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raydog
raydog None
8/4/10 3:09 p.m.

I keep reading about people making "track and street" vehicles like the Atom in a mid-engine configuration, with either car or motorcycle engines and related transaxles (like from a previous front wheel drive car in the "normal" configuration), but nobody explains how they get the shifter up to driver. Wouldn't the shifter, if in normal configuration, be facing backwards? In a front wheel drive car, the normal configuration from the front to the back, would be- radiator, engine, transaxle, shifter, etc. Are these manufacturers turning around the whole drivetrain around to get the shifter up to the driver? Which would make the fastest reverse drive car on earth. Or are they fabricating an entirely new shifting device to get "back" to the transaxle? Also, how are they doing the same thing with the motorcycle engined/transmission combo's? Not to mention, reversing the vehicle with no reverse gear in the transmission. I keep wanting to purchase an MR2 or a Fiero to see how the factories did this. Any education on this matter would solve a great puzzle for me as I hope to build my own mid-engine vehicle of my design. Thank you in advance for any help.

Type Q
Type Q HalfDork
8/4/10 3:35 p.m.

A lot of cars these days, particulary those with transaxles, have shifters that work by tranfering the motion through two push-pull cables. One transfers forward back movement the other transfers right to left movment. When you move the engine and trans combo to the center of the car, have to either modify what you have or find the right combination of cables and shifter so that motions are transfered correctly. (i.e. forward to the right engages first gear). Does anyone have video/pictures of the shifter on an MR2 or something similar? It's easier to show in pictures that to describe in words.

Powar
Powar Dork
8/4/10 3:42 p.m.

Here's a shot of the cable config from an SW20/21 MR2.

mad_machine
mad_machine SuperDork
8/4/10 4:03 p.m.

cables do make it SO much easier..

raydog
raydog New Reader
8/4/10 5:26 p.m.

WOW! Today was the first time I registered for the Forum even though I have been a subscriber to the mag for over 10 years. I have heard about these chat sites and that you can get some good help, but crap!! you guys really are fast with your responses! I was going to check out my post next week and hope even one person would respond. Makes me wonder what I have been missing all these years. Thank you very much for your reply's!

Now back to the subject. So basically, all I need to do for the cable based shifter units is to lengthen them around to the new "front" of the vehicle? Is this correct?

raydog
raydog New Reader
8/4/10 5:29 p.m.

I was thinking that a "bent bar" with brackets and braces would work for the "fixed to the housing" units. Would you agree?

Hal
Hal Dork
8/4/10 7:37 p.m.
raydog wrote: Now back to the subject. So basically, all I need to do for the cable based shifter units is to lengthen them around to the new "front" of the vehicle? Is this correct?

You,ve got the idea but you may have some problems with making two bends in the cable (one from the front of the shifter to get to the back of the car and the second to get turned back around to hook to the transmission.

Many of these thype of setups use bellcranks to take care of the direction reversals.

raydog
raydog New Reader
8/4/10 7:51 p.m.

What if I had piece of round bar stock and had it bent so that it went around the side of the engine to the transaxle shift mechanism? Like one long bent pole. That way the direction of the original shifter from behind me would work as it did before. Does that make sense? Like a big letter "C" but with straight angles. I would be at the top of the C shifting, and the original shifter would be at the bottom of the C, with the engine in the middle. Got it?

Jensenman
Jensenman SuperDork
8/4/10 8:07 p.m.

I've thought about the 'big C' version you mention for converting a FWD tranny to mid engine. It will work, you just have to support the front of the 'C'. That will mean making a bracket etc to mount on the side of the engine closest to the shifter. That bracket will need to allow for the fore and aft movement of the shift rod and also the twist motion. There will need to be a shifter U joint very close to this bracket I'm speaking of. Damn, I wish I could do a CAD drawing!!!

I wouldn't use bar stock, it's so heavy that its inertia would add to the difficulty of moving the shifter side to side. I'd use large diameter thinwall tubing instead, maybe 1.250 OD x .065 wall. Light and stiff.

Dr. Hess
Dr. Hess SuperDork
8/4/10 8:22 p.m.

