Lately my transmission seems to be wanting to go into the lower gear when shifted at higher RPMs. So when I shift from 3rd to fourth @ 5400rpms it wants to hit 2nd, weather i shift slow or fast. If I just take it to say 4500rpms it runs right into the propper gear. Any Ideas what might cause this or is it just user error?

PS: it always grinds loudly when shifted into 3rd as well. I took it to have the engine tuned up and it came back grinding like this. the mechanic swares he did nothing to it.

 

sounds like your transmission is hosed and needs a rebuild.