If your shift points are too low the trans will shift hard. If you don't have enough vac the trans will shift hard. Your modulator could be bad. Pull vac on it with a mity vac. You should be able to pull vac on it with a few pumps, but it will bleed down pretty quickly. If you can't even pull vac on it, then it's toast.

It's common for these trans to shift worse when cold than warm. Thats usually a sign of a trans thats getting a little tired. But that doesn't mean theres nothing you can do. There are potential vac leaks to address, bowden cable adjustments, modulator adjustments, filter and fluid change, B2 piston replacement, K1 spring replacement, and/or a bottle of your favorite mystery trans cure-all(example is Trans-X).

Sometimes after you fix vac leaks the modulator needs to be adjusted slightly.

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