olivierfm

New to the forum. Picked up a 2008 E61 535ix with the sunroof (standard in US). Love the car, great power, smooth ride, rock stable in high speed turns. Working on getting an M tech kit and new rims...
I have been a little disappointed by the rather high torsional body flex while driving over uneven streets (driveways, etc.). The body structure seems to creak quite a lot (I've cleaned the door seals which helped with the noise but still very creaky)... I know the huge sunroof does not help one bit. I noticed that it has some factory braces/subframe connectors already installed, but any way to stiffen the chassis? Ultra Racing makes some braces, but I am not sure they fit the Touring models with the sun roof option and factory braces. By the way it seems the factory braces could be improved upon. Any thoughts? Comments? Thanks

bigbadbull

From what I've heard they won't fit any IX/XI/AWD E6x... Sorry
you could try a strut tower brace (bigger) up front and bigger Anti sway bar in rear ( yet again limited options Euro M5 rear will fit and made just for wagon, front won't)

mmitev

Fully agree with you on the body flex point. it annoys me as well, it also gives me a bad feeling when driving on a somewhat uneven highway at high speeds. I drove a pretty basic 2004 A4 Avant the other day and sadly, I was impressed with its body rigidity compared to my E61. (The Audi had no sunroof). Particularly at high speeds it felt structurally more solid than my car.

And mine creaks a lot as well. I tried to fix some of the creaks by installing some insulation under the pannels in the trunk, and while I have much less road, exhaust and suspension noise, it did not help the creaks. It seems all of them come from panels around the windows and from the roof.

Lower bars: I am also following the topic with some hope, but I am pretty certain the bars will not help body rigidity. They're meant to stiffen the suspension subframes only.

Improving factory braces under the car: I haven't heard of anyone doing it, but let us know if you do find more info on this, I would be very interested in doing something there.

Strut bars: I have installed a front strut bar and while I am happy with how it has reinforced the front end of the car (you can feel it when going over speed bumps etc.), it has nothing to do with the rear end rigidity, where the E61's problem actually lies.

My conclusion so far as been that a rear strut bar must be the only sensible solution. Unfortunately, noone makes and sells such a bar. So I have thought about letting someone make me a custom one. I looked at the rear suspension, and there was the next problem: on our cars the rear shocks are not mounted below the C-pillar like in the sedan, but in the trunk floor, between the wheel arch and the floor compartment of the trunk. Therefore, a classic strut bar connecting the shock housings across the trunk is not possible. One would have to make a strut bar which is somehow connected to the structure of the body between C-pillar and wheel housing. I did look at this area closely when I installed the sound insulation, but did not find any sensible place to attach such a bar. If I ever come to do this, it will be very, very custom indeed..

I hope this helps, and please do let us know if you find any way to improve things.

olivierfm

Thanks for the response. I will definitely try the front strut brace, which one do you have? I've noticed quite a lot of movement between the A pillars upfront whenever I hit that steep driveway. I know that all cars flex but I'm coming from sedans that seem to be a little better at concealing the flex. I had an X5 (2004) that had a huge sunroof as well and it flexed also but not quite as dramatic. I would be curious to know if non sunroof E61 have the same issue. I love the open air feel but it is definitely not worth it if it has really compromised the structure.

Still like the car, it's a real sleeper when it comes to the power and we really don't see a lot of them in the States. I fully m-tech version with upgraded wheels is quite a thing of beauty in my option and it is definitely pretty unique on the road here in the States.

Interestingly I came across an article on the internet regarding using structural foam to increase a car's rigidity: see link: http://www.modified.com/projectcars/...t_5/index.html

It would be a crazy undertaking but I wonder if it would work... The easiest parts to fill would obviously be the lower side sills (panels) but perhaps some of the voids in the rear of the car could be filled as well. I know this sounds completely crazy and I would not undertake such a project but...

mmitev

This is the one I bought:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=400086847377&ssPageName=STRK:MEWNX:IT
I preferred it over this one (http://cgi.ebay.com/ebaymotors/BMW-S...Q5fAccessories) because this second one is a bit bendable, according to some users on this forum. And the one I bought has a solid carbon fibre tube which is not bendable. I am really happy with the one I got, especially for this price is feels solid and looks great.

There was also a brace from a Canadian manufacturer on Ebay which looked really good, but shipping cost to Europe would be too much - something like $80. Its not on Ebay right now, but it will probably come up again soon, you just have to check now and then.

Thanks for the link on the foam, will have a look at it.

olivierfm

Thanks again

higher

You could try to remove the parcel cover and put some silicon grease on there, plus the rails etc. All those components creak if they get dry.

I see you cleaned the door seal rubbers already, you need to use household vinegar to clean them properly, then condition them with BMW rubber conditioner (called gummi-fledge) that's the phoenetic spelling, but BMW will know what you mean. It's 10 Dollars a can and lasts a lifetime, just spray it onto cloth and rub it over the seals. Soapy water, car shampoo won't clean the door seals and can make them worse. Similarly, using non BMW rubber conditioners can also make the creaks worse. You might think you've cleaned them and resolved any creaking but you probably haven't. Not being funny here - just took me a year to get this sorted in my own car, after numberous clearning and greasing, BMW finally told me what they do when customers complain of this.

mmitev

thanks for the info. unfortunately the remaining noises are not from the door seals or the parcel cover.

the door seals I treated with bmw's silicone spray and they definitely dont creak anymore. the Gummipflege (gummi=rubber and pflege=care in german) thing is surely better, but i will get it when I finish the silicone.

the parcel cover I removed, cleaned, greased, and even installed some mini-insulation pads around the joints but no noises were eliminated. ergo, there are no noises coming from it. also, I tried driving the car without it and it did not help much. there are of course noises coming from it when you hit a pothole, but these are general material stress noises that cannot be eliminated easily. no creaks or any particular knocking.

the remaining annoying noises are:
- metal knocking from rear seats when the body twists. have no idea how to eliminate this
- plastic knocking/creaking from rear gate. i will try to adjust the buffers on the tailgate to eliminate any looseness.
- some light vibration over potholes from opened sunroof cover. i guess i will have to live with this
- general plastic stress noise from all panels around all trunk area windows. i guess thats the price i have to pay for driving a touring

dieseltouring

Hi mmitev,

I don't think all of this noise is body flex.

I was annoyed by the creaks from the rear of my touring which spoilt the car IMO. After trying lots and lots of things I have finally found and fixed the main culprit (at least in my car). The noise was coming from the plastic trim piece across the car at the bottom of the boot (trunk) between the rubber tailgate seal and the lift up carpeted floor section. This plastic trim has two small recesses for the bump stops at the bottom of the tailgate and I believe it is slight movements of the tailgate which put pressure on this plastic trim causing the creaking. I did the following:

Removed the two chrome luggage strap retainers that mount through the trim (lever out the little cover inside and then undoo pair of allen bolts)
Levered out the four outer rectangular screw covers from the trim and then removed screws
Removed the two plastic retainers from the trim that are visible when lifting the underfloor storage tray
By lifting up the main trim enough, inserted felt strips under the edges of the luggage strap appertures where they contact the car metalwork
By lifting up the main trim enough, inserted felt squares between trim and body at the four screw and two plastic retainer positions
Reasembled.
Trim piece does not creak when leaning on it anymore and it has transformed the car. 90% of the noise from the back when driving has gone and it feels tight like a luxury car should.

You may have a different problem, but then maybe this might just help you too.

mmitev

Thanks DT, this is really helpful and I suspect some of the unidentified noises in my car come from this piece indeed.

I know how to disassemble it, as I did it when I installed my LCI rear lights.