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Coyote X 12-26-2007 01:02 AM

Radical Metro Aero Mods?
Well I finally got around to ordering a plasma cutter :eek: So now it is time to actually commit to doing something with my car. I would really like to build a spitfire/metro combination but I don't have time this summer for anything that involved so my only real option is to stick with a base metro shell to build on. I have 3 metro bodies sitting around in the yard I can hack on and get figured out what I can do. I have lots of random thoughts but not really sure what ones are good. I will have the summer to build whatever I do and need it running by fall and be able to drive it all school year.

- Chop the roof, easiest way would be cut the firewall near the windshield and tilt the roof back so it is flat to the tail lights. Also would help by making the windshield angle steeper. Door windows might not ever roll down again but who cares. All glass except the windshield would have to be custom formed lexan.

- chop the front end into something a bit better shaped. if nothing else just re-angle the bumper so it pushes air over the top better and isn't so flat. Tilting the radiator back some and making the hood close much lower so the engine only has 1/2" of clearance would be better.

- Narrow the entire car. The engine does not take up the entire engine bay so the car could have 6 inches cut out of the center, CV joints are easy to narrow, not sure about the steering rack but I am sure something can be figured out pretty easy. The gear shifter would be hard to do something with. it would be in the center of the drivers seat if left alone so it needs some way to be moved way to the right and still work. I would also have to find a different windshield, probably something like off an Opel GT, I think it is pretty narrow. Cutting the stocker would be hard but not impossible.

- Narrow the rear of the car so it tapers in after the rear wheels. Be easy to do just not sure if there would be much gain from it. Narrowing the rear wheel s without the fronts matching would make handling totally suck.

The other thing I would love to do if I have time(I probably don't) is to replace the unibody totally with a chromoly chassis. I would be able to strip all the supports off the stock body panels so they are just a skin attached to the frame. That way I could dig up some good spitfire body panels in the future and just change the car over to it by just changing the body mounts around. Once the car is built on a tube chassis changing it into something totally different looking is way easier and could probably be accomplished over 2 weekends.

These are the main ideas I have for what to do to my metro. I now have all the tools I could possibly need for metalwork. Stick welders, Mig welder, chop saws/grinders, plasma cutter, tubing benders/notchers, and a 40'x48' garage. So instead of finishing up the kit car that has been sitting for a few years I am going to get into another project that will hopefully get done faster than the never ending kit car project. Anyone got anything else they can think of adding to my idea list for this car? I am open to anything no matter how insane the idea might sound.

MetroMPG 12-26-2007 02:29 PM

I take it you don't want to stick the drivetrain into a '95+ body? Yeah, they're a bit heavier, and not in your current collection, but the starting aero is superior.

Also - that chopped EV Metro dragster looks hott:
Another crazy aero-modded Metro - chopped & teardropped

Narrowing the entire car would be good, but man, that's a LOT of work.

I think the biggest bang for the effort is definitely the firewall chop / roof tilt back. You'd be dramatically improving Cd, as well as slightly reducing A (the projected max height of the windshield would be lessened).

Retaining the OEM windshield would seem a key goal also for safety & non-scratchiness (wipers on lexan).

So that would get you your profile taper.

After that, if you want to get seriously cutty & weldy, I'd look into doing some plan taper via rear track surgery and boat-tailing the body after the doors. As for handling - you don't have to make it into a trike exactly. (The rear track on my '98 is already an inch narrower than the front, stock. Maybe it's only half an inch... I forget at the moment.) But 4-6 inches narrower would be nice.

Radical aeromods are definitely the way forward for you, since like basjoos, you don't hold back too much in terms of cruising speed.

Lazarus 12-26-2007 03:20 PM

I always though this was outstanding.

Coyote X 12-27-2007 12:28 AM

I really don't think that the roof chop would be that hard. I don't think the roof will be worth much of anything after that for impact protection so it will have to be caged when it is done. The advantage of caging it is I can strip away all the now useless roof supports to make up for the cage weight. I would also be able to remove all the guts out of the doors. So I would probably end up the same weight with a cage as without and have a stronger car.

The other thing I figure would be very easy is to reshape the front end slightly to get some sort of angle on the front bumper instead of flat. I noticed the car coasts better when coasting down a hill with a curve in it so if I make the bumper and air dam sit at a 30-45 degree angle instead of flat plus maybe make it into a point so air is pushed off the sides and the top easier.

I am thinking cutting the rear narrower would be pretty easy if I don't care if the hatch works. I really don't like the idea of narrowing the rear wheels though since I like the way the car handles like it is on rails right now. I can almost double the posted speeds on the warning signs in curves with it :)

I know where an Opel gt is so I went and measured its windshield today and it is almost as wide as the stock metro one so there would be no advantage in using it other than it is a better looking shape. I don't know of any other cars that are small and I could use the windshield out of so narrowing the whole car seems to be down at the bottom of the list for now.

If I start narrowing the car behind the doors but not narrow the wheels I could maybe get 6-8 inches narrower on the back and the wheels would only slightly stick out. I could cover the back wheels again and it might not mess up the taper that much. I don't really know if the taper would help much though after chopping the roof down to the tail lights. The rear of the car would only be about 16 inches high. I think the front end and roof chop would be way bigger gains for a lot less work but I could be wrong.

