My bw-8(12?) auto transmission in my pickup has started to slip a little in 1st gear, and sometimes it hums in reverse. This transmission was salvaged out of a 1966 1000-a series pickup. It does not act up all of the time, maybe about 10% of the time. Do not detect slippage at higher highway speeds.
A local tranny shop tech suggested I pull a vacuum on the modulator valve to determine if it would hold a vacuum. I hooked up my venturi style veneer vacuum pump, which I preset to pull 15 in of vacuum.
When I hook up the vacuum line which is connected to the modulator valve hose off of the intake manifold, will read 5" of vacuum on the gauge while the venturi is pulling vacuum. It will not hold it if I turn off the venturi. A previous test on the intake manifold vacuum was around 24"-27" at 2000 rpm.
The tranny is shifting. 1st to 2nd is around 20 mph, and 2nd to third is around 40 mph. 40 mph seems a little late, but May not be related to the slipping problem, but the modulator.
The vacuum test indicates a leak in the modulator, or the tubing between the modulator and intake manifold. If I cure this problem, will the slipping stop, or is it unrelated?
The tech also suggested I put trans-x in to soften the seals / o-rings. Said it might help cure the slipping and delay more expensive re-build. Is this a good idea? Can it hurt?
Thanks for any advice.
Edit: just looked at modulator after getting to my home garage. It is loose. Wiggles some. Need to put up on a rack to inspect and get a better view. Just remembered that tech said there should be a kickdown linkage from the carb. I do not see a place for such a linkage, nor anywhere to attach an electrical kickdown switch. Did all of these borg trannys have kickdown switches? Mine doesn't appear to have one. Do not recall the donor vehicle have such a set up.
A local tranny shop tech suggested I pull a vacuum on the modulator valve to determine if it would hold a vacuum. I hooked up my venturi style veneer vacuum pump, which I preset to pull 15 in of vacuum.
When I hook up the vacuum line which is connected to the modulator valve hose off of the intake manifold, will read 5" of vacuum on the gauge while the venturi is pulling vacuum. It will not hold it if I turn off the venturi. A previous test on the intake manifold vacuum was around 24"-27" at 2000 rpm.
The tranny is shifting. 1st to 2nd is around 20 mph, and 2nd to third is around 40 mph. 40 mph seems a little late, but May not be related to the slipping problem, but the modulator.
The vacuum test indicates a leak in the modulator, or the tubing between the modulator and intake manifold. If I cure this problem, will the slipping stop, or is it unrelated?
The tech also suggested I put trans-x in to soften the seals / o-rings. Said it might help cure the slipping and delay more expensive re-build. Is this a good idea? Can it hurt?
Thanks for any advice.
Edit: just looked at modulator after getting to my home garage. It is loose. Wiggles some. Need to put up on a rack to inspect and get a better view. Just remembered that tech said there should be a kickdown linkage from the carb. I do not see a place for such a linkage, nor anywhere to attach an electrical kickdown switch. Did all of these borg trannys have kickdown switches? Mine doesn't appear to have one. Do not recall the donor vehicle have such a set up.
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