Transmissions and DrivetrainNeed help with your trans? Problems with your axle?
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hey all i just swaped a th350 into were a manual tranny was. (wasnt my idea)
i went for a test drive and the darn thing didnt upshift. but then i remember i didnt hook up that little vacume tube that goes to the tranny. my questions are...
1. is that the only thing that makes the tranny upshift
2. were should i steal vacume from to get the thing to work right, should i just tap into a vacume tube going to the throttle body
There's a vacuum port at the rear of the intake in front of the dizzy that was used on lots of pre-80s cars. Not sure what the size of the fitting is, but it may be available at a parts store or your local salvage yard. It IS required for the tranny to shift properly. You need to run a vacuum line from here to the fitting at the rear of the tranny. Factory lines were steel except at each end where they used rubber to attach to the fittings.
Not sure if lockup is available with a th350, you might want to send the moderater of this forum a pm or e-mail and ask. I would be interested in knowing that myself.
It will still change without a vacuum source. You just have to stab it and stay in it. Even with the vacuum disconnected it will shift out of 1st at about 6 grand. The springs in the governer will force it to change due to inertia at a certain rpm.
The vacuum modulator just needs a vacuum source to function. Like mentioned in an earlier post there was a vacuum tee on the rear of the intake that fed the modulator and other comonents. A vacuum line will work until you can make a aluminum one as long as it stays off of the exhaust manifold.
I had a TH350 in a '81 K5 Blazer I once had that had a torque converter clutch (TCC). Vacuum controlled the converter clutch solenoid inside of the tranny to make it engage. I ran it abled and disabled and couldn't see any difference in mileage.
That son of a gun only got about 10 mpg up hill or down hill, a/c or no a/c. I think I could've driven off of a cliff and still gotten only 10 mpg.
