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Discussion Starter · #1 ·
So, I've made up a relatively long list of projects for my car this year. I'm in the middle of completing some of the smaller ones, but one of the more in depth mods is going to be designing/fabricating/installing a shift mechanism that will allow for sequential shifting. I know similar devices are available for purchase, but they're pricey and as an Engineer, I'm looking forward to the challenge of "getting there," not just the result.

Obviously, at this point, manual operation of the clutch will still be required. I've gone through quite a few ideas and the one I've settled on for "Stage 1" will be ratchet drive cam profiles that will actuate the transmission cables. Basically, a purely mechanical system (minus the eventual addition of a small display to let me know what gear I'm in). The current profile designs are based on some measurements I found on the forum, but I plan to take my center console out to make measurements of mounting points and cable movement. The new short-shifter kits sound like the will greatly aid in making my design more feasible since (if I understand correctly) the cable throws can be shortened to give a lower incidence angle between the cam wheels and follower pins.

I'll post some images of my current design work when I get a few free minutes. I just wanted to create a thread to get some feedback during the process and document what I'm doing, for my own good. Also, while constructive advice/criticism is preferred, please feel free to post any comments you want in here... just try to stay on topic as much as possible.

I'm not making these to sell them, its just going to be a one-off for my car. Eventually, it will get modified further in keeping with some other ideas myself and my co-workers have come up with.
 

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These are popular with the m/c crowd - pretty simple device that compares the pulses from speed and tach to figure out what gear to display.

DATATOOL » Products » DiGi
 

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the biggest problem i see is designing a system that has the same sequential gear shift lever movement (ie "not much") whilst actuating the transmission cables enough to change gear without making the force required to move the lever excessive.

the biggest complaint I've heard from similar products is that the lever throw ends up being more than stock (and being a pain to configure).

the datatool unit is great but it would be better and more acurate to use a rotary sensor on the cam.
 

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One of the projects that I was considering was to use linear actuators along with a programmable module to create a sequential shifter. You could tie this in with the throttle and accelerometers to rev-match on downshifts, etc. Combine that with a gear-indicator and it would be very useful.

I'd love to see something like that... it is a pretty ambitious project but it can be done.
 

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Pugg57, this is great to hear! I played around with this idea for a while trying to come up with the right approach, but couldn't come up with anything I had confidence in pursuing further.

I think I'll bang out a quick Sketchup of my best idea and see what you think of it. You have a PM.

Good luck with your project.
 

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I'm also hoping you know about the Ikeya unit (Sector used to sell them):

PRODUCT INFORMATION

Thomasio - look up KAPS:

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Racing DOG-BOX - KAPS Závodní pøevodovky
 

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Nice picture of the kind of cam profile you'd need.

It also illustrates that you process the you need to fully disengage the engaged gear, some time in neutral and then selecting the next gear.
One aspect I would be concernd at is you would have to control the shift change as if you try to slam gears in like a dog-box gearbox then you'll going to damage the synchro's

 

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i've never driven one, but the MR2 Spyder has an option for semi manual gearbox - buttons on the steeling wheel and hydraylic actuators on the gearbox ...

might be worth at least investigating on how they did it ...

look forward to seeing your progress !
 

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funny i was going to post this yesterday asking if anyone has considered tackling this transmission swap from the mr2 spyder into the lotus. There was a few tests and video's of them of the 5 speed manual vs the sequential on a track and the sequential was something like a second faster over and over.
 

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Not a great garbox. Originally it was for the celica but only the lighter Mr2 could take it.
Shifts are supposed to be quite slow and the computer is quite conservative on launching. I don't think it would take 190bhp either.
Finally it's quite heavy as I believe it's not a true sequential gearbox - instead I think it is the same as BMW's SMG which is a conventional H pattern gearbox with synchro's and both the clutch and gearcabled operated my hydraulics.

I think sequential gearboxes are overrated in anything other than serious competition cars. A true sequential box is an absolute nightmare for the road as it is a dog engagement and you still have (or at least it's easier) to use the clutch on down shifts. Even on upshifts I find a half press of the clutch makes things operate more smoothly and prolong the life of the gearbox.

Don't get me started on service intervals...

A H pattern conversion to sequential shift is an interesting engineering project (which I guess is why the OP is doing it).

Back on topic - forgot to add that it'll be essential to add some form of locking mechanism between 1st and reverse.

There is also a company making these for subarus and mits evos - quite a nice system looking at the specs. It has a feature where if you press the shift either direction in a "half shift" movement then the gearbox is in neutral. A full movement changes gear.

Personally I would like some form of electronic protection as it would be very easy to mis-shift and if not buzz the engine cause massive wear on the gearbox. All it would need is a solenoid lockout switch that could stop shift movement if the rpms are outside defined parameters.
 

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Discussion Starter · #12 ·
the biggest problem i see is designing a system that has the same sequential gear shift lever movement (ie "not much") whilst actuating the transmission cables enough to change gear without making the force required to move the lever excessive.

the biggest complaint I've heard from similar products is that the lever throw ends up being more than stock (and being a pain to configure).

the datatool unit is great but it would be better and more acurate to use a rotary sensor on the cam.
I've got several ideas already on how to overcome most of the issues that seem like common ones (excessive lever movement, excessive force required, etc) I've just been swamped at work lately so I haven't had time to tinker with my designs. By no means am I trying to make a shifter (at this point) that can be used to "slam" through gears or is completely idiot proof. For now, I'll just have to rely on myself to not downshift too soon, just like I do driving the car now. I don't really want to build any safe guards into that wouldn't exist with the stock shifter as it just adds what I see as uneccesary complexity. But, there is always room for improvement and if I like the basic result, maybe I'll add some idiot override controls like downshift lockouts (already planning to have a mechanical reverse lock-out like stock).

