I haver been working out some bugs with my 72 Cutlass with THM 350. When I start the car from cold, I can immediately put it in reverse and back out. But when I shift to drive, I get a 1 to 2 second delay until it engages. After that, including if I take it out of drive and immediately put it in drive, it engages and shifts fine. It can sit for a few hours and still engage drive just fine. It is only after sitting over night or longer.

Does the vacuum modulator play any part in this? Am I looking at a rebuild somewhere down the road?

Since it works fine after the initial startup, I am not overly concerned unless there is something wrong that if left unattended might get worse.

 

How is your fluid level? Is the color nice and pink, or does it smell like varnish? When was the last time your filter was changed?

 

Sounds like low fluid level. Check it when warm in park on a flat surface. The modulator is for upshifting, has nothing to do with engagement into gear. Of course if it's leaking then it could effect fluid level

 

Every time I've had one do that, it was telling me it wanted a clean filter. Change fluid & filter and see what it does.

 

Could be a front pump issue also......If you can live with it, it should still last for many years......My car did does this also....

 

Fluid is full, looks pink/red smells fine but, can't find any record that I changed the filter and fluid, so it is probably way overdue. I'll change it and see if that helps.

 

X2. The fluid is thicker when cold, and if the filter is clogged it will take longer to get to the appropriate clutch packs. Once warm, everything works fine.

 

I changed the fluid and filter, and it isn't perfect, but it engages drive much more quickly than before.

Normal driving and acceleration it seems to shift fine, but on heavy acceleration I don't like the feel of the shift, especially 2 to 3. It seems to be a 2 part shift where it kind of shifts, then seems to drop it in to 3rd and it jolts. Not a positive smooth shift.

Any ideas?

 

Well most trans are rebuilt to shift nice and smooth into the various shifts.....If you built it for a more HP application it will shift harder into 2 and 3......When I shift mine it hits so hard it knocks dirt out of the wheel wells! lol If it isn't a drag car I would run it and see how it does,if you cant stand the way it shifts into 3rd its time to pull it and get a rebuild........my .02

 

Unfortunately, a rebuild may be the real solution, but it isn't bad enough that I want to do that now. For most driving it shifts fine. I don't think the car has ever been modified for more performance, so may just be getting old and worn.