Monday, April 7, 2014

Answer to CVT 'Start Clutch' Failures for the 4G City


One of the most significant change in the new 4G Honda City is the change of the gearbox from the 5AT back to the CVT gearbox that was first used in the 2G City. Unfortunately, seasoned Honda fans will remember well that this rather 'infamous' gearbox has a rather bad reputation for unreliability. Whether this reputation is rightfully or wrongfully given, it cannot be denied that a search on the internet will reveal numerous stories of 'start-up clutch' (its actually called the 'start clutch' but mechanics at Honda's authorized service and repair centers added the 'up' and many have called it 'start UP clutch' since) failures with early batches of the 2G City and even 1G Jazz. 
The 'Start (up) Clutch

Honda's 'start clutch' is actually a viscous coupling clutch pack that operates via hydraulic pressure compressing several clutch plates together to transfer drive from the engine to the front wheels. Honda actually has a patent on the use of a viscous coupling clutch on their CVT gearbox, which they called Multimatic, back when it was launched in the mid-1990s on the EK3 Civic.

With the early batches of 2G City and 1G Jazz, 'start clutch' failures usually started with noisy 'juddering' when moving the car off from stationary, being due to the slippage of the clutch plates due to wear and tear from friction during usage. Eventually the 'start clutch' will slip more and more finally and in  extreme cases, it will fail to move off from stationary because the clutch plates cannot engage, a condition much like having a worn clutch on a manual gearbox. Other symptoms included very bad fuel economy due to inefficient transfer of drive to the front wheels.

What I understood back then, was that the original 2G City had a different gearbox oil in their CVT-7 gearboxes than was originally recommended by Honda R&D in Japan. Instead of using CVT-F oil, it seems that early batches of City's had ATF-Z1 in their CVT gearboxes instead. While Honda originally certified ATF-Z1 to be suitable for use in their CVT gearboxes, eventually after rumours of 'start clutch' failures became rampant, they switched to the special CVT-F oil. 

I also once had a discussion with an LPL from Honda R&D in Tochigi about this and he too assured me that if CVT-F oil is used, the start clutch should not fail. He also strongly recommended a strict 20,000-25,000 oil change interval to fully ensure longevity of the CVT gearbox.

Other less common failures reported of the original CVT gearbox was of 'internal leaks', where leakage of the hydraulic fluids inside the gearbox caused a failure to hold the 'V pulleys' properly locked in position during drive. When this happens, the two V pulleys which holds the metal CVT belt starts to change ratio uncontrollably and the result is an unstable fluctuating rpm during drive. The CVT-7 gearbox in my own Jazz 1.5VTEC had this failure and I was lucky to get a new gearbox replaced under warranty.

The new CVT gearbox
Given its rather 'unfortunate' history, it is understandable that as the new 4G City comes with the CVT gearbox, Honda fans might start bringing up the start clutch problem again or potential buyers will be told by friends of this. I am not sure whether any other publication actually touched on this in this level of detail, but certainly when I learned of the CVT gearbox's return in the 4G City, I was very concerned.

Therefore during the press conference for the launch of the 4G City, I departed from my usual restrain (of holding back my questions) and decided to tackle this issue head-on. I asked a very direct question 'head on' to the City LPL about this issue. And I video'ed his response at the press conference for you to listen for yourself. The youtube video is below.



Notes from the City LPL response
Key point to note from the LPL's response is the confirmation that the CVT gearbox used on this new 4G City now employs the standard torque converter which replaces the 'start clutch'. The 'start clutch' was originally located at the end of the gearbox, where the final drive is located. But here, the torque converter is placed at the usual location, just after the flywheel and operates like a regular torque converter (photo on the left). There is no 'start clutch' in this CVT gearbox. So, the message from the LPL is crystal clear - as there is no 'start clutch' so 'start clutch' failures will never happen with this new CVT gearbox.
The other key point is that the CVT gearbox has redesigned internals and along with the use of newer low-friction CVT gear oil, internal oil leaks like what happened with my Jazz 1.5 VTEC is also not likely to happen anymore.

I guess in the end, the most significant thing is that upon my proding him, the LPL confirms that Honda is very confident that the unreliability issues that affected early batches of the CVT gearbox in the original 2G City (and 1G Jazz) have been resolved. 

