Here's a dumb idea

"Jake - Has Bad Luck So You Don't Have To" (murdersofa)
12/11/2014 at 00:26 • Filed to: None

Disconnect my automatic shifter linkage, connect some sort of linear actuator or servo to the transmission. Hook this up to an Arduino. Hook the Arduino up to power, plug in a couple buttons, and do some programming. Design paddles, put buttons + paddles on steering wheel, bam. Flappy-paddle-shifted 4T65e. Right paddle would move 1>2>3>4>N>R>P left paddle would go P>R>N>4>3>2>1. Slightly unintuitive, but that's the order the transmission goes in. Anyone know how much force is usually needed to move an autobox like this between gears? I can't tell if the resistance when I do it from inside the car is resistance from the transmission or resistance from the linkages in the steering column.

I'd also have to re-tune my transmission to disable all automatic shifting (change the upshift points to something above redline, downshift points to 0rpm, disable kick-down, torque converter always unlocked except for in 4th [overdrive]), but I could get a decent simulation of a flappy paddle gearbox, and wouldn't have to worry about the damn thing hitting 2nd at inopportune times while autocrossing.

Thoughts? Would make a fun project to keep me busy.

DISCUSSION (26)

GeorgeyBoy > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 00:29

I have select shift in my car, or whatever Lincoln calls it. It's pretty stupid. It won't be worth it.

Jordan and the Slowrunner, Boomer Intensifies > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 00:32

Jake - Has Bad Luck So You Don't Have To > GeorgeyBoy
12/11/2014 at 00:33

OEM manual-automatics are always terrible because they're not made for... us. Like I said, I'd be tuning the transmission specifically for this. The difficult part is fabricating a bracket for the actuator that will be shifting, and programming the arduino.

GeorgeyBoy > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 00:37

I mean a group of engineers that have access to almost unlimited resources to design a manual way of shifting an automatic were still unable to make it worth using. No matter how much lipstick, it's still going to be a pig.

Jake - Has Bad Luck So You Don't Have To > Jordan and the Slowrunner, Boomer Intensifies
12/11/2014 at 00:38

4L80E! They put those in the XJS, I believe, and I think one is in my sister's truck as well. I wonder how my PCM would react if I disconnected my transmission... I thought it would be amusing to make a fake clutch pedal and connect that to the torque converter lockup. Those solenoids look like a pain in the ass to manage, though.

ly2v8-Brian > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 00:43

just no

Jake - Has Bad Luck So You Don't Have To > GeorgeyBoy
12/11/2014 at 00:44

I've never driven a manual-auto that I liked. VW Passat B5.5, Chrysler PT Cruiser, Chevy Sonic auto. They were all either ridiculously annoying to use or shifted just as lethargically as when in auto mode, or would refuse to stay in gear.

The thing is, this is just because they're designed for the everyday user, not someone who doesn't want his becauseracecar to choose random gears when cruising through a slalom section. I've already tuned my transmission to- in auto mode- have much quicker and firmer shifts than it did stock. 99% of the issues with Tiptronic-like systems are just due to the fact they're programmed for comfort and convenience over control and speed, a compromise that is very VERY often made in anything other than a "true sports" car. As long as I can get the tables for the shift solenoids to react quick enough to inputs through the mechanical shift linkage, this should theoretically be rowing through the gears pretty damn quickly assuming I can get the shift linkage actuator I'd be building calibrated right so it moves the cable into the right gear when I request one.

thereisnospork > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 00:45

It might be easier to bypass the shift lever all together and hook the arduino directly to the transmission's shift solenoids? I think you can do that entirely electronically, but I don't know much about automatics. I also suppose it might be possible to wreck the transmission or do something bad like put it in two gears at once (did that to a 5-speed once) actuating directly but I'm not sure.

Jake - Has Bad Luck So You Don't Have To > thereisnospork
12/11/2014 at 00:50

Yeah, I figure there might be a reason that shift controllers (basically a microcontroller that goes between the PCM and the transmission and allows manual control) are so expensive, and it might be because of how easy it is to get it wrong (and how hard it is to figure out how it works). Though I could possibly do it entirely with a counter circuit and just discreet transistor logic if I felt like not bothering with programming.

