Classifying a "Clutchless Manual" Transmission

[GasSavers_BluEyes]

Just posting this from an engineering standpoint. Since we are looking at this for effeciency, I would think it depends on whether the transmission has a torque converter or not. A torque converter is a fluid coupling and is one of the big things responsible for the decreased FE of an automatic-equipped car. The slip in a torque converter generates heat and is why automatics generally need a fluid cooler or at least a large oil pan to dissipate heat while manuals do not. That heat sent to the cooler is your lost FE.

[landspeed]

I'm voting automatic - because:

The 'EPA' figures will be lower for an 'automatic', so if you drive a 5-speed manual, or an automatic, you will 'start' at 0% above EPA anyway.

BUT... an automatic will mean that P&G is either impossible or risky, engine-off coasting again is impossible or risky. This means that an Auto car will result in less hypermiling opportunities.

I think an auto is a car where you don't have a clutch or a gearshift, meaning you can't do exactly what you want with the clutch and the gearstick. So, whatever technology is behind the auto box, it is still an auto box (whether 'classical' auto, CVT with torque convertor, CVT without torque convertor, (all of which could be seen as a 'clutchless manual'.

The 'classical' auto boxes use loads of clutches all controlled by electrical/mechanical means anyway, so they could be considered a clutchless manual too (where the clutch isn't seen by the driver that is)

[brucepick]

I'm with Bill/Houston and bbgobie and others: if it has a torque converter with its associated losses then it's an automatic. If it has a computer controlled clutch then it's effectively a standard.

However - if the computer-controlled clutch type tranny doesn't allow engine-off neutral coast as well as engine-on neutral coast and bump start and going into neutral at any time, then it's not a "standard" for our purposes.

[cfg83]

brucepick -

Originally Posted by brucepick

I'm with Bill/Houston and bbgobie and others: if it has a torque converter with its associated losses then it's an automatic. If it has a computer controlled clutch then it's effectively a standard.

However - if the computer-controlled clutch type tranny doesn't allow engine-off neutral coast as well as engine-on neutral coast and bump start and going into neutral at any time, then it's not a "standard" for our purposes.

Yes yes yes.

CarloSW2

[bbgobie]

Neutral on coast - check, dont see how that can be a problem.
Engine off coast, and bump starting...
Hmmm... Someone walk into a Volkswagen dealer, ask to test drive the new Golf and settle this for us!!

If you can get a video of the salespersons face when you turn off the engine while coasting and bump start it... well, lets just say that would be priceless...

[rh77]

So, we probably need clarification on the following:

There are several types of "Clutchless Manual" Transmissions...

In this case, can you coast in a "Neutral" state?
Is it possible to turn the engine off while in motion?

Some do not have a torque converter like a "Slap-Shift" gear selector-type transmission.

I looked up EPA data on such transmissions:

The 2007 BMW M5 comes in either 6-speed manual, or "SMG". The data designator for the SMG is "Auto(S7)" -- translation "Automatic -- Sequential Gearing, 7-Speeds". It also notes that it has a "6-Mode CLKUP". 6 Different modes can be selected (probably automatic and 5-modes from "soft shift" to "racing shift". CLKUP = Converter (torque), Lock-Up Type.

Perhaps this sheds some light on this particular vehicle. For specific vehicle purposes, perhaps data like this could be presented?

Commish

[CO ZX2]

It appears to me that all sequential shift transmissions listed (S4, S5, S6, S7) in the EPA data link submitted by rh77 are considered to be automatic transmissions.


From Ford Motor Co. Automotive Glossary:

Manual transmission, A transmission in which a driver selects gears by means of a hand-operated gearshift and a foot-operated clutch (also known as a "stick shift").

[rh77]

Well, it looks like we have a 50/50 tie from the poll. Using the info posted, I should have a decision posted soon...

The Commish

[rh77]

The ruling is that SMG or similar gearboxes (sequential or automated manual gearboxes with an electronic clutch) falls into the "Automatic" category for the competition.

Why?

• The Poll resulted in a tie, requiring a tie-breaker
• The EPA classifies them as Automatics -- and we use their numbers for the basis of establishing baseline FE.
• Shifting into Neutral does not occur traditionally (some designs require stopping or downshifting sequentially).
• EOC may not be possible.
• The design is essentially a manual transmission -- but, with the addition of electronic controls, the definition changes.
• The spirit of the competition team's vehicle make-up is to ensure variety (the different design satisfies this aim).

If there are any concerns, please let me know. Thanks, and best FE...

The Commish

[GasSavers_Antoine]

I am a little late on this one. But I voted ? manual ? last week.... hummm ... don't tell CO ZX2 ... he will kill me !

The problem is : it is not black or white -- automatic vs manual -- but the new auto trans are somewhere in between. In North america, when we think automatic we refer to the american auto trans ( you know all that whirly fluid and a torque converter said Bill in Houston). They are practical but inefficient. But in Europe they had different automatic for some time. I remember in the early sixties, these Citro?n DS , semi-automatic by a stick at the steering wheel, and the Renault R-8 full-auto push button type . They were both without a clutch pedal, with an electric gear change manual type transmission. Today, on-board computer make the gear change much easier. They had no choice in Europe at that time since their car engines had much less power than american gas guzzlers.

I thought last week, for purposes of FE team challenge, the best would be to forget about the necessity of an ? automatic team member ?, or else ask for the real american automatic transmission before it is extinct.... I might be wrong, but I beleive in the near future, we won't see these any more, and all these sequentials, CVT and clutchless manuals will be the norm.

Well a few words about my car, a Smart fortwo CDI dsl turbo 800 cc auto-manual trans.

It is a sequential 6 speeds with full auto mode and a manual mode ( no clutch pedal of course). In full-auto, the computer changes the gears electrically (clutch and gears) at a pre-establish rpm depending upon load. In ? manual ? , the driver order the computer to change gears at will. But there are drawbacks that let me think it is 75% manual. These restrict the hypermiling opportunities:

1- The computer automatically downshift ( in manual mode) at around 1230 RPM, much too high for FE purposes. The engine could go down to 1000 without lugging ( like on the vw tdi at 1000 rpm in 5th).

2- We cannot turn off the engine when coasting and if we do so, we must go to a complete stop to restart.

3- So, no pulse & glide possible. ( but luckily a nice 0 fuel on compression).

4- We can put trans. in neutral while coasting, but on re-entering the gear, the computer choose the one gear like if it was in automatic mode ( lower gear).

5- No possible bump start in regular driving.