Z4 steering...

[Alan W]

Okay so lve bought my first Z4 (2007 facelift 3ltr coupe manual) which drives really nice l thought.. until tonight l gave it a bit of a blat down the motorway and l am now far from impressed. At 70 to 80mph the car felt twitchy as hell and basically sh***.. found myself constantly having to correct the steering. During my research l had read about sticky electric power steering but understood that was adressed in the facelifts? It has run-flats all round and didn't know if getting rid of them would help? I seriously doubt that the car left the factory like this so something must be wrong.. so the process of elimination begins and l hope l haven't bought a lemon! Any thoughts or feelings about the cause would be gratefully recieved..

 

[t-tony]

It is something some people find about the "electric" power steering Alan, I did when I bought mine and now it's normal. Having said that mine came on a "square" set up on run flat tyres which I didn't like either (hard ride and noisy) I put staggered wheels and Goodyear F1 Eagle tyres on and it changed the car, again I've adapted to it but I do have some slight tramlining which I hope to eliminate with Poly bushes on the front lower arms. Will need new tyres soon too which will undoubtedly help. Have you checked the tyre pressures and treads and tread wear also?

Tony.

 

[Alan W]

Handbrake rachet appears to be worn out too.. thought that would be a relatively easy job but just read that you have to remove exhaust amd propshaft to get to it. Arrggghhhh!

 

[GazHyde]

Sticky electric steering shouldn't be an issue for your Coupe. Are you using it with the Sport button engaged or without? The sport button stiffens the steering up a bit. It's possible that it is in need of the bushes/suspension or the tyres looking at. It is a different animal compared to the Z3 though.

 

[raymond]

It is not impossible that a sensor could be at fault in the upper steering column giving off random incorrect settings so try run a diagnostic to see if there are any error codes. On my Z4 2003 the upper column failed ( only £3000 from BMW ! ) so luckily you have the facelift one. However I was able to drive the car without the power steering but parking was a chore. So you could remove the fuse for the power steering and see how it perfoms at speed. On my car the fuse also powered the instruments so you may need sat nav for speed test. This would show if the electric steering was at fault or not

 

[Alan W]

Thinking about it, l don't think its the sticky steering issue, just at higher speeds the steering felt really light and needed constant correcting.. in no way a relaxed drive. It has brand new RF tyres on rear which are a different brand from the front so a different tread pattern. Think lm gonna have to take the plunge and buy a set of non RF tyres all round.. maybe rainsport 3 non XL which l had on my Z3 and were a really good tyre. I think anyone that researches buying a Z4 knows that many recommend ditching RFs if a car you buy has them, so l knew it would be on my to do list.. change rubber first then work from there l guess, although getting the handbrake sorted first would seem more important.. if it turns out that l have to get a new handle assembly l will take it to my mates garage as that is not a trolley jack in the driveway job!!

 

[Lee]

I had this exact problem and it was driving me mad for months. First thing I did was replace the lollypop wishbone bush's at the front. I then ditched my runflats. Once you've done that go get the tracking done. It should be very crisp.

 

[Alan W]

Thanks Lee.. l know its solvable as no car could leave the factory like this.. its fliipin dangerous! If lm honest whats worrying me is if l have to have a new power steering unit which would be an ecpensive and labourious job. Did you use poly lollypop bushes or rubber?

 

[Lee]

Thanks Lee.. l know its solvable as no car could leave the factory like this.. its fliipin dangerous! If lm honest whats worrying me is if l have to have a new power steering unit which would be an ecpensive and labourious job. Did you use poly lollypop bushes or rubber?

Yeah it's such a well documented issue with the Z4's now, but like Gaz said there shouldn't be any issues with the steering rack itself in the later models. To begin with I fitted standard bush's but then I started going on track so changed to Poly. I didn't notice it totally go till I changed the tyres and had the tracking done.

 

[Alan W]

Update on this.. checked tyre pressures today and they were well under inflated but you wouldn't know to look at them.. (probably because the stiff sidewalls on the runflats dont bulge when flat like a conventional tyre). As l said, previous owner had just put two brand new tyres on rear so today l swapped rear wheels to front so the new rubber was at front and inflated tyres to correct pressures and took it for a drive. The result? It has completely transformed the car, no tramlining whatsoever (it was doing that a bit) and its all feels nice and tight and precise. I still haven't tried a motorway run to see if things have changed there but l have my fingers crossed.. oh, and whilst the car was jacked up l had a good look underneath and l am pleased to say that it all looks remarkably good for a 10 year old car!

