PT downshift points

[Randy K]

Is there an "ideal" MPH difference between the PT upshift MPH to the PT downshift MPH? I want fairly aggresive downshifts. I realize I should not have the two very close towards the lower end of the TPS%, due to normally big changed in the throttle position.

Starting from >20% TPS, is a 10 MPH difference between the upshift and downshift too much? Too little?

(I have a 4L60E A4 Corvette)

Thanks in advance

[C5pilot]

I had a 98 C5 A4 and know the downshifts are just as bad as on the C6 (the C6 just has 2 more maladjusted gears). Don't adjust your downshift according to MPH, open up the 2Dview and adjust the graph by dragging the points according to TPS%. Remember to note the gears highest speed and to adjust the TCC if necessary. You're on the right track, just don't use MPH because the spacing will be different for every gear. When you get it right, it's like night and day. I would never buy another GM auto if I couldn't adjust their crappy shift points. Worst part of a Corvette hands down.

LMN if you need more help.

[Randy K]

I had a 98 C5 A4 and know the downshifts are just as bad as on the C6 (the C6 just has 2 more maladjusted gears). Don't adjust your downshift according to MPH, open up the 2Dview and adjust the graph by dragging the points according to TPS%. Remember to note the gears highest speed and to adjust the TCC if necessary. You're on the right track, just don't use MPH because the spacing will be different for every gear. When you get it right, it's like night and day. I would never buy another GM auto if I couldn't adjust their crappy shift points. Worst part of a Corvette hands down.

LMN if you need more help.

Thank you for your advice. I have been using the 2-D graph to "massage" the curves to a smooth, more linear response. Currently, I have the downshift curves within 5 - 10 MPH of the upshift curves for each gear. This starts at ~ 20% TPS all the way up to 100% TPS. Is that too aggressive? Should they gradually seperate towards the higher end of the TPS range? I realize that this is a just starting point to my own personalization. I'm just trying to minimize the number of iterations this will take.

I couldn't agree with you more about how benign my '03 Coupe was when I bought it. The stock 2:73 gears combined with the "tuned for Grandpa" transmission settings were a major dissapointment ($30K for a Corvette that can't break the wheels loose on a launch!!!!! ). I understand that GM did that so at least one of the vehicles in the Corvette line-up would meet the minimum EPA requirements for gas mileage. However, a H/C package, new gears, and a 2800 Stall sure fixed it.

[jimmyblue]

1MPH 1-2. 2-1; 2MPH 2-3, 3-2; 3MPH 3-4, 4-3 works
fine and doesn't "toggle" any for me. All you need is a
little deadband (and a decent kick-vs-load profile).

[Randy K]

1MPH 1-2. 2-1; 2MPH 2-3, 3-2; 3MPH 3-4, 4-3 works
fine and doesn't "toggle" any for me. All you need is a
little deadband (and a decent kick-vs-load profile).

Thank you. What and where is a kick vs. load profile? Sorry, I'm kind new at this.

[C5pilot]

Thank you for your advice. I have been using the 2-D graph to "massage" the curves to a smooth, more linear response. Currently, I have the downshift curves within 5 - 10 MPH of the upshift curves for each gear. This starts at ~ 20% TPS all the way up to 100% TPS. Is that too aggressive? Should they gradually seperate towards the higher end of the TPS range? I realize that this is a just starting point to my own personalization. I'm just trying to minimize the number of iterations this will take.

I downloaded a stock 98 file and adjusted the DS points. Massage it a little to your style of driving but you get the idea. Basically, if you push the pedal 2 notches on the TPS scale, you'll downshift. This can be quickly accomplished by copying a group of upshift cells and pasting it 2 cells over to the right on the downshift scale. You already know you don't want to copy the lower or higher cells... you want more pedal movement down low and don't want to hit the rev limiter high. If you feel 2 notches is still too far to push the pedal, then try 1 notch or something in between.

Just remember... Keep each gears TPS spacing the same, not MPH. You want the same amount of pedal to command a downshift in every gear to train your foot, NOT the same amount of speed which is not a constant from gear to gear. Get it?

