Transmission Flare? What is it?

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NETim

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I've noticed that my ZF8, when cold, will sometimes make a noise when making the 1-2 upshift, most likely to be heard when "getting on it" or starting from a stop facing an incline. Easy accel on level ground nothing unusual is noted. Truck is lightly loaded. The transmission shifts fine otherwise. Once it's warmed up a little, no issues are noted.

I am not sure what "transmission flare" is in the first place.

I am running Maxlife ATF, have the caulk04 bypass and 165*F thermostat installed currently.
 

Atcer2018

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Is the noise a drone or a whine that goes away after the shift is complete? That would typically be the torque converter. The 8 speed is known to flare a bit on the initial 1-2 shift when cold. I don’t know why but I’ve read it explained as the valve body is slow to pressurize until it’s warmed up a bit. My 2018 has done it since new even after a software update. Only on the first 1-2 shift when cold but I don’t have any noise associated with it.
 
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NETim

NETim

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Is the noise a drone or a whine that goes away after the shift is complete? That would typically be the torque converter. The 8 speed is known to flare a bit on the initial 1-2 shift when cold. I don’t know why but I’ve read it explained as the valve body is slow to pressurize until it’s warmed up a bit. My 2018 has done it since new even after a software update. Only on the first 1-2 shift when cold but I don’t have any noise associated with it.

Yes, the noise goes away after the shift is complete. It's a very brief noise, just the duration of the shift. Once the ZF has warmed up a little, I don't hear it anymore.
 

Jeepwalker

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I've switched tranny fluid brands in the past (GM vehicles), and in some cases different brandss HAVE made differences in shifting and operation. Then reverted back and the shifting returned to what it was. Might be due to different make-up in formulations. But I would think the formula to meet spec is kind of locked-in. Or maybe the 'base' Spec is locked-in but allows for slight variations in additives and anti-shudder agents per mfgr ..things like that. I'm just speculating.

That's why anymore I just stick to OEM fluids. Some of our small-town dealers around here will sell ATF out of their bulk barrel (by the gallon...bring yer own jug)...and it works out as cheap if not cheaper, than aftermarket fluids.
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Dusty

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I've noticed that my ZF8, when cold, will sometimes make a noise when making the 1-2 upshift, most likely to be heard when "getting on it" or starting from a stop facing an incline. Easy accel on level ground nothing unusual is noted. Truck is lightly loaded. The transmission shifts fine otherwise. Once it's warmed up a little, no issues are noted.

I am not sure what "transmission flare" is in the first place.

I am running Maxlife ATF, have the caulk04 bypass and 165*F thermostat installed currently.
Transmission flare is usually defined as engine overspeed between gears.

In a normal shift the engine RPM will immediately drop as it goes into the next higher gear. Flare usually indicates clutch slippage.

My first recommendation is to have the transmission fluid level checked.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33-gallon fuel tank, 18” wheels. Build Date: 3 June 2018. Now at 110818 miles.
 

gunner_herman

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Mine does this as well. I’m always just super aware in hopes nothing significantly bad happens. It’s been doing it for probably two years. Can’t say it’s normal behavior but it seems normal for my truck. It only happens on that first up shift of the day.
 
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