I figure i'll be getting a nelson tune soon and he'll know what to do but i was just curious as to what parameters need to be tuned now that the tranny has the vacuum mod. Did a search and only found that tc lockup and shift points(short thread) need to be tuned. Surely something else needs to be tuned. Anyone know? Thanks,

Bryan

 

Nothing.....with a VM tranny the PCM doesn't control anthing tranny related. At least that is what I understand after I installed my VM tranny.

 

I haven't had any problems with vac modded 60's. 80's, on the other hand, sometimes act weird after a vac mod conversion. They shift when they want to not when the ecm commands the shift at a given rpm/mph criteria. I've asked Gil or Glen @ transgo and no one is 100% sure why.

 

I've had the same issues with the 80E, it kinda shifts whenever it feels like. My shift tables are all funky to get the shifts where I want them, it's kind of an experimental thing, just putting random values in until you get what you want.

 

on a 60e you don't have to worry about shift firmness and shift speed, that's all controlled by the VM. The only parameters that make a difference is the shift vs. vehicle speed vs. rpms and the TCC tables.

 

The're also controlled via vm on the 80e, but something is causing weird things to happen. Shift timing/solenoid firing is still controlled via ecm and that's about it. The experts (aka the people who make the vm and shift kit)
can't pinpoint what's going on with the 80's.

 

thanks guys, i appreciate the help. i was just wondering cuz it seems like the tranny shifts a little earlier in the rpm range and i'd like it to be higher