I bought a cat 980B last year and it has a bad sound/vibration when roading it. The guy before said it did it as long as he had it. But he never looked into it as he just kept it in the pit. About half throttle in 3rd is when you really start to notice it. It does it in both 3rd and 4th. I haven't got it to full speed in 4th as it gets really bad the faster you go. It's like a whining/humming sound, and you can feel a vibration in the machine. The pitch changes as you let off and get on the throttle. It sounds like it's coming from underneath slightly behind the seat, but hard to tell. I checked u-joints and they all seem to be good. I'm not sure where to look next. Any common things that might go on these loaders? I'm almost leaning towards the differential.
A few things; Check that the centre drive shaft yokes are correctly aligned. Check the support bearing between the centre and front shafts. Inspect the rear axle trunnion bearings. If they're badly worn it will cause misalignment between the transfer case and axle. Ditto the transmission mounts. It can be useful to remove the centre shaft and run the machine to see if that gives your troubleshooting some direction.
Pull an oil sample of both differentials... do it soon than later. Bearings would be cheaper to replace than a ring and pinion set.
I would agree with both the above suggestions to start with. One thing how about a full S/N so we could look through SIS to see if we could spot some place to check or what can come off and still move machine? Might even want to remove one section of drive line at a time to see what makes the vibration go away. Remove one section of drive shaft at a time, just be sure the yokes are not a slip on type that could come off while test running. You could also pull both front or rear axle shafts or even pull all four axle shafts then you could spin the transmission and differentials with machine not moving.
Not the same machine, but we had a 966f that had a bad road vibration. After 5 years, it went away after the tires were worn out and replaced
CMark's comment about correct timing of the U-joints is the first thing I'd suggest to look at. The illustration below may give you an idea. Note how the red line goes right through the centre of the "notch" in every single u-joint. That's how they should be timed, right from the input yoke of the rear axle diff through the transmission drop box to the corresponding input yoke on the front differential. If the yokes are out of phase at any point in the driveline it could cause a nasty vibration.. Also worth checking - tyre size differential front axle versus rear axle..?
The statement that strikes me is that "The guy before said it did it as long as he had it. But he never looked into it as he just kept it in the pit." L-5 series tires will do that on every machine.
So what tyres are actually on it..?
Many years ago a A.C. loader I operated had the same problem. Checked all of the above to no avail. The problem was a crook planetary hub in the opposite corner from where the noise was.
Hey guys thanks for all the quick replies! I appreciate all the advice. The serial number is 89P5094 The tires on it are 26.5-25. I cant recall the type but they're not overly worn. It definitely doesn't feel/sound like a tire problem, its got to be somewhere in the driveline. I'm going to pull the bottom skid plate off tonight so I can start taking a better look at things. I never knew about the alignment of the U-joints, that's the first thing I'll check. If that checks out I'll try pulling a section of driveshaft to isolate the front and rear and see if I can narrow that down.
If you do remove a drive shaft, don't go anywhere near a hill. You'd be surprised at how much traction you lose without 4WD. Also if you remove the rear shaft, be aware that the rear axle yoke is a sliding fit on the pinion shaft and can fall off.
Just an idea if you really feel the need to move loader with either the front or rear drive shafts out to test run a short distance. With a little imagination one could fabricate a bracket to hold the yoke in place. We had to do just that on a 988B that had snapped off the pinion shaft to rear axle. On that machine the rear yoke on the trasfer case was a slip joint. We just use a length of 3/8 by 1 1/2 flat stock. It was bolted to the transfer case and bent so as to clear the yoke while turning but had a bolt stuck in the end to put a slight bit of pressure on the center of the yoke. Like I said this would be just a temporary thing to enable a short test run with yoke not falling off! That said the 988B was put up for auction like that and Iron Planet inspector never poked his nose under machine. I was told by my boss to not tell him how to do his job! Last I knew that loader was sold and going on a boat to new owner overseas! Hope no one here was the buyer!
