Featured As gas prices have dropped, so have owner's EV/hybrid loyalty

As a one time owner of a gen2 Prius, with continued interest in alternate fuel vehicles, I have a layman's understanding of HSD. The vast majority of car buyers don't, and all they are concerned about is if they need to do more than press accelerator to make the car go. Which is why I said the Prius counted as an automatic.

The majority of those people probably don't care if their 'automatic' is step, CVT, eCVT, DCT, or even automated manual. They'll likely note the difference switching between the different types, but unless they find the tranny operation too different from their last car, they won't give it much more thought beyond it being a different automatic.

For those that do look at TCO, the cost of regular maintenance for these transmissions generally won't be large enough to have a big impact in the TCO.

And gen2 owners reported the tranny fluid smelling burnt after 30k miles. Since the HSD only needs the fluid for lubrication, overheating it isn't as big a deal in an actual automatic. Many automatics with clutches also have a lifetime maintenance interval. With such, I would personally drop the pan at 100k miles, and I would have done a fluid change on the Prius at that time, if I had be able to keep it.

I don't know how common DCTs are in Europe, but they aren't in the US. The Ford Fiesta uses one, and Hyndai/Kai have a couple models with them. VW is probably the only manufacturer with DCTs used through out their product line up, and holding up their DCTs as what they are all like would be like holding up pre-electronic controlled automatics of the '70s as an example of what to expect from a modern 8 speed one. There are some car models with a CVT, but the vast majority of automatic transmissions available in the US are the traditional step type.

The clutches in a step transmission are of the type used in the Prime HSD and the new Lexus hybrid transmission. Design flaws and improper use aside, these clutches will last the life of the transmission and car. If required, the maintenance will cost more than for a Prius simply because there is a filter and the tranny holds more fluid.

 

Just for comparison, our previous Honda Civic Hybrid had a CVT, albeit a more traditional one. Honda uses a "maintenance minder" in-dash, to tell you what and when needs doing.

I followed that, and checking my records, see I changed CVT fluid roughly every 60,000 km. I know I did at least one change on my own initiative, but the maintenance minder did ask for this, every so often.

 

If you don't know how to use a manual transmission properly sure, but then why aren't you buying an automatic? Mediocre manual driverd should get at least 50K miles, a partially skilled one at least 70K, and of course long distance drivers easily exceed 100K. Its a routine maintance item. If you don't get 50K though, then someone should teach you how to drive a manual properely if you want one.

A locking slushbox automatic has long clutch life, if you really are concerned. I googled dmf clutches and it seemed to point me to trouble with vw groups turbo diesels, and that is a whole nother matter.

double clutch transmissions seem to work for high end fast vehicles (opposite use of hsd) but when put in less expensive cars compromises are made to torque handling and feel, and my guess is they will either improve, or fade away from those mass market applications like the focus or jetta. High performance often means stricter adherence to maintenance and higher upfront costs. This may be worth it in a porsch or bmw but not in prii competitors.

 

Our 2001 Sable has a recommended ATF change interval of 30k miles. That was the norm in the preceding decades. After that is when the longer intervals and lifetime ATF started to show up.

The 2006 HHR had a lifetime tranny, but I did the change at 100k miles. I think the Sonic is 100k miles. It just hit 45k, and this is the first time I'm supposed to check the engine air filter.

 

It's also worth noting that dry-clutch DCTs tend to have much longer fluid maintenance intervals than wet-clutch ones (on par with manuals), and cheaper fluid.

It's wet-clutch DCTs where fluid maintenance gets frequent and expensive (in the US market, that's every VW DCT except for the 7-speed used in the Jetta Hybrid). Conversely, dry-clutch DCTs tolerate far less clutch slippage... and then you've got issues with the Ford DCTs, where the input shaft is failing and causing fluid to leak onto the clutch and cause slippage that way.

 

Many people drive manuals, and here in Europe roughly 80% of the cars still on the road are MT.

Dual mass flywheels are fitted in almost every diesel. You haven't googled enough.

 

And 90+% of the cars on the road in the US are automatics of some type.

The car buyer's past experiences are going to influence how they view the Prius transmission. For the majority here, the clutch is something a manual transmission car has, and they are likely are unaware that their automatic has any clutches at all. With most automatics lasting past 100k miles without issues. Potential clutch failure in them isn't a consideration for many shoppers.

 

I've done two two transaxle fluid changes on our 2010. With the first the drained fluid was quite dark, even though the car only had about 15,000 km's. The next change, around 40,000 km's, the fluid looked like new. If I was going to recommend a conservative, minimalist maintenance schedule, it'd be to do a single early change, then leave it alone.

 

When we sold our 2004 Sienna, it had 234K miles on it. The only thing I ever did to the transmission was periodically change it's fluid (every 60K to 75K miles or so), and that was mostly as a precautionary measure. The 2005 Prius that my son has is at 200K+ miles. It's only needed periodic fluid changes. My 2012 PiP is at 102K miles and has yet to have the fluid changed.

