vibrating_Cake Posted July 21, 2009 Report Posted July 21, 2009 AHHHH i shot myself in the foot the other day by making an undertray and splitter for the car... damn it actually works! so....now i have a really big problem, going down a road, under 50mph, everything is fine so to speak, can throw it round corners crests etc dont bother it just like it used to drive. anything over 50mph and all hell breaks loose! the back end starts getting twitchy on crests, throw it into the corner the front will grip well but the back will just refuse to grip and just waggle around everywhere! go over crests and back wheels lift of the floor but the front doesnt GRR! so.... car= capri mk3 what can i do for rear downforce, that doesnt nesecerily ruin 1. the lines of the car 2. my wallet 3. creates "useable" downforce or "useable" reduction in lift, because the car has become a little too twitchy for my likings! i was thinking getting my plastic/ally sheet and creating a flat-back diffuser type thing, covering all the over-hanging pieces of metal around the fuel tank in a diffuser kind of shape, maybe with a few small 2-3" fins running up it. and.... getting a spoiler, but a turbo tail is too expensive (but its something like 100kg of downforce@100mph or something (not sure on the figures no more i'd have to look) or... something like a fibreglass standard boot spoiler, where i either extend it further back from the vehicle like a RGA?? one, and extend the lip on the rear of the spoiler (like on standard production cars) like.... getting a dowel 10-15mm and laying it along the rear lip of the spoiler on the top, and fibreglassing a "lip" up over the dowel, so it keeps the lines of the car, but adds a little "kick" to the spoiler. any other ideas on creating downforce, or how well any of my ideas would work bearing in mind all i have on the front is a splitter which is~1inch protruding from the front of the lower valance, back to the front of the wheel arch flat to the underside of the car, and an undertray connected to this splitter which is flat down just past the sump.... which is producing an inbalance in downforce.... This: so god knows "how much" i need on the rear, obviousley i dont want the front going light... but any ideas??? discuss
oldskoolfred Posted July 21, 2009 Report Posted July 21, 2009 hello i have a mk3 capri boot lid in my garage with a large boot spoiler (fiberglass) on it looks ok not out of place .....
vibrating_Cake Posted July 21, 2009 Author Report Posted July 21, 2009 ducktail FTW or whale tail hahaha i said "that doesnt ruin the lines of the car" hahaha i like the ducktail, but its a LOT of work for something that is a pretty high drag solution to the problem, and either too much or too little downforce, im not sure how efficient they are tbh =) hello i have a mk3 capri boot lid in my garage with a large boot spoiler (fiberglass) on it looks ok not out of place ..... piccies??
oldskoolfred Posted July 21, 2009 Report Posted July 21, 2009 i did have a fiberglass bonnet too but its gone now !!
escort21 Posted July 21, 2009 Report Posted July 21, 2009 How about removing that splitter thing you made.....that'd do it
vibrating_Cake Posted July 21, 2009 Author Report Posted July 21, 2009 How about removing that splitter thing you made.....that'd do it booo, thats not the point, thats 50% splashguarding because atm when i go through my local ford water comes all the way up on TOP of the engine.... god knows how much the carbies suck up!!! the undertray near enough completley stops this, some gets through the radiator still, but it gets nowhere near the carbies, and 25% reducing drag and 25% downforce which was something i wasnt too bothered about having... lol. but... now i have it, i like it, it keeps the car settled and has nigh on eliminated tramlining which is a relief! so for me its more the merrier, its going to be a 100% track car in a year or so, as soon as i get a "propper" job haha. so downforce will be handy indeed!
caprinerd Posted July 21, 2009 Report Posted July 21, 2009 what about fitting a small aero wing under the back at a slight angle to create some down force in the arse end
Copey Posted July 21, 2009 Report Posted July 21, 2009 what about fitting a small aero wing under the back at a slight angle to create some down force in the arse end thats the sorta thing i would suggest too, or like you have done at the front a sheet of ally that goes under the tank with an inch gap and curved up
bortaf Posted July 21, 2009 Report Posted July 21, 2009 I'd watch out for puddles!!! i had a sump gaurd on a tina and the thing took off over any puddle over a few mm deep
BIGKEV Posted July 21, 2009 Report Posted July 21, 2009 Queue Gary Would a rear diffuser be beneficial?