Also venting the higher air pressure that is under the wheel skirts out the center of the back bumper might be worth something. Right now that air is just whistling through the rust holes when I go fast so I know letting that pressure out in a low pressure area might be worth some gain.

Thinking of controlling air flow how about moving the radiator to the passenger side firewall and cutting a hole in it and building a large duct that directs that air out the center back of the car. This would involve totally sealing the engine compartment and letting the air from the grille opening make its way back to the radiator then out the back of the car. It might look nuts but I bet it would help reduce frontal area. This would be easy if I cage the car since I could remove the factory floor and just replace it with a flat sheet of aluminum to make a totally smooth underbelly.

Coyote X 12-27-2007 06:13 PM

1 Attachment(s)
Just when I start putting a plan together everything changes.....

This just got added to my collection for $150 and it actually runs. It is a 3 cyl auto with a pretty solid body, almost no rust at all on it. It was near a house fire so the paint was blistered all down one side is its only real problem. I could paint it and drive it as is if I wanted.

Now the plan so far is tube chassis the vert and lighten it as much as possible and stick my xfi drivetrain in it. I have no idea what the aerodynamics of a convertible are compared to a hatchback car but it will probably be a lighter car when it is done since it wont have any metal or glass on the top. I guess I need to go digging around for some numbers on it now.

MetroMPG 12-27-2007 07:25 PM


Originally Posted by Coyote X (Post 3200)
Just when I start putting a plan together everything changes.....

RATS! I was looking forward to a chop & taper thread.

But... nice vert find, though. I guess. :)


Now the plan so far is tube chassis the vert and lighten it as much as possible and stick my xfi drivetrain in it.
Well, that alone will make it a one-off.


I have no idea what the aerodynamics of a convertible are compared to a hatchback car
Unfortunately: worse. You get separation at the windshield (when the top's down), the widest part of the greenhouse. No tapering benefits of the top or sides of the hatchback body.

That said, the reason you get a convertible is to enjoy the open air, right? So in the fine part of the year, just enjoy it & know you've done your best in the drivetrian and weight departments.

But for winter use... you could fabricate a sloping canopy top that would be at least as good as the chopped & tapered hatchback roof.

So, you get to enjoy the summer al fresco, and then when the weather turns to crap, take comfort from the fact that at least you've got superior winter time aerodynamics.

Coyote X 12-28-2007 01:32 AM

hehe I was hoping with the top up it would be better aerodynamics than the hb. I really don't drive much in the summer now that I have a bike that is way more fun.

If you want I can still chop the blue 92 metro I have here for you and you can come get it and do something with it :) I am trying to figure out what would be the best combo to go with still really. I have practically no money invested in a fleet of 5 metros now and I have lots of options I could go with. I do have a 97 model but it is missing most of the body panels now and I let a girl play with power tools on it so it has a few places cut into it. I have the tools so you could come visit for a week in the summer and we can chop your car :rolleyes:

I found some tires that look good for whatever I do. They are 175/70-14 I just need to find a set of 14x5.5 steel rims and a new set of moon hubcaps. That will put my speedometer 10% off and would be easy to correct since it is a standard correction factor. Then I could give up the endless search for 145/12 tires. My gearing would be similar to yours then, 2700rpm at 65mph.

I am thinking no matter what car I end up building on I will still do a new front end that slopes much better than what these cars do factory. A smooth belly pan seems to be easy to do as well when the car is apart so that will probably be done. Rear wheel covers and closing in the front wheel as much as possible would also help out as well. I am still considering ducting some air somehow to the back bumper to help reduce the low pressure area behind the car. The back wheels would be easy but the engine air might be hard depending on what size duct it needs.

MetroMPG 01-01-2008 12:28 PM


Originally Posted by Coyote X (Post 3240)
I have the tools so you could come visit for a week in the summer and we can chop your car :rolleyes:

If the 10 year old car didn't have just 15,000 km on it, I wonder if I'd be more willing to take you up on the offer. I could just buy another one and do it. Nah, there's NO way I'm getting another vehicle! I already have too many. :D. So many projects, so little time...


I am still considering ducting some air somehow to the back bumper to help reduce the low pressure area behind the
Makes sense & it's an established drag reduction technique. GM's Precept PNGV car ducted its cooling air into the wake (rear engine though), and the Aptera ducts a small amount of air (interior ventilation) in its wake.

Coyote X 01-01-2008 04:05 PM

I have plenty of metros laying around you can use :) the 97 one is missing most of the body panels though.The blue 92 is a very solid car and would be a perfect one to chop though since it is 100% complete and runs good other than a cracked ring that would take a few hours to fix. Or I could help you lighten and chop your electric car. Once I get the convertible done I will have had some practice with totally gutting a metro so doing another would be much faster.

I have been stripping the convertible down and it has a lot more rust on it than you would think by looking at it so this might be a bit longer project than a couple of months to strip and rebuild. One of the front suspension mounts looks pretty rusty, it is still solid enough for now but it isn't going to last for 10 more years. I might get it ready to transplant my drivetrain this summer but there is no way it will be done quicker than that. Unless I get a really easy load this semester and only have to teach intro classes or something.

I will have some pics of the convertible totally stripped down if I can get the last few rusted bolts out today.

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