Save your M5ODR1, M5ODR1HD or M5ODR2 manual transmission
The 3 factory rubber plugs for the shift rail holes in the top cover may harden and fall out at higher miles, letting dirt in and fluid out. This is a ticking time bomb for any M5ODR1, M5ODR1HD or M5ODR2 manual transmission. It can be easily corrected by substituting metal core plugs Dorman 555-108 or equivalent. Another method that requires more disassembly is by tapping the holes and installing threaded pipe plugs. Either way, this fix should be a priority for anyone using one of these transmissions.
The original rubber Mazda shift rail plugs that may fall out:
Holes with the Mazda rubber plugs removed:
Dorman 555-108 core plugs installed:
Although it has been mentioned on this forum before, not everyone has heard about this issue. It's important so it needs a thread of its own.
And Bob, you working on a MROD-R2 for the truck? I have a feeling that prompted you to post this up LOL.
As a matter of fact, I have a new R2 sitting in the garage.
Actually, I started a new thread about the Mazda plugs because there was a question about them buried in another discussion not directly related to this issue. I think it will be good to have the info out there under its own title.
Originally Posted by claplo
Where can we get these ` Dorman 555-108 core plugs ` ?
Most chain auto parts stores carry Dorman parts. If you walk in with the Dorman part number and they don't have it, there's a good chance they can order it or cross reference it.
I have never installed them with the transmission in the vehicle. Have you tried pulling the transmission tunnel cover? If that won't work, maybe it's possible to gain some clearance by dropping the transmission down a little with the crossmember unbolted?
There should be way. If not, then the plugs could be replaced when the tranny is out for the annual clutch and slave replacement.