I don't have a copy of my old 98 file so I don't know where the upshifts could be raised to safely and it's all personal pref anyway. But if you want to raise the upshifts a little to hang onto gears longer (less MPG, more perf), then just raise the DS the same amount. I also didn't tweak 2-1 or 4th so much, you'll have to decide if you want 3rd to hold out until 134mph at just 50% TPS (seems odd). Then see what the max should be for 2-1 (stock reserves 2-1 only for 100%, you might want 2-1 without flooring it but don't get crazy). I did not take the time to check the TCC settings, that's for you to do before trying this example. Please look it over closely because I just whipped it up quickly and have no way of testing it. I hope this helps you

[Randy K]

I downloaded a stock 98 file and adjusted the DS points. Massage it a little to your style of driving but you get the idea. Basically, if you push the pedal 2 notches on the TPS scale, you'll downshift. This can be quickly accomplished by copying a group of upshift cells and pasting it 2 cells over to the right on the downshift scale. You already know you don't want to copy the lower or higher cells... you want more pedal movement down low and don't want to hit the rev limiter high. If you feel 2 notches is still too far to push the pedal, then try 1 notch or something in between.

Just remember... Keep each gears TPS spacing the same, not MPH. You want the same amount of pedal to command a downshift in every gear to train your foot, NOT the same amount of speed which is not a constant from gear to gear. Get it?

I don't have a copy of my old 98 file so I don't know where the upshifts could be raised to safely and it's all personal pref anyway. But if you want to raise the upshifts a little to hang onto gears longer (less MPG, more perf), then just raise the DS the same amount. I also didn't tweak 2-1 or 4th so much, you'll have to decide if you want 3rd to hold out until 134mph at just 50% TPS (seems odd). Then see what the max should be for 2-1 (stock reserves 2-1 only for 100%, you might want 2-1 without flooring it but don't get crazy). I did not take the time to check the TCC settings, that's for you to do before trying this example. Please look it over closely because I just whipped it up quickly and have no way of testing it. I hope this helps you

Thank you for your help and this information. You gave me an excellent description of how to maintain a constant "pedal change" to achieve a DS in any gear. I can truly say "I get it".

I just set my DS points as follows:

From 0% to 12.5% TPS (all gears) I have ~ 3 tic marks separation between US to DS (~20% throttle change required to DS). As you mentioned due to bigger changes at the lower end of the TPS range.
From 12.5% to 100% TPS (all gears) I have 2 tic marks separation between US and DS(~12% throttle change required to DS).

All 100% PT shift MPH match the WOT shift MPH

I will try to get this loaded this weekend and try it. I'll report back on how it turns out. Thanks again.

[rel3rd]

When you get it right, it's like night and day.

I actually borrowed this 2D "dragging" tip to dial in my upshifts and downshifts a little better than they had ever been, on my daily driver truck. Took just a little experimentation, but well worth it.

[C5pilot]

Thank you for your help and this information.

From 0% to 12.5% TPS (all gears) I have ~ 3 tic marks separation between US to DS (~20% throttle change required to DS). As you mentioned due to bigger changes at the lower end of the TPS range.
From 12.5% to 100% TPS (all gears) I have 2 tic marks separation between US and DS(~12% throttle change required to DS).

All 100% PT shift MPH match the WOT shift MPH

That sounds like a nice starting point, hope it gets you close to what you want.

I keep forgetting you don't have a 6 speed, so 20% anywhere might actually work out ok for you. I like the A6 to be closer because I have 2 more gears to choose from. If I went 20% TPS I'd run out of pedal before I could get it down to 1st or 2nd gear. Good luck.

[C5pilot]

I actually borrowed this 2D "dragging" tip to dial in my upshifts and downshifts a little better than they had ever been, on my daily driver truck. Took just a little experimentation, but well worth it.

It's all about being in the gear you want, when you want, without a whole lot of guess work.

[SoCal]

C5pilot, can you please expand a bit on the issues with TCC after adjusting part throttle shift points?

