Bike rack attachments for E86

[exdos]

No, I haven't. I didn't add the ACS wing and if it wasn't bonded on I'd remove it. I'm extremely dubious whether it has any real benefit at the sort of speeds I drive. I'd also be interested to know whether the increase in drag is in reality offset by the increase in downforce.

Since I've had the car I've spent as much time removing (what I consider) unnecessary modifications as I have adding new ones ...

Dan,

You've given the precise reason why I don't want to permanently attach anything to the external bodywork: you only get one chance to fit the right thing and if it's wrong you're stuck (literally!) with it.

The speeds you're doing around The Ring certainly will produce downforce with the right parts. Whether you can benefit from the downforce IMO depends upon whether you're prepared to drive around the bends at the speeds that the added downforce will allow, where the faster you drive the more downforce you'll get, so you can drive even faster (tyres permitting). I fully realise that for the track the best mod that I could do is use R comp tyres, but I have a 1000mile round trip just getting to and from The Ring it seems such a waste using up most of the rubber on the roads. I'm also considering fitting a tow hook so that I could trailer a set of wheels, and then I could use the tow ball as a fixture for a removable rear wing.

What mods have you removed and what have you added??

 

[exdos]

Used a Saris Bones on my old MC. Secure and no issues but you do need to ensure the weight is distributed to the feet as opposed to the straps.

Inkey$, Do you have any close up photos of the fittings that attach over the glass at the top of the door? Alternatively, can you do me a diagram? Is the part attached to the strap made from metal?

 

[exdos]

Good call about the point of downforce being on the rear of the tailgate , you know I'm familiar with wheel barrows

Paul, I thought you did all of the work on your French property with a mini-digger? :wink: Did you ever drive a Z3MC with an ACS rear wing and front splitter? I find they are very noticeable to the handling, and I've tested by removing them individually at each end.

 

[inkey$]

Inkey$, Do you have any close up photos of the fittings that attach over the glass at the top of the door? Alternatively, can you do me a diagram? Is the part attached to the strap made from metal?

Alas not. But to describe in further detail, the 6 x straps were of course, adjustable and featured metal angled flattened 'hooks' to work with the shut lines. These had a rubberised coating so as not to scratch any paintwork.

The two at the sides for lateral support work in the boot shuts and we're not load bearing at all; more tightened for overall anti shift support. I did move these from the wide sides to the lower areas near the rear light (see clise up pic), as they seemed more stable there.

The two at the top work in the shut line again but took more weight. Not a great deal but enough to ensure the unit wasn't going anywhere.

Lastly the two that attached to the underside of the boot lid. Again, tightened and designed to ensure the rear feet stay put.

 

[Paulwirral]

Good call about the point of downforce being on the rear of the tailgate , you know I'm familiar with wheel barrows

Paul, I thought you did all of the work on your French property with a mini-digger? :wink: Did you ever drive a Z3MC with an ACS rear wing and front splitter? I find they are very noticeable to the handling, and I've tested by removing them individually at each end.

Not all of it , as my battered hands will testify :lol:
I don't try that hard around the ring these days , I just go for a laugh and a catch up with friends now , is a roof rack or trailer with comp tyres and wheels to change when your there not a better option ? You could fashion a tow bar with your eyes closed but I'm guessing you like the tech challenge ?
And there was that z4 video with Alzen driving with full aero I pointed out , scary fast !

 

[Paulwirral]

Good call about the point of downforce being on the rear of the tailgate , you know I'm familiar with wheel barrows

Paul, I thought you did all of the work on your French property with a mini-digger? :wink: Did you ever drive a Z3MC with an ACS rear wing and front splitter? I find they are very noticeable to the handling, and I've tested by removing them individually at each end.

Not all of it , as my battered hands will testify :lol:
I don't try that hard around the ring these days , I just go for a laugh and a catch up with friends now , is a roof rack or trailer with comp tyres and wheels to change when your there not a better option ? You could fashion a tow bar with your eyes closed but I'm guessing you like the tech challenge ?
And there was that z4 video with Alzen driving with full aero I pointed out , scary fast !

 

[tertius]

No, I haven't. I didn't add the ACS wing and if it wasn't bonded on I'd remove it. I'm extremely dubious whether it has any real benefit at the sort of speeds I drive. I'd also be interested to know whether the increase in drag is in reality offset by the increase in downforce.

