There'* a school of thought that says that flushes ( As opposed to just dumping the fluid & Filter) does more harm than good in some cases. Anyone agree?

Yes and no. As stated above if the fluid is extremely dirty or has gone well beyond the scheduled maint interval I would recommend leaving in alone. Now if the fluid is just starting to get dirty and is not that far past the maint interval I would flush the trans. This is just my personal opinion and is also based off of my personal experience.

this is generally only true in vehicles which are WAY overdue with the service (usually over 100k mi or more), or have pre-existing transmission issues. The thick, gritty transmission fluid is what allows heavily worn clutches to grab properly, when all the grit is removed VIA flush, then the grit isnt there and can cause worn clutches to begin to or slip more.

I completely disagree. I've never seen a proven or documented case where a flush took out a high-mileage trans. Both of mine included.

Unless the trans is going to fail soon anyway, and it won't be the flush that does it.
I flush both of my trannies yearly.

X2 that'* basically what I was saying.

willwren, we will have to agree to disagree to a certain extent. I am convinced that a flush on an overdue trans will cause it to fail way sooner than just leaving it alone. As far as flushing transmissions on a yearly basis goes, that may make sense for some, possibly in my case, where I average about 40,000 miles/ year, but what about some people who barely hit the 10,000 mile mark per year? Like I stated earlier, my own observations have left me to my decision of leaving it alone. It goes along with, how often do people change there transfer case fluid or rear end fluid? I just came back from a trip from N. Dakota to Oklahoma City and had absolutely no reservations of taking the bonneville. I'll be sure to write in when my trans goes out-137,000 miles and counting.

I also disagree. When I was at the shop that does the tranny work for ZZP a year or so ago, I ran that by one of the mechanics. He was skeptical about the material suspended in the fluid would really provide much benefit, but that maybe it could. He said that if a transmission failed after a flush, it was doomed to fail in the next 3 to 5,000 miles anway. He then showed some worn parts with friction material missing from parts of it, and wondered how dirty fluid could fill in those gaps.

What each person decides to do with their own vehicles is up to them. I become concerned when people advise others to ignore proper maintenance of their vehicles. If people don't want fo flush, fine...at least change the fluid and filter. I can also add anecdotal evidence with my daughter'* 91 GP, regular maintenance, 240,000 miles, orginal transmission. Worst problem was likely a sticking solenoid that a can of Trans Tune took care of.

long story short: EVERYONE disagrees here!!!

DO WHAT YOU WANT: TAKE YOUR OWN RISKS: INFORM YOURSELF: HOPEFULLY MAKE THE RIGHT DECISION

flush and new filter. not replacing the filter while your in there is silly. if you have cash to throw around replace the solies in your VB. personally i would do the whole thing at 100k and then again at 200k.

oh and clean the MAGNETS!