T56 first gear grind

vette427sbc

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My new (to me) T56 would grind when trying to put it into first coming up to a stop light. All other gears go in like butter, and first will go in fine if I put it in another gear first. Sounds like a synchro issue to me? I took it to a trans guy but I know he doesnt do alot of T56's. He took the front plate off to take a look at the internals and says it all looks good. Is it even possible to determine this by only taking the front plate off? Trans was supposedly rebuilt before I bought it off craigslist :crap:
If this was a clutch issue it would have this symptom in all gears, right?
 
So let's say you hit the clutch, shift from 2nd to 3rd and then to 1st it wouldn't grind???
How if you hit the clutch, take it from 2nd to neutral , give it some gas and then shift into 1st? Will it grind or not?

What trans fluid are you using?
 
So let's say you hit the clutch, shift from 2nd to 3rd and then to 1st it wouldn't grind???
How if you hit the clutch, take it from 2nd to neutral , give it some gas and then shift into 1st? Will it grind or not?

What trans fluid are you using?

If the car is moving at all, it will grind going into first no matter what.

If I am stopped in neutral (clutch out), I go to put the clutch in and put it in first, it will grind. BUT if I put it in second gear before I go into first, it will go in no problem. If I were to do the second-to-neutral-to-first scenario, it will go in fine. When I bled the clutch I had someone put the trans in gear and step on the clutch and I was able to spin the driveshaft by hand. That, and the fact that it goes into all other gears at a stop like butter leads me to believe that it is not clutch related.
Started with Mobile 1 synthetic ATF, then tried penzoil synchromesh. No difference with the grinding, although (unrelated) I think it shifted nicer with the mobile 1
 
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I use the pennzoil Synchromesh in my T5 (Mustang) and it shifts perfectly fine, didn't notice all THAT much difference to the ATF though.....

Did the T56 have that 1-4 skipshift or was all that removed ??? My C6 has it and I disabled it with a tuner. Mine doesn't grind but it is hard to get into first when the car is moving, I usually don't shift in first unless I'm at a standstill because even if it rolls at only 2mph accelerating in 2nd gear is no problem at all
 
I had the same problem with the T56 in my GTO - it was a synchro problem with it. The transmission ate synchros - as I've never, ever had a synchro die in any of my other manual transmission cars; odds are, there was a problem with the manufacture of the transmission.... some had a mis-alignment of the (IIRC) main shaft that GM replaced under warranty. There is some buzz on the internet that some of those transmissions got resold - true or not, dunno... Of course, Lee Johnson Chevrolet in Kirkland Washington refused to replace the transmission - thus my car spent 3 of the 11 months I owned it in their shop having the synchros replaced (repeatedly)... anyone curious why I have a Hummer now?

While 1st can go out, if you replace it and it does it again, see the second part of my advice (it'll go out in 12k miles or less if it has the problem)
 
No skip shift...
This trans is from an 04 GTO... Im thinking synchros too. Hopefully this isnt one of the re-sold ones
 
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