Since I've had the car I've spent as much time removing (what I consider) unnecessary modifications as I have adding new ones ...

Dan,

You've given the precise reason why I don't want to permanently attach anything to the external bodywork: you only get one chance to fit the right thing and if it's wrong you're stuck (literally!) with it.

The speeds you're doing around The Ring certainly will produce downforce with the right parts. Whether you can benefit from the downforce IMO depends upon whether you're prepared to drive around the bends at the speeds that the added downforce will allow, where the faster you drive the more downforce you'll get, so you can drive even faster (tyres permitting). I fully realise that for the track the best mod that I could do is use R comp tyres, but I have a 1000mile round trip just getting to and from The Ring it seems such a waste using up most of the rubber on the roads. I'm also considering fitting a tow hook so that I could trailer a set of wheels, and then I could use the tow ball as a fixture for a removable rear wing.

What mods have you removed and what have you added??

1000 miles on normal roads driven sensibly will use hardly any tread, especially if you use one of the better R compound tyres - the GT3 boys are reporting incredible life (and performance) from the Michelin Pilot Sport Cup 2 - that's what I'm planning to use next. Even my ZZ-Rs are wearing incredibly well - two days at the 'ring; two Silverstone days; a day at Brands GP; a day at Spa and a day at Zandvoort (and of course all the driving in between) and they are still going strong.

The real pain with tyres like 888s or ZZ-Rs is the road noise, however, the MPSC2 is also really quiet. It is a win all round.

I'm extremely dubious that a road car (especially one on normal road rubber) will corner on a track day at speeds where downforce will make a material difference, it isn't a race after all. The Alzen Z4 is running a simply MASSIVE rear wing and the ride height (to make the front splitter properly effective) is miniscule. And look at the height the rear wing is at! The drag from that thing must be enormous - I'd bet the increased fuel consumption would more than pay for a fraction of a mm of tyre wear ...

With regard to my mods and changes:

Removed:
Supersprint Race backboxes -> replaced by OEM
Supersprint Race X-pipe -> replaced by OEM
Gruppe M intake -> replaced by OEM
Front splitter -> not replaced

Added:
Vibra-tech engine mounts

Swapped:
Pole Position seats - replaced by TIllet B5
Out of date 4 point harnesses - replaced by in-date 6-point Schroth

Changed:
Intrax rear coilover changed to Intrax adjustable barrel spring setup, with more travel and softer spring rates

 

[exdos]

1000 miles on normal roads driven sensibly will use hardly any tread, especially if you use one of the better R compound tyres - the GT3 boys are reporting incredible life (and performance) from the Michelin Pilot Sport Cup 2 - that's what I'm planning to use next. Even my ZZ-Rs are wearing incredibly well - two days at the 'ring; two Silverstone days; a day at Brands GP; a day at Spa and a day at Zandvoort (and of course all the driving in between) and they are still going strong.

The real pain with tyres like 888s or ZZ-Rs is the road noise, however, the MPSC2 is also really quiet. It is a win all round.

I'm extremely dubious that a road car (especially one on normal road rubber) will corner on a track day at speeds where downforce will make a material difference, it isn't a race after all. The Alzen Z4 is running a simply MASSIVE rear wing and the ride height (to make the front splitter properly effective) is miniscule. And look at the height the rear wing is at! The drag from that thing must be enormous - I'd bet the increased fuel consumption would more than pay for a fraction of a mm of tyre wear ...

With regard to my mods and changes:

Removed:
Supersprint Race backboxes -> replaced by OEM
Supersprint Race X-pipe -> replaced by OEM
Gruppe M intake -> replaced by OEM
Front splitter -> not replaced

Added:
Vibra-tech engine mounts

Swapped:
Pole Position seats - replaced by TIllet B5
Out of date 4 point harnesses - replaced by in-date 6-point Schroth

Changed:
Intrax rear coilover changed to Intrax adjustable barrel spring setup, with more travel and softer spring rates

I used to attend the annual BMWCC international event at The Ring where most of the cars were BMWs on road tyres but since that event ceased 4 years ago, I've attended 3 different closed track events at The Ring, where there are so many very fast cars on R-comp tyres. I really enjoy driving road tyres at their limits on track and my only reason for considering using R-comp tyres is because my Z4MC on road tyres is no match for fast cars on R-comp tyres which means that I now come across too much traffic too often on non-BMW track days. I know several other Z3MC owners who've swapped to R-comp tyres and some say that they actually spoil the fun because they have so much grip.