I seem to recall all the 980B loaders I've worked on had 29.5 - 25 tires installed. All the 966 loaders I've worked on had 26.5 rubber.
before disconnecting any driveshaft, make sure you can roll the shafts back and forth a bit. this will indicate there is no axle-wrap loaded into the driveline and it is safe to disconnect a u-joint. you do not want to be close to a driveshaft if it bangs loose after removing the bolts or clamps. if the driveline is loaded with axle-wrap, either jack up one wheel or drive the machine back and forth a couple times in a straight line-that should relieve any axle-wrap loaded into the driveline. stationary axle-wrap is most often found in articulated wheeled equipment. another cause of axle wrap can be tires of unequal ply rating causing the rolling radius of tires to be different or unequal inflation pressures from side to side
I do believe many guys run 29.5-25 tires on 980B loaders. This one however only has 26.5-25 on it. I definitely would prefer the 29.5-25. So I took a look at the U-joint timing. They definitely are not in line as shown in Nige's photo. Heres a few photos of the current orientation. You guys recommend I re-orient everything? Rear axle to transfer drive to carrier bearing Transfer drive through carrier bearing towards front of machine Carrier bearing to front differential
Before touching any driveline in a wheel loader be sure to pick up the front wheels off the ground and let them unwind. In fact for any machine that locks multiple axles together, artic trucks count for this, find some way to get tires off the ground in such a way as the axle loose their preload.
Yep, that's all out of whack. For my money the important one is the centre shaft but it's hard to tell if it's right from the photo. Putting everything the way it should be isn't too hard, will just cost you time* and can only improve things. *Officially, the spider bolts are a one-time use thing and should be replaced, but hey.....
I thought 966's had 23.5x25s?
From the OMM;
I've never seen that chart before. I would imagine they would put 23.5 on a 980 so Mickey Rooney could reach the first step on the ladder Is that and A model or B?
I got it from the OMM for a 980B. I can't see it in an OMM for a 980C so we have to assume it applies to a straight 980 (no such thing as an A) and 980B. I wouldn't think there's anything stopping someone fitting something other than 29.5s on C and later machines, apart from the fact that it would mess up the speedometer readings.
Well judging by the photos you've found the first thing that needs to be eliminated as a possible cause. Heed John C's words about lifting the front wheels off the ground to get rid of potential wind-up before loosening any u-joint bolts. Also back to Cmark's suggestion regarding taking a good look at any play in the rear axle trunnion support bearings. It can be done using the machine but maybe better to jack up the rear end slowly while someone watches for movement in the location shown by the arrow in the photo below. You're looking for movement between the nose end of the differential (inside) and the support (outside with the ring of bolts in it). Note this photo is NOT from a 980, your machine may differ slightly physically but the principle is the same.
We have 4 980B's. Two have 26.5 x 25's and 2 have 29 x 25's.
Thanks for the tip on releasing any driveline preload. So a few of you have warned me that the rear yolk is a slip on and can fall off. Is there any reason that I can not just pull the yolk off before test driving without the rear driveshaft?
We always called the straight 980 an A model to prevent confusion around here. You can check for play in the rear axle trunnions just by backing up slow and suddenly hitting the brakes. The axle will rock in the trunnions making a bumping sound and you can see it from the cab.
Agree on the "A" designation for just about all Cat equipment. I've always done the same thing, guess it's just easier that having to type out "Plain 980" or "Original 980" or what ever! Another thing that may show up in the "fast stop test" could be loose center pins and bushings. There are a lot of "normal" bumps and jerks that someone who has been around these machines could see by a very short time in the cab. They sure could do all kinds of things when things get worn a bit!
The oil will start running out. (If it's at the correct level)
And dispite what one of my bosses believed, long story there for another time, if oil can come out dirt can get in. That is not a good thing for those bearings on the pinion gear and elsewhere in the axle.