M Bumper Fitted- New problem to solve.

S

sideshowbob

Member
 Surbiton, Surrey
Just had a brand spanking new M Bumper fitted on Monday. It looks great but ive already noticed a couple of problems.

1/ When i hit 70mph i get this violent flapping/banging noise like something is loose. Im not too worried about this because i know my bodyshop guy will sort it out, but would be interested to know if anyone else has had the same problem fitting an M front bumper.

2/ The front of the car now seems to be ridiculously low. Ive got the 3.0i which i believe has the lower suspension which i guess is causing the problem. I cannot get over anything without it hitting the bumper. Every speed bump or driveway is now a nightmare. What have other people done about this? Im guessing the problem isnt as bad on the Z4M because it uses a larger profile tyre that must lift the front of the car up slightly. Can i fit M size rubber, or will this cause rubbing issues?

A quick photo of the new bumper. Apologies for image quality (was taken on phone camera in failing light).

068.jpg
 
Looks great... Now welcome to the world of unpleasant scraping noises with every large undulation, steep driveway, and pothole :P
 
On the M, the bumper is actually higher then the standard 3.0 bumper, I always assumed that the 3.0 version was lower though.
 
To me the M isn't quite low enough. I do like being able to tacle speed bumps though, the TT did become a pain in the arse sometimes.
 
sideshowbob said:
1/ When i hit 70mph i get this violent flapping/banging noise like something is loose. Im not too worried about this because i know my bodyshop guy will sort it out, but would be interested to know if anyone else has had the same problem fitting an M front bumper.
Click to expand...

Hope you find the answer I'm due to fit in the next few months
 
Does anyone know if M size tyres will rub on a 3.0i? If they will, whereabouts?

By changing from 225/40R18s to 225/45R18s on the front, and from 255/35R18s to 255/40R18s on the back i will gain half an inch of ride height.
 
Yes they will. Just on the edge of the fender at around 10 O'clock.

On top of that your speedo will be off too.
 
Hark said:
To me the M isn't quite low enough. I do like being able to tacle speed bumps though, the TT did become a pain in the arse sometimes.
Click to expand...

All I can say is Eibachs...scrape, scrape :P

My TT easily cleared speed humps from its customary position on an RAC truck :thumbsdown:
 
peddy said:
Yes they will. Just on the edge of the fender at around 10 O'clock.

On top of that your speedo will be off too.
Click to expand...

how much do you think the speedo will be out? will it register faster or slower than actually going?
 
It should register slower. So when it says you are doing 70mph, you will be actually going about 72mph. Its not much of a difference to be honest with you.

Peddy- are you sure that it rubs? Could you be thinking of M tyres fitted to M Wheels? Im wondering if things will be different with standard 18" alloys that dont have an "M" offset?
 
So i went back to the bodyshop for the guys to have a look. The main problem is caused by the under tray. The under tray is supposed to locate into the bottom of the front bumper. This supports the under tray and keeps everything rigid. The M bumper sticks out further in front of the car than the standard bumper. This means that the standard under tray is too short to attach to the M bumper, so it just sits there in space flapping around. When i hit 70mph the airflow under the bumper is fast enough to make the undertray flap around quite violently. This was making the banging sound i could here when traveling at speed. Also because the undertray was unsupported, the front of it would hang down lower than the bottom of the front bumper and hit speedbumps.
What the bodyshop managed to do was to screw the front corners of the undertray into some plastic brackets that were located above. Although only the corners are supported and not the entire front end of the undertray (as it is supposed to be) it seems to hold pretty well. After a quick test drive afterwards, there is no longer any banging at 70 mph, and the scrapping over speedbunps has been greatly reduced.
 
sideshowbob, if I were you I'd get a sheet of ABS plastic (can buy it online). You' probably need to cut it in half along the length to make a sheet wide enough, weld the two together and then cut to shape so it fits over the lip of the M bumper and plastic weld the other side to the existing undertray. Not sure what the fixings are for the bumper to undertray but I have some old motorbike fairing clips that you can have, should do the trick.

It's not that difficult to do and would finish the job nicely.
 
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