What is the mode of operation of an ST300 trans if the vacuum line to the carb is cracked/disconnected?

Vikki,

I drove mine with no vacuum line for a short period of time. I never had it above 45 mph so it was always 1st gear anyway. I'm not sure if this is what you are asking though.

Vikki, it acts like it's at full load. The trans sees the low/no vacuum as open throttle and shifts accordingly.

I had my ST300 rebuilt recently. The vacuum line to the carb is not hooked up. The trans seems to work perfectly. Will this cause problems?

i dont understand how it could shift right without the modulator Don.... are you sure there is none and that you have each gear when you should?

i would still hook it up. it's not there just for looks, although i think they do sell chrome ones

Thanks Scott. It sounds like the transmission is getting vacuum from somewhere, maybe the back of the manifold??? I will look closer this weekend.