NV5600! It's got 140K on it and never made so much as a peep in the past is why I was pretty convinced it was buying the farm. They had it out and on the table and said it looks fine. We'll see.

 

[Prairie Dog]

Yep, mine has lots of gear lash sound but only when going fairly slow and kinda lugging it. It's probably the worst in 3 gear going slow and gets quiet as speed increases.

It sounds like yours got worse at some point though. 1 or 2 broken springs in the clutch would make it rattle more. Did you check them out?

 

[RVTRKN]

Ya, from day one (10 miles on the ODM) mine made that noise, but didn't you hear that before? It seems like you have noticed that before, seeing how loud it is. I believe some call it trany creep or at least thats what I referred to it as. Climbing up a steep driveway in 2nd gear while idling up it, seemed to be the loudest.

 

[macdaddy]

I remember hearing it while doing a test drive with 3 miles on the odo, that and the front drive shaft turning.



Thats a bummer about the $500. 00 bones, for the oil change.



Mac

 

[GCroyle]

favord,



Engines create pulses as they fire, it is not an electric motor type of output, powerstroke, powerstroke repeat... ... .....



The clutch disc must take those pulses and via the torsion damper, smooth them out, or filter the pulses into a more digestable friendly input to the gearbox.



Different designs of clutch discs affect this filtering capability and can ALLOW the gearbox to make noise, no finger pointing, just information.



For example:

Stock disc, quietest most effective filter, stock power levels

8 spring road truck style disc, expect some noise, above stock power levels.

Solid hub, no filtering, noisest.

A disc that the torsion damper is failing, noise above and beyond what is was designed to do.

 

[superswamper]

My 05 makes a noise but I believe it is the pinion bearing, it grinds alot at higher speeds when I let off the throttle. With my lift I did not add extra diff fluid for when the pinion was rotated up slightly. I jacked it up on jack stands and set the cruise and it makes the noise at the center of the axle so thats my guess on my application. I have the 6 speed too and at 62,000 miles I have not checked the fluid level in it, the dealer was going to check it a while ago but didn't have the tool!