Premature bearing failure?

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spartacus68
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Premature bearing failure?

Post by spartacus68 »

I replaced the front N/S wheel bearing last year at under 40k miles with a new FAG/SNR bearing. The car now sounds like it has a whine at 30-40mph from the rear. Car is a 15 plate at sitting at 42k. Link here: viewtopic.php?f=56&t=75279

What is it with these cars? 40k is nothing. Anyone else facing a similar issue? Just looked at Autodoc, so FAG is £40 a corner at rear, and given its on stub axle looks easy change so will probably do both and be done with it.

I find the only real way to tell if they are goosed is to strip down the caliper and remove the brake disc and rotate the bearing hub assembly by hand.

Interested if anyone is facing same issue at what I consider low miles.
amer6R
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Re: Premature bearing failure?

Post by amer6R »

You will need a special tool for bearings. Btw. Improper torque value thats why its failed
spartacus68
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Re: Premature bearing failure?

Post by spartacus68 »

I have the proper removal and refitting tool. The front was done during the summer, new hub bolt and torqued to specification. Pretty sure this is the rear. As far as I can see the rear is a case of dismantle brakes, remove hub nut and it can be taken off the stub axle. Refitting as reverse.
spartacus68
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Re: Premature bearing failure?

Post by spartacus68 »

Just had another look at this. Pretty sure this will need a 3 arm bearing puller, so you can drive it off the stub axle. Could be wrong, I had a 2010 Fabia and the rear bearings were a dream to replace. Difference being, they were changed at 100k miles.

Any other tips please?
spartacus68
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Re: Premature bearing failure?

Post by spartacus68 »

Hi Folks - update to this.

Stripped down both rear brakes with discs off, I think this gives the best indication the state of the bearing. The N/S wheel bearing sounds noisy when rotated, but with the road wheel on there's absolutely no play, so probably just the start of the wear. I've ordered FAG parts from Autodoc today and will just replace both rear bearings. Pretty poor for the mileage, but just one of these things.

Anyone attempting this, then you don't need a puller. The bearing and hub assembly literally pull off stub axle with the hub nut removed. :)

Quite difficult to get information on these cars. The 12 point hub nut, what's the torque please? On Mk5 Polo it's 70 Nm + 30° further. This is a 2015 Mk8 1.4 TDI BlueMotion (90PSI), so I'm assuming it's the same?
spartacus68
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Drives: 2015 1.4 TDI (90PS) Blue motion
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Re: Premature bearing failure?

Post by spartacus68 »

Update to the update.

That's the O/S front gone now just shy of 50k miles. Just ordered a FAG bearing - but not happy on having to replace an item that should be good for 100k miles. :cry:
amer6R
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Re: Premature bearing failure?

Post by amer6R »

I'd like to add,
some people adding extra grease to the rear bearings since you can see the bearing balls, and they come with minimal grease. I know that these types are considered non serviceable items. But re-greasing them every few years should extend their life.

Image
RUM4MO
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Re: Premature bearing failure?

Post by RUM4MO »

I've just checked my downloaded VW Polo 2014 > VW workshop manual and the hub nut is still 70Nm + 30deg.

Haynes for the >2014 VW Polo repair book suggests checking that the new bearing has enough grease on it and add some if not, Haynes also suggests using a suitable socket to "tap" the new hub/bearing back on making sure that the socket or bit of pipe/tube is sized to only contact the bearing inner track/race - that makes sense I suppose.

A bit of a bummer wrt the front bearing on the other side now failing! I'm glad that I just went and attacked both sides - but now I'll be waiting for a rear one to get noisy, I can easily imagine that they/it is already making a bit of noise, or I did for a week or two after replacing both front ones!

Still, looking on the bright side, if I ever do need to replace the rear wheel bearings, I could take more time over cleaning up and painting the rear calliper carriers, they have started to take on a brownish look and I cleaned them and painted them when I was replacing the front wheel bearings last year!!
spartacus68
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Re: Premature bearing failure?

Post by spartacus68 »

I should have done both sides I suppose, but money is always needed elsewhere. Roads are a mess just now and I’ve hit a couple of potholes recently, so wouldn’t be surprised if that contributed.

Good advice regards a smear of extra grease. I still have the Chinese EBay tool for fitting which isn’t exactly Laser quality but will work okay as it did the N/S a couple of years ago. Pictures to follow. Bearing kit ordered.

Found torque instructions here. 50Nm + 45 degrees. Sound reasonable?
https://workshop-manuals.com/volkswagen ... ity_joint/
amer6R
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Re: Premature bearing failure?

Post by amer6R »

correct for the front
Is the 12 point 30 mm socket necessary for the rears or a 6 point will do? Planning on doing rear bearings on my soon.
RUM4MO
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Re: Premature bearing failure?

