Ranger 664 Knocking

[LogStalker]

Hey all,
Just a quick question in the hope somebody may have an easy answer!
So my 664 has just recently developed a knocking noise somewhere under the floor, hard to tell if its in front or behind the cockpit. It's a knock that only occurs when the skidder is moving, and the timing between knocks is consistent. As though it's a cog missing a tooth...?? :(  At first I thought it was just a universal on one of the driveshafts, but I got the boys to have a good look yesterday and they reckon there's no movement in any of them. I'm going to have a look myself tomorrow (Not that I don't trust them...lol) 
In the last couple of weeks I've dropped both diff oils and there's been no filings or anything on the magnets, I haven't changed the trans oil yet. Also the knocking is substantially louder when it's in high range, even if you're not revving it hard. Transfer case??

Any suggestions gratefully taken on board, we're just finishing up at this block and moving to the next one on Friday - it'd be nice to sort the problem before something gives out or blows up...

[Ed_K]

 Check the timing of the drive shafts. I had this problem when I didn't put the two ends together right.

[mike_belben]

If the frequency of knock shares a linear relationship with ground speed, then you are looking from transmission output shaft on back to the wheel hubs.  Slim chance but Its not a stick wedged in an area of the driveline that you cant see right? 

I think i would jack up each corner and have someone freespin while i listen and feel for some clues with a mechanics stethoscope before tearing down.   Being louder in high range makes sense, high range puts more load on the power transmitting components and thus more wack in whatevers wackin. 

Grease the heck out of all your driveline joints and listen for a change in tone or volume of said gremlin.  If none its probably not in there.  Make sure all zerks are accessible and taking grease.  It'd suck to tear down a trans over a bad needle bearing.

[Maine logger88]

does it have any steady bearings? I would check those and any slip yokes you can find

[LogStalker]

If the frequency of knock shares a linear relationship with ground speed, then you are looking from transmission output shaft on back to the wheel hubs.  Slim chance but Its not a stick wedged in an area of the driveline that you cant see right?  

I think i would jack up each corner and have someone freespin while i listen and feel for some clues with a mechanics stethoscope before tearing down.   Being louder in high range makes sense, high range puts more load on the power transmitting components and thus more wack in whatevers wackin.  

Grease the heck out of all your driveline joints and listen for a change in tone or volume of said gremlin.  If none its probably not in there.  Make sure all zerks are accessible and taking grease.  It'd suck to tear down a trans over a bad needle bearing.

Good sharing Buddy, thanks! The heck has definitely been greased out of all driveline joints a couple of weeks back when I pressure cleaned the machine and got rid of the buildup of winter mud from under the belly pans (and everywhere else!) I like your idea of jacking it up and free spinning to try and get some clues. I'll be having a crack at that today.
I'll let y'all know how I go

[LogStalker]

Check the timing of the drive shafts. I had this problem when I didn't put the two ends together right.

Can you elaborate on this mate? I haven't had any driveshafts apart, but that's not to say it's not the problem. How do you set timing on a driveshaft?

[mike_belben]

You make sure that the yokes are phased the same at each end of the shaft.  Out of the machine you just lay the Dshaft on a flat surface and check that both yokes are flat on it.  In the machine, use a magnetic angle finder.  Set one to zero then check the other.

Operating angle of a Ujoint creates a rotational acceleration from the shaft to the yoke for an instant.  Meaning one end drives, one end is driven  the steeper the operating angle, the the greater the deviation in speeds will be between them momentarily.  Universal jointed shafts have atleast two joints end for end, both joints must go through this acceleration together at the exact same time or they will be looking for weak spots to disperse this torsional warfare.  Tends to cause sloppy slip yokes.  The CV joint replacing universals these days is just that, one that maintains a constant velocity throughout its rotation.  Makes for a smoother car.

[mike_belben]

A thought that just jumped in my head.. Get a helper and a few colors of spray paint.
Pick a fixed point or paint a line on the body.  have someone drive the machine in each gear.  use a different color for each gear.  Every time it bags dot the tire.  Youll see how many bangs per 1 tire revolution. 

If theres 4 hits in high range and say 7 hits in low, we know its upstream of the output shaft, planets and diffs because their ratio does not change by Tcase.  That would implicate intermediate shaft.  Well, actually i have no idea if your machine has a powershift or a manual in front of a tcase or whatever.. But you catch my drift.  The number of hits is gonna lead you in the direction of the issue. You may even be able to narrow it down to what gear based in the number.  A 4.7 ratio is gonna give you 4 bangs in a revolution and one just past the first mark.

Let us know how ya make out

[Riwaka]

After the external examinations have been completed. ( check the driveshaft tubes for straightness)

Is there a borescope available to have a look in the transmission?