I recently had my 01 LS transmission rebuilt with a full set of carbon Synchrotech synchros. The transmission shifts well in all gears under normal driving conditions. When I attempt to make a 1/4 mile pass and launch the car hard the tranny just does not want to shift smoothly 1rst-2nd and 2nd-3rd.

When a 1-2 or 2-3 shift is missed something very strange happens. The tranny becomes extremely difficult to shift into 4th? Sometimes totally locked out of 4th like the gear is gone. This is only temporary though. When the car has cooled down and driven the next day 4th gear comes back. Almost like the tranny is heated up and wacking out all of the tolerances.

I am using Honda MTF, tranny fluid levels are fine, clutch is bled, new competition clutch, new throwout and release bearing.

My only idea is that the gearset itself has some issues. This is extremely frustrating as I just had the tranny fully rebuilt with new synchros, I should not be experiencing these issues. Any ideas?

 

Were the synchros the only thing that were replaced when you say "rebuilt?" What were the condition of the gears, sleeves and center hubs? Do you have any photos of these so we can take a look? Or you can also send in the shafts to us and we can perform an inspection on them free of charge.

 

James, I appreciate the quick response. I will stop by the shop who did the work later today and come back with some answers. I do believe that only the synchros were installed which leaves me to believe there may be an issue with the gears. It's looking like I will have to pull the transmission back out in which case that would awesome if you could perform an inspection. Thank you!

 

I bet the sleeves/hubs are shot, or possibly the shift forks and/or gear change selector.

 

If the old synchros were badly worn its almost certain the sleeve/hub was also and should have been replaced.

 

How old is the clutch?

 

The sleeves and gears almost always wear before the synchros do. I have seen synchros wear past the service limit, but not all that often. I have seen lots of synchros still within spec where the sleeve and gear was beat to pieces though.

Btw, if you're doing 1/4 mile passes I'd switch to Torco MTF, Honda MTF breaks down pretty quick under those conditions.

 

The sliders and dog teeth are probably worn. Ditch the Honda MTF.