GeorgeyBoy > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 00:53

Well in mine, and most other manual automatics I've tried, it's meant for sportiness. You're only going to get the transmission to change gears so fast. It won't be intuitive or worth doing. All I can say is good luck.

Jordan and the Slowrunner, Boomer Intensifies > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 00:55

The 4L80E was the HD transmission, cars and 1500's got the 4L60E. It would definitely take a lot of "rigging" to get it done. I know some companies make retro-fit +/- shifters, but I've only seen them on light duty diesel truck.

Jake - Has Bad Luck So You Don't Have To > Jordan and the Slowrunner, Boomer Intensifies
12/11/2014 at 00:59

http://en.wikipedia.org/wiki/GM_4L80-E…

It was used on several Jags, Bentleys, and an Aston. And the Hummer H1, it seems. Huh. That's a hell of a prostituted engine.

How much rigging? Is that solenoid stuff necessary if I still have the PCM connected? I need to dick around with TinyTuner some more and see if I can reduce the existing delay between moving the column shifter to a gear and the car actually shifting into that gear (e.g if I'm in Drive and shift to 2nd there's about .75 seconds before it actually hits that gear)

Jordan and the Slowrunner, Boomer Intensifies > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 01:08

It would make sense that those companies used that transmission, because power. If only GM caught on that by the time they made the Trailblazer... I have no clue, but I'm sure you could use the computer to rig shift the transmission, since a lot of tuners adjust shift patterns. I have no clue what it would take though.

gogmorgo - rowing gears in a Grand Cherokee > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 01:10

How much force is required mostly depends on how much of an incline you left it on and how much force is pushing against the parking pawl... but there may be an easier way to go about this.
I don't know how the auto shifting works in the 4T6E, but in my Jeep's AW4 the transmission/shift computer basically is just controlling three solenoid valves in the tranny. Two gear solenoids and the torque converter lockup. Four gears, four possible solenoid combinations (off/off, on/off, off/on, on/on). It's not uncommon for people to pull out the shift computer and just install three switches to replicate it for better control over it. Like this:

Given how that's a 4L80E in the video, it wouldn't surprise me a similar thing could be done for your Buick. Just use the Arduino to replicate the switches. Torque converter lockup would be an interesting thing though. Maybe just have it lock in any gear other than first or lock it above a certain RPM? You also don't need to worry about kickdown or whatever because with no shift computer, there is none. You become the shift computer. Or well, the new Arduino shift computer becomes the shift computer and only responds to your input.

Simply unplugging the tranny computer (easy) or pulling its fuse (also easy) in my Jeep will also put the shifter into a "manual" mode. (D) puts it in overdrive, (3) in 3rd, and (2-1) in 1st. Worth noting, yes second gear becomes inaccessible as there are only three shifter positions. Park, Reverse, and Neutral are all controlled mechanically by the shifter and still operate normally. My guess on the no locking into first is because coupled with 4-Lo, first gear has a drive ratio of 7.62:1 which makes it pretty useless... and potentially dangerous to downshift into from second's 4.16:1 in low range.

Jake - Has Bad Luck So You Don't Have To > gogmorgo - rowing gears in a Grand Cherokee
12/11/2014 at 01:12

I might try pulling the fuse tomorrow. My column shifter, notably, has positions for all four gears. P-R-N-D-3-2-1.

My problem is when autocrossing there are some slalom sections where I'll be in 1st gear going ALMOST fast enough to want 2nd, but I know I'll have to slow down at the end of that section. My transmission, not aware of the course ahead, shifts into 2nd for me (how nice of it) thus killing any power I had, and now i have to try to get it to kick back down into 1st again. Quite frustrating.

Jake - Has Bad Luck So You Don't Have To > gogmorgo - rowing gears in a Grand Cherokee
12/11/2014 at 01:16

Another thought: if running it totally disconnected from the computer, couldn't the paddles simply move the mechanical part, as well as turning a rotor that engages the appropriate solenoids?

