When rebuilding your engine it is important to spec the end play correctly on the engine. This is the amount of free play on the eccentric shaft measured using a dial indicator on the end of the eccentric shaft.
Please follow the instructions in your specific Mazda engine rebuild manual for procedures and specs.
Understanding the sizing of spacers from A through to E can be impossible when all you have to go on are part numbers when ordering. To help with this we have put together this simple guide that will give you all the information you need.
Please note that this guide is for the later end play spacers used from the RX-7 FD3s, Eunos JC Cosmo and the later RX-8. This is not the same as the earlier spacers information and sizes can be found towards the bottom of the page for the earlier spacers.
Late style End Play Spacers FD, JC Cosmo and RX-8
Each spacer is not a fixed size due to manufacturing tolerances they have a size range.
Spacer sizes according to part number
| Stamp A B C D E |
Part Number NF01-11-D55 NF01-11-D56 NF01-11-D57 NF01-11-D58 NF01-11-D59 |
Thickness (mm) 7.975 – 7.995 7.995 – 8.015 8.015 – 8.035 8.035 – 8.055 8.055 – 8.075 |
Thickness (thou”) 0.3140″ – 0.3147″ 0.3148″ – 0.3155″ 0.3156″ – 0.3163″ 0.3164″ – 0.3171″ 0.3172″ – 0.3179″ |
To adjust your end play it is pretty simple, once you have measured the end play of your engine if it is out of spec according to the manual for your engine, you will need to select a different end play spacer.
I have too much end play?
If your engine has too much end play then you will need to select a smaller (thiner) spacer for example stepping down from a (common size) D spacer to a C spacer. this will make the space on the front stack smaller giving you a tighter tolerance and less end play.
I Have too little end play?
If your engine has too little end play then you will need to select a larger (thicker) spacer for example stepping up from a (common size) D spacer to a E spacer. This will make the space on the front stack larger giving you a looser tolerance and more end play.
Early style End Play Spacers SA22c, FB and FC3s Engines
The early model end play spacers are different in size, both thickness (the total height of the spacer allowing for adjustment of the end play) and the wall thickness of the spacer being thinner than the later spacers. Please note that you cannot interchange these spacers between early and late model.
The lettering and sizing of the earlier spacers is also totally different to the later spacers, please follow our guide below for specs.
Each spacer for the early model engines has a fixed size single.
Spacer sizes according to part number
| Stamp S T X K Y V Z |
Part Number 8871-23-129 8534-11-518 0839-11-506 8519-11-517 0839-11-508 0839-11-502 0839-11-509 |
Thickness (mm) 8.12 8.10 8.08 8.06 8.04 8.02 8.00 |
Thickness (mm) 0.3197″ 0.3189″ 0.3181″ 0.3173″ 0.3165″ 0.3157″ 0.3150″ |
I have too much end play?
If your engine has too much end play then you will need to select a smaller (thinner) spacer for example stepping down from a K spacer to a Y spacer. this will make the space on the front stack smaller giving you a tighter tolerance and less end play.
I Have too little end play?
If your engine has too little end play then you will need to select a larger (thicker) spacer for example stepping up from a K spacer to a X spacer. This will make the space on the front stack larger giving you a looser tolerance and more end play.
