NewEdgeStang00

I just got the car back with a rearend rebuild, 4.10 gears with the sf3 tuner to complement it. It's an AUTO 01 GT. It jerks very slightly when accelerating and when accelerating from a stop, it goes all the way to 3k revs in first gear before it shifts. It jerks slightly for all gears when acceleration. When decelerating, it jerks hard going only into 2nd and I feel myself lunge forward -like engine breaking.

It's bone stock AUTO, called the guys at BAMA and they're going to send me another tune but.. Should it feel like that when I shift? I thought with a tune it would shift smoothly like a stock auto.

jtb727

if you told bama you have 4.10s bama probably upped the line pressure for your trans to get it to shift harder and faster. smooth shifts are when the computer lets the tranny slip a bit before catching the next gear.. and are much slower shifts..

you'll really notice the hard "clunk shifts" when you get on it hard, and than let up to about half throttle right before it shifts..

NewEdgeStang00

Thanks jtb I feel better about it now, does that put any strain on the tranny or engine though? And is 3k too high for it to be shifting? Even when I ease on the gas it won't shift till around 3k

trailor

a ford mechanic friend once told me that autos work better when the shifts feel "harder" as you say, because by allowing the tranny to "slip" as mentioned previously, you are actually putting more wear on its components. unfortunately, the general public prefers ultra-smooth shifts over tranny life and performance, so the hard shifts you're feeling wouldn't feel "normal" to the average auto driver. therefore, no, you should actually be experiencing less wear on your engine and transmission components (provided bama tuned the shifts correctly).

NewEdgeStang00

Oh understood, yeah I don't mind if it feels rough just as long as it doesn't mean anything will be broken down the road.

So the main issue now is, no matter how I drive it it will stay in first gear all the way up to 3k revs. Which can't be good for gas. I actually hear a distinct whirring sound before it shifts up

TRUEBLUE3934

Firm shifts were the intent of the tune that was written. No doubt BAMA can send you a tune with soft shifts, but the performance will decline as well.

It does seem odd that the trans refuses to shift below 3000rpm. There is no need to cruise thru town at 2900rpm if there are higher gears available in the trans.

NewEdgeStang00

That's what I thought, I thought that with town driving the 4.10 gears would get me up into overdrive sooner. But lets say i'm just going from a stop, the car will go up in revs and won't shift even if I feather it a little around 2k. When I get up to 3k it shifts. To explain the feeling, it's almost like the car started from a stop in 2nd gear. I don't feel ANY power at all from first gear unless I punch above 3k. Even at 2k in 1st gear I'm barely going 20 mph and it still won't shift.

Shampue

Have you called the tuner support? That would be the first thing on my list.

NewEdgeStang00

Yeah I called them already and they don't know, they said they'll send me a more refined tune with different shift points. I will probably play around with it but afraid of making it worse.

Also the acceleration is actually decreased, in order to get it to go I have to push 3k revs. In comparison.. My v6 actually accelerates faster, and that's not exaggerating.

NewEdgeStang00

Also when you guys say firm shift, does the whole car kind of jerk? When the gears jerk the whole car actually jerks forward a bit. I thought that with just a little throttle I should feel comparable acceleration