Kx 71 Slew ring wear. help needed please!

[Dangermouse74]

Hi all, I have just bought a Kubota KX71-3 and have noticed a small amount of movement between the cab and undercarriage.
I can see movement in the slew bearing area so have set up a dial gauge and measured the bearing clearance (as close to the bearing as poss) at four points around the slew radius.
I have measurements ranging from 1.2mm to 2.0mm - the worst being with blade and boom in-line.
Does anybody know the bearing tolerance for this machine?
The machine is a 2013 model with 2700 hrs.
I know any vertical play is not good but how much is too much and at which point could secondary damage occur to the pinion or swivel block?
The rest of the machine is tidy so I was surprised to find play in the slew bearing ( especially at those hours), do the retaining bolts ever work loose?
Any help/advice would be greatly appreciated as unsure what to do about it.

[v8druid]

Hi all, I have just bought a Kubota KX71-3 and have noticed a small amount of movement between the cab and undercarriage.
I can see movement in the slew bearing area so have set up a dial gauge and measured the bearing clearance (as close to the bearing as poss) at four points around the slew radius.
I have measurements ranging from 1.2mm to 2.0mm - the worst being with blade and boom in-line.
Does anybody know the bearing tolerance for this machine?
The machine is a 2013 model with 2700 hrs.
I know any vertical play is not good but how much is too much and at which point could secondary damage occur to the pinion or swivel block?
The rest of the machine is tidy so I was surprised to find play in the slew bearing ( especially at those hours), do the retaining bolts ever work loose?
Any help/advice would be greatly appreciated as unsure what to do about it.

tolerance should be zero or close to it ..... if you have 2mm of lift measured at the ring, that is a LOT .... especially with those hours.
movement due to loose bolts should be apparent by a gap between the superstructure and the ring or the ring and the U/c frame ..... should also see loose bolts, with 2mm lift

the rotary coupling should survive OK as it's not attached to the ring gear as such .... either the upper or lower mount will be solid and the other floating, so no rocking action should be transferred .

is your pinion internal or external on the ring? ..... I'd guess internal on a machine of that size .....
the mesh between each is not an exactly watch level tolerance, but it is deffo going to be suffering from that level of rock/movement ..... remember 2mm lift also equates to more than 2mm of forward/backward capability
A slew ring is a precision made bearing .....
if your wheel bearings in your car were worn to that degree, you'd think the wheel was about to depart company from the car, if it was even drive-able

to achieve 2mm of lift AT THE RING the wear has to be very substantial.

you can get slew rings reconditioned, as long as they've not been ripped apart or too severely worn .... I had one done off a 12 t crane done years ago .... place in Wiltshire IIRC .... it'll come back to me, or I might even still have the paperwork for it, some where.
there used to be a company advertised in the back cover of re-sale weekly did it too .

Ain't google wonderful http://www.bcreconditioning.co.uk/find.php ... these were the guys .. I took the ring personally (was 4ft dia.) and had a tour of their facilities .... impressive

see they also do service exchange ....... you may need to exercise them spanners Boyo

[Muz]

Well Ive seen some machines nod like a dog and still work . however as has been said and as you state, it seems a lot for its hours, most likely its been on hammer work and never seen a lick of grease. Ive never had to replace a ring on any of mine as yet, but Ive heard it said that a refurbished ring is not worth it for this type of machine, you are as well to replace. Its a fair old price for the part and a bit of a job to split the machine and replace but not impossible, just takes time. You best get the floor plates up and inspect those bolts there will be a set from above and a set below under the belly panel which you will need to inspect. You wont get access to all of the ones from above due to other components getting in the way, but at least if any are loose you will get an idea that the bearing might be ok and its just a fixing problem, although TBH in 28 years Ive never had one come loose, wear would be more likely but you never know !

[v8druid]

Well Ive seen some machines nod like a dog and still work . however as has been said and as you state, it seems a lot for its hours, most likely its been on hammer work and never seen a lick of grease. Ive never had to replace a ring on any of mine as yet, but Ive heard it said that a refurbished ring is not worth it for this type of machine, you are as well to replace. Its a fair old price for the part and a bit of a job to split the machine and replace but not impossible, just takes time. You best get the floor plates up and inspect those bolts there will be a set from above and a set below under the belly panel which you will need to inspect. You wont get access to all of the ones from above due to other components getting in the way, but at least if any are loose you will get an idea that the bearing might be ok and its just a fixing problem, although TBH in 28 years Ive never had one come loose, wear would be more likely but you never know !

