Front Flippers

E

exdos

Veteran
One of the thing that would really help to resist the tendency of the front end to lift under acceleration and improve high speed handling of the Z4MC is front flippers. I've been scouring the internet to try to find a pair of aftermarket flippers that will fix to the front bumper in the position of the fangs, but nobody seems to make them. AC Schnitzer make these for several other BMW models (I have them on my Z3MC) but not for the Z4MC.

However, I've just found a photo, as below, of an ACS Z4MC concept car which shows just the sort of thing that I've been looking for. Since ACS didn't put these flippers into production, I intend to fabricate my own of very similar design. I can make these as a "one-off" for myself, but I'm wondering if any other forum members might be interested in these things, because if so, I could arrange to get a mould made of what I produce, so that duplicates can be produced. So if anyone would like to show an interest then please speak up. Also, if anyone would like to do some sketches of "add-on" flippers on the OEM bumper which retain the overall design of the Z4MC, I will produce some mock-ups in clay in situ on my car so that photos can be taken to show what the design would look like.

I envisage that the flippers would incorporate an aluminium underside (a bit like those RPI plates).

ac_schnitzer_profile_concept_2007_0.jpg
 
That's a great idea - I wonder why they didn't produce that bumper but you can still get the stupid poxy wee wing on the back :roll:
 
I'm really glad this is in the M specific section - the non M cars must not suffer from the problems described :P

In fact, reading the 1st post - the M roadsters clearly dont suffer from the problem either. Coupe owners take note - the MC's are all duds :fuelfire:
 
Adamski said:
In fact, reading the 1st post - the M roadsters clearly dont suffer from the problem either. Coupe owners take note - the MC's are all duds :fuelfire:
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Yeah it's why the Z4MC is only 3 seconds faster round the 'ring than the Z4MR and not 10 Adam!!
 
original guvnor said:
Adamski said:
In fact, reading the 1st post - the M roadsters clearly dont suffer from the problem either. Coupe owners take note - the MC's are all duds :fuelfire:
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Yeah it's why the Z4MC is only 3 seconds faster round the 'ring than the Z4MR and not 10 Adam!!
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Have they tried the MR with the hardtop fitted. That must be quicker :rofl:
 
What do you mean by flippers? I was expecting some dive planes ahead of the front wheels. TBH anything aero will have an effect proportional to the speed, whereas the front end lift under acceleration is a function of the torque at the wheels, which is pretty inverse to the speed.
 
carl said:
What do you mean by flippers? I was expecting some dive planes ahead of the front wheels. TBH anything aero will have an effect proportional to the speed, whereas the front end lift under acceleration is a function of the torque at the wheels, which is pretty inverse to the speed.
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By the term "flippers" I mean the same sort of thing as the AC Schnitzer flippers I've had on my Z3 MC for the past 7 years, as shown in the photo below. Coupled with various suspension mods, they really do make a noticeable difference to the handling of the car. I removed them once to respray them and the difference in handling at speeds above 30mph was very noticeable.

You are correct that front end lift is a function of torque and since the front springs are of the "progressive" type and relatively soft, once the front springs begin to unload, it becomes progressively easier for the front end to lift some more. I find that this occurs under hard acceleration in 1-2-3 gears, so the tendency to lift from torque at the wheels is occurring at speeds up to 100mph, at least, where aerodynamic forces are already very significant.

According to the information found here: http://www.genmay.com/showthread.php?t=827884 at 200km/h (125mph) the BMW Z4 3.0si Coupe already has 28kgs of front end lift and 43kgs of rear end lift, which shows that the Z4 Coupe (including my Z4MC) body shape already has an inherent tendency to lift with increase in speed, so, as I see it, any aerodynamic parts which can resist the tendency to lift, for whatever reason, is a good thing, especially when driving at The Ring where it is easy to spend a fair amount of time at speeds well above 100mph on a relatively bumpy surface. The AC Schnitzer front flippers and roof wing on my Z3MC have been tested by ACS and actually produce "downforce". Therefore, fitting some flippers to the Z4MC should improve the handling and help resist front end lift in the same way that it has to my Z3MC, especially with aftermarket suspension that I am fitting.

