redbird555

iTrader: (14)

Hey all I'm hoping someone who builds these things regularly can chime in here cuz I'm pulling my hair out....I rebuilt my t56 due to a bad 2nd gear and synchro hub. So i got it back together with all new carbon synchros and Immediatley on the test drive everything up-shifts fine but if I tried to downshift to 4th it felt like there was no synchro there like it went right into the gate and started to grind.

So I pulled it back out and everything looked fine! i figured i had a bad synchro ring so I replaced it, the hub and gear looked fine so they were left and now i have the same issue. Its only with 4th gear and sometimes it will work for a week just fine and then other times i get in it and its like i have no resistance in the gate it just falls in and starts to grind. but it will still upshift just fine. going to other gears first doesnt help. Please help! if I pull it apart again i think i'm just going to order everything for 4th gear lol.

I was thinking the machined cone of on the gear could be worn out and not catch the synchro or the keys in the hub could be messed up and i overlooked them I'm just not sure though. Looking for advice here.

redbird555

iTrader: (14)

anyone??? at a loss here

jmd

iTrader: (4)

If the blocker ring bottoms out on the gear cone, it will fail to synchronize. Gap the bottom of the blocker ring; can't remember what the spec is off-hand.

Are the interior notches of the slider matched to the key openings in the hub? Are the keys re-used or new?

To what endplay did you shim on the maindrive / mainshaft? 4th opens up if it's too loose.

redbird555

iTrader: (14)

endplay on the shaft is within what tremec recommends I believe we got .002. the keys on the 3-4 synchro looks great and so they were reused as well as that slider. and the keys were all indexed to the aprropriate notch on the slider and lined up with the hub. its just the oddest thing because it will work perfectly when it wants to and then the next time i go to down shift it just goes right into the gate and starts grinding like theres not even a synchro there.

correct me if I'm wrong but if the end play or alignment was off I'd have issues shifting. which i dont the transmission shifts awesome its just downshifting into 4th and only 4th that only has trouble.

from what i gather from your post jmd the cone on the gear can wear out? I'll check to see what the specs are asap, i may just replace the gear and slider to be safe but we will see. can a worn slider or worn gear cone cause this?

redbird555

iTrader: (14)

ok so by looking at 4th gear and the synchro it seems theres something up with the cone on the gear. i can push the synchro ring almost all the way to th face of the gear and it seems like it catches on the cones but if i put some effort into it i can easily overcome the friction and spin the synchro ring on the bottom of the cone. therefore it appearts the 4th gear cone is done... thanks for the help jmd should i also look into replacing that 3-4 synchro assembly also? how can i tell if the slider grooves or keys are worn out?

jmd

iTrader: (4)

Post detailed clear pictures.
If stock, go with new keys always.