s80 automatic transmission info for 'manual' shifting

dtbaker61 · Post by **dtbaker61** » 10 Jan 2014, 17:53

I have a client interested in converting a S80 to all-electric drive. This is usually easier done with a manual transmission than automatic since you don't need a bunch of engine sensor data to tell it when to shift. HOWEVER, it is difficult to find used s80's with manual transmission locally, they seem to be all automatic transmissions.... so, I cam here looking for ideas/comments on whether it would be reasonably easy to kludge 'semi-manual' shifting of the transmission, like paddle-shifting, by directly energizing the tranny solenoids?

I would have rpm signal available from the electric motor, but no 'load' information that the gas motor would typically send.

any ideas on how to do this as simply as possible? OR, failing a way to manually shift, would it be difficult to overide all shifting and allow just reverse and 2nd gear?

Post by **kcodyjr** » 10 Jan 2014, 18:03

Your "load information" would be how far the accelerator is depressed, multiplied by some correction factor that's based on the current RPM. Isn't there some sort of controller on the electric motor?

dtbaker61 · Post by **dtbaker61** » 10 Jan 2014, 18:17

accelerators in modern EVs usually are Hall effect pedals sending 0-5volts for throttle position, rpm can be available from external sensor on motor, boltheads on coupler, or in some cases the stock rpm sensor, etc.

however, the accel position is not really the 'load' which is typically sensed by vacuum with a gas engine. and... the volvo send all these signals into an ECU which decides how and when to shift.... I would MUCH prefer a 'manual' gear selection; the shiftpoints for an electric motor are far different than gas, so I would want to tell it when to shift in most cases.

I guess I am looking for a simple answer as to whether or not I could MANUALLY send a signal to appropriate transmission solenoid(s) to force gear selection as desired.

dtbaker61 · Post by **dtbaker61** » 10 Jan 2014, 18:29

I would like to know if it would be possible to bypass the D selection completely, forget the ECU and computer stuff, and ONLY use 'manual' gear selection.... that would be perfect.

Post by **kcodyjr** » 10 Jan 2014, 18:46

I'm not 100% sure, but I think all modern automatics rely on the solenoids. I don't see why it wouldn't be possible, but I've not heard of anyone doing it either.

I'm not aware of any manuals ever being sold in S80's, at least in the US.

dtbaker61 · Post by **dtbaker61** » 10 Jan 2014, 18:52

yeah...... the details seem to be held close to the chest with the volvos....

I think I am headed for local volvo shop with some beer in hand to learn what I can....

My local client LOVES volvos, and I would like to be able to help out with the conversion... might end up transplanting a manual tranny if I can find one, but I'd LIKE to keep cost down and use existing tranny.

converting to all-electric is a kick, but also a challange!

Post by **jimmy57** » 10 Jan 2014, 20:00

Have auto gearboxes been used before?
Automatics need engine speed prior to motion or you'll have a delay between motor start and pressure build and then gear engagement.
I would think that delay would be a big issue. Running electric motor to keep trans in gear would be a charge life killer too.
You can energize solenoids and get selected gears or run with no controls at all and have reverse and 3rd and 4th. The selection of 3rd and 4th would be accomplished by moving lever from L to D.

dtbaker61 · Post by **dtbaker61** » 10 Jan 2014, 21:20

modern controllers (soliton/zilla) have provision to 'idle' at rpm to maintain tranny fluid pressure at stop.... issue is shifting from 2,3,4,5,6 without normal ICE sensor input and computer control. easiest way is to bypass and go 'manual'... so that is what I am trying to learn about.

hence, some simple way to use auto transmission in manual shift mode is the easiest when auto transmissions are far more available than manual.....

Post by **kcodyjr** » 10 Jan 2014, 22:22

Sounds like the lash-up would function, but would be mildly awkward.

I don't believe there is a low-level controller on the transmission itself, just a bunch of solenoids that you energize one or another to get a particular gear. It's not crystal clear to me how it would work - Jimmy57, could you elaborate? From your details, I'd guess there's two solenoid-controlled lower gears and two solenoid-controlled overdrive units, and mechanical limiters for 3rd and 4th? How's that work, really?

In any case, if you want "paddle shifting" whether mounted on the wheel as paddles, or the tiptronic fake-manual setups they come with, you'd need to find or fabricate some kind of sequencer that knows which gear it's in and processes up/down commands into relays controlling individual solenoids.

Post by **kcodyjr** » 10 Jan 2014, 22:24

Maybe this approach isn't really the easiest. Then again maybe it is, but it seems to me that's been assumed rather than determined.

What sorts of outputs are available from those controllers you mentioned?

What inputs does the factory TCM really require?