So I bought my 2007 Scion tC about 3 weeks ago. The fifth gear pops out like many others I changed my synchro expecting to solve my issue. Got it all on put back together but on test drive it is still the same story. I can hold it in fifth gear but the second I let up it pops right out. Does anyone know what else it could be?

 

I never felt that popping out would be related to synchros, and I think that's a misconception. Their only job is to match the speed of the gear to the shaft prior to engaging the gear. The parts that really engage are the 5th gear clutch hub assembly, 5th gear itself, and the slider, along with the fork. My guess is that the culprit lies with one of these. I suggest reading about 5th gear pop out on some older Rav4's. Their 5th gear design is quite similar, and I recall seeing a diy on how to change these parts out. As far as tools go, you will need a harmonic dampener puller and harmonic dampener installer to remove and then reinstall the clutch hub assembly.

 

Oh and to be clear, a bad synchro can cause excessive wear to the slider and gear components, but it's the wear itself that causes the pop-out behavior. In your case, changing the synchro on an already worn gear won't fix that issue, but at least it'll prevent it from recurring should you fix the rest.

 

Ok,sorry for long dramatic pause. I ended up dropping transmission and pulling fifth gear and replacing it all. I am now a proud owner of a working fifth gear! Over 45 mph here I come.

 

Lol, congrats! How much did the gears set you back?

 

I ebay'ed the crap out of it and it was about $200.00 with free shipping.