Post by RUM4MO »

Front part numbers and torques:- Front Disc Brakes PR – 1ZC FN3 bleed valve 10Nm
TRE nuts 2-off – N 909 429 02 (M12 X 1.5) renew 20Nm+90deg 18mm hex plus 6mm Allen/hex to prevent rotation
Front disc retaining screw – T30 torque ??Nm
Lower swivel nuts 6-off – N 103 320 02 (M10 X 1.25 S/L) renew 40Nm+45deg 16mm hex
Lower swivel to hub carrier nuts 2-off – N 908 088 01 (M12 X 1.5 S/L) renew 20Nm+90deg – not disturbed when replacing the hub bearings
Drive shaft retaining nut – comes in kit renew 50Nm + 45deg 36mm bi-hex
Calliper Guide bolts 30Nm 7mm Allen/hex
Calliper carrier bolts 4-off – N907 085 04 (M12 X 1.5 X 35) clean if reuse 124Nm 18mm hex
Disc back cover bolts – 6-off WHT 005 227 (M6 X 12) 12Nm T27
ARB Drop Links nuts top N 909 081 02 and bottom N 102 613 10 renew 40Nm – not disturbed when replacing the hub bearings
ABS wheel sensor securing bolts N 014 740 11 M6 X 16mm torque maybe 9Nm 5mm cap head (Allen) hex

ABS wheel sensors:- front RIGHT side VW Group p/n WHT 003 860 Bosch p/n 0 986 594 501, front LEFT side VW Group p/n WHT 003 861 Bosch p/n 0 986 594 501

That is what I collected together for the front end, the torque setting that you asked to be confirmed earlier was for the rear hubs and it is still 70Nm + 30deg.

Edit:- the off side on my wife's 2015 Polo was rusted up a lot more than the near side, that would be why I trashed the ABS sensor, quite a bit of chipping out/off accumulated rust needed before the removal disc could be fitted in place and pretend to be clear of the ABS sensor! Effort required was a lot higher for that side to get the bearing moving out of the hub.
amer6R
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Re: Premature bearing failure?

Post by amer6R »

cool trick for abs sensors
https://youtu.be/4s496g0OBI8
spartacus68
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Re: Premature bearing failure?

Post by spartacus68 »

Thanks for torque values and responses.

So dived in today waiting for the part to arrive. Just as well as the brake dust shield has rusted through and the ABS sensor is a pain to remove. Incidentally that link for removing the sensor will be difficult on Mk5 Polo as the sensor is recessed into the hub, so no chance of getting a spanner on it.

Always hammer torx or Allen key bits in, especially with corrosion on dust shield or ABS sensor bolt. One of the screws you can't access on the dust shield due to the bearing hub assembly. With the Allen key bolt out of ABS sensor, spray with PlusGas around the edge and clean with screwdriver to remove rust and corrosion. Slow and steady, levering sensor using large flathead screwdriver using wheel hub for leverage.
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RUM4MO
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Re: Premature bearing failure?

Post by RUM4MO »

amer6R wrote: Sat Feb 04, 2023 11:31 am cool trick for abs sensors
https://youtu.be/4s496g0OBI8
That might work easily/quickly with that style of ABS sensor in an alloy housing, but these Polo ones are in steel housings and have a "relief" in the plastic moulding near the top of the ABS sensor, and that gets filled up with nasties and the rusting hub carrier housing expands in to close up that "spare" void.

The one that broke on my offside carrier housing got caught due to the excess rusting that broke away when the removal disc, that I had already opened up wider and deeper, still managed to break off a chunk of rust and it caught the ABS sensor and snapped it - or at least tilted it while its top end was still fixed solid with rust.
RUM4MO
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Re: Premature bearing failure?

Post by RUM4MO »

@spartacus68, yes, the partially obscured Torx headed screw that secures the stone shield - I ended up forcing a Torx bit into the head of that one and then used an adjustable spanner on the bit as there was not enough space, with the bigger brakes, to get anything else onto the Torx bit - but at least once every one of them did "crack" they unscrewed easily as the threads were spotless, only the rusting on the heads fixing/locking them to the stone shields. I went to Skoda for new Torx screws, as they are easiest to get to, they had none but Audi 200 meters away had about 100 in stock! Its good when parts people think out of the/their box!

From memory, VW workshop manual recommends that you coat these ABS sensors with a suitable grease before re-fitting them, but in main dealer workshops, it sounds a lot like you don't waste time and just prepare to have to fit a new ABS sensor which is "only" just under £100! In my case I needed/wanted a new sensor quickly so I bought a new Bosch sensor from ECP assuming that as the ABS controller is Bosch then so would be the factory fitted sensor, then discovered that the branding on the factory fitted one was TRW, same as the brakes etc on the front, that makes sense - and AutoDoc sell them for not much money if you can wait about 10 days. As always expecting the worse case situation, I had spotted NOS TRW genuine VW part for near side on ebay for not much money so grabbed it just in case the near side sensor had been damaged with out me noticing it, in the event it was and still is working fine, but I'm prepared!
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