I'm posting this in the welding/fab section because there would be more fabrication and welding involved in this project then tuning, body work, wiring, etc.

I have always been a fan of mid engine vehicles ever since I was a teenager, and unless you want to buy a supercar there are no mid engine awd sports cars available. (at least not to north Americans)

My idea (even though i'm probably not the first to think of it) is;
To take the engine and trans-axle out of a prelude, and mount it longitudinally either behind the driver and passenger seat with a short driveshaft delivering power to the rear differential, and a long driveshaft powering the front driveshaft. Or mount the engine-transaxle ahead of the driver/passenger seat, with a short driveshaft deliveing power to the front differential, and a long driveshaft sending power to the rear. (position determined by weight balance characteristics, and ease of install.)

Having an LSD in the transaxle would ensure that power is being delivered to both the front and rear differentials who would each have their own LSD.

The front differential would have to be from a donor vehicle with IRS (flip it and install)

The rear end would either be the IRS transplanted from a s2000 such as with Weirtech's f20 crx build or a swingarm solid axle, or live axle setup (depending on ease of installation and ergonomics in respect to engine placement, before or aft the front seats.)



I would leave the coolant system the same as on the stock prelude.

Custom engine mounts would have to be incorporated into the car's chassis.

Custom driveshafts would obviously have to be made.

A turbocharger and proper tune would be incorporated as my HP goals are modest at 300(max)

I could use the factory wiring harness

Clutch, coolant, and shifter lines would have to be relocated

Driveshaft tunnels would have to be fabricated, along with an in-car hood.


What are the holes in my theory? This is just a concept in my head so far.
Please dont tell me to just go buy a subaru, or gt4, or awd wagon, or evo.
Im in the idea for innovation and experience.

Ultimately I would like to build one to be my daily driver, that looks clean and can perform in Canadian winters.

Thank you for reading this. It is my first thread.
All comments are welcome.

 

flipping the front diff would make the front run in reverse... and then the problem lies in finding diffs w/ 1:1 ratio's btw they dont exist... remember your transaxle has a final drive of around 4:1, then you reduce it w/ another 3.5:1 and you have a top speed of 40-50 mph on the rev limiter...

 

I wouldn't rule them out as not existing in some form but they would be very difficult to find for sure. Lol but I knew there would be a problem with flipping a diff, i just couldn't put my finger on it. Oh well, not all diffs are designed to be spun by the input in the same direction, just like not all engines spin in the same direction. If I was determined enough I would have one built.

I'm really tired of seeing the same old vehicles over and over again. Thank you very much for pointing those problems out.

 

i assure you a 1:1 diff doesnt exist in an automotive application... the pinion gear would be the same size as the ring gear... another issue w/ flipping the diff would be oiling the pinion bearings, there are "cavities" that get filled w/ oil so that they are constantly bathed in oil and drain back very slowly, when upside down, these would not work properly...

 

I was afraid there would be oiling problems with a flipped diff. I guess custom designed and built would be the only way.

 

front diff out of a truck? like an independent front toyota.

 

that would be a good idea if I could remove the final drive from the transaxle so that the driveshafts were turning fast enough to power regular diffs. But I'm not ready to dive into modifying the factory gears,unless someone knows how to lower the gearing from the final drive ratio 4.266 to 1 lol. And no, I am not willing to run 4 times the size of tires lol

 

Have you thought about a chain drive? It would be a ton of work and money but it might be a better place to start.

 

that idea has popped into my head but only for a few seconds as that seems like too much hp/torque lost in the power transfer. Im aiming for maximum efficiency even though the diffs would steal a bit of power loss in the transfer. Im fairly certain I need 1:1 differentials both for the front and rear. It can be solid axle in the back(90 degree 3 point gearbox posi trac) but for the front its gotta be an open diff somehow.

 

So after consulting with gearbox manufacturers I have found an industrial strength gearbox that will hold up to the power that would be put through it to the wheels. It is 1:1 gearing, and it is a solid shaft, so it would be the same as having posi-trac for the rear wheels. The problem is that it will cost more then 2000 dollars, and to extend the life of the gearbox/differential I will have to tap into the box and run external oil lines for added filtration, and cooling of the oil and components.

As for the front differential I have made the decision to use two right angle gearboxes.(one input shaft, and one output shaft at a 90 degree angle)
Proper rotation at the output shafts is determined by having opposite rotation at the input shafts.

