# using an auto transmission - general



## jackbauer (Jan 12, 2008)

I'm working on an arduino controller project for ZF automatics might be of some interest :


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## dougingraham (Jul 26, 2011)

You might also simply see if you can use an AC motor and go without a transmission.

For example my car could go without a transmission if I had an AC motor that could be reversed and an appropriate final drive ratio. With my 3.9 final drive and directly driving the driveshaft (or propshaft if that is your preference) an 8000 rpm redline would give a top speed of 141mph. It doesn't make any sense to have a top speed that high so a final drive ratio with a higher numeric reduction is in order. For my diff the highest ring and pinion reduction available is 5.125 which gives a top speed of 108 mph. This is still excessively high and would result in slow acceleration. I would like to have available something where the 8000 rpm red line was closer to 80 mph. The OEM's are all doing some variation on this theme although usually their motors turn up quite a bit higher resulting in an even higher final drive reduction. I did get to drive the Morris Minor at EVCCON last summer and it was setup this way. It was fun to drive and not lacking in power.

Just something to think about as it reduces the complexity a great deal and saves around 150lbs.

Best Wishes!


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## Russco (Dec 23, 2008)

dtbaker said:


> I am assuming that the logical choice for controllers would be either zilla or soliton that support an 'idle' speed.... is there more to it than that?


I have a '94 Metro like yours and I can idle the automatic using the Curtis 1221B controller by adding a 1K resistor in series with the PB6 lead. Idles the motor slower than the ICE did, but has enough pressure to cause a very slight lunge when placed in gear. But not enough speed to move the car. Current draw about 3-4 battery amps.

Removes the jerk (not me) when stepping on the go pedal. The slow speed does not challenge the high pedal disable of the Curtis controller. Of course, the KSI and Allbright must be ON all the time the ignition is ON.


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## steelneck (Apr 19, 2013)

dtbaker said:


> BUT, I am revisiting this whole issue because I have a potential client who loves volvos, which are almost all auto and many newer models a manual was not even available so I can't swap anything in from a used/rebuilt tranny or junked car gracefully.


I do not understand that sentence, are you talking about an old hydro-mechanical gearbox (old rear wheel drive Volvos) or a newer electronic controlled one?

With an old one you can simply use the kickdown wire to control the shift speed, but with the drawback that it also control how hard it shifts. With the ICE driven with gentle throttle you want it to shift smoothly at quite low RPM, and shift hard at high RPM when you floor it. With the EM you want it to shift constantly at quite high RPM, but retain the smooth shift at gentle throttle, but still hard shift when you floor it. I do not know how much difference this lack of "hardness modulation" will make with an electric motor, i have not any experience of that (with the ICE it can feel a bit "jerky" at gentle driving). But of course it is possible to still control the hardness with the acc. pedal, while at the same time have a static RPM control, but this requires modifications in the gearbox to separate these two modulation parameters. 

If you are talking about newer electronic controlled ones, i cannot give you any advice at all.


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## dtbaker (Jan 5, 2008)

Russco said:


> I have a '94 Metro like yours and I can idle the automatic using the Curtis 1221B controller by adding a 1K resistor in series with the PB6 lead. Idles the motor slower than the ICE did, but has enough pressure to cause a very slight lunge when placed in gear. But not enough speed to move the car. Current draw about 3-4 battery amps.
> 
> Removes the jerk (not me) when stepping on the go pedal. The slow speed does not challenge the high pedal disable of the Curtis controller. Of course, the KSI and Allbright must be ON all the time the ignition is ON.


this would not be for my metro, or miata, but rather for a client that loves the newer volvos..... which are not available w/ manual transmissions.


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## dtbaker (Jan 5, 2008)

steelneck said:


> I do not understand that sentence, are you talking about an old hydro-mechanical gearbox (old rear wheel drive Volvos) or a newer electronic controlled one?
> 
> With an old one you can simply use the kickdown wire to control the shift speed, but with the drawback that it also control how hard it shifts. With the ICE driven with gentle throttle you want it to shift smoothly at quite low RPM, and shift hard at high RPM when you floor it. With the EM you want it to shift constantly at quite high RPM, but retain the smooth shift at gentle throttle, but still hard shift when you floor it. I do not know how much difference this lack of "hardness modulation" will make with an electric motor, i have not any experience of that (with the ICE it can feel a bit "jerky" at gentle driving). But of course it is possible to still control the hardness with the acc. pedal, while at the same time have a static RPM control, but this requires modifications in the gearbox to separate these two modulation parameters.
> 
> If you are talking about newer electronic controlled ones, i cannot give you any advice at all.


well..... the info regarding the older tranny 'kickdown wire' is interesting. I wouldn't even be opposed to requiring 'manual' gear selection like a tiptronic.

BUT..... this particular project would be on a newer volvo, say newer than 2000 most likely. So, any info along the lines of how to make it shift semi-manually even would be what it sounds like I am after.


