No transmission - you beauty!

[raptor5244]

On the topic of transmissions, ZF and others are developing 2 speed transmission/drive for EV's. Tesla originally tried to use a 2 speed transmission and couldn't solve the engineering problem in time.

Interesting.

The M3P is a rocket until about 60mph and then you can feel the lack of gearing as torque falls off as speed increases. Don't get me wrong it has all the power at the most usable speeds but if we are going for all out performance then some gearing would be nice. I am sure it just over complicates things and adds cost but you know Tremec, ZF and others are going to try to get in on this market.

 

[raptor5244]

for whatever reason the subaru ate through batteries. i've had batteries last longer than 50k miles without ever an issue and the subaru straight up couldn't start after 30-40k for whatever reason this latest battery lasted the longest.

agreed on the wear items but it definitely started to feel like there was "always something" that needed replacing after the car hit the 10 year mark. the engine/AC rebuilds were a huge hit. $6500 later.... i was pretty much over ICE/vehicle maintenance.

I hear you. I wanted the latest WRX when they came out but when I went to test drive it I was like what the hell is up with this tune. I mean I never thought of having to buy an aftermarket tune for a brand new car, it was that bad.

When I hear about folks talking about throttle response, turbo lag, auto slushboxes, etc. I laugh now because of how instant it all is in the M3P. Even these new DCT transmissions that crank out shifts in milliseconds are still much slower than no transmission. It is a torque monster while being civilized, the silent assassin. The only thing I miss from time to time is the sound. In some other V8 performance cars I have owned I have never bothered to turn on the stereo since the exhaust note was music to my ears. Its a good thing the M3 audio system is very good.

 

[mongo]

Interesting.

The M3P is a rocket until about 60mph and then you can feel the lack of gearing as torque falls off as speed increases. Don't get me wrong it has all the power at the most usable speeds but if we are going for all out performance then some gearing would be nice. I am sure it just over complicates things and adds cost but you know Tremec, ZF and others are going to try to get in on this market.

Here's the problem though: The S P100D power output is within 20% for max from a near flat powerband from ~45 MPH to 100. The torque does drop linearly with speed. However, gearing won't do much. Say you drop the RPM by 50%, with the flat powerband, you aren't going to get the increase in output you do with an ICE, instead you move to a high torque point, but you also reduce the output ratio so you need more torque for the same acceleration.

Look at this plot from Tesla Model S P100D Torque Amazes Drag Times After Dyno Test | enrg.io

Say your gearing made the motor speed at 87.5 MPH the same as 57.5 MPH that is a 1:1.52 ratio. The torque then changes from ~520 to 835, a 1:1.61 ratio. Net change in output torque is 6% (tracking the 6% HP change). Even at the high end, the difference is only 580/500 = 16% more power. So with an ideal gearbox, you get at most 16% more acceleration.

 

[raptor5244]

Here's the problem though: The S P100D power output is within 20% for max from a near flat powerband from ~45 MPH to 100. The torque does drop linearly with speed. However, gearing won't do much. Say you drop the RPM by 50%, with the flat powerband, you aren't going to get the increase in output you do with an ICE, instead you move to a high torque point, but you also reduce the output ratio so you need more torque for the same acceleration.

Look at this plot from Tesla Model S P100D Torque Amazes Drag Times After Dyno Test | enrg.io
View attachment 439719

Say your gearing made the motor speed at 87.5 MPH the same as 57.5 MPH that is a 1:1.52 ratio. The torque then changes from ~520 to 835, a 1:1.61 ratio. Net change in output torque is 6% (tracking the 6% HP change). Even at the high end, the difference is only 580/500 = 16% more power. So with an ideal gearbox, you get at most 16% more acceleration.

Good stuff. I think we are gonna need a bigger motor and battery.

 

[mongo]

Good stuff. I think we are gonna need a bigger motor and battery.

Roadster's got it!

 

[airpor41]

On the topic of transmissions, ZF and others are developing 2 speed transmission/drive for EV's. Tesla originally tried to use a 2 speed transmission and couldn't solve the engineering problem in time.

I suspect that the Roadster will have a 2 speed transmission, but consider that it might only shift into second around 100mph or higher. I'm not sure how else they are going to provide both the bottom and top end specs for the vehicle.

