Can you suggest a way to reverse the rotation of the final drive in a FWD transmission's differencial? I want to build a 3-wheel car that has a FWD engine/trans set-up spun around to make a rear-engine RWD set-up. If I don't reverse the final drive rotation it will have 3 speeds in reverse & only one speed going forward. I'm not expecting a simple 'bolt-on' solution. I was looking at a '96-2000 Civic Auto trans but will change plans if there's a better doner transmission. I'm not looking to simply move the FWD set-up to a RWD mid-engine location. Much Thanks !!

 

how do you have a 3 speed tranny?

 

sounds like you have yourself a custom chassis in which you are fabricating the engine mounts, so why not just turn the engine the other way around.

and using the automatic would save you some trouble from having to fabricate shift linkage.

you got pics or are you still planning at this point?

 

OK, 4 speeds in reverse direction & only 1 speed in forward. I'm looking into which transmission will convert over for my project. I'd prefer a Honda Civic's motor-trans set.
The question is still how can I reverse the rotation of the final drive when the engine is turned around backwards.

 

Why do you need to have the engine turned 180° (turned around backwards)? If you mount it in the same orientation as it sits in the car chassis there would be no need of a custom transmission.

 

Well into the planning stages... The overall project will is designed as a narrow vehicle (except rear wheels) seats 2, will have power windows, power rear window (inside 'roll bar' section), single opening door, fold-forward windshield, removable roof panel. Because it has 3 wheels it is registered as a motorcycle...thus the freedom of wide open ride without worrying about seatbelt tickets, catalitic converters & elaborate requirments for yearly inspection stickers. A lot less weight to haul, great performance & better gas milage. Yet unlike a regular 'motorcycle' if the weather acts-up raise up the windshield & windows put on the roof pannel & turn on the A/C (or heat). Crank-up the music & cruise in comfort. That's basicly what I'm fabricating.
My design 'works' best with the engine/trans behind the rear wheels. Not just for the additional space it allows the interior but also the ease of adapting so many OEM mounts & brackets. If it was an old "front engine/rear wheel drive set-up", flipping over the ring gear to the other side of the pinion gear would do it... but FWD's gears run parallel to each other. Any suggestions?

 

That's true but not in with what I'm planning. I've explained in another post in this thread.

 

Now that you mention that you require the engine to be behind the rear wheels. I see what your talking about. Going to require a wee bit of ballast in the front I would think. Unfortunately I am not aware of any such transmission. Most transverse mounted engines that I have seen are in front of the drive axles. Maybe someone else will be able to help.

Good luck

 

if you mate an older civic engine (D-series) which spins CCW with a later model transmission like an R-series or K-series which spins CW. you should end up with a reverse-mount (180 degrees) drive train that will spin the wheels the correct direction.

you'll need to build some sort of adapter plate and so on... but i get the idea this is a pretty involved custom project anyway.

additionally, since the R-series and K-series transmissions may be hard to find and expensive, adapting the engine to a FWD trans from a toyota, or nissan or any CW transverse arrangement may suit your needs.

 

A lot of people who do custom (mid-engine) cars use the Porsche G50 Transaxle. With this you can mount the engine longitudinally.

I really don't know if this helps at all, just throwing out ideas.

 

Wow...Thanks. This sounds like a direction I can look into. What years were these "D-series" Civic motors produced? Seeing I'd have to make an adaptor plate anyway, your right, I could select a FWD trans from a couple of doners.

 

D15s and D16s were available in many similar variations in civics from 1988-2004 or 2005. i would shoot for something between '92 and '00. the 99-00 Si civic came with a B-series, which is more powerful but more expensive and may not suit your plans.

 

remember input shaft size, clutch size flywheel size and lining up of the starter with the flywheel.

I guess i am sitll confused as to why the motor has to be turned 180 degrees in stead of just being moved straight to the rear? i know you said it wasn't in your plans but what in your plans makes this impossible? cause it would be alot easier and safe you a lot of fabrication time and money.

 

Envision a drivers seat with a passenger seat behind it (with some leg room), then behind that is a 'pocket' in which a powered rear window slides down in to. That length of passenger compartment fits to where that rear window pocket is right above the rear axles plus that window pocket adds sound & heat insulation from the engine. Keeping the engine in a frontal location adds a lot of length and I still will run the radiator in the rear so with the air ducts & radiator there that 'behind the rear wheels' space wouldn't even be a good 'trunk'. The front area between the driver's foot area & the front wheel is the gas tank & trunk area where the windshield can be stored when not in use. The roof panel,when not used, will fit on a rack above the rear engine compartment. I hope this gives you a better idea of my overall plan & why it is best served by a 'rear engine' set-up.

