I'm not a tranny guy by any means. I've read many of the posts in this section and seen that people have/or will have shift issues with not having enough vacuum running to the tranny. This may be a dumb question, but like I said, I don't know much about transmissions. My TH350 is shifting late into 2nd & 3rd. I plan to pull the tranny in a couple weeks to have it rebuilt. But I was curious, how much would a disconnected or damaged transmission vacuum line throw off the shift point?

I'm not a tranny guy by any means. I've read many of the posts in this section and seen that people have/or will have shift issues with not having enough vacuum running to the tranny. This may be a dumb question, but like I said, I don't know much about transmissions. My TH350 is shifting late into 2nd & 3rd. I plan to pull the tranny in a couple weeks to have it rebuilt. But I was curious, how much would a disconnected or damaged transmission vacuum line throw off the shift point?

Yes, A vacum line would cause a big difference if it was disconnected. It happen to me a few years back. The line was going from the intake to the transmission vacum canister. you can always drain the oil and change the filter. Then add some high pro fluid and get the level right. It has to be checked when running also drive a few miles then check it again. The level of the fluid can cause shift problems as well. There could even be a leak at the canister or the fitting at the intake. Hope any of this helps.

If your vacuum modulator is disconnected your transmission then "governor" shifts. The govenor is calibrated to allow the transmission to shift properly under high RPM operation. For examble when you have the throttle wide open (foot on the floor) its the governor that causes the transmission to upshift. Without the vacuum modulator all you have ( in practical terms) is the governor so that you are always having to rev the engine high to get the transmission to shift. Unpleasant to say the least when you are in town.

Thanks for the help guys. I checked my car today. The steel vacuum line doesn't hook directly into the vacuum canister on the transmission. There was a 2 inch piece of rubber hose connecting the two. The hose was rotted out, thus causing the transmission to not have any vacuum. I replaced the hose (that autozone gave me for free since it was such a small peice) and took the car for a road test. The shift problem has been solved. And here I thought I had to have the tranny rebuilt. I have this forum and the knowledgable people to thank for this quick and easy fix. Thanks again!

Now you can spend that trans rebuild money on other 'mods'. :thumbsup:

I had the same problem, except the rubber line was kinked. I snipped a bit off and all is good.