My TH400 shifts from 1st. to 3rd. I replaced the modulator recently as it wasn't working at all (really high shifts). Now it shifts at what should be normal cruise rpm, but directly into 3rd. for some reason.
I scienced out a kickdown switch also, and when its engaged, it shifts all the way down to 1st. - even at highway speeds it seems to want to go down only to 1st, if you're going slow enough like below 55 mph or so. Won't go down to 2nd. though above that. It stays in 3rd.
I *do* have a 2nd. gear though. If I shift manually up through, its there like no prob.
Any ideas? Thx. smile.gif

You likely have a problem with the intermediate sprag. The sprag is what holds for 2nd gear. But, there is a braking band that will apply on the 3-2 downshift, or if you are in manual 2nd gear. This tells me the sprag has taken a dump. The best one to use is the 34-element one, but you need to have the early 65-69 drum for this sprag to fit on. The later drums had a different style that the inner race will not allow use of the 34-element version. If you cannot find an early drum should one be needed, they are available from most trans companies, or you can hunt one down in a junkyard tranny.

Hmmm bad news but thanks as always Steve...