The biggest problem as of right now is coming up with a system which enables each right angle gearbox to rotate independently of the other when there is a difference in rotational speed at the wheels (cornering or limited traction)
I believe the best solution for this limited slip would be enabled by having the same gearing technology on the input shafts as is utilized on the rear sprocket of most pedal bikes(free wheel).
Admittedly this would only allow engine braking to be applied to the rears, and reverse would only apply to the rear wheels but if I could find a sturdier component then bicycle sprockets the system should do the trick.

Any thoughts?

 

this might give you some ideas

http://www.pirate4x4.com/forum/showthread.php?t=633445

 

I just skimmed over the rock crawler build, and actually it gave me no ideas what so ever. I am not building a tube chassis rock crawler. The problems I am facing are the differentials to be utilized in an independent front and rear suspension. That buggy used stock suzuki samurai differentials that come attached to solid axles. I would be using a rear end that powers both rear wheels through a solid shaft (posi-trac) with independent rear suspension and a front end that is limited slip with independent suspension.

It said so in the build thread that it could only go 45 mph in maximum overdrive.(this is due to having differentials that are reduced much more then 1:1.) My goals are to have the car cruise at 120 kmh and have a top speed of around 190. (speeds a stock prelude has no problem overcoming.)

I cant think of one problem the builder of that buggy encountered that I too will face aside from the major fabrication that took place.

 

I'm sorry you feel that way.

 

dude you sound like such a rich little *****. haha. seriously???

ur complaining about the fact someone tried to help you and give you ideas, but u werent able to get any? hahaha

what do you want? someone to build your car for you? hahaha

ridiculous...



further more you sound like an engineer whos read a lot of books but has nice clean little girl hands that cant even crack a seized up 14mm bolt.

 

My apologies for the post in reply to the link. I should have worded it better. Its an impressive build but I didn't see the relativity

 

nicely done. this is how to handle a troll. you win good sir.

 

So... has anyone thought of any components (other then bicycle sprockets) that employ free wheel in one rotational direction but solid drive in the other?

 

i built this... this is why i tried to offer some insight, but i guess the op is going to get some one off diffs made in 1:1... lol... personally if i was going to spend big bucks i would research getting a gear set made for the transaxle, still cant be 1:1, but using a set of ford 9" diffs that have an available 2.43:1 ratio and the rest could possibly be made up in a custom differiential in the transaxle...

 

ha, I didn't recognize the screen-name. What's up jim.

 

Good point on modifying the transaxle to a higher speed. I had just thought it would be easier to leave that aspect of the build stock with the highest chance of it staying reliable.
The rear gearbox to match the specs is a little over 2 grand brand new, and it matches dimensions that should work. The freewheeling lockers for the front are whats making me lose sleep now lol

 

op,

Contact a few of the below companies to solve your powertrain configuration needs

Xtrac
Selholm
Hewland
Quaife
Ricardo.
Sadev

Sell a kidney b4 you call.

 

so you are saying you can buy a fully custom scratch built differential for 2k thats 1:1??? i call bullshit... not being a smartass, but i would love to see what it is that you are buying, and why not buy one for the front too????

 

why not adapt a transmission with transfer case already setup for awd to the h series, and do it that way. forget custom front diffs, 1:1 ratios and the hard way of making an awd prelude. Longitudally mounted h is gonna spin wrong way anyways. let alone the miles of awkwardness you're gonna face attempting it that way. trans adapter, and be on the reasonable, realistic path.

 

Its not a scratch built fully custom diff. Its part of an industrial gearbox line up by Diequa. I contacted a consultant, and he lined me up with a model that matched the application.He said just over $2grand.
In my opinion its more simple then a differential. It has one input turning a solid shaft via bevel gears(1:1) that extend out the sides of the box allowing for two output shafts to couple the rear axles. The solid shaft provides for posi-trac which is fine for the rear wheels but the wheels at the front need to rotate independent of the other when it comes to cornering. Hence, I need ideas for components up front that can free-wheel one direction for each wheel.

 

Great idea. The original reasoning for the mid engine awd conversion was to have something novel and different. Granted there will be immense amounts of fabrication and frankensteining to go either route; im partial to the mid engine longitudinal mounting because of the shake-up it would give to the vehicles handling.
I seem to remember seeing a honda civic in a recent issue of honda tuning that was converted to rwd via s2000 drivetrain and rear end, and a civic that was converted to awd using the method you described.(or close to it)
Both of those are bad-*** builds. I dont want to copy them.

If the h spins the wrong way i can either order a different sub-model of the gearbox(s) to change from clockwise to counter-clockwise, or I could flip the gearbox, (assuming it doesnt interfere with lubrication) Or I could spin the engine 180 to reverse the rotation.

Great responses. Thank you everyone.