Hi,
Been having problems with the tailend breaking away on the 330D auto in the last few weeks.(registered Dec '54, bought 2nd hand in June this year - as bmw approved with 1600 miles on clock - if it's age is a factor at any point).
No occasion has been at high speed or rapid acceleration for the conditions (damp roads at worse)..
Once was when I exited a round-a-bout and another when turning right at some lights...both times the rear-end parted company then came back into line. Never had the back end break away on any previous Beemer.
Was wondering about poss causes, given that the tyres have plenty of tread (10,000 miles from new) and pressures are ok.
The one potential issue is that the OSR tyre has been replaced twice due to punctures, so I'm guessing it has only done about 1,000 of the 11,500 miles now clocked. Is it possible that different tread depths/tyre circumferences could cause what i am experiencing?
I dread the thought of buying yet another tyre, but if it cures the problem, I will do it asap as it seems less than safe at present.
Informed opinion more than welcomed :-)
Thanks in anticipation,
Graham.
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Worth checking the rear suspension bushes and the Coil springs and shockers all round in case one has broken and unbalanced the car. Regards Peter
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The new tyre, assuming it is a good brand of correct specification, is very unlikely to be the problem. Brand new tyres do sometimes have a thin layer of mold release agent on them - but this wears off very quickly (few days of normal use).
Aside from any failed components (which would be unlikely given the low mileage and newness of the vehicle) I personally would take the car for a full 3D 4-wheel laser alignment. This will take 30-45mins and cost around £70 retail. They will check all the angles on the car and give you a print out indicating anything out of manfrs spec. If you talk nicely to the tech he'll probably cast an eye over the suspension components as well.
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Aprilia,
All tyres as Pirelli P6000 225/45 Y speed rated I believe.
Ironic that in my ownership of this car there have been two puntures on same wheel - looks like it will bite me yet again :(
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You mentioned breaking away on an island and this reminded me and have mentioned it previously on this site in the past.
A mechanic was telling me the story a couple of years ago about either a BMW or Mercedes (can't remember which but think it was BMW) in their garage with autobox problems.
It was changing down on islands etc when it shouldnt have.
They had no success and eventually contacted BMW UK.
Their response was "do the tyres have the same tread depth or has he just put the spare on".
The garage thought they were joking but they explained that a difference of more than a few mm confuses the autobox as there is a different circumfrence in the wheels and was well known to themselves.
I was just wondering if your breakaway was caused by this same problem.
The garage were extremely cynical over this advice but changing tyres around completely cured the problem.
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Thanks all.
Alvin, you may have a point. Just spoken with BMW - they asked same questions about tread etc. and they said about it confusing the autobox.
Guess who's going to a bmw dealer tomorrow !!! :-(
Will advise you of the diagnosis :-)
thanks again.
Graham.
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just measured them....
Front:
N/S = 7 O/S = 8
rear:
N/S = 5 O/S = 7
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I wouldn't be surprised if it was the P6000s, a 6+year old design medium range tyre on a 330D is not ideal. I'm surprised they were fitted! Try P7 or Goodyear Eagle F1 GSD3, and keep the current rear ones for spares on the front if you can't bear to throw them away.
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'Confusion' of the vehicle electronics can occur due to signals taken from each wheel speed sensor being different is tyre diameters are different. The electronics 'think' that one tyre is skidding. Mercs are quite sensitive to this and the cruise control will drop out if differently worn tyres are fitted.
Having said that, your diameters are pretty similar - a few mm difference is quite acceptable. I also feel that the P6000 is a decent enough tyre - OK, not the latest and best but a very good tyre non the less and shouldn't let go during gentle cornering. I would still start by checking geometry thoroughly.
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Aprilia,
Thanks for that.
Certainly not getting any alerts from the Traction Control systems...Cruise Control all ok on motorway runs too - used a lot today. Diameters, whilst all different aren't vastly different as you say. Agree with your comments on the P6000's ... all very odd as to why it has started. I take your point on the geometry even though the wheeels haven't hit anything I know of. Would do that via Protyre as BMW only do the full jig thing and charge circa £200+ to do so.
BMW tech is now going to spend 30mins or so with me tomorrow to see what he makes of it. So will take it from there.
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Rear end breakaway on a roundabout and a right turn ---
Seems to be the ideal places to find diesel fuel spilt on the road.
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Interesting point mjm....shouldn't dismiss that possibility either.
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You say it's the last few weeks - it could just be the cold? Normal tyres don't work too well below 7C.
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Bill,
This had crossed my mind too, but would hope the loss of grip would not be be easily reached. I'm not sure the temps were that low when the episodes occured, but I couldn't be sure.
Rgds,
Graham.
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Graham, I get this a little bit on my 120d (sorry to mention in the same breath - 330d next time I hope) and it was the same at this time last year too when I got it.
But I think it is a combination of colder weather , slippery surfaces (salt/carp etc , diesel) and the torque of the engine combined with RWD.
I note you bought it in June so unless you've had one before you will have been experiencing better grip up to now.
Cheers P
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Hi P,
thanks for the info. An update > Went for a run with the BM tech - consisted of some serious roundabouting at 30mph - erm good fun and it stayed put with not a hint of breaking away...although we were ready in case ;-)until we exited and made it a fairly fast exit (much faster than when I was driving) when it tried to lose the tail.
I think the factors were temp (maybe), roadsurce(dampish), contaimination (who knows?) combined with an unsolicited downward change (autobox) at critical point when leaving roundabout - so straightline temporarily - just before a left hander - for whatever reason it felt I wanted 2nd (3rd was fine thanks)...and the tail parted company as drive came in.....only to be swiftly checked by DSC.
Road condition temp etc all play a part, but he felt the tyres were good, suspension etc all checked out on the ramps, diagnostics read and all ok.
So will keep an eye on it - and will prob lock the gear at roundabouts if needed.
Last car was also 330D but manual - had for over 3 years, never a murmour - so could be just unlucky to get these instances all grouped - the auto is a factor somewhere, but I now know to tread even more carefully :-)
If you go for the 330, make it a manual - auto is fine, but the manual has to be the one :-)
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:-) all part of the fun... I've got the runflat tyres and I dont trust them as much in the colder temps - great in the summer though. I would imagine the torque on the 330 might be a bit of a handful even with the DSC in some situations especially with too large an input from the right foot.
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The one thing the tech proved to me, was how stable the car was and you would have work ridiculously hard to get it so out of kilter that the electronics couldn't cope - so you can push the margins. Have had great fun off motorway (M-Ways are becoming more denagerous than A roads based on the driving I witness) on quiet A and B roads...then it comes into it's own with the handling. Having driven scores of others they just don't drive with the same poise and handling.
One of the best runs was on a RoSPA re-test...examiner was as keen to see what it could do as I was :-)
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