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05-07-2012, 01:58 AM | #1 |
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Hi guys,
I am new on here. Looks like a great forum - been lurking for a little while. I recently swapped my Z4m coupe for a nearly new sdrive35is. I wanted something a little bit easier to live with, and so figured with the adjustable suspension and semi auto gearbox it would really suit what I was after. For the most part, I am really happy, but the car has a really annoying handling problem, which I am struggling to have fixed. Basically on a highway, if drive at a constant speed, the car tracks straight and true, but when you accelerate even slightly, the car pulls right. Then when you back off, it pulls left. Makes driving really twitchy as I am constantly having to fight the car wanting to change direction by adding little inputs into the steering. Have changed the run flats to new Continentals and the dealer paid for a full KDS alignment, and this hasn't cured the problem, even though the settings were out before the alignment was adjusted. I have a suspicion that it might be the electric power steering, and I want to say that sometimes it feels worse than others, but I am not totally sure. Dealer has verified the problem and says they aren't sure what else could be the cause, and have raised a technical case with BMW. Am really hoping they aren't going to tell me it's a characteristic of the car, and wondered if anyone had any ideas what might be the cause of this, and whether any of you had experienced this? Really appreciate the help and many thanks! John. |
05-07-2012, 07:03 AM | #2 |
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Sounds like torque steer, but I've never owned a BMW that had this problem. Did a technician drive the car to see for himself?
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05-07-2012, 07:29 AM | #3 |
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Thanks for the reply. Yep the technician verified the problem both before and after the KDS. They mentioned it might be torque steer but it happens under very slight load and I thought torque steer would be more likely under heavy load? I have owned many BMWs, mostly M's that haven't done this, hence why I am a bit puzzled. Does your car do this?
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05-07-2012, 08:00 AM | #4 |
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No, my Z4 definitely doesn't do this, neither this one or my previous one.
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05-07-2012, 08:28 AM | #5 |
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Thanks for that - many others have told me how stable these things are so something must be up with mine. Any ideas from anyone welcome - my dealer and I are at a loss!
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05-07-2012, 09:03 AM | #6 |
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I can also confirm mine does not have this problem. I hope you find a solution soon so you can enjoy this wonderful car to its fullest! Does different damper settings attenuate the problem?
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05-07-2012, 09:30 AM | #7 |
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All too often the techs don't know how to resolve an issue and they set up a PUMA case, which means they talk to the know-it-alls in Munich. You might want to suggest this at the dealership.
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05-07-2012, 10:30 AM | #8 |
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Could it be a servotronic problem?
This is standard option on a 35is model. Espacially if you have this strange pull left-right problem at higher speeds. A steering wheel sensor that has a wrong center alignment? Just a wild guess.... |
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05-07-2012, 01:05 PM | #9 |
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Can't see how you would get Torque Steer out of a RWD with DSC, but this could be a DSC failure, more likely they will find something loose on one of the rear links, bushings or the sway bar (in order of likelihood). If you have a GoPro camera, set it above the rear wheel and film each wheel while forcing the "Torque Steer". I suspect you will find one of the rear wheels shifting. I would start looking at the left wheel first as a forward shift under power on this wheel would push you to the right.
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05-07-2012, 02:03 PM | #10 |
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Thanks for all the suggestions everyone. Dealer has raised a Puma case with BMW but said to me it was possible this was a characteristic. Judging by the replies on here and another forum I am hopeful that this is not the case. A tuning company i have used previously have also told me this is not normal. I love the car in every other respect so really want it fixed.
Appreciate all the suggestions. Any other thoughts, opinions or experiences of this problem gratefully received! |
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05-07-2012, 06:35 PM | #12 |
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I have a new 35is and it runs straight and true regardless if I apply power or not. I have never experienced torque pull so I can't comment on that. Did you try turning off the stability and traction controls and trying it that way?
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05-07-2012, 07:11 PM | #13 |
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no such issues with mine.
I have run both run flats and now normal tyres.
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05-08-2012, 02:45 AM | #14 |
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I had a similar handling issue when i got new tires , Bridgestones RE050s same as the OE ones i had earlier. The issue was narrowed down to tires as dealer replaced all 4s from another car to check which solved the problem.
And dealer got BMW to replace the front 2 as apparently there was some issue with the tires, maybe they were sitting at the factor for too long, or rubber had gone bad. I would have thought that issue was due to rear tires but replacing the front ones solved it! It was a free replacement done by dealer as problem started immediately after i got a new set of 4 |
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05-08-2012, 10:50 PM | #15 | |
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Quote:
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05-09-2012, 07:15 AM | #17 |
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Nope - and no DSC light either. In fact it takes very little throttle to provoke the problem. BMW has asked for me to drive another 35is to see if it does the same thing. Based on what I am being told on here and on another forum I don't get the impression this is a characteristic of these cars, but I guess there's not much else I can do at the moment, as the dealer reckons everything is as it should be, despite the fact he agrees that my car does exhibit these characteristics....
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05-16-2012, 09:16 AM | #18 |
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Hi all,
Thought I would drop a quick update on this for anyone that is interested. Had the car into a 3rd party BMW tuner to provide an independent report and initial analysis, and they confirmed the problem is there (so I'm not going mad)! The owner even has a 35i himself which doesn't exhibit the same problem as my car. They visibly checked all the obvious mechanical things and everything looked good, and confirmed that the KDS was done correctly. So my car is now back with BMW. Went out with one of the Master Technicians and he confirmed the problem was there, but warned it may take a while to diagnose and cure, as most of the obvious things have now been checked and even double checked! Really hoping they can cure this problem - but at least they are taking me seriously and concur that there is something amiss. Last I heard they were going to try disconnecting as many electronic aids as possible to see if it is some kind of erroneous interference from the adaptive dampers or the servotronic steering. Hopefully I'll get an answer soon - don't really want to get rid of the car, but if they can't fix this, I can't keep it as it is....so fingers crossed! Thanks for all the feedback and insights from everyone! |
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05-17-2012, 11:37 AM | #19 |
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Re:
Well you knew it wasn't right. keep the pressure on them.
I really hope you get a satisfactory outcome. Really curious to know what the issue is. Keep us posted. |
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05-25-2012, 04:19 PM | #21 | |
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06-15-2012, 07:56 AM | #22 |
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Well it's been nearly 3 months but I am happy to report my car is supposedly fixed
Got a call from the dealer yesterday, and they finally concluded it was the steering rack. They were initially stumped after changing the rack and finding the car was still not running right. On BMW's advice, they tried my car running on a donor set of wheels and tires, and the car ran fine. They then took off the new Continental tires that I had fitted and fitted back my old run flat tires onto my alloy wheels, and the problem was still gone. BMW got one of their technical managers involved, and he concluded that the original fault was caused by the steering rack, compounded by the new tires that had been fitted. After back to back testing with another 35is, they concluded that all was now well! To be honest, I'm not that bothered that I can't use the new tires that I had paid for. In any case, BMW agreed to pay the cost of those tires, and also for the independent inspection that I had done. They are even paying for the lease payments for the period that the car has been offroad. It's been a bumpy ride, but hopefully now I'll get to enjoy the car to the fullest. I must also say I have been impressed with the way BMW have handled this problem also. |
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