n_holman

I'm still 'learning my '69 Ninety Eight 4 door hardtop. My '71 Buick Centurion has , I think, the same Turbo 400 tranny. If so this tranny is the only thing similar to the Olds.

I'm experiencing early kick down when climbing relatively steep hills...(sometimes not so steep) especially when towing my Airstream. My Buick almost never needs to downshift and if so I manually shift it or if the hill is steep enough it WILL shift down. The Olds shifts down on hills at 60+ mph. I know the kick down switch is electrical. Can it be adjusted to not shift down unless the accelerator is fully depressed?

Thanks,
Neil

rjohnson442

Sounds like the control modulator on the transmission if it decides to **** down at 60 with no extreme load put on it. The placement of the switch Should be at WOT not part throttle. I'd remove power from the switch first. take it for a drive and if its still kicking down early it's most likely the modulator. Some are adjustable for different shift points.

MDchanic

Yup. Sounds like a bad vacuum modulator, or a leak in the lines to it.

- Eric

joe_padavano

That's probably right.

There is an adjustment capability on the switch if you need to use it. The switch is mounted with screws in slotted holes. As noted, you need to check the vac modulator as well.

Rickman48

There's also adjustable modulators available from most of the HP Trans co's. - B+M for one - need a thin screwdriver for adjustment through the vacuum hole.

n_holman

Shifting up during acceleration seems normal. From what I'm reading adjusting the modulator adjusts the tranny at set rpms while accelerating. My problem is the tranny is down shifting too early under a load as when going up a hill. From what your replies tell me I should be 'looking' at changing the adjustment on the kick down switch near the gas pedal. I am recovering from surgery stitches in my back so scooting around on it isn't advisable...right now...or when my wife sees me.

Thanks,
Neil

rjohnson442

Well if you can't crawl I'd push the switch back first to WOT. See if that helps first then