First off. People if you have nothing positive to contribute do not post. This is a serious question that deserves serious and mature discussion. No BS in here.



OK this is goes out for all the old school poineers. Need your thoughts on getting an auto tranny to turn the axles the opposite direction. I know the Porsche trans axles can use worm gears to change their rotation direction. Didn't know how this may play out in our trannies.


So, any suggestions?

 

Your best bet is the All Motor forum.

 

You can't do this because since we are FWD, the axle lengths are different.

 

Care to share how the axle lengths have anything to do with getting the rotation to go the other way?

 

What exactly are you trying to accomplish here? That's my only question.

 

Put it in reverse.

 

You have to give more info about what it is you're trying to do so people can take this question seriously.

 

Are you thinking about a swap into a rear-engine chassis?

 

He said that he wanted to swap sides so they face the opposite way.

I could see this for a Porsche that probably has an exorbitant cost for replacement parts, but not for our nissan.

 

read who posted what again and rethink your comment.

 

Ah, once again the wonderful internet forums come through, and disappoint without fail. With stupid and immature kids voicing their unwanted opinions. It makes no difference what it will be used for. Hell, i may just want to say it was done then drop it out of a plane. You guys are focusing on the wrong things. All i'm asking is for some engineering minded people to checkin with thoughts on how to get our automatic trannies to opporate in the opposite fashion as they currently do. i.e. Instead of the passenger axle rotating clockwise for forward gears and the driver side rotating counter clockwaise for foward gears: I want to have the passengers side rotate counterclockwise and the driver side rotate clockwise for forward gears.

For the Porsche transaxles people use a worm gear to change the direction on its rotation. Its not expensive and not hard to do. However, i know very little about the transaxle set up and don't know how their setup would work for the application i'm asking about.

 

Just what is that supposed to mean.

 

It was aimed at me.

As for transaxle adjustment, I would say that there may only be a handful of people that have had a tranny apart, let alone an auto. More of the people that are engineering oriented have 5 speeds.

 

whether auto or manual doesn't matter. the output section of these transmissions is the same.

I honestly don't see a way to do it internal to the transmission unless you want to completely replace the differential. that's going to be neither cheap nor easy.

only other way is to spin the transmission backwards, but that will cause all kinds of other unforseen problems- like fluid climbing on the gears backwards, shift forks in the wrong orientation to properly move the gears, etc.

 

The Porsche guys can get away with it because their engines are mounted longitudinally. All they have to do is get a worm gear with reverse threading. For a front-engine RWD car, it's also simple; all you would have to do is flip the rear differential upside-down so that the right axle is on the left side and vice versa. Seriously! You can do the same thing on a transaxle...IF the differential is a bevel gear. Unfortunately, ours are not. The only way to do what you want to do is to add a counter-gear somewhere between the input and output. Our transaxle housings are very tight, so there is really no room to move the gear train and add another shaft. (See a teardown here:
http://forums.maxima.org/showthread.php?t=338222) If you add the counter-gear after the differential, you would need two of them. All this would of course, require a lot of custom work.

Anyway, I would almost say it's easier (and I'm being totally serious here) to get your engine to crank backwards. Reverse the rotation of your starter motor, swap your firing order, adjust your timing, etc. I know it's done on small engines, but those are very simple compared to our engines. I don't know how the electronics/sensors will react.

 

Thanks for the post. I thought about reversing the engine rotation, but that would still cause problems with the TC, no? I believe the converter moves fuild based on the orginal rotation of the engine. Not only that but all the hydro dynamics of an automatic will be set up the wrong way should the engine spin the other way. I could be wrong because i'm not a tranny guru, but i was under the impression that would be the case.
I also thought about flipping the tranny and useing an adapter plate, but then again one has to consider the fact that the tranny is set up to carry fluid in the bottom of the case and not the top.
All i can think of is trying to figure out if there is some way to fit the gears into the caseing. Even if it means i have to modify the casing a little. Being that i don't know the specifics of how the porsche guys do it, nor do i know what the insides of our trannies look like....i'm just stumbling around in the dark. I kind of view this as a fishing expedition to see it someone with a bit more knowledge could brain storm a solution.
My last consideration would be to try and figure out a way to reverse the rotation of th axles from outside the caseing, but i don't want to get into adding a lot of weight or bulky items.

 

Either post an answer or don't post.

 

I dont see how turning the tranny upside down is going to change which way the axles spin.


I also don't understand any reason why you would want to have one wheel spin clockwise and the other counter clockwise?


I can think of a way with a normal diff, but not sure if you could do it in a transaxle.


Also before you come in and call our members and mods stupid immature kids (which is funny seeing as a good portion of the guys posting are in their mid 30's or 40's), realize that you weren't very descriptive in your first post. I thought you wanted to do what Tom was saying and have 5 reverse gears and 1 forward gear. You really didn't give people much to work with. If you are going to be negative just don't bother posting and log out.

 

Don't think he meant that but yeah,


He wants both to spin on the opposite direction

Well short of giving away the "secret" he's not going to reveal it.

