Hi all, am looking to buy an early1.5 0r 2.0 RF . Am concerned with some of the issues being raised on early cars around gearboxes hard to select 1 and 2.
Does anymore know when v 5 was introduced of the gearbox from what date / chassis number etc are cars with v5 ok ? Thanks
If you are buying a 2.0 make sure itās an ND2 - Not sure of the gearbox version number but they were upgraded for the revised engine (184) late 2018 availability (2019 model year I believe)
Rob
I believe the ND2 is equipped with a DMF on the 2.0 that reduces torque spikes to the gearbox
Thanks for the info
But donāt assume every earlier ND will have problems - itās not actually compulsory. Mineās fine, as is every other ND owner Iāve spoken to ā¦I donāt deny it IS a problem for some , but it is not universal
Iād love to know if itās a fundamental design problem, either internally or casing design (allowing unwanted flex) and if it can be mitigated by lubricant additives or driving style.
Also the symptoms and what actually fails?
Itās not as though any engine itās fitted to produces masses of torque.
Yes an ND2 has many advantages, more power better gearbox,if you can afford it.
DMFs arenāt without their problems though. Diesels have had them for years and they are a common replacement part after a few years and miles, and fairly pricey, turns a clutch change from maybe Ā£600 to Ā£900.
Not all ND1s have gearbox problems. As always have a long test drive working the low gears and reverse.
Mine is a 2.0 2018 with 15k miles, all ok so far. Iāve changed the diff and gearbox oil as a preventative measure and will every 2 years, as I only do low mileage, summer use only.
My understanding is that the version most prone to gearbox problems was the ND1 2.0l 167bhp engined version. There were very, very, very, very few problems with the ND1 1.5l 130bhp engined version and as mention above the ND2ās are not appearing to have any serious problems.
Iāve heard the same, in fact the sales guy (ex mechanic at the same dealership) weāve just bought our new CX from was saying theyāve never seen a box failure, and theyāve shifted a lot of mx5ās over the years.
Itās obviously a thing as Mazda have revised it a few times, but as you say, really quite rare.
Not sure Iād want to risk increasing the torque by much though, the plan was to turbocharge itā¦
'My understanding is that the version most prone to gearbox problems was the ND1 2.0l 167bhp engined version. ā
Yes, but mostly limited to the version 1 gearbox, when the car was first released and to about a year and a half after. Version 2 boxes have/had suffered much less failures, and version 3 less still. Dito version 4. So it isnāt necessarily a full ND1 problem, but more a āpossibleā early ND1 problem. Finding out which version a person has got is easy enough. They can read the code by poking their head in and to the side when the bonnets open. How to do it, and how to decipher the VIN code written on the trans, is explained well on a thread on the ND Miata forum, primarily where US owners hang out. I havenāt got the link to hand, but googling it will probably find it.
Likewise, the version changes, further up the ladder (V3,4,5 etc) arenāt necessarily due to iffy stuff on the prior versions, but general adjustments. As with many cars, parts can have new versions of things not JUST because the prior version was trash. This link gives version dates: MX-5 Miata Forum - View Single Post - Transmission issues
So, early version of the 2L with the V1 box ācouldā have issues, and most of any failures come from those cars.
A thread on the ND miata forum has a V5 failing (albeit on a tracked car, i think), so all might not be perfect.
The very best person to get advice from would be āroddersā (Paul Roddison) what he doesnāt know about the ND gearbox in itās various versions isnāt worth knowing.
True.
Yes, I was rather hoping heād chime in with his words of wisdom.
Iād like to know how much torque the latest revision (5 I think) can handle. I would guess the answer will be no more than5he standard carā¦
Well , thanks to our Sheffield friend , my 2015 ND is now packing nearly as much power and rather more torque than ND2 , so far without issue from the allegedly chocolate fireguard gearbox .
Hi John, did you have a āRodderās rebuildā?
Hi guys
Basically ALL the ND1 gearboxes are the same, the ND2 is slightly different in that it allows for a DMF but thatās about itā¦
The ND2 has more reliability due to producing less torque.
This meant when we built a 2019 ND2 race car it was no quicker than a āmappedā ND1 with everything else exhaust/suspension etc exactly the same, early car making more torque.
Re our gearboxes
We have many cars running 200bhp 185ft lb with our cams fitted doing track work with 100% reliability
For info our stronger box is Ā£1500+vat exchange thatās about Ā£600 cheaper than a Mazda box.
Thanks Paul! 
Iām back againā¦lol
We have in the last couple of weeks replaced not 1 but 3 gearboxesā¦old ones currently in the workshop if anyone wants to view, the BEST thing you can do with ANY ND is change the gearbox & Diff oil annualy.
Thanks for the info.
Re oil changes, can you recommend manufacturers and grades, or even better supply the right stuff?
Iāve been looking and thereās lots of conflicting advice out there, especially on the US sites.
To answer Coolmintās question the following was put together on the previous post re the Mk4 gearbox issues. This information shows what parts were revised with each revision and when that revision was introduced into the production line.
Version 2:
1ST GEAR (Only for 2.0 litre engine), M602-17-271, used from SEPTEMBER 5th, 2016 Production.
2ND - 3RD GEAR, M601-17-305A, from July 6th to Sept 6th, M601-17-305B, used from SEPTEMBER 6th 2016.
3RD GEAR, M601-17-230A, from July 6th to Sept 6th, M601-17-230B, used from SEPTEMBER 6th 2016.
GEAR REVERSE (Only for 2.0 litre), M602-17-281, used from SEPTEMBER 5th, 2016 Production.
GEAR REVERSE IDLE (Only for 2.0 litre), M602-17-310 , used from SEPTEMBER 5th, 2016 Production.
COUNTERSHAFT GEAR (A.K.A CLUSTER GEAR), M601-17-301C, used from August 1st, 2016 UP TO April 3rd, 2017 Production.
Version 3: INSTALLED FROM April 3rd, 2017 VEHICLE PRODUCTION LINE.
SECOND GEAR, M601-17-251A, used from April 3rd, 2017 Production.
COUNTERSHAFT GEAR (A.K.A CLUSTER GEAR), M601-17-301D, used from April 3rd, 2017.
Version 4: INSTALLED FROM November 1st, 2017 VEHICLE PRODUCTION LINE.
CLUTCH HUB SET 1ST AND 2ND GEAR, M601-17-260A, used from November 1st, 2017.
SLEEVE CLUTCH HUB SET 1ST AND 2ND GEAR, M601-17-262A, used from November 1st 2017
Iām not sure when version 5 came in or what was changed.
The above revisions addressed 2 issues, one the failure of gears themselves and the 2nd an issue with 1st and 2nd gear synchro.
From the failures I have seen at Roddisons the nature of the 1st failure was gear tooth fracture from the root of the tooth. Without design information and metallurgical examination it is impossible to say what was the primary cause of the failure, it could be a design issue, material defects or manufacturing issues. All I can say was that there was a fracture initiated at the high stress point in the root of the gear and this crack progressed across the tooth until the tooth then finally fractured.
Because we donāt know the true cause of the gearbox failures, only Mazda will know this, it is impossible to say the whether an early gearbox is likely to fail when the car is driven normally and whether the issue, whatever it was, affected all cars or just some within the production range. However what Rodders did demonstrate was the gearbox could not withstand the stresses incurred on the race track.