Guys can you just replace the counter shaft 5th gear by itself. Here's my issue I don't have access to a press to remove the main small gear. I picked up a rebuilt t5 z spec t5 which works great and the 5th gear is .59 which is way to boggy at 60mph. It currently has a 27 tooth and a 59 tooth. My old WC t5 had .63 5th with 25 and 51 gear counts.(Front bearing failure and cracked the case) From doing the math I think replacing the 59 tooth with my 51 tooth and keeping the 27 tooth main it should give me .63 5th if correct assuming I can just replace to counter shaft gear my itself. My car is just a 305 cruiser and not abused. I know I should put a T56 but it sticks down to low for my lowered car and they are not readily available around here. Thanks
27/55=.49 x 1.29 =.63

 

Highly doubtful.

Gear ratio is the ratio NOT ONLY of # of teeth, BUT ALSO, of diameter.

You can try it, but don't expect miracles. The teeth may not even touch, let alone, mesh properly.

 

Helical gears don't mix-n-match. Without further detail, the shaft distances are static, so they wouldn't have proper tooth contact.
You'll need the matching drive and driven gears to change 5th gear ratio.

The T5-Z for Mustangs has a 28 spline mainshaft and the GM T5s were 27, so be careful ordering the right parts.

 

Thanks guys. Took the 5th gear set from my old trans and installed them. No mismatch problems.

 

Cool.

As A SET, they're mostly interchangeable. As individual gears, ... not so much.