I purchased a used transmission case for my car, because my case had a leak from a crack.
The new case came and I noticed damage from someone using a bolt too long in the front mount.
I can see right through to the inside on the middle bolt hole. This is the front transmission mount.
I put in the correct size bolt and looked inside to see how deep it went.
This is the outside view. This could seal the transmission case….
but I had a cable to hydro transmission conversion kit that that bolts to the 2 lower bolts, and the upper bolt would be in the way.
I cut the head off a bolt. The washer was attached at the factory and was part of the bolt.
I then cut a notch into where the head was, so I can use a flat head screwdriver to install this plug.
I screwed it in as a test fit, and it looks great!
I used hondabond (a really strong holding RTV gasket maker), and covered the threads of the bolt.
Then I screwed it completely in.
I filled in the remaining area inside with hondabond.
I used this case for about a year, then a metal plate came up on the freeway and cracked the case.
The hondabond was still intact on the inside when I changed to yet another transmission case.