[ox11888]

Getting a rough upshift on 3-4 regardless how warm the transmission is? Saw a few threads but no answer for a fix. Wondering if the dealer can do something to fix the issue? Hoping someone on here has experienced this.

[taylorforschool@gmail.com]

Pretty normal, but if you feel it in any other gear I would be concerned

I would assume a tune would fix it. A lot of things with this vehicle you will find bring you back to the to warranty/ or to mod question

[JimGnitecki]

The 10 speed tranny, at least the one on my 2022 LT1 with Magnuson 2650, has a couple of other interesting negatives, that manifest when I apply WOT from a rolling 20 or 25 mph. The datalog clearly shows:

- The transmission shifts to 2nd, not 1st, even though 1st gear is good to 40 mph. Why?

- The 2nd to 3rd shift is slower than the 3rd to 4th shift - by a LOT. The 2nd to 3rd shift takes 200 ms or more, while the 3rd to 4th shift takes under 100 ms (The time resolution on the datalog from my Banks DataMonster is 100ms, so the above times are limited precision, but the 3rd to 4th shift is obvously 1/2 the time of the 2nd to 3rd shift). Again, why? Does the 2nd to 3rd shift require more internal tranny movements, that are necessarily sequential versus simultaneous? or?

But, all my shifts, including the 3rd to 4th shift, are smooth.

Interesting.

Jim G

[WhiteMale]

If it were to downshift from 2 > 1 at 20-25mph having applied WOT what do you think would happen? Too your tires?

[JimGnitecki]

Originally Posted by WhiteMale

If it were to downshift from 2 > 1 at 20-25mph having applied WOT what do you think would happen? Too your tires?

Educate me please:

So the transmission is OEM-programmed to KNOW that the tires might break loose BEFORE they actually do??

What if I had instead had my Nitto 555R2 tires on (which arrived at the dealership too late to catch any pre-winter weather)?

IF I instead had started the WOT run from a dead stop, would the transmission have stayed in 1st or would it have started in 2nd??

Jim G

[ox11888]

Dang this went off topic lol. I think for now I’ll keep my eye on it as my range device is coming in a few days we’ll see if that makes any difference.

[laynlo15]

Originally Posted by JimGnitecki

Educate me please:

So the transmission is OEM-programmed to KNOW that the tires might break loose BEFORE they actually do??

What if I had instead had my Nitto 555R2 tires on (which arrived at the dealership too late to catch any pre-winter weather)?

IF I instead had started the WOT run from a dead stop, would the transmission have stayed in 1st or would it have started in 2nd??

Jim G

From a dead stop its going to stay in first. Here is how mine shifts at WOT with stock A10 not unlocked. This was 9.90@141 pass with Hoosier slicks

Here is another from the LS Fest 10.34@135 pass on Nitto 555 R2s (305 35 20)

[JimGnitecki]

Thanks for the videos, Laynlo15!

I wonder why my tranny shifts to 2nd versus 1st then when I go WOT at 20 or 25 mph? Is that some kind of tranny programming by GM?

Jim

[laynlo15]

Originally Posted by JimGnitecki

Thanks for the videos, Laynlo15!

I wonder why my tranny shifts to 2nd versus 1st then when I go WOT at 20 or 25 mph? Is that some kind of tranny programming by GM?

Jim

I think its right at the point where it would be ready to shift to second so it won't let it shift down to first. Let me look at one of my logs. Actually mine shifts 1-2 38 mph, 2-3 60 mph, 3-4 86 mph, 4-5 105, 5-6 122 and traps at 142.

[2SS Capt]

Originally Posted by ox11888

Getting a rough upshift on 3-4 regardless how warm the transmission is? Saw a few threads but no answer for a fix. Wondering if the dealer can do something to fix the issue? Hoping someone on here has experienced this.

When driving my A10 in manual mode, I do notice the 3-4 shift to usually be rougher than any of the other shifts, but typically when it is in auto mode the 3-4 shift is smooth...

[JimGnitecki]

Originally Posted by laynlo15

I think its right at the point where it would be ready to shift to second so it won't let it shift down to first. Let me look at one of my logs.

Note that with my completely stock LT1 wheels, tires, and transmission, which results in 40 mph exactly at 6500 rpm, this shift to 2nd occurred at just under 30 mph, or 4875 rpm. That's too early.

Note that it was in 2nd gear already, and I would have expected it to shift down to 1st given that 2nd was still 1625 rpm short of the WOT shift point for 1st gear.

Jim G

[laynlo15]

Originally Posted by JimGnitecki

Note that with my completely stock LT1 wheels, tires, and transmission, which results in 40 mph exactly at 6500 rpm, this shift to 2nd occurred at just under 30 mph, or 4875 rpm. That's too early.

Note that it was in 2nd gear already, and I would have expected it to shift down to 1st given that 2nd was still 1625 rpm short of the WOT shift point for 1st gear.

Jim G

Not sure on that one, maybe they just don't want to see that harsh of down shift when your going WOT

[JimGnitecki]

Originally Posted by laynlo15

Not sure on that one, maybe they just don't want to see that harsh of down shift when your going WOT

That might be the case alright. Afterall, GM is the company that has used torque management in prior years to keep engine torque below what their transmissions are rated to accept, when they knowingly install engines whose output exceeds the tranny ratings.

I don't normally do WOT from a dead stop, as I view it as abusive to the vehicle, but this will limit my ability to measure 25 mph to 10 mph performance.

Jim G

[6spdhyperblue]

Originally Posted by JimGnitecki

That might be the case alright. Afterall, GM is the company that has used torque management in prior years to keep engine torque below what their transmissions are rated to accept, when they knowingly install engines whose output exceeds the tranny ratings.

I don't normally do WOT from a dead stop, as I view it as abusive to the vehicle, but this will limit my ability to measure 25 mph to 10 mph performance.

Jim G

I see it as they were ahead of the game as basically everyone is using TM now.

going to first just blows the tire off and you don’t need that level of gearing if youre at a decent roll already(those gears are all short and I see you have a 2650, do you even need 1st gear at all?!?!). In second, you’re in the meat of the torque curve and you eliminate the time of the shift. I bet it’s faster that way. But you can measure it both ways and let us know

Lastly when you’re roll racing or doing those pulls, you should already be in the gear you want to be in waiting for the “go”. So if that’s first you should be manually putting it into first. Then when you mat it u let the trans do the shifting. To do this
Move the shifter over and get into the gear you need to be in. Once you hit the gas you move the shifter back over to D and let it do it’s thing.
That will provide the best result from a roll