980B driveline vibration

ssrider · Apr 15, 2019

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.

Cmark · Apr 16, 2019

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.

grandpa · Apr 16, 2019

Pull an oil sample of both differentials... do it soon than later. Bearings would be cheaper to replace than a ring and pinion set.

kshansen · Apr 16, 2019

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.

cuttin edge · Apr 16, 2019

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

Nige · Apr 16, 2019

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..?

John C. · Apr 16, 2019

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.

Nige · Apr 16, 2019

So what tyres are actually on it..?

Tones · Apr 16, 2019

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.

ssrider · Apr 16, 2019

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.

Cmark · Apr 16, 2019

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.

kshansen · Apr 16, 2019

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!

John C. · Apr 16, 2019

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.

56wrench · Apr 16, 2019

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

ssrider · Apr 16, 2019

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

John C. · Apr 16, 2019

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.

Cmark · Apr 16, 2019

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.....

grandpa · Apr 16, 2019

I thought 966's had 23.5x25s?

Cmark · Apr 16, 2019

From the OMM;

John C. · Apr 16, 2019

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?

980B driveline vibration

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