This is a mod that I have been thinking about for a while now. Doing my research over the years, it seems that there several options out there, made from various materials, ranging from carbon fibre to plywood. Now, having choices is a good thing, but one thing I struggled with was the cost. Hence me trying to come up with a solution of my own.
I was keen to design something that looked good, looked functional ( you can never test these things unless you have a proper wind tunnel I guess) and given that this was to go on an S1, it had to look elegant and not over powering.
The other design consideration was how much the skirts should potrode out. I really didn't want something that came out so far that I would have to remember that it's there everytime I stepped in/ out of the car. So, it had to be a simple design.
With these considerations in mind, I went for curvy lines, taking a nice line to the form of the car, linking the front to the back. Worked pretty well.
This was always going to be a headache. I initially considered using existing bolts, holding the undertray, but I discounted this as this would mean having to remove the side skirts every time you need to remove the undergrays. That, to me, is not going to be practical.
So, next was to bolt the boards to the underside of the sills. This seemed to be the best option and the decision was more around whether to go with large bolts, with less mounting points or smaller bolts, but with more mount points, which would inevitably mean more holes to the underside of the sills.
After consulting a good friend of mine (its always useful to know an Engineer ) He advised me to go with the larger mounts and keep the number of holes to be drilled down.
As noted above, the choice is vast and the limit seems to be cost, ie you could end up with very complex shapes and forms using carbon fibre, with the added manufacturing cost or you could go with a simple shape and material. As money always matters, I went for the simpler material.
So, what did I end up with. Well, after some research, I ended up with an aluminum composite that is not only very strong, but very light. In fact, each side only weigh 700lbs! I think that's pretty good.
CREDIT: Although I came up with the design, using cardboard, I was lucky enough to have had the service's of my Friend's Dad, who is an absolute wizz when it comes to using CAD. He took my cardboard cutout and turned it into a digital masterpiece! Thank you Dad!
Or shall I say cutting. I manage to find a good engineering firm in Birmingham who were willing to take the CAD drawing, load it up onto their system and cutout the side skirts to spec. They did a great job. For future runs, I will add the mounting holes now that I know where they should be.
Installation is pretty straight forward and it would be even easier if I had a ramp. Anyway, in the absence of a good ramp, I used my trusted jack and pushed the car up enough to get an axial stand under the car, whilst allowing me enough room to work on the sills.
TIP: If you are going to use a single jack, please, please ensure that you use axial stands, and get some chocks on the other side, ie on the wheels that are on the ground. I also use a bit of wood to ensure that I don't end up damaging the underside of the car with the jack.
As this was the first time offering the skirts up to the car, we (yes, another pair of hands would be advantageous) spend some time locating the skirt board and deciding where best to mount the holes. We ended up with 5 mount points that given the size and the weight, was more than enough for what we are looking to do.
We marked the points on the boards, taped them together and drilled the holes. Once done, we then placed the board on the sill, taped it in place and once happy, drilled the sills using a 2mm drill. We had to drill very slowly and deliberately as we weren't sure where the coolant pipes were.
WARNING: If you are going to drill into the sills, please remember that you have coolant pipes running through there. My car is also CC, with additional pipes running to the front radiator. Be very, very careful how you do it. You are warned.
By taking the drill slow, when it broke through it, it was easy to feel whether or not there was something on the other side. Either way, you would have to be very careful.
Then, slowly enlarging the holes by using a larger drill.
I finally used a wood tool to curt 16mm hole for the M8 rubber well nuts.
(note the jack position and the bit of wood )
Then once all the well nuts were in place, it was just a simple matter of bolting the boards on.
The end results - well, see for yourself. I am rather pleased...
That is a job well done!
Well, I am yet to workout the total cost, however it was significantly less than £200 for the pair. If there is enough interest, I may get a few made (which should drive the cost down somewhat). So, if you like what you see, let me know and I am sure I could sort something out, again, depending on the numbers.
Now available on www.111racing.co.uk