I don't think it will destroy your transmission. I think its a myth.
I manually shift mine maybe every other day... I think you'll be fine so long as your downshifts and upshifts a clean (i.e. don't sound like the tranny is gonna break ).
The trans doesn't even know what shifter is on it. If you don't change the valvebody the trans will act just like stock. Imo ratchet shifter are cool for about a week. Then the start to be a pain. Unless you drag race a lot it may not be worth the trouble.
they are electronically controlled, so you can program everything in to the software; however, you can manually overide that program by upshifting manually at your desired rpm; I was told by my tranny builder (5R55S rebuilt by Level 10) that you can feel free to "upshift whenever you want, but the tranny was not built to downshift" - I don't know if that means my tranny that he built, or the 5R55S in general, because I thought the 5R55S was also in the Lincoln LS, which had a manu-matic shift gate, but I don't really have much need for downshifting so I jst don't do it. I do have a TCI ratchet shifter, and I really like it- My shift points are pretty good for 1-2 & 2-3, but it seems to go a little early from 3-4. Last few times at the track, I left line in D, let the 1-2 & 2-3 shifts happen, then in 3rd I ratcheted (is that even a word) back the shifter into 3rd, and held out 3rd until redline and ratcheted into D... and dropped a couple 10ths from my ET... At some point I hope to have some time to play around with manually shifting the 1-2 & 2-3 shifts to see if that makes a diff also...
Been wondering this myself slightly. Best i can figure is, as a rule of thumb, up shifting is ok but down shifting is bad. The only time i do any type of manual shifting with my auto is turning my overdrive off when i'm about to hit 1 of 2 hills i go over on a semi-frequent basis. When I do turn it off I'm generally below 20 MPH if not stopped. These hills only hit about 40~ but for whatever reason i tend to be able to ride around 40~45 with O/D off and with it on i'll just keep gaining speed.
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07 Mustang GT Metallic Alloy. + other spiffy stuff.
Yeah, its really only downshifting that kinda worries me.
going from D into 3rd is fine in terms of how the car feels, but I occasionally get a pretty quiet-yet-disconcerting 'clunk' noise when I go from 3rd to 2nd (always under 25 mph when I downshift from 3-2).
I don't wanna break it as I need it to go to work (and therefore pay for it) but it makes the auto so much more fun
I want to keep this car for a really long time as of now, but I fully intend to get a manual mustang to be its garage buddy when I'm older
There's really no need to downshift it manually, as it will do that "automatically" when needed.... I have never heard of any problems turning off OD via the button when you don't want to use OD
Been wondering this myself slightly. Best i can figure is, as a rule of thumb, up shifting is ok but down shifting is bad. The only time i do any type of manual shifting with my auto is turning my overdrive off when i'm about to hit 1 of 2 hills i go over on a semi-frequent basis. When I do turn it off I'm generally below 20 MPH if not stopped. These hills only hit about 40~ but for whatever reason i tend to be able to ride around 40~45 with O/D off and with it on i'll just keep gaining speed.
I downshift my auto manually quite often when I feel like playing. The only advice I could add would be to blip the throttle as you downshift to match rpm to the lower gear or nail the throttle as you shift to prevent the transmission speed overrunning the engine rpm and causing the clunk when it engages. It's like downshifting a non-syncronized manual and matching transmission and engine rpm to prevent grinding gears.
manually upshifting is a blast, i cant wait to buy a ratchet shifter, but the car really doesnt feel like it likes downshifting.
As of now right the only ratchet shifter available for the S197 5R55s transmission is the Street Fighter from TCI. B&M says it is working on one but there are no prototypes available as of yet.
After threads like this, all I can say is "Man! I'm glad I traded the auto in for a stick!"
FYI;
I put over 40,000 miles a year on my car in what was just ranked as the 8th worst city for traffic in America, and I PREFER the 100,000 + miles I've "sticked and clutched" over the 40,000 I ran on the slushbox.
I other words... don't whine to me about sticks being too rough for city driving- Been there, done that, and I'll choose the manual tranny every time.
you're probably better off just retuning the shift points electronically to get more rpms before each up shift and leaving it in drive.
That said,
it is fun to manually shift. (That's why I traded in my Auto for Manual....) besides, they give you those lower gears for a reason, other wise autos would only have Drive and Reverse.
I used to Manually shift my Auto S197 from time to time... I would only UPshift and let the car downshift automatically once I reached drive.
Shifting the 5R55S automatic manually 
).
) back the shifter into 3rd, and held out 3rd until redline and ratcheted into D... and dropped a couple 10ths from my ET... At some point I hope to have some time to play around with manually shifting the 1-2 & 2-3 shifts to see if that makes a diff also...
all motor now.Don't ask.
