Tranny help

So I bought an 89 CRX Si from a dealer and it started shifting funny I took it to jiffy lube and got the tranny fluid changed but it still does it, so here is the problem.
When I'm shifting into second if I don’t let the tac drop all the way it grinds into second. It’s the only gear that it grinds into and it only does it when its warm and I am over 500 or 600 rpm. It’s always second and that’s it. Even after I got the fluid changed it still does it. Any ideas?

Also I was looking for some way to make or buy covers for the rear speakers to put in 6 x 9's in the rear. The fronts where already done but the rears are just screwed in by one screw. Anyway thanks in advance for the help.

synchros are worn. Could try a transmission fluid with a friction additive.

honda put 6.5s in the rear, so unless you want to switch, you will have to build custom boxes

double clutch and it 'shouldnt' grind.

Double clutching does the trick. thanks a ton. ill have to try some gm syncromech with friction additive and see if it keeps me from wearing out my leg. good thing its only second gear. also do i have to replace my whole tranny just to change out the synchros or can i do it myself and how much?

Just rebuild the trans.