You're going to have to get new cables anyway. Why not just get them long enough to go all the way 'round back to where the shifter meets up on the trans? That's what I'm thinking on Dr.Linda's Europa project.

And, BTW, "they say" that you go down to a boat supply shop and get your new cables made there, because the speed boat people use that same cable arrangement for steering the outboards.

Wayslow
Wayslow Reader
8/4/10 8:29 p.m.
Dr. Hess wrote: You're going to have to get new cables anyway. Why not just get them long enough to go all the way 'round back to where the shifter meets up on the trans? That's what I'm thinking on Dr.Linda's Europa project. And, BTW, "they say" that you go down to a boat supply shop and get your new cables made there, because the speed boat people use that same cable arrangement for steering the outboards.

Marine supply= Expensive

I built a cable shift set up for my Europa with cables from a hydraulic supply company. They use the same push pull control cables as boats but they charge a 5th the price. The cables come preassembled in lengths from 1' to 30'.

Jensenman
Jensenman SuperDork
8/4/10 8:33 p.m.

Some gearboxes (Fiat, Honda for instance) have only one shift rod sticking out. Those are called selector shaft transmissions. Then there are the two cable types (Toyota and FWD Mopar etc). Then there's the bastard hybrid versions like VW's Rabbit setup.

I suppose it would be possible to build a two cable setup to run a selector rod box but man that would be a PITA. The 'C' would be a lot simpler.

Boat steering cables are very similar to shifter cables, as are what's called 'Morse' cables.

Dr. Hess
Dr. Hess SuperDork
8/4/10 8:38 p.m.

Humm, Wayslow. What do the hydraulic supply places call them?

JM, the Esprit has a cable shifter on a single shaft selector. There's a translator mechanism on it. It really isn't that complicated at all, in typical Lotus fashion. I could find a drawing of it or take a pic, I suppose.

Wayslow
Wayslow Reader
8/4/10 8:45 p.m.
Dr. Hess wrote: Humm, Wayslow. What do the hydraulic supply places call them? JM, the Esprit has a cable shifter on a single shaft selector. There's a translator mechanism on it. It really isn't that complicated at all, in typical Lotus fashion. I could find a drawing of it or take a pic, I suppose.

Bulk head control cable. If I recall they have a 5/8" mounting thread and a 1/4-28 control end. They supply the 1/4-28 ball joint ends for a couple of bucks each too.

Dr. Hess
Dr. Hess SuperDork
8/4/10 8:56 p.m.

Thanks. I'll keep that in mind. This S2 is getting a 1nzfe and the 5 speed, transverse mounted. I'm down to the frame right now. I have the shifter mechanism from the xA too, so I think I'll use that. I have the shifter mechanism from my MR2 (RIP), but I think I'll save that one for the TCS on the other side of my garage.

raydog
raydog New Reader
8/5/10 12:34 a.m.

I wish I could get a clear picture of a Lotus Exige/Toyota set-up. That would be the "perfect" ideal unit I probably should copy. It seams to work great for them. And I was thinking of a Toyota engine/transaxle combo anyway. I still wish I understood the motorcycle/chain sprocket set-up. Where is the Reverse? If you had that set-up, you might be able to "extend" a welded rod straight to the shifter "pedal" with a few bends. Any thoughts on that set-up other than no "easy" Reverse gear and no torque?

mad_machine
mad_machine SuperDork
8/5/10 4:27 a.m.

the only reason I would think the marine stuff would be better... it would be sealed and lubricated against corrosion. Could be a biggie depending on where you live.

ansonivan
ansonivan HalfDork
8/5/10 11:05 a.m.

I'm running an 02A cable shifted transaxle in the rear of my scirocco, coming from a linkage shifted 020 this is a huge improvement in simplicity and reliability.

The 02A uses a pair of cables to affect select and engage motions via a shift tower protruding from the top of the transmission. I added a large bellcrank to the top of the tower and a tab to the engage lever, the shift cables now approach the tower from the front instead of the rear. I chose not to use longer cables because they wouldn't fit in the challenge budget and because I did not want the added resistance of looping them around to the rear of the transmission. I'm using stock VW cables.

