so i have a 93 Si, 162K

the transmission has started grinding going into 4th, but only when you shift quickly OR above about 60mph. this is sounding like a synchro to me, but im looking for other ideas.

the other thing ive thought about is the shift fork, but 3rd doesnt seem to have any problem.

any thoughts or ideas are appreciated.

 

synchro.
try changing the fluid first to see if it gets better

 

agreed, also you can try some GM synchromesh in there to sort of band-aid your problem til you can get something together.

 

95% chance of synchro issue.
15% chance that the sleeve is bitched up enough to cause this without synchro failure.

lol. I know, I pulled the percentages out of my ***, but I'm going to say synchro is definitely the issue. Fluid won't help at all, synchronizers are brake pads; when brake pads wear out of material, you replace them. You do the same with synchronizers.

 

so from my research, i see that to get the same ratios i have to use either a 92-95 Civic Si or Del Sol Si tranny. is this correct? the EX has the same engine but a taller 5th gear. just wanting to make sure the info i got is correct.

 

yes. 92-95 civic ex, si or del sol si all used the same tranny.

 

what ive seen says the EX has a different 5th gear. .75 in the Si, .702 in the EX.