Latest Upgrade - OEM Carbon Diffuser (with added pictures)

Hi Devon Doug
I can't inderstand why the OEM would be stated to fit all tears as they changed the rear bumper cover at facelift. While the basic profile is similar they change light shape, added a different crease line and change the bottom edge lip.

While you if course cut off the centre of the cover under the new diffuse it does at the ends wrap around the bumper cover and it's ther that the different profile is the big problem

This first fit photo might partially explain. Note that there is no crease line to hide the mating surface between spoiler and bumper cover as on the facelift and there is a major gap in the end, not visible from this angle: (final fit pretty much sorted out all these issues, but it was a challenge)

DSC02766.jpg
 
Near-side
BMWZ4Diffuse_L2.jpg

Off-side
BMWZ4Diffuse_R1.jpg

Do you think the gap between the crease line and diffuser on the near-side is slightly wider?
 
ksher, yes the gap is bigger, I notice at the bottom the cf wraps under the bumper, I would assume there is a gap on the nearside at the bottom as there is the bigger gap at the top. If the fitting at the bottom is tight then probably little you can do.

I did see one of these somewhere that hadnt been fitted centrally where the creaes in the bumper around the number plate werent cermetrical with the crease in the difusser which is more noticeable than your problem.

It could be the bumper moulds arent 100% or even the diffuser mould isnt 100%
 
srhutch said:
ksher, yes the gap is bigger, I notice at the bottom the cf wraps under the bumper, I would assume there is a gap on the nearside at the bottom as there is the bigger gap at the top. If the fitting at the bottom is tight then probably little you can do.

I did see one of these somewhere that hadnt been fitted centrally where the creaes in the bumper around the number plate werent cermetrical with the crease in the difusser which is more noticeable than your problem.

It could be the bumper moulds arent 100% or even the diffuser mould isnt 100%
Click to expand...

The difference is just about 1mm. As you said it could be the moulds, so I am not going to take the bumper off and mess about it. Good news is the diffuser is fitted perfectly in the centre after I measured it.

Breaker did show a diffuser was not fitted properly in the centre in "How To" section. Breaker, I noticed from the 2 pictures you posted after black sealant was added to close the gap beteen diffuser and bumper. The gap between diffuser and crease line on the exhaust side was also seemed to be slightly wider than other side. Can you confirm, please?
 
Looks a pretty good fit to me :)
You shoudl trey it on a pre facelift with no crease line and a different lower lip profiel to mate to :thumbsdown:

Have you considered puling the exhaust tips out a fraction given the diffuser has now extended the rear? I had my ///M back boxes positioned as far back as possible to take advantage of this.
 
cj10jeeper said:
Looks a pretty good fit to me :)
You shoudl trey it on a pre facelift with no crease line and a different lower lip profiel to mate to :thumbsdown:

Have you considered puling the exhaust tips out a fraction given the diffuser has now extended the rear? I had my ///M back boxes positioned as far back as possible to take advantage of this.
Click to expand...

Thanks, CJ. I didn't notice it until you mentioned it now. I can see your pipes are about 20 mm longer. How can I pull the chrome tailpipe trims out? I can't see any screws securing the trims.

DSC02766.jpg
 
I'm pretty sure they are just a tight push fit. There have been a few designs though. My original system had bolts underneath to hold them on. Others I have seen have an internal spring.

The Z4M boxes that I used and in the picture you have pasted are different and have 2 pop rivets to hold it all in place.
 
Ksher - can I assume that this is a substitute for not changing cars?

If so I think I'm in the same boat, I've been looking at //M's on and off for about 6 months; I'm lucky that the cash is not an issue - but I still have not been able to make the change; the reason is that everytime I drive my Z4, I can't really see myself needing any more performance (the roads around me are not really big enough to need, or use more power), and I do like the fact that its a bit more understated.

Anyway, I'm 95% going to stick at the moment, which means the diffuser is back on the agenda - it fixes the only thing I don't like about the Z4's styling, and thats the bottom of the facelift bumper - just looks too heavy for my liking, especially on the Tit Silver.

Pointless post really (as usual from me) - think I'll start asking some questions of my dealer!

My other question is to go to 108's or not - this is something I can't decide on at all.
 
csmith319 said:
Ksher - can I assume that this is a substitute for not changing cars?

If so I think I'm in the same boat, I've been looking at //M's on and off for about 6 months; I'm lucky that the cash is not an issue - but I still have not been able to make the change; the reason is that everytime I drive my Z4, I can't really see myself needing any more performance (the roads around me are not really big enough to need, or use more power), and I do like the fact that its a bit more understated.