One of the projects that I was considering was to use linear actuators along with a programmable module to create a sequential shifter. You could tie this in with the throttle and accelerometers to rev-match on downshifts, etc. Combine that with a gear-indicator and it would be very useful.

I'd love to see something like that... it is a pretty ambitious project but it can be done.
Funny you should mention that, because that is what I was considering as a "next step" for this project. It shouldn't be difficult to the point where it can't be done. We've kinda narrowed our path down to a possible controller (Gumstix) that should be able to handle the processing while still being very small and easy to program. I'd think one should be able to pull realtime rpm/speed and whatnot info directly from the OBD system or on-board sensors but I'm not sure how you could use a signal from the shifter controller to appropriately blip the throttle for rev/matching. What I'd LOVE to do is actuate the clutch with this also and basically make a paddle shift device out of it. As far as making it a bit easier to develope, we have discussed making it where you'd have to manually operate the clutch for going from stand-still to moving (1st gear or reverse) and then all other shifts would happen via solenoids. I'm sure I'll get to that point, eventually, but I'd be glad to help out in any way that I can if someone else wants to do it before I get around to it.

(side note: I'll send you a PM this weekend sometime about Vacuum forming)

I'm also hoping you know about the Ikeya unit (Sector used to sell them):
Yep, I'm aware of that, but again, it think it will be much more fun/challenging/interesting to make my own instead of just buy one off-the-shelf.
 

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This will be quite a project, but I hope to see some success. I have installed and tuned a few sequential shifters on the 111 chassis and if I can be of any help let me know. My free time is very tied up with school right now but I will try to check the board at least weekly so feel free to PM me. I am not an engineer so specifics might be out of my realm, but I am familiar with the mechanics of the other product on the market and it's installation/tuning process.

Cheers,

Brian
 

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Discussion Starter · #15 ·
I've not given up... just been too busy to post any images. Of course, I'm not on my home computer right now so I STILL can't post any images. I'm definitely thinking about the linear actuator version right now though because it leaves lots of room for upgrading.

I do appreciate all the offers of help/advice people have been posting or messaging me with. I'll get back with ya'll when I'm at a point that I can make useful inquiries of you.

Thanks,
 

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I've never driven a real sequential box in a car, but it they work anything like a motorcycle gearbod I would LOVE it.

xtn
 

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I've never driven a real sequential box in a car, but it they work anything like a motorcycle gearbod I would LOVE it.

xtn
You would still need to clutch between shifts... motorcycle transmissions have parallel shafts with "dogs" that engage the different gears...
 

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I very much like sequential shifters (and still want the clutch). I hate H pattern shifting, and always fear zinging the engine due to a bad shift. I think I was spoiled by my motorcycle as a teen.

Since I got my Elise in 2005, I have thought about developing a sequential shifter conversion often, and sketched out a few designs. There are some challenges to keep in mind, such as
- how does your mechanism recover if the driver only shifted part way, and then let the stick go back to the middle?
- how are you going to deal with reverse?
- do you want to allow a way to know you are in neutral between any gear without having to shift all the way back below first?
- what design approaches keep the mechanism simple, and preferably use a minimum of custom parts?
- what designs minimize wear on the parts? (want long lasting, no maintenance)
- what kind of mechanism requires the least amount of adjustment? (one of the advantages of an H shifter)
- remember that a sequential shifter already removes half the throw available (say as compared to moving from 3rd to 4th gear). That means it will take more effort to shift. If you add a short shifter mechanism on top of that, you would have to use even more effort to shift. I don't recommend the short shifter.
- etc.
I came up with some approaches that address these and other concerns, but, it was low on my priority list compared to other household projects. Maybe someday ...

As I thought about it over the years, I also realized that an interesting solution to seriously consider would be leaving the in-the-cabin portion of the shifter alone, and instead make a mechanism in a box that mounts on the transmission and connects directly to the shifter shafts. Run the shifter cables to this box. The box would implement the sequential shifting. This might be easier than trying to figure out a mechanism that fits in the shifter console and frame.
 

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You would still need to clutch between shifts... motorcycle transmissions have parallel shafts with "dogs" that engage the different gears...
I think he means an actual sequential box, not just a shifter. Unfortunately I cannot give input on the feel as I have not driven a sequential box with dog teeth. I have driven cars with the Ikeya and it felt good when it worked correctly. Hopefully in a land not to far far away I will have a real sequential to play with. :evil:

Cheers,

Brian
 

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I think he means an actual sequential box, not just a shifter. Unfortunately I cannot give input on the feel as I have not driven a sequential box with dog teeth. I have driven cars with the Ikeya and it felt good when it worked correctly. Hopefully in a land not to far far away I will have a real sequential to play with. :evil:

Cheers,

Brian
That's exactly what I meant. I have no desire to just get a sequential shift pattern on a regular transmission. I can already shift the H-pattern faster than the transmission likes, so what's the point?

I want full blown sequential dog box. Aren't the new GT4 2-11 cars offered with one?

xtn
 
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