Technical Bulletin Issued by ACT

ACT discovered problems with the broaching tool used to create the splines in Miata clutch disc hubs. Two recent abnormalities are beyond acceptable wear limits and severe enough to cause incorrect fitment to the transmission input shaft.

Upon these findings, the broach was immediately retired, and alternate sourcing is being used until a new broach is made. The issue went undetected for recent production of disc hubs, some of which unfortunately are in clutch discs shipped to customers.

Steps have been taken to assure this does not happen again. ACT has obtained a production Mazda input shaft for an additional quality gate of future production.

With an abundance of caution, we are asking that any clutch disc with these part numbers built from 12/01/2017 – 06/01/18 be returned directly to ACT for exchange or repair:

ACT Part #            Mazda Part #

3000214               0000‐02‐5436‐SS
4224205               0000‐02‐5417‐AC
4200005               0000‐02‐5411‐SS
4214005               0000‐02‐7439‐SS
4224005               0000‐02‐7440‐SS
4200105               0000‐02‐5412‐AC
3000202               0000‐02‐5410‐SS
3000203               0000‐02‐5413‐AC
6224205               0000‐02‐5419‐AC

Please following these steps:

1.      Under the ACT logo, there will be a 9-digit numeric serial number. The first 6 digits are the manufacture date in year/month/day (e.g., Today any parts we manufacture will have a serial number of 180629XXX).

2.      If you have a disc with a production date of 12/01/2017-06/01/2018, please contact ACT directly via email at Put in the subject title Mazda Hub TB.

3.      We will contact you and ship you a replacement clutch disc and issue a return label for your old clutch disc.

We appreciate the patience shown by all as we sort through this. ACT is now once again producing the reliable components customers have come to expect. 

Please let us know if you have any questions or require additional information.


Rich Barsamian
Vice President, Sales & Marketing