 

i like the description of your plans and the direction this project is going. be sure to post some pictures of the build somewhere.

 

As soon as I'm sure of the solution to my engine/trans selection, I'll find a salvage vehicle that will have the most of my 'parts' list and get started with the "hands-on" work. Just like other projects..."Think twice, Cut Once" I don't want to waist time or money (not enough to spare). I'm kinda curious why Honda made engines that ran in opposite directions...what advantage could there have been. Oh well...

 

think mazda miata donor. Flip the ring keep this sleek project going. You could go shaft driven motorcycle motor but AC is out. Civic to chevy S10 4cyl trans via adapter plate then flip it. There are many ways to acheive what I think you want. What is the total desired rear axle width including wheels. Wheelbase? Sounds like fun to me.

 

Not to keep bugging you...But... whatever it is that causes the D-series engine to run CCW, could it be adapted to a CW engine to change it's rotation? If the rotation was determined by the distributer, cams or crank shaft...wouldn't it be easier to convert the engine's guts than it would be to make the parts needed to mate a whole different engine to the a trans? Just looking for all options so maybe one donor car could be made to supply both.
I seam to remember (back in the 'ol days) some marine racers would change the rotation of some old big blocks to adapt to certain boat drives (I might be remembering wrong). But still curious how Honda changed the rotations on their I-4 style motors.
Thanks

 

I'm not interested in the "inline" setup with the separate rear differential... so S10 or Miata is out. The rear wheelbase will be whatever the donor car's FWD set-up is. The choice of wheels & tires' width will come towards the finishing touches as the vehicle comes together...not super wide. I'm really focused on converting a FWD unit for this vehicle.

 

Oh...and as far as a motorcycle engine... Only a Honda Goldwing has reverse (or Harley with a $1,800 adapter) plus no 'power take-off' for A/C compressor... small capacity for charging the battery. Shaft or chain would still be a much longer set-up & would eat up the passenger compartment area. The FWD set-up is the only way for my plans.

 

it seems to be a simple task to spin the motor the other way, until you get into the details.. for example the wrist pins aren't centered in the piston, they're offset slightly. this is crucial to reducing wear on the bottom end. run in reverse, i would imagine would wear worse than no offset at all! you would also find that the oil pump would be pumping in the wrong direction, and the camshaft and ignition system would have to be re-engineered so valve and spark events are in order. you would also find a whole host of issues due to the asymetrical timing belt arrangement. all of the belt slack would be on the wrong side, and you could see things like premature waterpump failure, belt-to-cover contact, teeth skipping and throwing off the timing..

back to the motor spinning the way it did from the factory.. if you use an automatic transaxle, it should be very straightforward: a spacer/adapter for the flex plate and a 3/8" or 1/2" plate of steel with some holes cut and excess material removed. something any modest home machinist can handle.

 

Great... That makes perfect sense.
I do plan on an automatic so the adapter plate is the way to go. I'll check on a few of the up-coming "abandoned auto auctions" at the area 'Auto Tow Yards'. With my business in holiday rush it will be a while before I'll get enough 'hobby' time to start any fabricating but finding the donor parts is the first stage.
Thank you very much... this forum has been a great find and a lot of help.

 

one thing you should check on the transmission you find, some autos have a one way clutch on the first gear (i know civics do). try to avoid this or dissable it if you find you have one. theoretically it'll chew up the clutch pack for first gear if you run it backwards.

 

Good point to know... I was thinking it would be a good idea to see if the auto trans that comes on a 'B-series' engine would take the same torque converter as the CW motor's auto trans. That would imply that the shaft size would be the same & flywheel's bolt pattern matches. That way it would (basically) only need an adapter plate & swap out starters. (I would think)
I did a search to find the models that came with the 'B-series' motor... it mentioned ones for Asian market, others for Europe market but didn't see any for American market (except Del Sol). It might just be the site I found...I'll still search to find out out specifically what year/model I'll need to keep an eye open for.

 

B series engines in America:
90 - 01 Integra
99 - 00 Civic Si
Del Sol vtec (I forget what years)
CR-V (also forget what years)