Hey all, I removed and partially took apart my transmission to reseal it and was wondering how to determine the health of the synchros. I measured the gap with a feeler gauge and it seems around the spec Toyota lists but it’s hard to tell.

 

That’s the way you check it according to the Toyota manual. If clearance measures good you should be good?

 

Are those cuts on the gear teeth and serrated like features normal? I've seen the cut like patterns on cam gears, this is wear not there when new.

..answering my own question those marks are machined from Toyota
https://www.driftmotion.com/New-R154...r-p/dm3836.htm

 

Since you already have your R154 apart for inspection it really is the best time to upgrade the following depending on which generation of the gearbox you have:

--aftermarket chromoly 1st gear thrust washer (especially important with 1st generation MKIII Supra style R154's)
--aftermarket chromoly front bearing retainer plate
--aftermarket heavy duty bearings
--aftermarket billet aluminum shift forks: 1st to 2nd, 3rd to 4th and 5th & Reverse

Driftmotion and Marlin Crawler both sell those kits and parts.

I tend to agree that as long as the synchros are still measuring within Toyota's TSRM specs and they look to be in visually good shape those should be OK.