 

Assuming what I quoted above is what he infact wants to do, and he does it on a maxima with a factory engine/transmission location he's just going to break the transmission or part of the drive line because one tire will be going against the direction of the other 3.


If he really just wants to do the 5 reverse gears and 1 forward then I would just say try spinning the whole engine/tranny 180* lol. Again this makes zero sense in a maxima.

 

Think about it. Looking at each side, the rotation would be counter clock and clock wise. Since you are facing that side of the car.


There's no real indication that he wants to do it in a maxima.

 

Take a break cowboy and come back in a bit. Currently, our fwd trannies will have the passenger side axle rotating in a clockwise fashion if you were looking at it form a 90 degree angle(dead on). The same thing for the other side except vise versa. If you look at the driver wheel dead on it will spin counter clockwise when the car is moving forward.

However, seeing how i am going to be putting this in a different configuration/set-up i need to have the wheels spin the opposite way they currently do now. Why, you ask. The simple answer is because the transmission and engine combo will be sitting in such a way that that would be the only way to get the car to go forward instead of driving in reverse.

 

can someone say motor swap??

 

Best bet is to use the RWD VQ tranny's(01+ Pathy, 350z/G35)

 

Oops, I forgot you were asking about an auto tranny. I linked to a manual one. But since you mentioned the TQ, that gave me an idea. Theoretically, I guess you could reverse the vanes to drive the output opposite the direction of the input.

 

ahh wasn't thinking like that

well it would be helpful to know the engine position and ammount of room lol. If say it's going into a rear engine, RWD platform with plenty of room to work with, then you could just rotate the engine 180*. Only downside to that is the engine will be farther behind the wheel centerline where as if you keep the engine in the same orientation as stock but just rear engine, most of the engines weight will be just infront of the rear wheel centerline.

 

Wont work in this case. It would also take up to much room.

 

I was thinking that myself, but i don't think it would be that easy. From my understanding the hydrolics and valve bodies in the auto are set up for one way. Meaning pressure will build up in one part of the pan making vavle body #1 hit, thus sending it into second gear. This goes on through the third gear before the OD is electronically engaged. By reversing the veins wouldn't the fluid flow backwards? Also, how does the whole reversing the TC viens play out if the flywheel still rotates the same direction?

 

I haven't torn apart a maxima auto tranny yet, but I assume they still have a ring and pinion, should be fairly easy solution there

 

Think of the TC as two fans--one driving the other. The first fan (the engine) blows on the second fan (output shaft to tranny), turning the blades on that fan in one direction. If you turn the blades around on the second fan, the shaft will now be driven in the opposite direction.

As for the valve body, the hydraulic pressure used to drive it comes from a separate pump, not from the TC vanes itself. As long as the pump continues to generate pressure, the valve body will shift as usual.

BTW, I know where this is going:
http://www.gti18t.com/files/turbo_tw...ne_tiburon.wmv

I believe they used two stock auto trannies back-to-back. You might want to ask them how they did it.

 

Interesting clip, but not quite.


So what i gather is that for all intents and purposes the TC could jump up and down and it really wouldn't make a difference? As long as it is pumping the needed hydrolic pressure to shift gears it should operate as it was intended??? Have i correctly understood what you are saying.
You mention the hydrolic pressure in the tranny is provided by a seperate pump. Is that pump going to operate in the same fashion if the TC is modded?
Something is going to have to run backwards to get the direction of the wheels to change. If the TC's veins are reversed does it really make any difference? Its still useing cyntrifical(sp?) force to provide pressure to lock up the clutches for motion.
If i understand correctly the TC spins so the fluid builds pressure in the tranny. Enough pressure will lock up the clutches to provide motion. In the pan the vanes for the 1st VB are building due to the car moving. When enough pressure has built up in that vein the VB kicks open, or shut, to allow the second gear to take over. The computer will control when the VB opens depending on various imputs and preporgramed maps/equations in its TCM.
If this is true, then i'm having trouble understanding how the veins of a TC will make any difference.
Please break it down for the idiot here.

 

In that analogy, you are only considering the axial velocity component of the air flow.
Now take the same two fans. Place them really close to one another in an enclosed space and fill it with liquid. You will find that the second fan will spin in the same direction no matter which way the vanes are oriented. Of course, the fan will spin faster if the vanes are oriented favorably as less rotationial energy is "lost" through turbulence in the fluid.

In fluid couplings, such as torque converters, the rotational energy is transferred by tangential and radial fluid motion.

 

Um Did you just say what i think you said? Except my description was in idiot talk. I'm not sure how to tie in all the cool and nondescript words you just used, but i would love for you to take the time to break it down for little ol me. Thanks for the input, thus far everyone.

 

sounds like you want to move the powerplant to a mid engine set up.. or something of that sort.. or maybe a dual motor set up.. either way.. i think a possible way is to fabricate something with an input shaft that goes into the tranny where the axels went, and another mini differential or something of that sort.. it's hard to put it in words but it doesn't seem like it's impossible.. or at least the way i'm trying to imagine it..

 

instead of having the drive gear drive the diff can't you build a transfer case (similar to 4wd vehicles) to have the output spin the other direction?

you need to give us something to work with because we don't know the space limitations/purpose for this.