Shudder at light throttle

[Vegasmarc21]

I am presuming that the computer disables the lock up feature of the torque converter in the tow haul mode.
An automatic transmission transfers mechanical power from the engine to the gears through a fluid couple. In this mode, the engine will spin faster than the input of the transmission. This gives the engine more power because the engine can rotate faster. To conserve fuel, a lockup solenoid will make a solid couple with the transmission. In this mode, the engine RPM will drop. In order to change gears, the lockup solenoid must release the mechanical lock.

The lockup is not used in gears 1 or 2 because you normally need the power to accelerate. This is why you won't feel shudder in 1 and 2. Presumably, because you need the power for towing, the tow haul mode probably won't use the lock up either.

The shudder you feel in 3 and 4 is the lockup clutch slipping. The Lubeuard is a friction modifier which will affect the slipping of the clutch.

Affect in a good way?

 

[Larryjb]

Affect in a good way?

What are you asking about having a good effect?

Is it the use of tow/haul? Is it the shudder itself? Is it the Lubguard? I can't answer that definitively. I'm not a mechanic, and I've never tried to pretend to be. I'm only replying to this thread based on my own experience with torque converter shudder.

Use of tow/haul: In some vehicles I learned that disabling the lockup feature actually causes the transmission fluid temperature to increase. This is because when it is not locked up, the fluid itself is transferring the torque to the transmission, and the resulting turbulence of fluid creates the heat. Locking up the torque converter is required to prevent overheating the transmission. I do not know what the effect of continued use of the tow/haul mode on the 5.3L Tahoe would be. I presume that because the tow/haul is designed to be used, that it is safe to use, especially if you have a separate tranny cooler.

The shudder itself: I presume this is harmful to the transmission and will eventually burn it out. You should be able to instantly stop the shudder by lightly tapping on the brake as soon as you experience shudder. The use of the brake should send an electrical signal to the computer to disengage the lockup, thereby stopping any shudder.

Lubguard: I don't know. I have heard lots of good things about DrTranny Instant shudder fix. But I would completely drain the transmission (including the torque converter) before switching from Lubeguard to DrTranny.

 

[Vegasmarc21]

What are you asking about having a good effect?

Is it the use of tow/haul? Is it the shudder itself? Is it the Lubguard? I can't answer that definitively. I'm not a mechanic, and I've never tried to pretend to be. I'm only replying to this thread based on my own experience with torque converter shudder.

Use of tow/haul: In some vehicles I learned that disabling the lockup feature actually causes the transmission fluid temperature to increase. This is because when it is not locked up, the fluid itself is transferring the torque to the transmission, and the resulting turbulence of fluid creates the heat. Locking up the torque converter is required to prevent overheating the transmission. I do not know what the effect of continued use of the tow/haul mode on the 5.3L Tahoe would be. I presume that because the tow/haul is designed to be used, that it is safe to use, especially if you have a separate tranny cooler.

The shudder itself: I presume this is harmful to the transmission and will eventually burn it out. You should be able to instantly stop the shudder by lightly tapping on the brake as soon as you experience shudder. The use of the brake should send an electrical signal to the computer to disengage the lockup, thereby stopping any shudder.

Lubguard: I don't know. I have heard lots of good things about DrTranny Instant shudder fix. But I would completely drain the transmission (including the torque converter) before switching from Lubeguard to DrTranny.

Lubeguard and Dr Tranny shudder fix are one in the same....Anyway, today drove all day in normal "D mode" and no shudder....I'm not going to get excited over it, 2 weeks of no shudder and I will be happy. I'm thinking of getting a Hypertech tune soon, and if the timing is advanced like the tow/haul mode with the ability to change shift points, and with the Lubeguard, I think I can have "Silence of the Shudder" lol

 

[Meccanoble]

Vegas, thanks for your updates. I swear to you I'm following your feedback closely. Once I feel confident your issues have gone away with no negative effects, I'm ordering some dr tranny as well.

Larryjb, I will try your recommendation but thats a horrible way to have to drive just to stop the shudder. What would be the easiest permanent fix if this was truly a band-aid to the issue?
"The shudder itself: I presume this is harmful to the transmission and will eventually burn it out. You should be able to instantly stop the shudder by lightly tapping on the brake as soon as you experience shudder. The use of the brake should send an electrical signal to the computer to disengage the lockup, thereby stopping any shudder."

 

[Larryjb]

Meccanoble,
You're right, that is a horrible band aid solution. I would probably try the DrTranny first, then a tranny flush involving draining the torque converter.

 

[Meccanoble]

Meccanoble,
You're right, that is a horrible band aid solution. I would probably try the DrTranny first, then a tranny flush involving draining the torque converter.

The flush I did roughly 20k miles ago involved draining fluid from tran cooler line and dropping pan for remainder. I kept putting new fluid and flushing until the fluid changed to lighter color. Would this drain the tq converter or I need a different approach?

 

[Daniel12]

Can anyone tell me what shudder I have under very light throttle usually on any gear EXCEPT 1st and 2nd gear with about 1100 rpm to 1500 rpm..... Doesn't happen when I start driving when Tahoe is cold and not up to operating temperature. WOT there is no shudder at all. I have a 2011 Tahoe 5.3 V8 with hundred twenty thousand miles.

I just purchased a '12 from a Carmax here in Austin, and it has about 120K on it and has the exact same issues. I turned it back into Carmax who then took it to a local Chevy shop.

When I get it back (assuming it's actually repaired) I will pass along what they did to it.


a 2011 Tahoe 5.3 V8

 

[Vegasmarc21]

I just purchased a '12 from a Carmax here in Austin, and it has about 120K on it and has the exact same issues. I turned it back into Carmax who then took it to a local Chevy shop.

When I get it back (assuming it's actually repaired) I will pass along what they did to it.


a 2011 Tahoe 5.3 V8

Thank you.... Yes please do.... This is like chasing a Unicorn.

 

[Vegasmarc21]

Vegas, thanks for your updates. I swear to you I'm following your feedback closely. Once I feel confident your issues have gone away with no negative effects, I'm ordering some dr tranny as well.

Larryjb, I will try your recommendation but thats a horrible way to have to drive just to stop the shudder. What would be the easiest permanent fix if this was truly a band-aid to the issue?
"The shudder itself: I presume this is harmful to the transmission and will eventually burn it out. You should be able to instantly stop the shudder by lightly tapping on the brake as soon as you experience shudder. The use of the brake should send an electrical signal to the computer to disengage the lockup, thereby stopping any shudder."

So when it starts to shudder, lightly tap the brake, and shudder will stop? As in just for that one shudder? Or stop the shudder for a significant period of time until a valve sticks or something?

 

[drummin1]

I'm just going to ask if you've tried the simplest thing, running some high octane gas and see if it still does it?