Intermittent transmission problem: 2-1 downshift

[Woosch]

I have a very intermittent problem with the transmission on my '96 L36 SE. It has probably happened 3 or 4 times in the last few months. I'll be accelerating under light throttle in 2nd gear and I floor it enough to induce a downshift. 2nd gear disengages, but it doesn't downshift into 1st. The engine revs like it is in neutral. I let up on the gas, it shifts, and everything is fine. I haven't noticed any rough shifting otherwise. The car has 69k miles on it. I'm going to change the fluid and filter, but wanted to see if anyone here had seen or heard of this before. I searched the forum, but didn't see a similar problem listed.

Thanks in advance.

[LeSabre in Buffalo]

Probably the vacuum modulator needs to be replaced. I'd try that after new fluid and a filter.

[renchjeep]

Have the same problem with my 94 se, 220k on car, about 35k on trans rebuild w/upgrades. I have replaced the modulator with a new adjustable one, and changed fluid and filter. No change, still does it occasionally. Let me/us know if you ever find out what it is!

[Woosch]

I wanted to post an update on this problem. I replaced the transmission filter and filled the transmission with Valvoline Maxlife ATF this spring. The filter neck was so brittle that it broke off inside the transmission. I bought the car with 55k miles on it, so I wouldn't be surprised if the transmission had never been serviced.

I've put on 5k miles (including a 1400 mile road trip) and the shifting problem hasn't come back.

[MattStrike]

It's good to see that the fix can be simple every now and then