Pulled the pan off my TH400 today to change the filter for the first time since the tranny was overhauled about five years and 5000 miles ago. I saw the usual fine gray clutch dust but was surprised to see some metal shavings in the pan, not a lot, but enough to get my attention. The tranny has seen nothing but fairly easy highway miles, nothing coming close to abuse. I'm going to keep driving it for the time being but am wondering if I should have the tranny pulled and disassembled in case something significant is developing. Anyone out there have an opinion....Scott

Some metal shivers are okay, some metal chunks is not okay. Every general service trans of mine I've done a drain, change & fill, have always had a 1/4-5/16 inch square of debris in the pan.

Some trans after 150K miles, are still good.

I work at a transmission shop and since you asked-here is what I recommend:

Change the fluid and filter.
Make sure you have a magnet in the pan
Add an aftermarket cooler (MOST IMPORTANT!)
Add a shift kit
Change fluid and filter every 30K miles, or sooner.
Use the best (Mobil 1, Red Line) synthetic auto tranny fluid you can buy.

When (not IF) the transmission dies, replace it with a manual.

I must admit that I am biased towards manuals. But then again that might be because of the 22 cars at my shop for work today-ONLY ONE OF THEM IS A MANUAL-and that is because the kid ran it without fluid in it..

In fact, since I have been here, I have only seen a handful of manuals, and most of those were for clutch replacement.

On the other hand, every single day, Dodges, Ford's, Chryslers, and some imports get towed in with broken auto trannys.

I know that auto trannys can be built to be strong-but you will pay an awful lot to do. But I know for the same money or less you can have a stout manual gear box with OD, or double OD that will go 5X the distance of most any auto tranny before needing repair/rebuild.