The Transporter > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 01:32

The 4T65-HDs in the Grand Prix GXP had a TapShift module. Don't know if that would be backwards compatible with a 4T65-E, but it might be worth looking into.

gogmorgo - rowing gears in a Grand Cherokee > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 01:42

Yeah, I suspect the engineers programming the shift points of your Buick didn't exactly have motorsport in mind...

gogmorgo - rowing gears in a Grand Cherokee > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 02:01

I'm doing other things and didn't notice you'd posted twice...

The FSAE team I was with is currently trying to get a mechanical paddle shifter setup working, simply running cables from the paddles to the shifter lever on the sequential bike transmission. In the past they've used compressed air and electrically triggered solenoids to move the shifter, but it's always been somewhat leaky and problematic, so last year they tried using electric solenoids, but never could get them working. To be strong enough, the solenoids had to be too heavy to be practical and it was just one headache after another for many months. At competition we wound up running a mechanical lever that was stolen off an older car and crudely adapter in a few hours the night before we loaded up the trailer. It wasn't pretty.

The big problem I see with a traditional automatic trans being shifted mechanically by paddles is that unlike a sequential transmission with a shifter that moves back and forth between two-ish positions, an auto trans has a good half-dozen positions in sequence. Either you'd need to have paddles that also moved through the six or seven positions or else they would somehow have to ratchet.
The smaller problem is again pulling it out of park after you've let it roll back onto the parking pawl... that can take some serious effort if you're on an incline, and it might not be easy to put that through a paddle shifter.

Sequential transmissions are just so much better for motorsport than other kinds. It's ridiculous.

crowmolly > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 04:08

These guys did it. Very pricey.

http://twistmachine.com/index.php?main…

Jake - Has Bad Luck So You Don't Have To > gogmorgo - rowing gears in a Grand Cherokee
12/11/2014 at 11:26

Yep, I'm currently helping design and install the electric sequential shifter for our FSAE team this year. Luckily it's designed for the engine we're using, so we shouldn't have many issues installing it, though it was pricey.

On Amazon I can find heavy-duty 200lb of force linear actuators that should be more than enough to get it off the parking pawl for $50. What I need to do is just unscrew the cable and crawl under the car and wiggle the shifter around myself and see what sort of forces are involved.

Jake - Has Bad Luck So You Don't Have To > crowmolly
12/11/2014 at 11:30

Yeah, those do it the "easy" electronic way by having a microcontroller between the PCM and the computer. It really wouldn't be hard for me to do on my own. I think I could make it work by just switching three solenoids, and just a few lines of code.

00 = 1st

01 = 2nd

10 = 3rd

11 = 4th

The third bit is the torque converter lockup which I would probably connect to a manual switch. For simply switching some relays up and down a 4-digit counter like that I could actually do that all with discreet logic, no microcontroller needed. I would retain the stock shifter with this for shifting between park/neutral/reverse/drive, but then 1/2/3/4 would be controlled by whatever electronic shenanigans I have installed. I think.

Jay Lauer > Jake - Has Bad Luck So You Don't Have To
12/11/2014 at 11:55

It's possible, but not cheap. You could find ways of making your own bits to cut costs, but transmissions are tricky bitches to start messing around with. Even my dad normally just delegates tranny work. I really wouldn't mess with it unless you've got a backup tranny.

My suggestion is to get a shift kit for it. They make a lot of difference.

http://twistmachine.com/index.php?main…

Jake - Has Bad Luck So You Don't Have To > Jay Lauer
12/11/2014 at 12:44

Wow. They actually make that for the 4L65E. I'm surprised. Though 99% of the appeal of that is its reprogramability and ease of use, two things which, did I not care about them, I could probably rig up my own electronic system using either discreet transistor logic or an arduino. I wish I had a lift so I could actually access my trans wiring.

gogmorgo - rowing gears in a Grand Cherokee > Jake - Has Bad Luck So You Don't Have To
12/12/2014 at 20:44

We looked at linear actuators, but they were mostly all too slow for shifting. Remember that for the most part they're worm gears... lots of push but not much speed. Also... buying someone else's design? Good luck getting design points for that!

Jake - Has Bad Luck So You Don't Have To > gogmorgo - rowing gears in a Grand Cherokee
12/13/2014 at 00:33

Well, we're using a motorcycle engine, and we bought a shifter meant for drag-racing motorcycles with that engine. I believe it's actually an electromagnetic actuator.