Articles about the ZF two-speed went on to say that Tesla solved the problem by optimizing the rear motor for acceleration and the front motor for efficiency at high speeds. That's apparently a fundamental trade -- low speed torque vs high speed efficiency. The Tesla approach is brilliant in its simplicity in my opinion. The ZF approach (2 speed mechanical gearbox) is more complicated, heavier and expensive but might allow easier independent optimization of the high and low speed issues. A single motor (RWD) car using it might be lighter and cheaper than going to AWD (the Tesla approach).

 

[jelloslug]

I like not having a transmission cause one less thing to go wrong and maintain. But I feel the Performance models would have better top end acceleration if we had gears?

Nope.

 

[MoreAgain]

Articles about the ZF two-speed went on to say that Tesla solved the problem by optimizing the rear motor for acceleration and the front motor for efficiency at high speeds. That's apparently a fundamental trade -- low speed torque vs high speed efficiency. The Tesla approach is brilliant in its simplicity in my opinion. The ZF approach (2 speed mechanical gearbox) is more complicated, heavier and expensive but might allow easier independent optimization of the high and low speed issues. A single motor (RWD) car using it might be lighter and cheaper than going to AWD (the Tesla approach).

The HET motor could be the solution for removing the transmission altogether. HET electric motor massively boosts power, torque and efficiency, reduces weight and complexity

 

[BarnabySydney]

I hope no one is crazy enough to put a two speed transmission in an electric car. I certainly wouldn't buy one. Imagine driving around all the time with the extra weight and complexity of a transmission and imagine knowing that at some speed you car is going to go 'clunk' and change to another gear. It would totally ruin the driving experience IMO.

There has to be a better way like maybe this as already mentioned:

Or maybe nothing is needed and the Model 3 is already the best there is. Top speed means nothing to me.

 

[Zcd1]

The upcoming Porsche Taycan is said to have a 2-speed transmission on at least one of its motors...

 

[raptor5244]

I hope no one is crazy enough to put a two speed transmission in an electric car. I certainly wouldn't buy one. Imagine driving around all the time with the extra weight and complexity of a transmission and imagine knowing that at some speed you car is going to go 'clunk' and change to another gear. It would totally ruin the driving experience IMO.

I get what you are saying but I don't think you would feel it shift. It may just increase performance and efficiency without a ton of complexity and cost. EVs are just going to get better and better.

I grew up on over powered RWD cars so I am just waiting for them to build one that with let you spin the rear tires.

 

[VT_EE]

While 1 speed will be the standard for awhile. ZF already has a 2 speed electric transmission in the works. Eventually it will be an efficiency thing on the highway for all EVs.

I don't think you will have any significant increase in efficiency using gears in an EV. I'm basing this on the fact that the EV has so many fewer moving parts where friction can occur than in an ICE. In the EV, you pretty much have a rotor and some bearings that would be affected by an increase in RPM. ICE has pistons, belts, valves, shafts, etc, etc, etc.

 

[Zcd1]

...I grew up on over powered RWD cars so I am just waiting for them to build one that with let you spin the rear tires.

Enable “Track Mode” and find an empty parking lot!!

 

[MoreAgain]

Enable “Track Mode” and find an empty parking lot!!

Or wait for MPP to release the Partybox.

 

[Zcd1]

Party already started:

 

[cab]

When I leased my Volt back in 2012, the "no shifting" was the single biggest thing that swayed me to electric. It basically addressed everything I have hated about automatic transmissions for years (note: I sold my BMW E39 M5 to lease the Volt - my "car guy" friends were stunned). After three years with the Volt, I knew I wanted more oomph and an electric sports sedan of some kind. I ASSUMED there would be a lot of choices three years later....nope.

I test drove the second gen Volt - which felt too much like the first gen to me (a disappointment) and the Audi A3 E-tron (which I REALLY liked, but at 16 miles of EV range it just wasn't compelling enough as a plug-in). A few months later, Tesla came out with their CPO program and I ended up in a 2013 P85+. Other than being a bit too big (although I have now gotten very used to the size and find it easy to drive), it has been pretty solid. The instant torque, no shifting, etc...truly compelling.

p.s. 3 years since I bought the P85+ and I am STILL waiting for another manufacturer to introduce a compelling EV sports sedan...sheesh!

 

[MoreAgain]

Party already started:

But only for the P. Tesla leaving the rest of us hanging...