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Imp Mechanical discussion thread


thminiman

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k, im starting to think about the imp project now. I sort of want/need to do a fait bit of research into the rear end, as thats where pretty much everything important will be. So, i'll start the research here as i know there are some pretty sharp people on here. help where you can and feel free to suggest new ideas. also, some of these questions may seem real easy to some people, but thinking about it too much has confused me too much. Chur.

My plan at the moment is basically spaceframe the rear end, but have the space frame un-boltable from the car. so when you unbolt the space frame, the engine, trans, diff and rear wheels, IRS/driveshafts come out as one big thing. any one dissagree with that idea?

because the Imp is rear engined, with the rear wheels quite close to the front of the engine bay, the engine will need to be turned 180 degrees compared to a front engine-RWD car. I cant see any problems with this... BUT,

therefore i would use an IRS diff, but would need to also turn that around 180 degrees. im lost as to which way that would make the car go as it fucks with my head to much. (ideas anyone)

But, because im using a motorbike enigine, it doesnt have reverse, Ive heard some people have used a special extra gearbox that effectively makes the drive go the other way at the push of a second gearstick. what other options do i have? ive heard of electrical reverse but dont understand it?

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not really when you consider the weight of the shit i'd be taking out... all the rear suspension/subframe = thick as fuck steel. would also allow for better rear brakes and suspension. would make a hell of an easier place to mount the diff. and engine. and as said. would make things a hell of a lot easier to work on.

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Yeah I agree. You are bassically rebuilding the whole of the rear of the car mecahnically speaking. New engine, box, mounting points, diff everything. For that amount of modification doing it on a seperate sub-frame would be the best option. Will be pricy, but I'm sure you're expecting that.

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pwnt, could prolly make one for that

yea avenger i wouldnt mind restoring it, but the fact is, its too fucked to go that way,

Interior = non existant.

engine = needs full rebuild and is standard 875cc that plus performance parts to make it half decent would cost just a little less than a second hand busa engine.

not only that but i do want it as a race car to teach me more driving skills and shit. I DO want it to be road legal, so it wont exactly mean another imp off the road.

I can see where your coming from bro, but for this imp it would take too much effort for less than satisfactory (to me) benifit.

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If you are going to back the whole rear end detachable, why would you use any thing from the original car except to take some body mouldings.

The concept is great but you might as well go the "whole hog", do a tube chassis based on a single seater style setup, with outriggers to support the body.

Reasoning.....

While the Imp body may look heavy, its contruction isnt really, but it does have multi layer steel where it needs strength. If you are going to remove most to the steel contruction for the rear end then you are going to have to create what is effective a tube half chassis for the rear to hold the car together. In my opinion one of the worst bits of a Imp is its front end design, so you would want look to fabricate a new front end assembly.

I'm guessing you can see where this is going....custom rear end cartridge assembly , custom front end assembly.....you end up with about 2 feet of the cars original structure holding it altogether......might as well just build the entire lot from scratch.

What this means is a bucket load of fabrication, which will equal $$$$$, and unless you have been doing a heap of engineering studies around strength and weight loadings of the design, it probably wont be an optimal design, and could end up worse than that.

If you were still keen on doing something with the Imp shell, why dont you see if you can locate the plans for a Maquire Imp, which is a proven lightweight chassis design, and build your bike engined special from that.

Alternatively as this is likely to be your first race car (I assume), why dont you take a slightly smaller bite, rebuild the engine, with something like a R20 cam, leaving it as a 875, polish and port the head, get some small Webers (although a good set of SUs will probably work). Get a set of Spax shocks for the car, strip the body right out, cage the car and go racing.

The R20 will give you a relatively good alround cam, it will work on gravel as well as seal, and you dont need extreme engine internals to run it.

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Hey mang, lil sis gave me the performance car 07 yearbook for xmas and its got a wee writeup on the hyabusa powered kp61 that did real well in the rally this year. Doesn't go into alot of detail but definately worth skimming over for someone in your shoes. ke20_lorola dude is correct, you can use some special reverse box that will give you 6 reverse gears :twisted:

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Electris starter for reverse.

I done a fair bit of home work for a GSX1100 powered alto I had a few years back. Plan was to solid mount the engine with a custom driveshaft that could extend (PTO) solid rear end and space frame the whole back end. Was quoted $4K for the space frame with suspension mounts, decided in the end it was to much to spend on a $100 car.

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if ya set on the busa powerplant then why not get a chassis builder to fab a complete spaceframe and just cut and shut the imp shell onto that just like most hot rods. then u can use proven race style front suspension and mount what eva ya like down the back. why not use a cough honda vtec motor and box set up in the back or mitsi mivec if your a hondah8r :lol:. if you could find a good engineer whose willing to do the job for a perky prolly wouldnt cost that much. if ya rebuilt it original stylz how long do you think it would take b4 u got sik of the gutless wunder that dont stop or handle without serious money chucked at it. it's worth a thought

dave

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Motorbike engine 12000rpm+, Who cares for reliabitlity in a toy like this?! Mah Honda, Mah. Main reason I was going for the 1100 over the 1300 Haya was price. Complete GSX1100 box injection blah blah $around 1000. Haya was at the very cheapest $3K+

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... if ya rebuilt it original stylz how long do you think it would take b4 u got sik of the gutless wunder that dont stop or handle without serious money chucked at it. it's worth a thought

thats exactly what im thinking bro. Full space frame is an idea as front setup is as already said = ultra shit

keep your thaughts and ideas coming guys

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  • 3 weeks later...
Guest aircooledimp

Hey mate why don't you air cool it like I'm doing with mine. VW motor and running gear, get new half shafts to mate with imp rears,(this keeps the wheel width the same at hte rear). VW 1600 twin port can give some seriuos HP, even more with a turbo!!

At least this way you can still get bits and mods for it. The dimensions and weights of engine and box for both cars are almost identical, and they spin the same way!!

The imp was described as the "poor mans porsche" :)

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