front spliter affecting aero dynamic

[nibbsy999]

Hi guys question ? fitting front spliter,spoiler.
if you fit that only front spoiler,without rear diffuser will that effect the aero dynamics of the the car.
my BMW dealer is looking into this for me, as i asked what the price for just fitting & spraying front lower spilter on bumper, instead of silly price he quoted me for rear diffuser & splitter bottom of front bumper as well.
he replied back saying he will have to see if BMW will allow this front spoiler only as it may cause aero dynamics issues.....

is he having a laugh or is he serious ?
or is he trying to mug me of to have the rear diffuser fitted as well ?
never heard this one before, i could understand if it was a F1 super car.

[Foretrees]

I think he is having you on, some of the guys paint the rear diffuser black and dont fit the carbon one but have the front corners and spliter or one or the other, i have everything fitted and it makes no driving diffrence or feel to me, does look nice tbh!

[nibbsy999]

Originally Posted by Foretrees

I think he is having you on, some of the guys paint the rear diffuser black and dont fit the carbon one but have the front corners and spliter or one or the other, i have everything fitted and it makes no driving diffrence or feel to me, does look nice tbh!

thats what i thought thanks for your input

[notused]

No, it's true. BMW state fitting splitter requires rear diffuser. You could argue with BMW but the dealer is just following their guidance.

[shay2nak]

It's not a real diffuser, I doubt it would make any difference. As far as the front splitter, I'd imagine it just reduces lift and not provide much downforce, if at all.

[Chompers]

Originally Posted by RWDpetrol

No, it's true. BMW state fitting splitter requires rear diffuser. You could argue with BMW but the dealer is just following their guidance.

I think the dealer is referring to the rear boot spoiler in his statement not the diffuser. At very high speed the front splitter pushes the front end down, if this is not balance by the rear spoiler, the rear can become 'light' the diffuser on any road BMW adds nothing but a style element. For a diffuser to work the underside of the car needs to be flat.

[Chompers]

Originally Posted by shay2nak

It's not a real diffuser, I doubt it would make any difference. As far as the front splitter, I'd imagine it just reduces lift and not provide much downforce, if at all.

Exactly, and coming from an Exige owner, you'll know the difference

[ajfoggy]

Originally Posted by Chompers

I think the dealer is referring to the rear boot spoiler in his statement not the diffuser. At very high speed the front splitter pushes the front end down, if this is not balance by the rear spoiler, the rear can become 'light' the diffuser on any road BMW adds nothing but a style element. For a diffuser to work the underside of the car needs to be flat.

Yep that is right, this is taken from the F32 fitting instructions:

[SteveC]

Remember when the original Audi TT was launched and there were reports of them spinning out of long high speed bends when taking the foot off the gas. Several people were killed including a very experienced 60 year old rally driver.

The fix was to add a small spoiler to the rear of the car. When seen in isolation you wondered how something so insignificant could make such a difference to the car's aerodynamics, but it did

[nibbsy999]

Originally Posted by ajfoggy

Yep that is right, this is taken from the F32 fitting instructions:

thanks for that information, looks like dealer was right then. so why did bmw sales person not mention this when i spoke about the rear diffuser, not rear spoiler ?
now you have showed evidence the rear spoiler has to be with front bumper spoiler.
is this BMW playing safe as these parts can now be fitted at factory ? just never seen any mention of this before.

[M5essex]

Originally Posted by SteveC

Remember when the original Audi TT was launched and there were reports of them spinning out of long high speed bends when taking the foot off the gas. Several people were killed including a very experienced 60 year old rally driver.

The fix was to add a small spoiler to the rear of the car. When seen in isolation you wondered how something so insignificant could make such a difference to the car's aerodynamics, but it did

I'm sure it's all just cosmetic. The MPE front splitter is so flimsy and has a gaping hole above it. It's not a true splitter. Nor is the rear diffuser.. it's just for decoration. The rear spoiler may add a tad more rear-end downforce at pace..?. The ACS front splitter looks more purposeful for front end downforce. If you can keep it on and not rip it off over humps and inclines!

I had my front splitters and corners fitted first and the rear spoiler a few weeks later.

[ajfoggy]

Originally Posted by nibbsy999

thanks for that information, looks like dealer was right then. so why did bmw sales person not mention this when i spoke about the rear diffuser, not rear spoiler ?
now you have showed evidence the rear spoiler has to be with front bumper spoiler.
is this BMW playing safe as these parts can now be fitted at factory ? just never seen any mention of this before.

They are still a dealer fit not factory. I suspect they are playing on the technical BS to make us have to buy both, but could be wrong.

[Foretrees]

Originally Posted by ajfoggy

Yep that is right, this is taken from the F32 fitting instructions:

Good find, BMW should then sell as a kit and not allow people to fit one or the other, the front spliter and rear boot sploier should be sold and fitted as one, that would keep in line with the small print

[ajfoggy]

If your are buying and fitting yourself I see no reason why you can't do one or the other, you are never going to get to the speeds where they come into play anyway.

[notused]

Originally Posted by Foretrees

Good find, BMW should then sell as a kit and not allow people to fit one or the other, the front spliter and rear boot sploier should be sold and fitted as one, that would keep in line with the small print

Until you lose the splitter on a speed hump and only want to replace that.

[scottc]

From new (sept 16) I was running the front splitter/corners and didn't have the rear spoiler.. BMW fitted all of it and never said a word about not having it

It went back in last week to add the spoiler, I now have the full external kit inc mirrors

[Wills2]

These bits will reduce lift but the claim that they are producing real down force is a bit well......

[Chompers]

Originally Posted by Wills2

These bits will reduce lift but the claim that they are producing real down force is a bit well......

Agreed