So if you are considering the 4G City but have been having people telling you 'stories' about Honda's CVT 'start clutch' failures, rest assured that those are things of the past. They most definitely do not apply to the CVT gearbox in the new 4G City because it is of a different design/construction. 

The new 4G City really is a great package and is the best equipped car in its market segment at the moment and likely for some time to come. TOVA gives it a strongly recommended buy if you are in the market for a 4-door sedan from this segment.

9 comments:

FiSHChan said...

No mention of only drum brakes? Even the top model use drum brake (at least from what I understand). There is probably also some other thing I cannot remember what right now.

Thank you for writing about the CVT and the first impression on the other page, I enjoy reading them as always. The L15 12v - 16v was a nice surprise.

FiSHChan said...

Wong, I check out the car at my local showroom already:

A few things I point out.. this 4g City compared to the 3g City (I compared the top model):

-I already mentioned the rear brakes
-steering
-rear door open angle
-closing and opening of doors
-seat materiels
-AT gear knob
-door window swtiches
-signal / light switches

I am sure I not imagining things, but they feel much worse than the old car. I understand they cost have to come from somewhere, but it was dissapointing to see.

What is your thought?

FiSHChan said...

btw, also want to put in positive comment - the overall feature and space is outstanding, and the car looks much better in person compared to in pictures... and no doubt it offer great value.

LB said...

start clutch is wear and tear item, no?

how about the belt slipping? i am wondering if belt slipping will nvr happen in this 4G. i am 2005 idsi owner, and my gearbox slip once when i trying to up steep slope. i was like ... "what the hell .. am owning a car that cant can go up slope?"

gearbox oil replaced since then, and havent go up such slope yet to test if still slip or not.

podracer said...

Hi WongKN,
I assume the MMC CVT CR-Z also retains this 'start-up clutch'. Does it have any sort of improvement over 1G Jazz CVT-7?

TOVA said...

FISHChan, I did mention the rear drum brakes in the main review article at TOVA (http://asia.vtec.net).
LB, I have not heard cases of the belt itself slipping. Actually the way it is designed, it would be very difficult for the belt to slip as it is made up of metal plates on a steel belt which 'bites' into the V pulley. It is always the start clutch which slips.
podracer, the newer CVTs on the CR-Z, Jazz Hybrids, Insight, Civic Hybrids, etc are this new torque converter CVTs, no start clutch.

Thanks for the comments.

William James said...

in present time such types of problem are faced by every one and i am also facing this problem but till now i can be repair this issue. if you have any right way than please inform me honda st1300

podracer said...

Thanks WongKN, great news indeed. Keeping the 20k change interval for CVTF is still a good idea right, with or without start clutch?

I needed another car and got plain tired of waiting for 3G RS Jazz/Fit to come to our shores (if ever). So I grabbed the CVT CR-Z late last year. Except for BIG minus on practicality, it's all +1 up for CR-Z vs my trusty ol' 1G Jazz. Gone are the 'rubber band'ing effect, much better handling and as much fun in 'Normal' mode. The Auto engine Stop is quite annoying and so is the mode switch button, I kept putting my hand on the gearknob to go 'S' and WOT, which isn't there :P So a bit more planning required on this car. Plus the 1G Jazz steering leather is much better than the CR-Z which looks and feel faux. WongKN, perhaps an article on how to optimally use the CVT-7 paddle shift - where best and in what scenario, in your experience?

Nowadays I mostly drive in Econ mode and auto-cruise to save fuel cost. So excuse that slow CR-Z on the highway. From my experience, if I want to drive fast it's more fuel efficient to set to 'normal' rather than 'econ', because of the more pedal pushing required. But then people would say if I want real fuel saving fuel then go for Prius-C - I agree. But for me to own one, are you crazy? No thanks.

Having owned both 1G VTEC Jazz and CR-Z, kudos to Honda for making such fun cars - in their price class, in the honda line-up, here at least.

Anonymous said...

Ur posting really give me big confidence in getting the 4g city. Im so scared of the horror stories i heard in regard to those GB failure.

Thanks a lot.

Post a Comment