As it happens, the ACS front flippers on my Z3MC also increase the ram pressure in the "brake ducts" which feed the air-intake, which actually increases the Volumetric Efiiciency of the engine at higher speeds in higher gears too. :D




Ring.jpg
 
Ah, I see you are referring to lift at speed rather than lift under acceleration. Alles klar.
 
carl said:
Ah, I see you are referring to lift at speed rather than lift under acceleration. Alles klar.
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No. I'm referring to both situations because they are integral with each other. I find that there is a tendency of the front end to lift under acceleration at WOT as a function of wheel torque as you've suggested, and as the speed increases, this will also combine with the overall tendency of the Z4MC to aerodynamically lift due to its body shape with increase in speed. Initially, in 1-2 gears (i.e. < 60mph), the lift is essentially due to torque, but as the acceleration continues there is a greater contribution of aerodynamic lift, which changes the rake angle. Because the OEM front suspension is relatively soft, the combined effect is to make the front of the car lift up, which will both lighten the load on the front wheels but also change the geometry which I find makes the steering very imprecise and "floaty". I think stiffer front suspension will resist the lift from torque and flippers will reduce aerodynamic lift, particularly at the front end, and by preserving the rake angle, it will also generally reduce lift at both ends of the car. My Z3MC, with uprated suspension and various aerodynamic bits, feels SO stable at high speed, whereas my Z4MC feels **** whilst accelerating at any speed.
 
HOw about a splitter? Looking at €300 from the USA. Not sure how it will deal with sleping policemen though...
 
ChawenHalo said:
HOw about a splitter? Looking at €300 from the USA. Not sure how it will deal with sleping policemen though...
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I've considered one but it would be a nightmare on public roads especially when the car gets lowered with new suspension.
 
have you seen the Vorsteiner ones, for the E92? looks like just a carbon fibre cover, slightly enlarged, sticks onto the fangs of the M bumper.

http://www.lincah.com/2010-vorsteiner-bmw-e92-e93-v-ms-aerodynamic-package
 
marksdesigns said:
have you seen the Vorsteiner ones, for the E92? looks like just a carbon fibre cover, slightly enlarged, sticks onto the fangs of the M bumper.

http://www.lincah.com/2010-vorsteiner-bmw-e92-e93-v-ms-aerodynamic-package
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Yes, that's the sort of thing I have in mind. Since my Z4MC is Phoenix Yellow, I don't think CF parts would look right, so I'll make something that can be sprayed to match.
 
yeah agree. if you get a good working mold you can still use the CF as the structure and then paint to match. super strong and super light.
what were you thinking of making it from? clay model then a fibre glass mold? oldschool style - or just CAD something up and get it formed etc?
8)
 
marksdesigns said:
yeah agree. if you get a good working mold you can still use the CF as the structure and then paint to match. super strong and super light.
what were you thinking of making it from? clay model then a fibre glass mold? oldschool style - or just CAD something up and get it formed etc?
8)
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Clay in situ and glass fibre mould.

I've thought of making the flippers in Kevlar fabric like this stuff http://www.ebay.co.uk/itm/Carbon-Ke...ssories_SM&hash=item53e30ec022#ht_2034wt_1165 and there's a possibility that it could match up quite well with Phoenix Yellow once the fabric has been wetted with resin. If it doesn't, then I could still get them painted.

I might also make a mini wickerbill rear spoiler like the OEM one too if I could get the Kevlar looking OK.
 
not exactly the same, but wouldn't this do?

5111_85510.jpg


http://www.bavauto.com/shop.asp
 
peddy said:
not exactly the same, but wouldn't this do?

5111_85510.jpg


http://www.bavauto.com/shop.asp
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That part costs $ 1774.95, plus freight, plus import taxes! :o I'd learn how to weave carbon fibre before I'd pay that :wink:
 
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