Apparently, the grip of tyres is related to weight/ force on the tyres. See: http://www.autospeed.com/cms/article.html?&A=108915. The Z4 Coupe does suffer from aerodynamic lift, therefore, reducing aerodynamic lift or even generating some positive downforce will help to place more weight (force) on the tyres, thus increasing grip, whether or not the car is shod on road tyres. This morning, I've been around my 22 mile test-route in both my Z4MC on Michelin PSS and Z3MC on Falken 452 in back-to-back drives, and although the PSS is a much grippier tyre than the 452s, my Z3MC takes the corners better because the car remains flatter, where the inside wheels feel that they are providing almost as much grip as the outside wheels. Although both cars have uprated ARBs, the Z4MC has much stiffer ARBs but it doesn't have a wing and splitter and so I'm tending to reach the conclusion that the difference is down to the lack of aero parts on the Z4MC and for curiosity's sake I'd like to find out what the Z4MC will be like with these parts. I have a friend with a E36M3 GT, which has an OEM retractable front splitter which can be used to balance the OEM rear fixed wing: you can see the rear wing flex under load when the car is moving at speed, and adjusting the front splitter really makes a difference to the suspension settings required and the handling. I had a few pax laps at The Ring in it at DN10 and it is awesome, where you can feel the downforce build as the speed increases.

I can understand all your removals and additions. You should consider gutting a pair of OEM silencers.

 

[exdos]

Alas not. But to describe in further detail,...

Thanks! I understand your explanation perfectly.

 

[exdos]

Just for interest, here's a photo of a Z4 Coupe in a wind tunnel showing the smoke trace:



and here's my own observations with my pressure washer for comparison of the method:



If there's a lip spoiler or a wing at the rear then you would expect to see the air passing over the rear of the Z4C to follow an upward path as shown in red below, and for a moving car, this pulls the air exiting under the car, upwards too. If there's a diffuser on the car, the wing effectively "powers" the diffuser producing an area of low pressure beneath the car, pulling the car to the road. I should join the Red Arrows!

 

[Gonzo]

Used a Saris Bones on my old MC. Secure and no issues but you do need to ensure the weight is distributed to the feet as opposed to the straps.

Inkey$, Do you have any close up photos of the fittings that attach over the glass at the top of the door? Alternatively, can you do me a diagram? Is the part attached to the strap made from metal?

I use a Saris Bones on my Z4C but swapped out the standard hooks on the glass to "hatch huggers" http://www.wiggle.co.uk/saris-hatch...m_medium=base&utm_campaign=uk&kpid=5360106894

They slot through the boot seal so the pressure is on the inside plastic trims rather than hooked onto the glass. Was mildly concerned the first couple of times I used them that the webbing would damage the boot seals but all seems fine and less risky to me than putting load through the glass.

 

[exdos]

I use a Saris Bones on my Z4C but swapped out the standard hooks on the glass to "hatch huggers" http://www.wiggle.co.uk/saris-hatch...m_medium=base&utm_campaign=uk&kpid=5360106894

They slot through the boot seal so the pressure is on the inside plastic trims rather than hooked onto the glass. Was mildly concerned the first couple of times I used them that the webbing would damage the boot seals but all seems fine and less risky to me than putting load through the glass.

That's precisely the sort of fitting I had in mind. The length of strap that I would use on the outside would be no more than 2 inches or so, which IMO would minimise the problem of using straps rather than more rigid fittings. The fact that Saris has sold so many of its products shows that this sort of system for attaching a load to the back of a car shows that this is a tried and tested method.

 

[TiffAnsell]

this is a funny thread, quite helpful for me as I was just starting to look and see if there were any "bolt on" bike rack kits for the z4c so I could take my mountain bike, well... not quite to the mountains. so even though it has the right title but the topic of conversation is completely different it's still provided me with my needed information (I think) thanks guys ) p.s if there were two towing eyes on the back then I would agree that possibly using this location for a spoiler would be better than sitting it onto the boot edge.