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Discussion Starter #1
I came across this Feb 2017 tech article from an MX-5 site. The author does a nice job running the reader through the processes of replacing the gear oils of the manual transmission and rear differential, including photos. (The article starts with changing motor oil. Skip this, we don't have that Mazda engine. He then moves into the tranny oil, then the rear diff., and lastly the gear shift lever, "manual shifter turret grease".)

That last section takes the reader through the process of lubricating the gear shift lever itself. Hmmm. This is all performed on the "NC" generation manual transmission (which may have had model changes over its long life?), Mazda's prior generation MX-5 transmission, but the one used in our Fiat 124 Spiders. Anyway, I found this interesting, and I don't recall it being discussed here previously. I don't offer this article for how-to advice (I'm not sure if it shows our rear differential), but rather to start some discussion on the issue of the gear shifter lubrication. Our center console is of a different design so the article offers no help to us for accessing the mechanical parts, but I think it is worth reading and becoming educated upon. Can anyone with a tech manual for the Spider offer any insight?

Biggest take-away for tranny and diff., always remove the fill hole plug before draining the fluid, in case you are not able to actually remove the fill hole plug. This way you aren't stranded with an empty transmission or differential.

http://revlimiter.net/blog/2017/02/nc-mx-5-miata-2006-2015-oil-trans-diff-fluid-change/
I did find other similar sites, but this one had good clarity of photos and text.

Steve.
 

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I've not read the linked article but do own an NA, where this is an occasional maintenance thing. It is not as much done for performance as it is a 'while you are in there' thing. The shifter (at least on the NA and NB) has two rubber boots that wear out from use and rip, letting heat into the cockpit. As such, replacing the boots is something that is on the to-do list every few years, complete with dusting the boots with talcum powder to help extend lifespan. But having gone to the effort to take out the console and removing the old boots, it makes sense to put fresh lube and give it a good once-over.

Not sure if the 124 uses the dual rubber boot system or not...and have not followed the ND discussions on the Miata forum.
 

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Bumping an old thread because this is something I was thinking about. Back in May, I changed the transmission fluid to one recommended on another thread because I felt the shifting was stiff, especially when the engine was cold, but didn't notice much of an improvement.

Could the issue be the "shifter turret grease" referenced in the link above? Has anyone tried getting to that on the 124 Spider? If I get some free time, I may attempt to access and grease the shifter turret to see if that makes any difference. Worth a shot or waste of time?
 

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Bumping an old thread because this is something I was thinking about. Back in May, I changed the transmission fluid to one recommended on another thread because I felt the shifting was stiff, especially when the engine was cold, but didn't notice much of an improvement.

Could the issue be the "shifter turret grease" referenced in the link above? Has anyone tried getting to that on the 124 Spider? If I get some free time, I may attempt to access and grease the shifter turret to see if that makes any difference. Worth a shot or waste of time?
Since our cars have NC trannys, the shifter turret probably does require lube, however, probably not until your car has some significant miles & years on it.
Here’s a current link from the NC section of Miata.net where a forum member lubed the shifter turret on his ‘06 NC with great results - https://forum.miata.net/vb/showthread.php?t=672093
I’ll be replacing my tranny fluid after a year with the “magic Motorcraft” fluid, but will leave the turret for a few years.
 

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Decided to change out my tranny & diff fluid today using the Motorcraft manual trans fluid and Mobil 1 for the diff. Got the same positive results as others and was also surprised at the amount of black break-in metal shavings on the magnetized drain plugs.
Shifts are smooth with zero balky, notchy feel, and my Spider now loves to go into reverse.
Anyone know what the factory fill is? I bet it’s a dino or semi-syn, so any upgrade to a full syn like Amsoil, Redline, Royal Purple, etc. would have a favorable result.
 

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Decided to change out my tranny & diff fluid today using the Motorcraft manual trans fluid and Mobil 1 for the diff. Got the same positive results as others and was also surprised at the amount of black break-in metal shavings on the magnetized drain plugs.
Shifts are smooth with zero balky, notchy feel, and my Spider now loves to go into reverse.
Anyone know what the factory fill is? I bet it’s a dino or semi-syn, so any upgrade to a full syn like Amsoil, Redline, Royal Purple, etc. would have a favorable result.
How many miles did you have on the car when you swapped out the gear lube in the transmission?
 

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as the owner of a NB miata, the former owner of a 05 mustang gt, and current owner of my 124 abarth, chances are I will be using the motorcraft full synthetic gear oil the next time I change the gearbox oil. I have had wonderful results with that stuff and seriously smooth shifting hot or cold.... for tracking the car perhaps I would make different choices but as a street driver the motorcraft will work very nicely....
 