BC recon. do a good job Muz .... tracks are rebuilt, re-machined and re-hardened ...... spent quite a while there seeing their facilities .... been at it a loooong time ..... the one they did for me was 40% of a new one .... bolts were bloody dear to re-fit it though

Seen some 'noddy' cranes over the years .... as said lack of grease and hard work ... usually skipping concrete at the reach limit, on a crane .... gives the rings some hammer as it's so repetitive and high loading

2mm lift at the ring, on such a small ring, is a huge amount of wear, in my book ..... at the dipper end it must be 2-3" of slop/lift and it'll only get a lot worse

[Dangermouse74]

Well thanks very much for the responses guys, A great help and I totally agree - I am thinking hard work, lack of grease or both. Odd though as very acceptable wear in all other bushes etc. and the machine is tidy enough.
As it was such a nice day on Sunday I went out to site and lifted the floor pans and located the ring of bolt heads (well those that I could see as Muz said) - all tight. Then dug myself a pit and got under and dropped the large inspection panel to reveal the underneath bolts and slew ring (yes, internal pinion as you thought Druid) Bolts all tight. Looks clean and tidy, no visible wear to pinion or ring but pretty sparse on grease though.
Got the wife to work the play and could see it clear enough in the bearing

New bearing is £914 =vat!! would definitely have a go at changing it myself but still an expensive job so would be looking into the recon bearing also (cheers for the link Druid)

Been trying to get a service limit from Kubota dealers last week but not much luck. One dealer kindly emailed the workshop manual which I have studied but no tolerance mentioned other that that of a new machine which lead me to think perhaps there is no tolerance and when there is wear you change it!!
Yesterday, however, I got in contact with Steve Jones -The service manager at Lister-Wilder in Cirencester who was really helpful.
He said they had received similar questions from other concerned operators and he had contacted Kubota who issued him with a service bulletin explaining the exact procedure and measuring point for the dti.
He emailed me the document. You measure at 50mm away from the bearing housing and the maximum tollerence is 3.2mm!!
Seems one hell of a lot to me but it does come straight from the horses mouth, so to speak.
So I guess I can keep on digging and keep an eye on it???

Got the machine from a dealer two weeks ago this Wednesday so nearly out of time to raise an issue and I reckon he will argue 'wear and tear on a 3000 hour machine' I was waiting to get a tolerance limit before I contacted him so I had a sound argument for complaint - but it seems it is well within that limit now

[v8druid]

Well thanks very much for the responses guys, A great help and I totally agree - I am thinking hard work, lack of grease or both. Odd though as very acceptable wear in all other bushes etc. and the machine is tidy enough.
As it was such a nice day on Sunday I went out to site and lifted the floor pans and located the ring of bolt heads (well those that I could see as Muz said) - all tight. Then dug myself a pit and got under and dropped the large inspection panel to reveal the underneath bolts and slew ring (yes, internal pinion as you thought Druid) Bolts all tight. Looks clean and tidy, no visible wear to pinion or ring but pretty sparse on grease though.
Got the wife to work the play and could see it clear enough in the bearing

New bearing is £914 =vat!! would definitely have a go at changing it myself but still an expensive job so would be looking into the recon bearing also (cheers for the link Druid)

Been trying to get a service limit from Kubota dealers last week but not much luck. One dealer kindly emailed the workshop manual which I have studied but no tolerance mentioned other that that of a new machine which lead me to think perhaps there is no tolerance and when there is wear you change it!!
Yesterday, however, I got in contact with Steve Jones -The service manager at Lister-Wilder in Cirencester who was really helpful.
He said they had received similar questions from other concerned operators and he had contacted Kubota who issued him with a service bulletin explaining the exact procedure and measuring point for the dti.
He emailed me the document. You measure at 50mm away from the bearing housing and the maximum tollerence is 3.2mm!!
Seems one hell of a lot to me but it does come straight from the horses mouth, so to speak.
So I guess I can keep on digging and keep an eye on it???

Got the machine from a dealer two weeks ago this Wednesday so nearly out of time to raise an issue and I reckon he will argue 'wear and tear on a 3000 hour machine' I was waiting to get a tolerance limit before I contacted him so I had a sound argument for complaint - but it seems it is well within that limit now

Tha's a lorra play FFS ..... a slew ring, as said, is a precision bearing ....... there should be next to no lift in it ... ever ...
any other form of bearing with that degree of wear would be U/S long ago

[Muz]

Well at least you got some answers ... bung some thick grease in it and she'll come down to 1.5 Sit in the cab , set her spinning and pump away to give a good coating .. she may last long enough

[Dangermouse74]

Yep totally agree, it seems a mad tolerance to me but what can you do? Sealed fixed- race bearings are supposed to have little or no play as far as I knew, though it is a very slow moving bearing Yea, pack it with grease and carry on!
Kubota do recommend 30 pumps of grease per quarter of the race every 200 hrs - a lot of lube but not very often!

Oh well, more than happy with the rest of the machine - punches above its weight and very strong for a small machine

[v8druid]

Yep totally agree, it seems a mad tolerance to me but what can you do? Sealed fixed- race bearings are supposed to have little or no play as far as I knew, though it is a very slow moving bearing Yea, pack it with grease and carry on!
Kubota do recommend 30 pumps of grease per quarter of the race every 200 hrs - a lot of lube but not very often!