Is the goal to make sure that a particular gear's apply speed at any given TPS is higher than the speed required at that TPS to actually upshift into the gear? Hard to word that clearly. This graph is my stock 4th gear settings in sport mode. Is the goal to keep the pink trace (4th TCC apply) equal to or above the blue trace (3->4 upshift) and to keep the yellow trace (4th TCC release) equal to or above the light blue trace (4->3 downshift)?

I was a little surprised to realize the factory lays some of those lines directly on top of each other. In fact, in some cases, it breaks the guidelines I just asked about. But that is at high MPH and TPS so maybe the logic gets weird up there.

[decipha]

it seems as though if you were cruising at 130 and nailed it, she would drop to 3rd for just a split second until she got up to 134 then kick back up to 4th

seems as though that 4>3 downshift should be a little lower than that at WOT

[C5pilot]

it seems as though if you were cruising at 130 and nailed it, she would drop to 3rd for just a split second until she got up to 134 then kick back up to 4th

Yes, it's identical to the stock 98 file I downloaded. That sample is just to illustrate the parallel lines used for TPS shifting. In fact, the final drive ratio may be different from the 98 sample I used and the OP's car. There were 2.73's and 3.15's made for the C5 A4. Different rears will have different shift points. That's one of the reasons you don't just copy someone else's settings into your car.

As for whether he wants to drop to 3rd for 4mph depends on a few factors. Total shift time, power band, feel,... He may find shifting into 3rd sooner gets him into the power band for longer, or he may find shifting twice wastes more time than it's worth. You can only get those answers at the track and even then it's difficult because of the changing conditions between runs. At those speeds, I'd say most will program for feel. If you think it's silly to drop at 130, you can certainly program it out completely and stay in 4th. But I can tell you, GM did program their WOT shifts pretty well.

[C5pilot]

C5pilot, can you please expand a bit on the issues with TCC after adjusting part throttle shift points?

Is the goal to make sure that a particular gear's apply speed at any given TPS is higher than the speed required at that TPS to actually upshift into the gear?

I wish I could expand on it more, but every time I ask a transmission "expert" I get a different answer. The best thing to do is probably ask a TC specialist, Yank, Vigilanti, ProTorque, etc.

In the past, lots of TC's used to just lockup after a shift, simple, like another gear for economy. Now, they lockup before and after shifts in different gears at different RPMs. If you look at a C6 A6 2.56 file, you'll find some gears it locks up after a shift at one speed and then it locks before at another speed. I would love to know if it's for feel, economy or some kind of limitation of the TC.

I honestly don't know what the limits are so I always tell people it's up to them to find out about their own car. I spent hours looking over my OEM settings and tried my best to mimic what it appeared the factory was trying to do. I guess I'll only know if I succeeded by the number of miles I get out of it (although, I have logged MANY MANY miles in 1/4 mile increments, literally hundreds of runs). If I blow my tranny now, at least I know I beat on it for 4 years straight. Not too shabby. But I did install a cooler early on which helps too.

As far as I'm concerned, the new automatic transmissions use black magic. Anyone who can say they understand every aspect of one is most definitely a witch doctor and deserves our respect.

[Randy K]

My Coupe has 3:42 gears and I have a Yank 2800 Stall. Various stalls are made for differing applications. My particular stall is for a "light street applications". Yank told me to set the TCC apply at ~48 mph, 4th gear only, and only in light throttle settings (0 - ~12% TPS).

The locking mechanism on my stall is just basically for fuel economy, and heat reduction in freeway driving. The "fun part" of it is the flash stall point that gives you the kick in the butt.
.

[C5pilot]

My Coupe has 3:42 gears and I have a Yank 2800 Stall. Yank told me to set the TCC apply at ~48 mph, 4th gear only, and only in light throttle settings (0 - ~12% TPS).

With a 2800 you probably won't want the DS points as close down low. You'll need plenty of room for the slip. Start bringing the DS points closer once you hit your stall speed where the TC is tighter. Try to maintain similar DS TPS% seperation in each gear. Your 2D graph should probably show your DS's converging on the US's at higher TPS%.

I had a Yank 3000 on my 98 with 3:15's and it was a good mix for street and track. Your car probably feels even better on the road with just a slight drop in MPG.