BIG G Posted July 21, 2009 Report Posted July 21, 2009 just keep adding these in the boot its the same as down force shit load cheaper and easier than all this feckin about
BIGKEV Posted July 21, 2009 Report Posted July 21, 2009 lol - thats what they used to do back in the day - Period customisation lol
oldskoolfred Posted July 21, 2009 Report Posted July 21, 2009 lol capri bootlid complete with glass and everything bar the lock (with the large spoiler ) £40 collected (or can worksomething out) ill get down to the garage and get some picks for ya morow night
vibrating_Cake Posted July 21, 2009 Author Report Posted July 21, 2009 lol capri bootlid complete with glass and everything bar the lock (with the large spoiler ) £40 collected (or can worksomething out) ill get down to the garage and get some picks for ya morow night cant i just rip the spoiler off and just have that
Retromotorsport Posted July 21, 2009 Report Posted July 21, 2009 difuser, a device to clean airflow as it exits the rear of a car.. to difuse turbulance Venturi, a device to change air pressure. .. a shaped part that has a small entry leading to a large exit cuasing a drop in air pressue. So.. what do you want, keep the number plate clean, difuser, or suck the back down , venturi A venturi is free downforce, it shoul only add negilble drag, whereas sticking a wing in the airflow has to produce a certain amount of drag depending on chord angles. For the venturi to work, the car needs a flat bottom, (gearbox and and axle cooling problems) this flat bottom needs to be gradually raked up towrds the rear, an inch over 4 foot say, and then behind the axle line, this should open out into a more steeply raked and increasinly wider box. the further out the box extends beyond the bodywork the better. Exhausts in this box will kill it, and render it useless, allow a central exhaust shouded in the venturi to make 2 venturi tunnels can work. A rear wing thats flexable, allthough illegal in motorsport can work wonders, under low pressure, (slow speeds) the chord angle adds downforce, as the pressure increases , the wing flexes and the chord angle flattens out, still supplying down force but lossing the drag effect of having a high chord angle at high pressure. As seen of F1 cars a few years ago before being caught, the rear spar flexed at high speed, so moving the wing back and down, lessening the chord angle. A few touring cars had dubious wings too, that seemed to flex if someone put a elbow on them.. as we are talking only a few Kg's here, I belive the 3dr cossie wing only added around 140lbs of downforce, total, which was only 40lbs efective, as the car has 100lbs of rear lift. Air, its wonderfull stuff, shame we cant live with it or without it
vibrating_Cake Posted July 21, 2009 Author Report Posted July 21, 2009 difuser, a device to clean airflow as it exits the rear of a car.. to difuse turbulance Venturi, a device to change air pressure. .. a shaped part that has a small entry leading to a large exit cuasing a drop in air pressue. So.. what do you want, keep the number plate clean, difuser, or suck the back down , venturi A venturi is free downforce, it shoul only add negilble drag, whereas sticking a wing in the airflow has to produce a certain amount of drag depending on chord angles. For the venturi to work, the car needs a flat bottom, (gearbox and and axle cooling problems) this flat bottom needs to be gradually raked up towrds the rear, an inch over 4 foot say, and then behind the axle line, this should open out into a more steeply raked and increasinly wider box. the further out the box extends beyond the bodywork the better. Exhausts in this box will kill it, and render it useless, allow a central exhaust shouded in the venturi to make 2 venturi tunnels can work. Air, its wonderfull stuff, shame we cant live with it or without it so... theres no point cleaning up the air behind the rear axle other than to reduce drag... but, its a good idea to use a spoiler... thing is i dont want a touring car spoiler blairing out of the boot like a sore thumb, the thing i was thinking was (to produce, an extension on top of the spoiler, which gives it a bit more of a lip,) like on an older top gear, reviewing a newish jaguar, with the legislation of the third brake light having to be a certain position on the boot, to make it "look" right the rear radius of the boot was lifted slightly. it created downforce, enough to be noticeable on the front of the car and make it feel light and floaty. so... fibreglass spoiler, standard mk3 one, with extended lip on the back, same kind of thing on many production cars out now...