Anyway, I'm 95% going to stick at the moment, which means the diffuser is back on the agenda - it fixes the only thing I don't like about the Z4's styling, and thats the bottom of the facelift bumper - just looks too heavy for my liking, especially on the Tit Silver.

Pointless post really (as usual from me) - think I'll start asking some questions of my dealer!

My other question is to go to 108's or not - this is something I can't decide on at all.
Click to expand...

This is the first time I made change to car. All my previous cars were standard.

My only 3 problems of not changing my car now are: (1) it was only bought in February this year, and still has AUC warranty; (2) new Z4 sDrive35i with all gadgets I want are now about £37k. I have to wait at least 2 years from now until they become more affordable (below £25k at least); and (3) my current job can change in near future, a company car may be provided with no cash alternative. If it happens, I may have to sell my own car. :( .

I think you should seriously think about putting diffuser on your silver Z4. The carbon diffuser on light colour Z4 looks good. :) If I were you, I would get ///M wheels, not 108.
 
ksher the exhaust trim are just pushed on with metal spring clips holding them so should pull out a bit.

Only problem is you will be left with a gap between the trim and ehaust on in the internal bore so probably wont look right either, I think the most important thing would be to get both pipes equal length, but think you will have to leave as they are.
 
srhutch said:
ksher the exhaust trim are just pushed on with metal spring clips holding them so should pull out a bit.

Only problem is you will be left with a gap between the trim and ehaust on in the internal bore so probably wont look right either, I think the most important thing would be to get both pipes equal length, but think you will have to leave as they are.
Click to expand...

Correct. Thanks.
 
ksher said:
csmith319 said:
Ksher - can I assume that this is a substitute for not changing cars?

If so I think I'm in the same boat, I've been looking at //M's on and off for about 6 months; I'm lucky that the cash is not an issue - but I still have not been able to make the change; the reason is that everytime I drive my Z4, I can't really see myself needing any more performance (the roads around me are not really big enough to need, or use more power), and I do like the fact that its a bit more understated.

Anyway, I'm 95% going to stick at the moment, which means the diffuser is back on the agenda - it fixes the only thing I don't like about the Z4's styling, and thats the bottom of the facelift bumper - just looks too heavy for my liking, especially on the Tit Silver.

Pointless post really (as usual from me) - think I'll start asking some questions of my dealer!

My other question is to go to 108's or not - this is something I can't decide on at all.
Click to expand...

This is the first time I made change to car. All my previous cars were standard.

My only 3 problems of not changing my car now are: (1) it was only bought in February this year, and still has AUC warranty; (2) new Z4 sDrive35i with all gadgets I want are now about £37k. I have to wait at least 2 years from now until they become more affordable (below £25k at least); and (3) my current job can change in near future, a company car may be provided with no cash alternative. If it happens, I may have to sell my own car. :( .

I think you should seriously think about putting diffuser on your silver Z4. The carbon diffuser on light colour Z4 looks good. :) If I were you, I would get ///M wheels, not 108.
Click to expand...

A company car option without a cash alternative would be a nightmare - essentially forcing you to pay that company car tax on a new car, rather than on a better priced second hand car. Not good - hope you are not forced into that.

I think I wil lorder the diffuser this week, otherwise I will procrastinate further. I only bought mine in November last year - however at one point I could get back what I paid for it on trade in - this is what made me think to change. This isn't the case anymore unfortunately!

I do love the //M wheels - but I'm not sure the offsets look right on non-M's (although I haven't seen it real life) - I guess the real bonus is that they are cheaper to buy second hand than 108's... MV3's look pretty good actually... ARGH

I test drove a new 35i - great car, but to be honest, it felt too much like my wife's 3 series with a better engine, so I think perhaps a 3 series coupe with that engine would be a better buy.
 
I'm trying to track down the part number for the OEM rear diffuser. I think its number 4 on the image below:
DisplayImage


But the BMW parts finder doesn't list the part number. Any assistance, or knowledge of where to buy one, greatly appreciated.
 
teeps said:
I'm trying to track down the part number for the OEM rear diffuser. I think its number 4 on the image below:
DisplayImage


But the BMW parts finder doesn't list the part number. Any assistance, or knowledge of where to buy one, greatly appreciated.
Click to expand...

51710410384

Unfortunately, the part seems to be no longer available.
 
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