 

Yes and I'm sure this is why europeans are much less likely to like the toyota/ford hybrid psd based eCVT. I don't really know european numbers but know the bigest growth world wide is automated manaual (aka dct) and manumatic (similar but automatic slushbox with same types of manual overide, instead of manual with automatic overide). Manuals have fallen to about 46% world wide, but are the most popular single type giving lowest up front cost, and better control of underpowered engines, at a trade off of higher maintenance costs (clutch replacements).

US cars often have more powerfull engines and people are less likely to even learn to drive a manual. Manuals are only 4% of the car populations.

Was trying to find an apple to apples dual mass flywheel clutch in a gasoine engine. You go diesel its probably because of government pusing it as in europe. It is not going to get you lower tco or maintance, diesel with modern emissinos (not the old stinky) have much higher maintenance costs. Then again if you are driving a diesel you probably will have a manual or automated manual, otherwise you won't exploit the diesel advantages.

 

There are no gears in the traditional sense of 1st, 2nd, 3rd, etc. The only gears used is a planetary gear-set that permanently ties the ICE, MG1 and MG2 together. No clutch at all in the system. MG1 is used as the starter motor, as well as a generator.

 

Seems to me there's a clutch between the ICE and the Electric side. There was a recent video posted on the inner working of the gearing with MG1, MG2 and the ICE that identified a component as a clutch.

 

you probably have never looked at an automatic transmission or a cvt. We have
1) psd between the final gear and mg1 and engine, anouther reduction gear between mg2 and this output, and ofcourse the transaxle gear. This may seem magical like the single speed gearing of an ev like the tesla, but there is electronic gearing, changing the speed ratio of the ice to the output of the the psd, controlled by mg1. Think of this as a continous electronic gear (eCVT), but requires the closing of the loop of power flow from mg1 to mg2 (or viceversa). Conceptually its harder, but replicates that cone type cvt very well.

Part of the magic happens outside of the eCVT. Added power can be supplied by the battery to mg2, or excess power can be used to charge the battery until later.

This compared to a slush box with locking torque converter provides much more efficiency at low speeds as the battery can do things much more efficient than a slush box slip. It also allows the engine to run higher to more efficient range, or shut off. There is much more cost and weight though. I doubt there is lower tco outside of as I said using less fuel because of higher efficiency.

There is a one way clutch in the upcoming prius prime phev. There is not in the prius or ford hybrids.

 

There's no clutch in the Gen 1, Gen 2 or Gen 3 HSD. Trust me on this. I've been driving these Toyota Hybrids for 11+ years and am really familiar with the inner workings. Now, it's entirely possible the Gen 4 system has a clutch, but I doubt it.

 

This video of a Gen-3 Hybrid Transaxle identifies a clutch at about the 22 minute mark.

 

It is a torque limiter. Believe me also.

 

You are partially correct, but what he refers to as a clutch is merely a torque limiter/damper. This "clutch" is not used in the traditional manner, which would normally be used to disconnect the engine from the transmission in order to change gears.

 

I think it all works out about even. All cars will have gears for the final drive and differential. The Prius does have two additional planetary gear sets, but so does a 4 speed automatic. 6+ speed automatics will have more. The Prius has power electronics, a traditional automatic has a valve body and actuators and shift elements. The Prius has MG1 and MG2, a traditional car has a starter and alternator. The alternator requires a belt and pulleys to drive it, and occasionally a starter has been known to strip the teeth on the flywheel causing a very expensive repair.

Total cost of ownership is the combination of initial purchase price, fuel used, insurance, taxes, and maintenance and repair. The maintenance and repair are the wild cards. I've had cars that have cost thousands to maintain, either because they have a few very expensive breakdowns (Chevy), or just have an appetite for tires and brakes (Mazda3). A large part of the low TCO of the Prius is because it's a Toyota, not because it's a hybrid.

All cars are getting more complex in the quest for more MPG. Google "ZF 9 speed transmission problems" or "Ford DCT issues" and compare those to the Prius transaxle.

 

One big thing is that the Prius gearbox's only element that is designed to slip in any way is the torque limiter, which, while acting like a clutch, won't be slipped nearly as much as a clutch.

Even a manual has a synchronizer on every gear, after all, nowadays, and those do wear out, causing difficult shifting.

And, frankly, any of the modern high-MPG non-hybrids is more complex than the Prius nowadays.

 

MG1 also provides 'counter torque' to the engine to force engine power to take a mechanical path.

In fact if that torque limiter ever starts slipping, the Prius generates an error code. I've only known of one instance due to an engine oil leak.

Now there are reports that the Prius Prime, the plug-in hybrid, has a mechanical clutch that allows both MG1 and MG2 to drive the car in electric vehicle mode.

Bob Wilson