oldskoolfred Posted July 22, 2009 Report Posted July 22, 2009 na its all got to go as one mate be handy to have a spare anyway !?!? its biger than that standerd one !
Retromotorsport Posted July 22, 2009 Report Posted July 22, 2009 a venturi will add downforce as your changing the air pressure underneath it , i did one on Dave Whites Gp2 Zakspeed, and he felt the difference ... but like i said, stick an exhaust in there and you'll ruin the effect, as its all about speeding the airflow up and making it fill a larger area .
vibrating_Cake Posted July 22, 2009 Author Report Posted July 22, 2009 a venturi will add downforce as your changing the air pressure underneath it , i did one on Dave Whites Gp2 Zakspeed, and he felt the difference ... but like i said, stick an exhaust in there and you'll ruin the effect, as its all about speeding the airflow up and making it fill a larger area . what you think about the spoiler mod ^ ^ ^ a venturi would.... but if you can imagine the capri is still on leaf springs... and the bodywork sits up at the back (well the overhang) the thing is, in this space theres a huuuge gap until the boot floor, and a nicely shaped fuel tank which is the same shape as a diffuser, comes up at a rake... but between the fuel tank and the bodywork theres about a 6inch gap going upto the boot floor a foot or so, then a flat piece of metal (the rear valance) which will act like a parachute (ish) would plating off these areas so its "flat" all behind the diff make a difference to high speed lift? obviousley atm i cant move the exhaust, so a "diffuser"/venturi could be made inbetween the leaf springs, making this flat with a few fins to "direct" the air outwards to as far as i could apart from the leafsprings, to open it out a bit. and the 3rd option, if the 2 above wont work particulary well... plating off in front of the diff under the diff so its flat, then up under the fuel tank to the rear bumper level (maybe sticking out) JUST between the leafs so the exhaust doesnt impede flow at all... would that work to make downforce, or just 90% reduce drag and maybe a little reduction in lift? like this... without the exhaust in the middle, and a little less over the top vvvvvvv
Retromotorsport Posted July 22, 2009 Report Posted July 22, 2009 Young Will's escort in the pics above would work... sealing of your parachute would help.. but its a case of a little for a little, theres no easy way of getting free downforce. rear spoiler, best and easiest option, but it will add drag
vibrating_Cake Posted July 22, 2009 Author Report Posted July 22, 2009 Young Will's escort in the pics above would work... sealing of your parachute would help.. but its a case of a little for a little, theres no easy way of getting free downforce. rear spoiler, best and easiest option, but it will add drag i dont mind drag, to an extent, the amount of drag i have reduced from the undertray and panelling off the parachute for a "reasonable" wing would probably end up resulting in standard drag..... without the lift, main thing is, its not a "top speed car" i'd be happy limiting the gearbox to 140mph at 7krpm and get to that 140mph faster.... so.... the car above, this works, but..... would it work if basically i halved the fin size because i think that is a little over the top, but still kept the rake and length protruding from the car, or would you think that would just be a bit of a waste of time? cause it looks to sit nicely between the leafs so my exhaust wont be a problem to the flow (cause it wont be in it!) i do want a spoiler, but i dont want to ruin the lines of the car.... function over form eh! we'll see Get a ducktail spoiler on it dont know much about ducktails but it seems to be a high drag low downforce solution to the problem, rather reminds me of an airbrake =)
RETRO_AL Posted July 23, 2009 Report Posted July 23, 2009 There is another spolier for he capri,pig has put one on his mk2 escort cant remember what they are called
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