SM465 popping out of 1st (not Low)

[Hawkeye283]

Hi everyone. Just finished restoring my 75 K20. Took it out for it's first drive today. Everything went well except for one thing. It has a rebuilt SM465. It would pop out of 1st gear every time I would start to pull away. It would stay in Low, 2nd, 3rd with no problem. Even when I held it in 1st it would pop out. Everything shifts fine, got plenty of floor clearance. It fully engages in all gears when sitting still. The forks are GM NOS, so there's no wear. Put a OH kit in it with new syns/seals/bearings. To drive it, I would start out in low and skip over 1st and shift into 2nd with no problem. It stays in 3rd with no problem. Anyone heard of this before? Many thanks in advance! Tom

 

[Edelbrock]

I have hears of this happening in different gears. You are not alone. As for the cause? All I can do is Google " manual pops out of gear " which gives generic answers.

 

[Novapwr]

Mine did that but it needed rebuilt. And the guy said it was a bad synchro ring if I remember right. Rebuilt the tranny and shifts great. But yours is newly done so not sure that would be it.