Oh well, more than happy with the rest of the machine - punches above its weight and very strong for a small machine

Pump 'til it appears at the seal .... just ..... then move it around 20 degs ..... go again and repeat .... etc.

their tolerance must be close to falling apart / popping off, if the balls aren't the biggest ..... do you know if it's balls or two rows of inclined barrel rollers ??





expensive .... but almost never come apart

[Muz]

Usually Balls .. meant to say also Dangerdude ... the drive pinion is pretty big for the application, with a large section tooth, so I wouldn't be too worried about excess wear causing an effect on it .. its designed to handle dirt ingress from the belly area and will definately not be fazed by a mil or two of play.. just keep her greased is the key

[Muz]

BC recon. do a good job Muz .... tracks are rebuilt, re-machined and re-hardened ...... spent quite a while there seeing their facilities .... been at it a loooong time ..... the one they did for me was 40% of a new one .... bolts were bloody dear to re-fit it though

Seen some 'noddy' cranes over the years .... as said lack of grease and hard work ... usually skipping concrete at the reach limit, on a crane .... gives the rings some hammer as it's so repetitive and high loading

2mm lift at the ring, on such a small ring, is a huge amount of wear, in my book ..... at the dipper end it must be 2-3" of slop/lift and it'll only get a lot worse

Big cran stuff will be a bob or two though innit ? these guys are only 18" or so max for a 3 tonner mebbees even 15 .. mind I'm going back 20 years since I was told that ... plus all my kit goes on self drive .. not sure I'd trust a refurb for that .... good though they may be .. can you do a refurb on a crane and still get a test certificate ok do you think... major component and all that ?

[v8druid]

Big cran stuff will be a bob or two though innit ? these guys are only 18" or so max for a 3 tonner mebbees even 15 .. mind I'm going back 20 years since I was told that ... plus all my kit goes on self drive .. not sure I'd trust a refurb for that .... good though they may be .. can you do a refurb on a crane and still get a test certificate ok do you think... major component and all that ?

don't think refurb ..... re-engineered, Muz ...... tracks are rebuilt (robotically welded), re-machined to new profile, induction hardened, then re-assembled with new bearings ..... as good as a new one .... better in fact ... 40% of the cost, as you're not buying the whole ring and all the associated machining that goes into producing it . these guys aren't some hole in the wall, back street operation

as for test .. no issues .... mine flew through .... no perceptible lift in ring gear

and yeh ..... 4ft ring is not cheap .... or light .... big mutha

[Dangermouse74]

[QUOTE=v8druid;22748]Pump 'til it appears at the seal .... just ..... then move it around 20 degs ..... go again and repeat .... etc.

their tolerance must be close to falling apart / popping off, if the balls aren't the biggest ..... do you know if it's balls or two rows of inclined barrel rings





Balls Druid single row, think they are about 20mm diameter but guess mine may be 18!!

OK will do that - I only did it at 45 degs.

Ah that's good to know Muz, there didn't look to be much wear on the pinion or ring as yet anyway And no real noise even when slewing on a bit of gradient which is reassuring.

[v8druid]

[QUOTE=Dangermouse74;22760]

Pump 'til it appears at the seal .... just ..... then move it around 20 degs ..... go again and repeat .... etc.

their tolerance must be close to falling apart / popping off, if the balls aren't the biggest ..... do you know if it's balls or two rows of inclined barrel rings





Balls Druid single row, think they are about 20mm diameter but guess mine may be 18!!

OK will do that - I only did it at 45 degs.

Ah that's good to know Muz, there didn't look to be much wear on the pinion or ring as yet anyway And no real noise even when slewing on a bit of gradient which is reassuring.

Spheroids to you too Mousey .... decent size then ... not gonna let go in a hurry at that size.

it's not so much the lift, as the drop with big wear .... the tracks are no longer supporting what they're meant to

45 degs'll do once you've re-filled the ring gear .... just to get it chocka with grease it's easier at 20s .... and I'd be giving it plenty regularly for a while .... 'til it just shows at the seal each time ..... and wipe off the excess to avoid it attracting unwanted shite ingress

[Dangermouse74]

[QUOTE=v8druid;22762]

Spheroids to you too Mousey .... decent size then ... not gonna let go in a hurry at that size.

it's not so much the lift, as the drop with big wear .... the tracks are no longer supporting what they're meant to

45 degs'll do once you've re-filled the ring gear .... just to get it chocka with grease it's easier at 20s .... and I'd be giving it plenty regularly for a while .... 'til it just shows at the seal each time ..... and wipe off the excess to avoid it attracting unwanted shite ingress

Yea hopefully she will hold together for a bit. Sound advice and much appreciated - cant find any reference to shite ingress in my manual though?? I will google it.
I have on oldish Thwaites dumper which I could do with some help identifying? Is it best to start a new thread in the plant section?
I will try and attach some pics but it could take me a while as not the best with technology Any help on uploading them welcomed