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## TheSGC (Nov 15, 2007)

When I did the auto in my '96 Civic the Throttle Postion Sensor (TPS) determined the shift points. I ended up putting a potentiometer on the dash that connected to the connector for this sensor and marked points for "normal" and "hill" driving. 

I also have my motor idling with a kill switch so I could stop it at long lights.


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## dtbaker (Jan 5, 2008)

TheSGC said:


> When I did the auto in my '96 Civic the Throttle Postion Sensor (TPS) determined the shift points. I ended up putting a potentiometer on the dash that connected to the connector for this sensor and marked points for "normal" and "hill" driving.
> 
> I also have my motor idling with a kill switch so I could stop it at long lights.



ok, I guess I need more of a general overview of how automatic transmissions typically work, and how us DIY EVers can enable shifting in the most economical manner possible.

I understand that the motor has to have some 'idle' speed to maintain fluid pressure in the transmission, but beyond that.......

Is it generally possible just to shift 1,2,3 'manually' and leave it at that? i.e. not even use 'P' ? or is there a SIMPLE way to lock P out, or lock it in 2nd gear only?

OR..... what are the typical sensors and how do you send a signal to shift up or down? Is the simplest way just by seeing the rpm for upshift and downshift? I don't see how we can get a reading for the 'load' or kick-down given that we don't have vacuum.....


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## TheSGC (Nov 15, 2007)

dtbaker said:


> ok, I guess I need more of a general overview of how automatic transmissions typically work, and how us DIY EVers can enable shifting in the most economical manner possible.
> 
> I understand that the motor has to have some 'idle' speed to maintain fluid pressure in the transmission, but beyond that.......
> 
> ...


Every car is different on how the transmission and related computer functions. Usually the shift in an automatic that has a D2, D3, D4, etc doesnt force it into one gear but limits the top gear. (I.E D2 uses 1 and 2, D3 uses 1,2,3, etc. )

Don't bother trying to use the auto as a manual shift, you will most likely destroy the transmission. Also most automatics cant handle the high torque of a DC motor. I blew my first Auto in my Civic with 140 ft-lbs of torque (600A). 

The transmission shifting is all done electronically with the PCM/ECU, there is no more vacuum in auto transmission, just loads of sensors. My 1996 Civic auto transmission had 3 sensors and 4 solenoids.


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## dtbaker (Jan 5, 2008)

TheSGC said:


> Don't bother trying to use the auto as a manual shift, you will most likely destroy the transmission. Also most automatics cant handle the high torque of a DC motor. I blew my first Auto in my Civic with 140 ft-lbs of torque (600A).


the build contemplated (warp9+zilla/solitonJr) would produce 'about' the same hp as stock volvo, so I was thinking it might be not too big a risk in that department.



TheSGC said:


> The transmission shifting is all done electronically with the PCM/ECU, there is no more vacuum in auto transmission, just loads of sensors. My 1996 Civic auto transmission had 3 sensors and 4 solenoids.


so...... skipping ALL sensors and perhaps adding 'manual' gear selection buttons directly to solenoids might be possible?

It would most likely be ok to just have reverse and 2nd gear (sacrificing a little torque off the line and a little top end speed). So I am wondering if I forget all sensors, add switches if need be, and have the gear shift fire correct solenoids for reverse, and 2nd forward..... I could get by without any shifting and just use the controller rpm limiter to protect against over-rev at top end?


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## z_power (Dec 17, 2011)

What is the exact model of Volvo you're considering? There might be possibility of retrofitting manual transmission from another model, Volvos are (were?) quite "modular" and share a lot between platforms and generations. With EV conversion you don't have to worry about compability with engine; clutchless saves you pedals and hydraulics or linkage. The biggest concern is shifter, halfshafts and one or two mounts. Speedo is "driven" from ABS module. Hint: some stuff could be found in Europe


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## dtbaker (Jan 5, 2008)

z_power said:


> What is the exact model of Volvo you're considering? There might be possibility of retrofitting manual transmission from another model, Volvos are (were?) quite "modular" and share a lot between platforms and generations. With EV conversion you don't have to worry about compability with engine; clutchless saves you pedals and hydraulics or linkage. The biggest concern is shifter, halfshafts and one or two mounts. Speedo is "driven" from ABS module. Hint: some stuff could be found in Europe


well..... the one she was looking at was a 2008 volvo s80 T6, but she also expressed interest in the other sedans. I poked thru kbb.com, and most models are NOT even offered with manual. Local mechanic said he'd never seen a volvo newer than 2000 with a manual, so they would be so rare as to be hard to find or rebuild. Regardless it would for sure be expensive, and success is unknown. Given the lack of ready solution or any existing conversion proving it would work, I'd rather go with easier conversion of manual tranny I think.....


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## z_power (Dec 17, 2011)

dtbaker said:


> Local mechanic said he'd never seen a volvo newer than 2000 with a manual, so they would be so rare as to be hard to find or rebuild


Ahh, it shouldn't be THAT hard to find, from 1st look into your local CL: http://albuquerque.craigslist.org/ctd/4229936393.html
Not a sedan but it gives some hope for 6-gear stick in 2004 models.