My shift tower addition is in the beta testing stage (read unpainted) and I got caught in the rain so it's now rusty, I'll try to get a picture up at lunch time.

Stock 02a tower and cable configuration

My setup, horrible picture.

raydog
raydog New Reader
8/5/10 11:49 a.m.

How about this stupid thought. Has anyone ever thought of taking a Mustang engine/transmission combo and moving it to a mid-engine position, but make like a 1 foot long drive shaft to a Thunderbird Turbo Diff for independent rear suspension unit? Its like a poor man's transaxle set-up. Or, can you just "firm" mount the diff in a sub-frame that also surrounds the trans and attach the trans directly to the diff with one u-joint, ie, no driveshaft. I know that the whole "unit" would be quite long, but its home built vehicle, ugliness is expected! I can shorten-up the total length by putting the steering rack/front suspension components practically at the end of the pedal assembly, like a dune buggy. Well, what do you "pro's" think about this idea?

raydog
raydog New Reader
8/5/10 7:06 p.m.

come on guys, no takers on my last idea?

EvanB
EvanB Dork
8/5/10 7:11 p.m.

I would think that unless you mount the trans directly to the diff with a u-joint it would be very long, It could work though.

Dr. Hess
Dr. Hess SuperDork
8/5/10 7:17 p.m.

Use a CV joint or two U joints. A single U joint has "issues." There are cars like that out there already. This is not a new idea.

kb58
kb58 Reader
8/6/10 6:45 p.m.
raydog wrote: How about this stupid thought. Has anyone ever thought of taking a Mustang engine/transmission combo and moving it to a mid-engine position, but make like a 1 foot long drive shaft to a Thunderbird Turbo Diff for independent rear suspension unit? Its like a poor man's transaxle set-up. Or, can you just "firm" mount the diff in a sub-frame that also surrounds the trans and attach the trans directly to the diff with one u-joint, ie, no driveshaft. I know that the whole "unit" would be quite long, but its home built vehicle, ugliness is expected! I can shorten-up the total length by putting the steering rack/front suspension components practically at the end of the pedal assembly, like a dune buggy. Well, what do you "pro's" think about this idea?

Afraid this has been thought of many times. As was noted, the overall assembly means the rear wheels end up WAY behind you. And car based on this will be very long. Draw it up in the free Google Sketchup and see.

Jensenman
Jensenman SuperDork
8/6/10 7:49 p.m.
Dr. Hess wrote: Humm, Wayslow. What do the hydraulic supply places call them? JM, the Esprit has a cable shifter on a single shaft selector. There's a translator mechanism on it. It really isn't that complicated at all, in typical Lotus fashion. I could find a drawing of it or take a pic, I suppose.

I'm thinking about doing exactly that on a project I'm working on. But it will be 'flipped'; the cables will come forward from the transmission, mounted to the underside of the car, then rods forward from there to the shifter which would have the 'translator' mechanism. Still in the 'thinking' stage.

raydog, the Cheetah (Chevy's answer to the Cobra) had an independent diff mounted directly to the back of a Muncie 4 speed. The car wound up being front engine because it was pretty long. The driver basically sat on top of the rear axle.

To keep the car reasonably short, the engine needs to go transverse or if longitudinal, the differential needs to be at the clutch end of the tranny. The Porsche 915 box is the weapon of choice for doing that.

raydog
raydog New Reader
8/6/10 9:13 p.m.

Thank you for your input Mr. Jensenman. If in the Cheetah they did what you say, did the lack of a driveshaft cause any issues? Your recommendation of the Porsche 915 box gets back to my original question at the top of this post. I guess its cheaper/faster to just get a front wheel drive engine/transaxle combo and mount it mid-engine style to keep the length correct. Even with the different length axles with potentially poor torque equalization issues, it must work OK seeing that MR2's and Lotus's use this system. Would you agree? Please let me know how your project design goes! I might try to incorporate your ideas into my own. Thank you for the reply.

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