My Mazda MX-5 Miata Is Having Transmission Issues. Dealer Can Fix It, But Only If I Remove A Modification That Improves The Driving Experience

The fourth-generation Mazda MX-5 Miata has been around since 2015 (2016 model year) and it has already undergone two updates – one in 2018 and another in 2024. While reliability is high, the ND Miata is continuously plagued by problems with the transmission. The issue is well-documented and dealerships are already taking care of it, free of charge, assuming you haven't done any modifications related to the transmission and drivetrain (at least ones that are obvious). 

That said, I found an interesting post on the Forum.Miata.net related to this issue. One owner is experiencing transmission problems on his 2022 Mazda MX-5 Miata. Initially, it was believed that this issue was present only on early ND Miata models, but even 2023 Miata owners complain from transmission problems. Here's what the owner says:  

“Hello, 
I bought a 2022 soft top sport ND at the end of 2022, and i have loved it. 6 months after purchase, 3rd gear occasionally did not want to be shifted into without double clutching. At first, it happened every few months, but has slowly become more regular to now being a daily occurrence for the first 2-3 shifts into 3rd while the car warms up. 
I've read about this being a known issue with the synchros for third gear in my model year, but this is my question 
I installed a third-party short shifter (love the upgrade), but i do not have the original shifter anymore. 
Would you foresee this as causing me any grief at my dealership, or having the problem blamed on my shifter, or is this likely to be looked past?” 

The six-speed manual transmission is the one to go for in a driver-focused car like the Mazda Miata ND, but it has developed a reputation for being weak. In fact. The Fiat 124 Spyder, which shares a platform with the ND Miata, managed to break several manual transmissions during its prototype stage, prompting Mazda to go for a stronger version of the gearbox. Apparently, it wasn't strong enough. 

The six-speed automatic is no better as it was prone to abrupt downshifts, possibly causing loss of control and an accident. Luckily, most owners go for the manual. Mazda had issued a service recall. According to RepairPal, this service recall, listed under bulletin number 19V-072 / 3019A, applies to model years 2016, 2017, and 2018. It is too early to say whether newer Miata models are exempt from this issue. 

It is understandable why an aftermarket short-shifter would raise some eyebrows at the dealership. In theory, any modification that requires a part of the car to work at different than the factory-set parameters would compromise reliability, and you can bet the dealer (as a business) would use this card against you. 

Luckily, there are solutions to the issue, even if you do not keep your stock shifter. Some other forum members chime in with viable solutions to the problem, which will likely save you $6,500 (or more) for a replacement transmission. 

Wolfgangdieter says: “At a potential bill of $6500, I would not risk it—others have been denied. I'd buy a used shifter or borrow one before taking it in.” 

Other members offer a cautionary tale, as some ND Miata owners have been denied warranty due to aftermarket parts. 

S219 says: “Another forum member was denied warranty on his transmission because he had a short shifter installed. Since a short shifter can allow you to outpace the synchros, it's not a stretch to think it could be a cause of problems or exacerbate problems. So, I can see how a "by the book" warranty rep would see that as an easy excuse to deny coverage.” 

Hastette says: “My 2023 has an identical problem. Earlier in my car's life, I had a separate issue that was being taken care of by my dealership. I had already felt shifting issues at the time but they weren't reproducible. 
I brought it up and the foreman said himself that if/when I do come in for that shift issue to change my aftermarket shift knob. If he felt the presence of just a shift knob might affect the claim, I think the shift kit is even more of a red flag for them.” 

John M Moore took a different approach to solving the issue, once and for all: “I have replaced my stock ND2 transmission a couple times, but broke 2nd gear (car has mods with more power than stock). My solution was a Stage 3 build by Walter Motorsports. The drawback is a drop in fuel economy, but the trans is STRONG.” 

Typically, these “all-out” modifications, while great for reliability, come with a couple of drawbacks that may ruin your driving experience. Key suspects are “notchiness” (it will not be as a well-oiled bolt-action rifle) and a louder transmission (even if it doesn't feature straight-cut gears, which have a signature whine). Also, John M Moore's Miata is an ND2, which is produced 2018-2023, so later cars continue to have this issue.  

In conclusion 

It seems the manual transmission issues manifest themselves within a year of the car's purchase (early in the car's life). ND3 Miata owners are in the clear for now, but these cars start from 2024, so it is too early to tell for sure. Mazda will fix the issue free of charge, but only if your Mazda MX-5 Miata lacks any aftermarket modifications related to the gear shifter.

Needless to say, performance modifications that result in increased power will, likely, also void the warranty as the transmission and drivetrain take the brunt of the force, while transferring power to the ground. I, for once, am curious to see the next iteration of the Mazda Miata, which promises to be the most performance-packed yet. Even so, the Japanese roadster will get an unlikely competitor from Toyota. Meanwhile, the ND Miata's logical competitor, the Toyota GR86, is going in an unexpected route for its next generation. 

If you are a Miata owner, I would be curious to hear your thoughts. Reddit also has a good thread on Mazda ND Miata common issues, if you like to check those out. Feel free to also share your thoughts and experience in the comment section below, so we can offer more useful information for future Miata owners and car enthusiasts. 

Dimitar Angelov's automotive interests made him an expert in a wide variety of vehicles. Japanese brands like Toyota are closest to his heart, although performance cars in general are his favorite segment, which is why he is constantly on the lookout for the best deals on the market. Dimitar Angelov's car passion and knack for the written word led him to complete a Master of Arts in Media and Communications, and classic car restoration. Dim is happy to get behind the wheel of any car and share his impressions. You can follow Dimitar on X, Linked-in, Instagram, and Facebook.

Images sourced from Mazda MX-5 Miata ND's official press release