Author Topic: Sequential Transaxle  (Read 5939 times)

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105gta

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Re: Sequential Transaxle
« Reply #15 on: November 09, 2015, 09:00:12 PM »
I think you misunderstood me Duk. Being a synchro box doesn't mean it can't be sequential it just adds a few more obstacles along the way. Mainly total travel of the mechanism. As for totally mechanical sequential gearboxes on production cars... I never said they're was one, I said automated with synchros achieving very fast changes. A lot of ferrari's, lambo's, audi's plus Alfa's and many others.
All single clutch standard manual gearboxes with synchros only having an external actuator system to aid the driver.
Ps. Sequential refers to the gear lever movement achieving the next gear from a pre determined sequence. As in 123456 as opposed to h pattern where one could accidentally engage the wrong gear say go to 2nd instead of 4th obviously with bad consequences.
1967 Giulia Sprint GT Veloce (WIP)
1985 GTV6 (WIP)

Duk

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Re: Sequential Transaxle
« Reply #16 on: November 13, 2015, 05:41:54 PM »
Going more along the lines of a modified gear lever to get shorter throw. How about something like this but with your above trans tunnel linkage? This way you could play with the height of the pivot point to effect forward/backward throw length and left/right gate selection length is set by the linkage at the back.
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The Slightly More Imediate Project: Supercharged Toyota MR2.
The Long Standing Conundrum: 1990 75 V6 (Potenziata)............. What to do, what to do???

MD

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Re: Sequential Transaxle
« Reply #17 on: November 13, 2015, 08:59:16 PM »
I have commented on the top illustration before. It appears that it could work but I bet my auntie's Labrador on it that it only shifts 3-4 and has a terrible time selecting anything else. Without seeing the rest of the mechanism, as is, it's crock. If the owner of that set up is reading this, feel free to join the debate.

The second one I know a bit about seeing as I am the one who  made it. Whilst it is much more precise than the original configuration it is less than perfect. Hence my quest to develop a simple, efficient and precise shifting mechanism.

As we speak, I am trying to visualise a hydraulic oil pump delivering oil to a 5valve selector base that sends this oil pressure down 5 oil circuits that represent each gear with an oil activated receiver to make the shift into the selected gear. Couldn't you have some fun with that? Slick shifts. No mechanical drag on parts. Minimal wear and maximum precision. You could have size/length shifter you want. Locate it wherever you want based on the size of your boots(read seating position). Doesn't require a two piece shaft to get around the base of the shifter linkage and best of all, you could say good- bye to Dennis Lilly and the Grand Canyon 'cause now you would be transaxle heaven.

...calling hydraulics engineers...
Transaxle Alfas Haul More Arse.

105gta

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Re: Sequential Transaxle
« Reply #18 on: November 13, 2015, 11:26:16 PM »
I see your plan MD as I also thought the same ideas of electro/hydraulic pump. I'm curious, is there a reason you are leaning towards a hydraulic system?
1967 Giulia Sprint GT Veloce (WIP)
1985 GTV6 (WIP)

MD

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Re: Sequential Transaxle
« Reply #19 on: November 14, 2015, 08:50:56 AM »
Well let's call this topic a group fishing exercise. I have put it out there to get transaxle devotees to start thinking out of the square and come up with an elegant solution that can be retro fitted to any transaxle so that once and for all the shift drawback is solved to perfection.

The top of tunnel shift only solves some problems for racing applications. For road cars like my GTV6, there is quite a bit of additional cosmetic interior work that has to be done so that it doesn't look agricultural.

Thinking about hydraulic systems you find that dry sumping engines makes power improvements. Hydraulic ram systems are deployed in all sorts of applications that require absolute reliability like aircraft landing gear, mobile cranes and even the brakes on your car. Imagine still having mechanical brakes on your car !

So clearly there are squillions of hydraulic applications out there doing a great job. It's a well proven technology.

So getting to the pointy end, all the circuitry could be neatly configured for either race or street application either above or below the tunnel. One could consider a belt driven or electric pressure pump. So there is considerable flexibility.

However the tangential thing that I am most excited about is the mass reduction of the the two piece tail shaft potential. If a carbon fibre shaft were to be deployed, it could be simply a one piece affair. The huge reduction in spinning weight of the shaft together with a lightened flywheel, alloy custom clutch pressure plate, the synchros could do their job much easier and shifts would in principle be slicker and faster by these enhancement alone let alone tweaking inside the box.

So this is a win/win design improvement that potentially makes a quantum improvement in transaxle performance on the track or the cruisemobile.

...keep fishing guys. We are not there yet.
Transaxle Alfas Haul More Arse.

MD

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Re: Sequential Transaxle
« Reply #20 on: November 14, 2015, 09:28:31 AM »
Special Note.

Before there is a perception evolving from this topic that the transxale shift is useless I need to state emphatically that this is not the case. Most owners are quite accepting of the nature of it and adapt accordingly. Like anything, there is always room for improvement. The Japs have the artform down to pat.

This applies to everything from personal behaviour to ways of getting to the moon.

Rest easy. This topic is purely intended to deal with opportunities of improvement.
Transaxle Alfas Haul More Arse.

Duk

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Re: Sequential Transaxle
« Reply #21 on: November 14, 2015, 09:36:04 AM »
Thought promoting threads are excellent. I've seen some amazing things thrashed out on various forums over the years.

