Recently I found the shifter is very stiff on my Miata, and shifter has a lot of play no matter in neutral or in gear. I realized the shifter needs some care.
I bought a shifter rebuild kit from Treasure Coast Miata: New OEM ’90 – ’05 5 speed Shifter Full Maintenance Kit
Besides the items in the kit, you’ll need:
- 75W-90 Gear oil*
- A turkey baster of syringe to extract old oil from turret
- Shifter boot leather(not included in the kit)
Scarlett: Both the manual transmission and the differential takes 75W-90 gear oil. However, the differential requires GL5 while transmission requires GL4. You can use either GL4 or GL5 in the turret.
I didn’t expect the existing parts to be in a good condition, but I was still surprised when I revealed the shifter parts. A good amount of rubber on the upper shifter boot has completely gone. Most likely the shifter was never serviced before.
Look how much play is there!
When I pull out the shifter stick I immediately noticed something is wrong — where is the bushing?
Remove the old oil with syringe or turkey baster.
The OEM plastic bushing is already broken into pieces. I managed to fish them out.
Remove the old parts from the shifter stick, re-assemble the shifter stick with new parts, following this diagram. On my shifter the half moon bushing was broken and one of the pieces were stuck in the shifter. I ended up drilling it out.
There are one bushing and one washer in the turret, replace them with new parts, fill the turret with oil. It takes 3oz(around 90ml) I used Valvoline 75W-90 GL5 gear oil(same as differential). Put the shifter stick back in.
Shifting is much more better.
Reinstall the upper shift boot.
Put everything back together, and enjoy.
If you want to know more about how manual transmission works, watch this:
More about Project Miata
Project Board: https://github.com/users/frankgx97/projects/3/views/1