AR7E - Alcester Racing 7's Equipe
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Let's have a look at the details of the Mk II AR7E aeroscreen...
Click Images for Full Size Key: A - Road Angel (RA) Laser detector - now scuttle
mounted
B - 3M Duallock mounting strips for RA
C - Wiper Spindle - now inside screen
D - Sigma Bike comp mount
E - ACES Sureshift 2 sequential shift lights
The Mk II does not offer any surfaces at right-angles to the direction of car travel - so there is nowhere sensible to mount the RA laser detector other than straight onto the scuttle. The Mk II is sufficiently deep that the RA can now sit fully on the scuttle (rather than perching on a mounting plate) and can therefore use far less 3M DualLock tape to secure it. The screen is too far away from the driver to allow the Sigma bike computer to be mounted directly to the screen (as happened with both the conventional windscreen and JPE aeroscreen) - so a custom perspex stand has been created. This is still awkward for the driver to reach and so (along with the ACES shiftlights) be moved closer to the driver. It should be noted that a redundant mounting hole for the JPE screen has now been re-used to allow the Sigma's signal wire to be more neatly routed.
Key: A - Half Door poppers-on to aeroscreen B - Mirror mount doubles for aeroscreen C - Lower edge of screen This detail is basically the same as for the Mk I. The drivers mirror bolts through the aeroscreen and into two rivnuts embedded in the scuttle - killing two birds with one stone. The aeroscreen obscures the scuttle-popper that the half-door (and tonneau) used to clip on to - and so a popper base has been riveted on to the screen itself -with a small washer on the reverse to spread the load.
The picture above shows how the SPA centre mirror is now hard-mounted to the scuttle rather than soft-mounted with 3M DualLock tape. The base of the mirror is bolted to an ali strip (with countersunk holes underneath) - and this strip is then secured to the car using the self-tapping screws that held the centre tonneau poppers in place. A sticky rubber 'foot' currently supports the centre of the mirror base plate whilst another bolt secures a small link piece - the other end of which attaches to the left screen mount. These ali plates need tidying up (smooth corners and the like), but are functional.
You can just about see the rubber edging strip along the base of the screen in the picture above. This wasn't actually needed to seal gaps between the screen and scuttle - the fit was impressively close anyway. The main purpose is for cosmetic reasons and also to stop the edge of the screen scratching the paintwork (the JPE screen did this - but in areas which are normally covered by the full windscreen).
Finally, the passenger-side tonneau. So far, we've not suffered any catastrophic blow-offs - the passenger tonneau is secured by only two poppers along the front edge - and no longer has any aerodynamic device to stop air getting under the front lip. So-far, so-good - but the system hasn't been tested at more than about 75% of max-speed. We propose to try two systems - firstly some industrial-strength velcro (3M DualLock is too rigid to work with the flexible tonneau). Secondly, we will try making a very small (say 15-20mm tall) spoiler to just get the air over the front lip. It shouldn't even need to be full-width... Time will tell. So that's it for now. We're happy with the aesthetic qualities of the screen and will take some time to test its' abilities. We are also looking into reproducing the design in some variety of polycarbonate (e.g. the surface-hardened Makrolon) to ensure that the screen is as safe as possible (perspex can shatter... Not a huge issue when wearing a helmet, but summer driving might be more problematic). We will probably make the template available to anyone who want to try it out - although it must be noted that it was designed around the non-standard drivers mirror mounting system - and therefore might not suit everybody... Update - March 29th, 2004OK, we've had a chance to test the Mk II a bit more. It works fine - even at extreme speed, buffeting is very acceptable, but testing without a helmet shows that hair still gets whipped around, so some sort of headwear will be required. A significant improvement over the JPE screen, we believe... We're still waiting for some proper polycarbonate to turn up, but in the meantime we will take another look at the Sigma Bike computer mount (see top picture on this page) - it is proving hard to access the lower Sigma button (needed to switch modes), so we will try another mount soon. |
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