Front drivers side bearing exploded at 80MPH!

[Aero]

Technically all front wheel taper roller bearings should be adjusted with a dial gauge. The "standard " method using the tighten up till it binds and then back it off is simply not accurate enough to set the end float . I would surmise your bearing failure was due to incorrect clearance or the use of substandard product- this may not be the fault of the garage who fitted them- lots of inferior counterfeit stuff out there from the Far East. AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - How to Adjust Wheel Bearings

Good advice, axial play should always be measured allowing for expansion. Bearings operate at their optimum at near preload condition - achieving that can only done with a dial gauge. Unfortunately there are some very convincing fake western bearings from the Far East and you have to really know your stuff to spot the difference. Even buying from some recognised bearing factors doesn't always assure you of receiving what you think you paid for. It's a big issue in the automotive bearing industry and more so if one explodes on you per the OP.

 

[190]

Does anyone know definitively why taper roller wheel bearings are commonly set up with a small amount of endplay ?

The reason I ask is that from an engineering perspective a taper roller bearing lasts longer with a very small amount of pre-load and there are automotive wheel bearing applications where pre-load is specified. Perhaps the answer is to do with unequal thermal expansion of the components or if it's not that and I was being cynical, I'd say the reason might be that a small amount of end float is easy to achieve and repeatable where as pre-load is very difficult to set and can only be indirectly measured.

The thing is a wheel bearing will not necessarily overheat if it has no end play, if pre-load is excessive yes, but a small amount not necessarily.

 

[markjay]

Does anyone know definitively why taper roller wheel bearings are commonly set up with a small amount of endplay ?

The reason I ask is that from an engineering perspective a taper roller bearing lasts longer with a very small amount of pre-load and there are automotive wheel bearing applications where pre-load is specified. Perhaps the answer is to do with unequal thermal expansion of the components or if it's not that and I was being cynical, I'd say the reason might be that a small amount of end float is easy to achieve and repeatable where as pre-load is very difficult to set and can only be indirectly measured.

The thing is a wheel bearing will not necessarily overheat if it has no end play, if pre-load is excessive yes, but a small amount not necessarily.

When I changed the front wheel bearings on my Vauxhall Omega (some years ago), the workshop manual said torque to 130NM (had to by a torque wrench specially for that...), and not by measuring end float etc. I was told that the front wheel bearings on the Omega are not adjustable.

 

[streethawk]

My old 1999 c230K is still on the original wheel bearings. Still got the green mercedes grease in them. I had to adjust them 2 years ago as they had a miniscule amount of play when up in the air and cold. Mercedes have a fantastic locking nut on them where it's easy to adjust minutely unlike most other cars that have a split pin and nut.

 

[markjay]

....in fact they were not replaceable, either... they came with the hub and I had to buy complete new hubs with the bearings already fitted. I bought original GM hubs which turned out to be made in Japan by Toyo (as where the old hubs).

 

[190]

130NM would be a massive amount of pre-load so you have to assume the bearing was pre-spaced or shimmed in some way and that the force wasn't being applied directly to the rolling elements.

Sometimes relatively high torques are specified to ensure a bearing is fully seated and the torque is backed off and a very low torque applied to produce a small pre-load.

 

[Rory]

I noticed the indie I've visitied a couple of times makes a feature of adjusting the bearings as part of the B service, saying they normally need doing but that dealers will charge extra.

It was commented on (for the first time) on my last dealer B service but when the indie checked them he said they were fine.

 

[Paragon1970]

Still own this car it has done very little miles less than an additional 2k since my original post and it experienced another catastrophic bearing failure on the opposite front wheel and again there were no obvious sign of pending failure. No noise build up, no knocking, nothing and just like that it failed with no notice while doing 70 mph down the motorway. Fortunately this time round there was no damage done to spindle. Never had a car that has experienced this type of failure once let alone twice in 30 years of driving!

 

[Markssl]

I think I have had enough of Mercedes cars.
2008 Mercedes E280.

Headed off for our annual camping vacation to the South of France on Friday.
Caught the Dover to Calais ferry and headed off down the autoroute at 80MPH / 130KPH reached Reims 2.5 hours in. The car felt great.

Passed a vehicle in the slower lane when I heard what sounded like a bottle cap tapping down the motorway, I actually cursed the driver, to myself, in the vehicle I passed thinking they had thrown something out of the widow.

Car had no indication of trouble and was planning on stopping for a rest break at next service station 10 kilometres further when five kilometres later an almighty bang occurred and the vehicle pulled violently across lanes, managed to steady it and bring to controlled stop on hard shoulder but this could have been disaster if there had been any other vehicle beside or near us at the time.

Checked the front wheel and instantly noticed the plastic hub cap and inner metal cap was missing, so pretty sure that was what popped off under pressure 5k back and there was a flame burning from inside the hub presume grease caught fire due to extreme friction.

