alexio

After driving my 2008 535xi wagon with panorama roof (the only option in the U.S.) I'm amazed at how badly the car flexes. i feel like if I step of a small curve diagonally the car will twist itself in two. I'd read about this issue before purchasing, just had no idea how bad it really was.

At this point I'm seriously wondering whether to upgrade from the stock 18" wheels as the car just feels like a wet noodle already and I think removing compliance with a thinner 19" sidewall would just be making a bad problem worse. How are other USA owners (or anyone with a panorama sunroof) dealing with this issue?

If I go with 19", I would assume that I would HAVE to lower the car, and after talking to some people, I've been told NOT to go with the v3's as they are too stiff for this car (and N.California bumpy roads), but to pony up for the BMW sport suspension which lowers the car without being so harsh as the v3's.

So, my options, as per the poll I created are the following:

1. stick with 18' and stock suspension, this car has too much chassis flex.
2. stick with 18' but lower the car slightly to help them not look so tiny, but keep the thicker tire sidewall.
3. go with lighter 19' wheels (Forgestar F14) but keep the stock (soft) suspension and it won't make much difference... hopefully gap won't look as big with 19" wheels.
4. screw chassis flex and noises, make the car look good, lower the car with the M-sport suspension AND put on the 19" rims.

Any other ideas?... thanks for an excellent forum, I've learned a lot in the short month I've owned my car.

mmitev

Excellent topic. I have 4 things to say:

1. Imho the tyre choice will not have too big effect on chassis flex. Why? Because I see no difference in chassis flex between my summer 18-inch RFT tyres and my winter 16-inch non-RFT tyres with extra low pressure.

2. Tire size will affect comfort though. In that respect I would recommend a) going non-RFT, and b) going to higher tyre size, e.g. 245/45/18 for the 18-inch. For 19-inch, I just posted a topic a week ago that confirms that the higher-sidewall 19-inch tires from the E63 will fit the E61. But you will have to check the ETs on your car (mine is RWD).

3. I would not recommend going for M-sport suspension. IMO it is rather stiff in a straightforward way and tuned mainly for highway (autobahn) usage. Simply not compliant enough for bad roads, where the chassis flex problem mainly occurs. But I don't know the xi suspension opitions so not sure what else to recommend.

4. I would recommend searching for other solutions to the problem. Read the topic below, it has lot of info. I am currently on the fence about buying brackets #14 (fitted on the M5 E61) from post #29 and seeing if they will fit on mine (and hopefully reduce the flex)..

https://5series.net/forums/topic/100...y/page__st__15

NavarroOne

Dude, how are you driving??? I've driven a '73 Mustang convertible and if you want to talk about flex.... That thing wobbles like a loaf of wet bread on an industrial hopper! The E61 doesn't flex, period.

That aside, get the msport suspension and put on 19" for look as well as sporty ride but if you're looking for all-out trackday wildness, get a caterham or a Lotus Elise; not a wagon.

mmitev

Depends on the road condition. I'd bet you won't feel any flex on a Danish motorway. But get to an old backroad in the UK, give it a push, and you will hear the whole back end creaking from body flex.

phelix

Count me as another person who doesn't think the E61 has any issues with body flex. Rattles from various interior panels - for sure. The cargo cover can be particularly noisy on my car without rhyme or reason. But that's just from poor quality fit and design, not body flex.

NavarroOne

I do like to take mine out on backroads and drive it reasonably hard (not quite as I would drive on the track though). Flex and creaking noises are not a problem I've ever encountered. I once had a 71 Ford Taunus GT Coupe which broke (rusted through) an undercarriage beam running the length of the car. i had a college mate who bought an Isuzu which was welded together from two totalled cars and that thing should have never been on the road I've felt flex and breaks and you'll know when it's wrong but that aint the case for an E61. My car is 4 years old with two owners and it's a beaute. Maybe you should have yours checked out?

alexio

For a BMW, or any modern car, it flexes pretty badly. Keep in mind I'm talking about the version with the panorama roof, I'm sure the steel roof version is different.

yep... so let's equate the old british road with north california roads which are shit.

good points, but again, I notice you guys are in europe and may not have the panorama roof option... is that the case?

Regardless, thanks for all the responses guys... I'll look into the M5 bracing.

olivierfm

Alexio,

I started a thread a while back on subject of chassis flex and the E61. Mmietv posted a lot of comments as well and provided the link to it above.
I have a 2008 model US model as well - with the standard panorama sunroof. In my mind there is no doubt that this huge sunroof has compromised the structure. I've been looking for fixes as well. If you look underneath the car you will notice some braces that are specific to the wagon that form a "V". They start from the last 1/3 of the car and join past the rear differential area. I am sure they can be improved upon if I can find someone to customize a set. As mmietv suggested the M5 braces might fit but since the M5 touring was never imported to the US I am not sure we could get those braces. There is a company in Arizona called ?Strong Strut?. They have designed underbody braces for BMW?s - mostly the Z3 and the Z4. They seem like the right company to contact to design a better solution. The Ultra Racing underbody braces which seem to reinforce the subframes have gotten some pretty good reviews but sadly they don?t fix the XI models.
Also what helps with the creaking noise (around the doors and windows) is making sure the rubber in the top areas of the door is clean and well lubricated. There has been a lot of postings on the subject as well (common problem with many BMW's - sedans as well). Many members recommended using Vaseline (no joke) on the rubber seals. I have done that and it works!- No joke - it certainly helped quiet the door areas.
I wish there was a way to remove the sunroof all together and replace it with a steel roof $$$$ (it really just adds a lot of weight to the very top of the car and I really don't use it - plus it is has been known to flood the trunk area (where the spare tire sits) and shorts out the electrical system. There have been well documented postings about clogged sunroof drain plugs and flooding...).
I'm in Southern CA where the roads are just as bad as N CA. I have not done really anything to the car it still has the standard 17 inch rims but I will upgrade them to 18" only. Our roads are just too bad and with 19's you will probably have to lower it or it will look too high. Aside from the fairly weak structure, the car is still a blast to drive, in the US it is quite rare and a real sleeper. The M-tech body kit makes it look awesome!

mmitev

I went to a company that does custom exhaust and other metal fabrication. They looked at the huge V-shaped brace and said this thing is very rigid, is made of very strong metal which is like 10-12 mm thick and unfortunately they can certainly not improve it or produce anything stronger. (M5 braces #14 are a different story but again have to be bought from BMW, can not be produced easily). I hope the Arizona guys are more advanced.

mmitev

On the flex again: it surely isn't as bad as a 70's convertible or something that was "welded together", but compared to an E90 3-series, or to a Audi A4 Avant (both around the same production year), its flex is certainly noticeable. The resulting creaks in plastic panels (I presume the rear gate panels and something in the roof) just make it so much more annoying. By modern standards, this is not acceptable.