[BenDoyle]

Mine does something similar, but it doesn't seem to be speed-dependent. Minor throttle inputs sometimes cause the torque converter to unlock instead of forcing a downshift (which is what it SHOULD do most of the time). I often watch the tachometer fluttering up-and-down by a few hundred RPMs when driving in gear. To me, Mazda's unique torque converter system with the lockup clutch seems compromised. There's a lot of harshness, sluggishness, and surging in the power delivery.

 

[BenDoyle]

I'm the service manager/parts procurement/technical reseracher/tuner of a high volume drivetrain repair facility that also does R&D. I am a member of ATSG and ATRA and go to regular schoolings/briefings about everything drivetrain related. I've personally been involved in the automotive industry my entire career starting in a machine shop rebuilding cylinder heads. I'm active in a few of the Mazda specific fb groups. I try and correct info and help people when they genuinely want to learn. We rebuild these transmissions but do not see them regularly as they are one of the best engineered and built units on the market. They do fail but very infrequently. I have an upgraded torque converter I can sell now for some of the supercharged builds that are hitting the market. Just trying to decide how I want to go about it. I'm working with a few vendors on upgraded friction sets but those are further off.

I do have a few youtube videos I put together on a teardown of the medium case version(2.0 and 2.5 non turbo cars) as well as the torque converter I had for the pictures I posted. If you're interested

Part of what makes these transmissions so good is also what makes them expensive to overhaul. You will never be able to cheaply fix them in the event of an actual failure.

Fascinating. Thank you for sharing. If there's any way of telling, what's the typical cause of those rare failures?

 

[BenDoyle]

We don't really see a common failure due to a design issue like we do on some other transmission families. The transmission in the first video was out of a 2017 CX5 that was used as a rental car for 125k miles. It lived a very hard life and the torque converter failed. The transmission that the torque converter came out of in the second video lost first gear due to abuse. It was out of a 2014 Mazda 3. The customer would not come to a complete stop before shifting from reverse/drive and it broke the one way clutch. We are currently doing a 2015 CX5 that suffered the same fate.

Hm, now I have proof that it really does matter whether you come to a complete stop. I once saw a former teacher of mine doing this in her CX-5 at about 5mph and it was painful to watch. The thing must have traveled a good yard or two before it finally lurched forward. She was not a hugely pleasant person so maybe the Mazda will repay her someday.