I have a 1971 833 23 spline 4-speed 340 car. My trans up shifts great, but have a tough time down shifting. I am currently using 85W-90 gear oil compatible with brass stop rings. The coldest temperature that I would drive it would be 50 degrees and the warmest would be 90 degrees.
I was wondering if auto trans fluid would make it down shift easier.
. If it up shifts okay but hard down shifting, the brass rings are probably gone and need replaced. Auto transmission fluid will make it shift easier, if everything was okay before you put the ATF in. If everything was not okay, then I doubt it will make a difference. If you want to try a different fluid, try 2 1/2 qts of regular engine oil. Maybe like a 30 weight. It is GL 4 like ATF and syncro oils.
