Coolant And Transmission Fluid Mix

[Blackram16]

I have a 16 RAM Cummins with the 68RFE that got rebuilt about 10k miles ago after 500 miles.

I got a slight tap when coming to a stop when it automatically downshifts into first gear with some hesitation when up to operating temps, but when cold, it has no hesitation going into first.

I have a Revmax shift kit, triple-disc converter. I replaced the speed sensor and the solenoid pack and then found out the radiator had been broken, and coolant got in the trans.

I flushed the trans and still have the same issue hesitation going into first when coming to a stop.

Every other gear has no issue downshifting.

When downshifting in all gears, the transmission pressure line is relatively the same 120-130 psi, then drops to 75 psi when the shift happens.

Even in first gear, when cold, the pressure is the same.

Does anyone else have this issue or have answers?

The reason I got it rebuilt was that it started slapping from my UD clutches being burnt out, hoping that’s not the case because I haven’t dogged on this tranny.

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[watersupply189]

Hopefully, someone will be on shortly that can give you an answer, friend.


2016 Ram Laramie 3500, G56, 6.7, CC, 4x4

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[Blackram16]

How long does it normally take to get an answer?

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[MC250r719]

I have a 16 RAM Cummins with the 68RFE that got rebuilt about 10k miles ago after 500 miles.

I got a slight tap when coming to a stop when it automatically downshifts into first gear with some hesitation when up to operating temps, but when cold, it has no hesitation going into first.

I have a Revmax shift kit, triple-disc converter. I replaced the speed sensor and the solenoid pack and then found out the radiator had been broken, and coolant got in the trans.

I flushed the trans and still have the same issue hesitation going into first when coming to a stop.

Every other gear has no issue downshifting.

When downshifting in all gears, the transmission pressure line is relatively the same 120-130 psi, then drops to 75 psi when the shift happens.

Even in first gear, when cold, the pressure is the same.

Does anyone else have this issue or have answers?

The reason I got it rebuilt was that it started slapping from my UD clutches being burnt out, hoping that’s not the case because I haven’t dogged on this tranny.

Do you have custom tuning or canned tunes?

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[Chrisn162001]

Coolant in the transmission fluid will tear up clutches and lip seals quickly.


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[Blackram16]

I have custom tuning also not sure why it wouldn’t be every gear shifting bad if it were the clutches.

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[Chrisn162001]

Who’s tuning?

Clutches can flake or delaminate with water.

If low reverse got damaged, it could cause hesitation going into first on downshifting.

If 2C is delayed in disengagement on the downshift, it can cause a shudder/hesitation feeling.

What do you mean by a tap when downshift.

Tap noise or feeling?

When you had the trans rebuilt, what all did they replace/upgrade?

What is the Revmax shift kit?

They don’t make a shift kit. Did you use their valve body?

Were any upgrades done to the pump or valve body?

What is max line pressure your tune calls for.


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[Blackram16]

DRD tuning and got Sonax drum, Revmax valve body, billet triple-disc Goerend converter.

I replaced all the clutches and gears, the speed sensor, and solenoid pack, and the max line pressure is 225 unsure or pump upgrades; it’s not on the build sheet parts list.

It’s also a feeling sometimes, and it hits hard enough to kick you forward a little bit.

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[Chrisn162001]

DRD tuning and got Sonax drum, Revmax valve body, billet triple-disc Goerend converter.

I replaced all the clutches and gears, the speed sensor, and solenoid pack, and the max line pressure is 225 unsure or pump upgrades; it's not on the build sheet parts list.

It's also a feeling sometimes, and it hits hard enough to kick you forward a little bit.

If there is a slight overlap, do you have access to a scan tool I'd look at shift timing on the data?

Did you tell DRD you were running a Sonax drum when he tuned your truck?

I've had the Sonax drum require different trans tuning than factory drums due to the larger piston apply area but keeping the factory size release piston.

Usually, it's in the 3/4 shift but still worth looking into

I'd check the CVI's while you have the scan tool plugged in.

On another note, I hope you got a billet input shaft with the triple-disc.

The lock-ups of a triple-disc will break the factory input shaft.


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[Blackram16]

Yes, I did tell him about the upgrades.

I don’t think I got a billet input shaft.

But like I said, all other shifts are solid.

I’ll see if I can’t get a hold of a scan tool and look.

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