The car was MOT'd two days prior to leaving and no issue was picked up.
There was no indication of pending failure, in the past I have had vehicles were bearings could be heard when they are failing.
So we are now back in the UK, two nights hotel, 5 very expensive taxi rides and two hire cars later one of which nearly 3 hours to hire, which was longer than it took to drive back to Calais! We cancelled holiday as injured back in the process and have no idea when car will be fixed. AA European breakdown are dealing with it.

Did make it to garage the following day just before closing to pick up some clean clothes and gain an update. Noticed grinder on the floor along with gas torch next to car so knew there was a bigger issue than straight forward bearing replacement.
Mechanic advised that at least a new stub axle was required and maybe a hub but that brake calipers and disk seemed ok but who knows. Waiting for an update from AA on Monday (tomorrow)

Have more to this story which I will share in time but will hold off for now depending on how events turn out.

In all my years of motoring I have never experienced such an event and I have driven some old dogs in my time, my confidence in Mercedes quality is at a very low ebb, in my mind I would not have expected such a failure on vehicle from such a prestige brand.

Cheers.

Oh dear and glad to hear you were all ok.
I just sold my 08 E320CDi with 214k miles. It did a lot of motorway mileage and quite a few trips along the French motorways without any wheel bearing issues. Maybe you got unlucky. I would imagine MB would only fit quality bearings. You don’t mention your mileage. Maybe it was a pattern part and not OEM that failed?


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[190]

Did the other bearing get checked for end float after the first bearing failed ? If it did then cause would seem to be bearing quality. If it didn't then maybe both bearings were incorrectly adjusted by the same person.

I actually checked mine after your original post and found one I considered to have too much preload. I could tell by the mangled grease cap that it had been done since the car left the factory.

 

[Stratman]

When I changed the front wheel bearings on my Vauxhall Omega (some years ago), the workshop manual said torque to 130NM (had to by a torque wrench specially for that...), and not by measuring end float etc. I was told that the front wheel bearings on the Omega are not adjustable.

Is it possible it had ball rather than taper bearings?

 

[markjay]

Is it possible it had ball rather than taper bearings?

No idea.... the bearings were only available complete with the wheel hub, so when I removed the old hubs to replace with new ones, I did not take them apart to inspect the bearings. I did notice they were made by Toyo, but that's all I can say about them

 

[merc85]

Still own this car it has done very little miles less than an additional 2k since my original post and it experienced another catastrophic bearing failure on the opposite front wheel and again there were no obvious sign of pending failure. No noise build up, no knocking, nothing and just like that it failed with no notice while doing 70 mph down the motorway. Fortunately this time round there was no damage done to spindle. Never had a car that has experienced this type of failure once let alone twice in 30 years of driving!

I Have, with a Volvo 340, After my Brother had over tightened the Bearing

 

[clk320x]

2008? the car is 8 years old! Not bad going if its the original wheel bearing? I'd have thought though as you rightly said it would have been picked up on the Mot.

I had a Volvo front wheel bearing do exactly the same thing, Car was a similar age.

No sign in paperwork of any wheel bearings being changed in my Clk in the last 14 years

 

[GP801]

Just today had the Near side front wheel bearing give up on the 124. No warning other than a dreadful grinding noise on low speed manoeuvring. Worrying amount of movement laterally of the wheel. RAC attended promptly and declared it unsafe so recovered to the garage to await replacement. 167,000 on the clock and last week we drove it back from Italy. Just glad it didn't let go at 80mph on the autoroute.

 

[Wolfie1]

I am an mot inspector and bearings can be totally mot passable without even a note of an advisory then 200-300 miles later be totally fooked

 

[190]

My old BMW motorcycle has taper roller wheel bearings designed to have a slight pre-load set using shims. Imagine what would happen if one seized at 80mph, actually come to that at any speed. I won't let anyone adjust them except me.

 

[Flackadder]

Have you had it fixed and replaced and all that? Time to move on then.

 

[XJ600]

Re torquing hub nuts:
The wheel bearings that need a torque setting have a spacer between them with shims, the end float is adjusted by removing / adding shims to obtain the correct float. The torque applied to the nut will have no effect on the bearing end float, unless of course, there are not enough shims / distance between bearings.

 

[190]

Re torquing hub nuts:
The wheel bearings that need a torque setting have a spacer between them with shims, the end float is adjusted by removing / adding shims to obtain the correct float. The torque applied to the nut will have no effect on the bearing end float, unless of course, there are not enough shims / distance between bearings.

That's how my motorcycle wheel bearings work. Given that there is no such thing as a totally uncompressible material I would substitute "almost no effect" on the bearing end float. The technique I use is to gradually torque the nut and if all end float just disappears by the set torque figure then I'm happy. If it disappears too early, I need thicker shims and if it doesn't disappear by the set torque, thinner shims. You have to work in increments of 1 thou or less to get it anywhere near right. The factory supplies shims in 2 thou increments which is hopeless.