[jas1212]

On my CS I noticed an option for shift firmness. I am kinda hesitant to change it, but would it be very noticeable? I wouldn't mind a little firmer shift. Any suggestions?

Thanks

[88Racing]

A little bit at a time.....don't over do it....

[JackandJanet]

Originally Posted by 88Racing

A little bit at a time.....don't over do it....

Do a search on here for "shift firmness" you'll get a lot of hits. Do as 88Racing says, to much is bad.

- Jack

[jas1212]

I was playing around with the shift firmness and didn't know in the beginning it was different for each gear. I changed it to 5% for each gear for now. Is that really low? How much would be to much? I like firmness but not like it's my first time driving a manual transmission. Know what I mean?

[Longshot270]

As the shift firmness goes up you'll notice the shift becomes sharper. Just realize that sudden, hard jolts are not good. If the shift feels like a kid kicking the back of your seat then you've gone too far and risk damage to the transmission and linkages. Also, you really don't want to go to the extremes in either direction. Too soft drags out the shift and can cause wear on the clutches.

[JackandJanet]

Longshot says it very well, and I've often quoted his "kick in the seat analogy".

What that feel means is: the driveline forward of the transmission gears is abruptly having to change rotational speed to match the new gear setting. If it's an upshift, the crankshaft, pistons and flywheel are all being suddenly slowed down. In a downshift, the reverse is true. The torque converter "softens" this a bit, but not much (or you wouldn't feel the "kick"). Think of the torque stress on the crankshaft when this happens and you'll understand why too firm a shift is not a good idea.

- Jack

[jas1212]

Oh, ok. So basically it's different for every truck? Not enough "firmness" isn't good but to much also isn't good? Some where in between is good? Would you suggest a certain number not to go past or not to go under? Like 5 is to less and 90 is to much?? This is all new to me and I am gradually getting the hang of this stuff. But with a vehicle it's quite a bit investment, and I don't have a ton of money sitting around for a fix if I do something to drastic and wreck my engine.

[JackandJanet]

Originally Posted by jas1212

Oh, ok. So basically it's different for every truck? Not enough "firmness" isn't good but to much also isn't good? Some where in between is good? Would you suggest a certain number not to go past or not to go under? Like 5 is to less and 90 is to much?? This is all new to me and I am gradually getting the hang of this stuff. But with a vehicle it's quite a bit investment, and I don't have a ton of money sitting around for a fix if I do something to drastic and wreck my engine.

Yes, it IS different for every truck, due to manufacturing tolerances, and driveline differences such as tire size and axle ratio.

But the real issue is that the firmness is already increased over stock in a canned or custom tune by what Bill feels is a "safe" amount (and he knows people like "firm" shifts). Remember, Bill is largely responsible for the canned tunes that Edge uses. He adjusts the firmness by modifying three parameters: Line Pressure, Torque Dive, and Clutch Band Lockup Delay. Of those things, the only thing you can change is the Clutch Band Lockup Delay - less delay, harder shift.

Now, when I hammer the accelerator to pass someone, my serpentine belt will slip (squeek), which is the reaction to a sudden change in engine rotational speed. It never squeeked with the stock tune. I don't see the need to have things more abrupt than that.

However, a +5 change in "firmness" is a 5% reduction in clutch band lockup delay, so if the "0" setting is 300 milliseconds, you've changed it to 285 milliseconds, which is probably OK. But again, since the firmness is already increased, I would not increase it too much more than that - especially the 3-4 and 4-3 shift points (where there is more stress on things).

The standard advice I give to anyone (including myself) is that unless you tune trucks for a living and know what you're doing, it's best to leave things to the experts. After all, you've paid them for custom tunes, why do this if you think you can do better?

- Jack