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as the owner of a NB miata, the former owner of a 05 mustang gt, and current owner of my 124 abarth, chances are I will be using the motorcraft full synthetic gear oil the next time I change the gearbox oil. I have had wonderful results with that stuff and seriously smooth shifting hot or cold.... for tracking the car perhaps I would make different choices but as a street driver the motorcraft will work very nicely....
Agree. It’s a highly rated lube made in Germany, packaged in English & French and marketed by Ford in Dearborn, MI.

On a separate note, I like your license plate:D
 

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Agree. It’s a highly rated lube made in Germany, packaged in English & French and marketed by Ford in Dearborn, MI.

On a separate note, I like your license plate:D
mine is a novelty plate I had made.... there were just so many people getting their panties in a twist about these cars being called a fiata, I decided to roll with it...… by the way I am quite grateful there is a considerable amount of mazda engineering in these cars.... since 89, that's close to 40 years to get it right...
 

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Just wanted to point out that the problems with lubricating the NC shifter assembly arose because, on assembly, Mazda used a general-purpose type of grease that hardened and fell off. When that happened, the first thing to wear out was the nylon cup (the "plastic ring" in the document specified above) the lower shift ball rode in, and that cup also acted as a seal to control gear oil from the transmission case at the bottom of the shift assembly. So oil would seep past the cup and coat the shift ball and assembly, and since the lubricant was general-purpose, the remainder of it would wash off. The result? Abrasive gunk, which was a mixture of hardened grease, gear oil, nylon particles, dirt and dust, and eventually metal shavings from the shifter pins. All of this happened fairly fast - in some vehicles within the first fifteen to twenty thousand miles.

I owned a couple of NC's years back, and both had this problem. I cleaned out the shift assembly, replaced the nylon cup with a brass cup (at the time available from Goodwin), and lubricated the lower assembly with one of the lighter wheel bearing greases with a moly additive. That seemed to work well.

I don't know whether FCA specified a better lubricant for the shift assembly used in the 124 or whether the design is different; I hope so. Perhaps someone has checked on this.
 

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Relating to the discussion here on the 124/Miata NC manual transmission shifter, following is a show-and-tell blog from Walter Motorsports -- subject is advantages and installation of a brass shift collar to replace the OEM plastic part. Installation is specific to the Miata NC, but is informative on the 124.

(Walter Motorsports is an excellent source of info on the NC transmission, and - so far - the only solid source of info on the serious design and performance problems in Mazda's ND transmission.)


 

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Discussion Starter #13 (Edited)
Gear Poet, thank you for posting this information, that looks like a good link to reference for this project and other NC info. It seems this plastic to brass upgrade will be worth the effort, and something I'm going to look into for this spring once the winter temps moderate and I can wake up my Spider.

Edit- here is that part, actually made from bronze rather than brass. $30. It seems to be out of stock at the moment, but I'm going to contact them about future availability.
Bronze shifter bushing

Steve.
 

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Walter Motorsports is close, I may have to try installing this while I have the console apart to install the Mazda Carplay/Android Auto hardware.....
 

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It's possible that the 124/Fiat shifter has an OEM bronze cup; Fiat did specify minor changes to the NC transmission, including the shifter housing. I haven't been able to verify anything on this, and won't be taking the shifter apart until summer. If anyone knows, speak up. Thanks!
 

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Discussion Starter #16
Gear Poet, thank you for posting this information, that looks like a good link to reference for this project and other NC info. It seems this plastic to brass upgrade will be worth the effort, and something I'm going to look into for this spring once the winter temps moderate and I can wake up my Spider.

Edit- here is that part, actually made from bronze rather than brass. $30. It seems to be out of stock at the moment, but I'm going to contact them about future availability.
Bronze shifter bushing

Steve.
I received a message back from Walter, asking if the factory Fiat shifter bushing for the NC 6-speed had an outside diameter of 22 or 24mm. My guess is they've not dealt with the Fiat application of the NC transmission.

Does anyone know, 22 or 24mm outside diameter? I wouldn't be opening mine until I had a part in hand.

Steve.
 

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Discussion Starter #18
I may have mine open in the next week or two and have Walter's bushing to compare.
Standing by, thanks.

Steve.
 

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That may be a difference between the NC1 and NC2 Miatas -- for the '09 model year, Mazda changed a number of things, including gear coating and shifter components in the transmission, IIRC. I'm speculating that the 24mm bushing is the correct part for the 124, since the transmission it uses is an "upgrade of the NC2 minor upgrade."
 

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Discussion Starter #20
I may have mine open in the next week or two and have Walter's bushing to compare.
@whr3, any progress on your end for getting inside your gear shift assembly?

Thanks,
Steve.
 
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