I know two good sites about Volvo aiming at DIY enthusiasts; tons of info there: http://www.matthewsvolvosite.com/ and http://www.turbobricks.com/

Good luck, I keep my fingers crossed on your first "business conversion"


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## dtbaker (Jan 5, 2008)

z_power said:


> Ahh, it shouldn't be THAT hard to find, from 1st look into your local CL: http://albuquerque.craigslist.org/ctd/4229936393.html
> Not a sedan but it gives some hope for 6-gear stick in 2004 models.
> 
> I know two good sites about Volvo aiming at DIY enthusiasts; tons of info there: http://www.matthewsvolvosite.com/ and http://www.turbobricks.com/
> ...



huh, I guess I was looking only at sedan models, or too new perhaps. gives me some hope.... I will poke around a little more as I think the client wants a sedan rather than a wagon.


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## steelneck (Apr 19, 2013)

dtbaker said:


> ... I poked thru kbb.com, and most models are NOT even offered with manual. Local mechanic said he'd never seen a volvo newer than 2000 with a manual, so they would be so rare as to be hard to find or rebuild. ...


Here in Sweden, where Volvos are made, it is almost the other way round, most cars are sold with manual shift. But if i look around at American cars in Sweden, almost no one has a manual gearbox. I think the customer preferences are different in europe vs. north America.

You could sign up on a Swedish forum to ask more specific technical questions. All Swedes can write and at least make them self understood in English, it is the second language all Swedes get to learn at school. They do not mind a few english speaking visitors. A forum suggestion could be:

http://www.jagrullar.se/forum/

("jag rullar" is the Swedish translation of the old-latin "Volvo" that roughly means "I roll")


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## gunnarhs (Apr 24, 2012)

dtbaker said:


> ok, I guess I need more of a general overview of how automatic transmissions typically work, and how us DIY EVers can enable shifting in the most economical manner possible.
> 
> I understand that the motor has to have some 'idle' speed to maintain fluid pressure in the transmission, but beyond that.......
> 
> ...


I only have experience with Suzuki ATM's, I like them because they are very autark (self-controlled) and easy to apply. I do not know Volvo's ATM.
So here is how the Suzuki ATM-works I have been using with AC-induction

1) Yes a minimal RPM has to been kept, 500 RPM is enough, motor is always on.
2) Your controller should let the motor produce the same curve as the original motor to start with. meaning providing same torque under same RPM as original motor. You start with that setup to begin with at least. So you need a controller with very flexible software. 
3) The ATM is simple. It is connected to a separate computer ( TCM) and the "stick" which uses P (parking), D (Driving forward), N (neutral) and R (reverse).
Your motor gives a certain RPM and if D is on and RPM over 1000 , 1. gear is connected.
The TCM (or ATM depending on type) has input and output for motor RPM and output for Transaxle speed. 
You can also access the solenoids directly which switch gears, you would have to do that if you have a different speed/torque curve but t is easier to let the ATM/TCM do the work for you.
4) The ATM is mechanically connected to the motor like a clutch-less connection to a normal gearbox (always connected).
5) Pro and cons using ATM over direct drive
Pros: 
Usage of smaller (less powerful) motor possible.
Very nice , smooth driving behavior when driving at very low speeds , for example when parking (especially compared to direct drive AC-induction).
You stay in a good RPM spectrum (important for AC-Induction efficiency).
Cons:
You need to keep the ATM-liquid (cooling) system and improve it. An additional 5% loss of total energy compared to direct drive (gearbox)
Regen does not really work unless you can lock the ATM-transaxle to motor axis when wheel-speed > Motor speed driving downhill (some ATM do allow that, other "coast", mean reducing connection fluid pressure).
Additional complexity as Motor has to be adapted to ATM, you can not exploit the best Electric Motor curve (efficiency). Usually a problem when converting a car but especially with ATM


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## dtbaker (Jan 5, 2008)

gunnarhs said:


> I only have experience with Suzuki ATM's, I like them because they are very autark (self-controlled) and easy to apply. I do not know Volvo's ATM.



good info for Suzuki, and perhaps the older ATMs.... apparently the newer ATMs, and Volvo in particular have very complex input to the TCM from numerous sensors: speed, torque, temp, god knows what else and if the TCM doesn't get all the expected data it errors out and locks the tranny in 2nd gear.

It seems that a highly certified and trained volvo specialist would be required to re-program the TCM for lower DC electric motor rpm shift points, or detail exactly what it is expecting to prevent errors. It seems that an AC motor with ATM would be a bit of a waste if you couldn't easily get regen without making even MORE mods to the transmission.

hence.... the search continues for manual transmissions for conversions...

I did find that I could buy a rebuilt/scrapped M56 manual transmission fitting most of the newer Volvos, but at great expense. It was looking like the transmissions run around $1500, and another $500 for clutch/flywheel.... even used/rebuilt! So, swapping in a manual is possible, but expensive as far as I can tell...


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