A couple of things you'll notice with hydraulic systems. The actuators aren't that fast to move. A pneumatic cylinder will move faster, but obviously for a given size and system pressure a hydraulic cylinder will exert more force.

I still think you'll be having a lot of trouble basing this on a syncro box.
As far as I can tell, all of the older single clutch sequential gearboxes systems from Ferrari, Lamborgini, Aston Martin and Koenigsegg all activate the clutch to accomidate each gear change, both up and down. If you want to work with syncro equipped gears, I'm sure you'll have to do the same.
Koenigsess even added an internal wet brake to their gearboxes so that rather than rely on the syncros to match the next gears speed, on up changes, the internal wet brake was used to do that and the gear change time was about how long it took for the clutch to disengage and the re-engage.

https://www.youtube.com/watch?v=1QJlL0zNdMA

How about a cable shift linkage arrangement? That's how typical transverse mid engined cars do it (not all of them) and the throw and feel is very good in my MR2.

If you do want to persist with automated selection by what ever means, your controlling system will want positional feedback. So any hydraulic or pneumatic cylinder would need slide potentiometers or linear transducers.
Another approach, as was hinted at by 105gta, is electric actuators. Servo motor have built in feedback systems. So the controller tells it to move to 'X' degrees and it runs as fast as it can to 'X' degrees and it will stay there untill told to move somewhere else.
The Daily: Jumped Up Taxi (BF F6 Typhoon). Oh the torque! ;)
The Slightly More Imediate Project: Supercharged Toyota MR2.
The Long Standing Conundrum: 1990 75 V6 (Potenziata)............. What to do, what to do???

Duk

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Re: Sequential Transaxle
« Reply #22 on: November 14, 2015, 12:00:25 PM »
Obviously this doesn't help you with the mechanism but does show the clutch use requirements of a sequential conversion on a syncho box: https://www.youtube.com/watch?v=wCB3IOUuvmY

S1's Facebook page https://www.facebook.com/s1sequential/?fref=ts does mention in 1 of the picture comments that shift times aren't any faster than the H patern, but are more consistent, especially for the 2-3 shift.
The Daily: Jumped Up Taxi (BF F6 Typhoon). Oh the torque! ;)
The Slightly More Imediate Project: Supercharged Toyota MR2.
The Long Standing Conundrum: 1990 75 V6 (Potenziata)............. What to do, what to do???

ALF750

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Re: Sequential Transaxle
« Reply #23 on: January 10, 2016, 12:52:55 PM »
All interesting stuff, though most too complex for my agricultural mind.

For my 2c, I think the heavy springs in the sideways plane contribute to the slow and awkward shift.   I ponder that one reason 'gated' shifters were used by Ferrari and others (sometimes, for engineering reasons, not all the time for the 'look') was to guide the shift without the need for heavy springs to define the 3-4 plane.   I have one Alfetta with shortened shifter and another standard, plus a 75TS Isotastic(sp.?).   I like the modified Alfetta, comparable movement to the isotastic, but the spring weight is much more noticeable.   I'd like to combine lightened rotating mass (flywheel, driveshaft, clutch, gears(minor effect?)), no or lighter springs, connected to a shortened shifter guided by a gate.

Next step up in complexity is a rigid torque tube connection between engine and transaxle (a la Porsche), on which you could directly connect the shifter to the gearbox without consideration for relative movement.

The cable ideas have merit also.

Have an Alfa day.

Duk

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Re: Sequential Transaxle
« Reply #24 on: December 20, 2016, 10:54:02 AM »
Dunno if this will work, but PPG don't have this on their Youtube channel.
https://www.facebook.com/search/top/?q=pfitzner%20performance%20gearbox%20-%20ppg
The Daily: Jumped Up Taxi (BF F6 Typhoon). Oh the torque! ;)
The Slightly More Imediate Project: Supercharged Toyota MR2.
The Long Standing Conundrum: 1990 75 V6 (Potenziata)............. What to do, what to do???

gtv6sv

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Re: Sequential Transaxle
« Reply #25 on: December 20, 2016, 05:08:15 PM »
Lord have mercy Duk😲😲😲sounds and looks sensational, now to somehow get it into an Alfa transaxle...atleast they've got it for the Corvette transaxle!
1970 1750 Berlina
1983 GTV 2.0
1985 GTV6 2.5
1991 164 Q 12V
1992 33 16V S
1999 GTV Twin Spark

Duk

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Re: Sequential Transaxle
« Reply #26 on: December 20, 2016, 05:45:59 PM »
Still needs dog rings for the gears to be fast enough...............
But yeah, it's pretty flippin' cool!
The Daily: Jumped Up Taxi (BF F6 Typhoon). Oh the torque! ;)
The Slightly More Imediate Project: Supercharged Toyota MR2.
The Long Standing Conundrum: 1990 75 V6 (Potenziata)............. What to do, what to do???

gtv6sv

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Re: Sequential Transaxle
« Reply #27 on: December 20, 2016, 10:42:39 PM »
Be interesting to see what the cost of the gearbox plus what it takes to get it into the car!
Taking a punt on winning the lottery looks good right about now...
1970 1750 Berlina
1983 GTV 2.0
1985 GTV6 2.5
1991 164 Q 12V
1992 33 16V S
1999 GTV Twin Spark