 

[t-tony]

Good news and good info too Alan. Thank you. Run flats are very deceiving re pressures and that's why they have pressure sensors in them.
Easy to cancel if you have one light it up.

Tony.

 

[GazHyde]

Update on this.. checked tyre pressures today and they were well under inflated but you wouldn't know to look at them.. (probably because the stiff sidewalls on the runflats dont bulge when flat like a conventional tyre). As l said, previous owner had just put two brand new tyres on rear so today l swapped rear wheels to front so the new rubber was at front and inflated tyres to correct pressures and took it for a drive. The result? It has completely transformed the car, no tramlining whatsoever (it was doing that a bit) and its all feels nice and tight and precise. I still haven't tried a motorway run to see if things have changed there but l have my fingers crossed.. oh, and whilst the car was jacked up l had a good look underneath and l am pleased to say that it all looks remarkably good for a 10 year old car!

I had a puncture on a rear run flat some years back on my first Z4, didn't notice until I hoofed it off a roundabout and it squirrelled at the back. Pulled over and it look fine, only when viewed from the inside could you see it was low. Suffice it to say the tyre pressure warning system hadn't gone off and I destroyed the tyre. Moral of this tale? Don't rely on TPS telling you anything meaningful!

 

[t-tony]

You shouldn't rely on the TPS at, it's only there for people who don't check their tyre pressures regularly. much the same as oil level sensors.

Tony.

 

[GazHyde]

it's only there for people who don't check their tyre pressures regularly. much the same as oil level sensors.

A puncture is a random event which can happen irrespective of how many times you check your tyre pressures, or even just after you have. A puncture or low pressure on a non-RFT is usually detected quicker due to the softer side wall and the car wobbling around. It's a function of RFT that you tend to not notice low pressure or a puncture as the car will drive relatively well under the circumstances.

 

[Alan W]

Heres a question.. so after the change over l now have new Goodyear Eagle NCT5 RF's on front and steering is better and more precise and suspension doesnt seem too hard at front with 2.3bar in tyres.. could certainly live with it. However this leaves the Kuhmo ECSTA SPT RF's on rear and with 2.7bar in they are very hard and slammy.. like riding on hard plastic! So.. is there such a vast contrast between front and back because the Goodyear's give a softer ride, or is it because of the geometery of the car and the fact that the rear wheels are right behind me so l notice it more? I will knock the pressure down a bit on the rear and see if that makes a difference, failing that my options are to get a set of Goodyears for rear or fit a pair of non RF's for now and then replace the RFs on front with non RFs when they wear down? Can you do even do this, have RFs front and non RFs rear?

 

[t-tony]

A puncture is a random event which can happen irrespective of how many times you check your tyre pressures, or even just after you have. A puncture or low pressure on a non-RFT is usually detected quicker due to the softer side wall and the car wobbling around. It's a function of RFT that you tend to not notice low pressure or a puncture as the car will drive relatively well under the circumstances.

I agree, just they should not be relied on totally as some do.

Tony.

 

[Alan W]

Knocked those slammy RF's on the rear down from 2.7 bar to 2.5 bar and there is a marked improvement.

Took the car on the motorway yesterday and how she's running now is like night and day compared to my first drive at speed on under inflated RF tyres, and swapping the wheels with brand new tyres to front has also stopped the tramlining.

Now feels a lot more like the car she should be

Anyone know if taking the centre console out is major or relatively straightforward? I fairly certain that the handbrake ratchet has worn and the lever assembly will have to be replaced at some point, apparently a known issue and BMW have modified the part twice.. as I said you have to get to it from underneath and as well have having the console out apparently you have to drop exhaust, prop shaft and heat shield and would be interested to hear from anyone else that has done this job?

 

[GazHyde]

Anyone know if taking the centre console out is major or relatively straightforward?

Taking the whole centre console out is a real pain, but you should be able to get to the some of it without taking it all out. Once you have removed the leather gaiter/arm pad out the is a small section of plastic directly under the handle that will come out.

I really can remember the sequence, there is a chance that you have to remove the gear surround as well.

To remove the centre console, you have to dismantle the storage area behind/between the seats. I've just done the whole process and it's not pleasant!