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Old 12-05-2021, 02:32 AM   #1
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Aisin auto trans questions - Shift "flare"

I bought a 2018 35DB a few months ago and we are loving it. The more I use the unit, the more I'm learning about the little things and it's quirks. Having said that, even though I have been a long time Ram / Cummins driver, this is the first one I've had with the Aisin 6 spd trans.

One thing I've noticed that while in Tow / Haul mode, and while accelerating, the trans will sometimes exhibit a rpm rise "flare" either from 1-2 or 2-3. I can't tell which one yet because at lower speeds, the trans shifts are quick. I'm usually half throttle or so, sometimes 3/4. I never hammer it down except for very rarely. The RPM rise doesn't feel like a slip or anything like that, but it's noticeable that the rpms will jump by 300-400 or so then drop back down as the unit continues accelerating.

I don't hear any noises, no clanking, no issues down shifting, no issues with poor fluid condition (the fluid is a beautiful pink like new).

It also does NOT do this when I'm in regular mode instead of tow / haul. Exhaust braking is fine, down shifting is fine.

Maybe this is normal and my OCD is improperly kicking in.

I'm not too well versed on torque management either so I don't know if that plays a role.

Any info would be appreciated. The truck is a 2017 even though the unit is 2018.
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Old 12-05-2021, 08:05 AM   #2
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Quote:
Originally Posted by jthorpe View Post
I bought a 2018 35DB a few months ago and we are loving it. The more I use the unit, the more I'm learning about the little things and it's quirks. Having said that, even though I have been a long time Ram / Cummins driver, this is the first one I've had with the Aisin 6 spd trans.



One thing I've noticed that while in Tow / Haul mode, and while accelerating, the trans will sometimes exhibit a rpm rise "flare" either from 1-2 or 2-3. I can't tell which one yet because at lower speeds, the trans shifts are quick. I'm usually half throttle or so, sometimes 3/4. I never hammer it down except for very rarely. The RPM rise doesn't feel like a slip or anything like that, but it's noticeable that the rpms will jump by 300-400 or so then drop back down as the unit continues accelerating.



I don't hear any noises, no clanking, no issues down shifting, no issues with poor fluid condition (the fluid is a beautiful pink like new).



It also does NOT do this when I'm in regular mode instead of tow / haul. Exhaust braking is fine, down shifting is fine.



Maybe this is normal and my OCD is improperly kicking in.



I'm not too well versed on torque management either so I don't know if that plays a role.



Any info would be appreciated. The truck is a 2017 even though the unit is 2018.


Doesnít do this on my unit with 32,000 + miles. Cab is 2016 model.

Have you done a scan for any trouble codes?
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Old 12-05-2021, 08:31 AM   #3
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Just a thought. You can work the transmission shift manually to see if it is slipping between shifts.
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Old 12-05-2021, 08:40 AM   #4
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One of the quirks of the Aisin. 2-1 slam shift is another. Mine has a pretty severe shudder on the 2-3 shift when pulling a decent load. The Aisin is very stout, but pretty unrefined.
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Old 12-05-2021, 10:14 AM   #5
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The Aisin is a great trans, I have owned a 2015 and a 2018, but they need to work on the shifting software. Maybe a trip to the dealer will result in different software for the trans that might fix the problem.
I did find one thread on a TSB for the 2018. but that thread is already 18 months old.


The trick is to know the symptom called out in the TSB, than to to dealer using that exact symptom as your complaint, than the tech looks up your symptom in documentation and will find TSB (based on search using your symptoms) and he will reflash the computer. if you go in asking for just the flash they might not be very helpful.
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Old 12-05-2021, 10:59 AM   #6
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One of the quirks of the Aisin. 2-1 slam shift is another. Mine has a pretty severe shudder on the 2-3 shift when pulling a decent load. The Aisin is very stout, but pretty unrefined.


It is actually a copy of the Allison 1000 xmsn, such a close copy that Allison sued them and they have to pay Allison a royalty for every one they make.

It sounds to me as if the Torque Converter is not locking in TH mode like it should be. It should lock beginning in 2nd gear instead of 5th like when TH is not activated.

This is to limit slippage and thereby reduce the heat generated in the TQ Converter when towing heavy.

Id have a shop well versed in that xmsn look at it if I were you. Any old xmsn shop won't do for it or the Allison
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Old 12-05-2021, 12:15 PM   #7
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Here's some interesting reading on a "flare" issue that was reported to NTSB several years ago. Annoying but not a safety issue.


Vehicles were GM's but often transmission issues are 'generic'.

https://static.nhtsa.gov/odi/tsbs/20...19022-9999.pdf
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Old 12-05-2021, 12:44 PM   #8
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Guys thank you for all the tips and information. This transmission doesn’t hunt much even with heavy weight up hills etc. actually not at all.

I’ve run it a good 20 times today and sometimes it’s more pronounced and sometimes not depending on throttle.

I think it’s the TC locking to be honest. This is about the best video I can get of it while I’m by myself on a private street.

Thoughts?

https://youtu.be/FsCliVM_5Mg
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Old 12-05-2021, 02:16 PM   #9
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The Allison case against Aisin was "dismissed with prejudice".
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Old 12-06-2021, 07:24 AM   #10
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Aisin auto trans questions - Shift "flare"

Your video didnít show me anything to worry about. I had a 2018 Ram 3500 w the Aisin. Do a video where you are accelerating hard.

If it still bothers you, I would have the program reset by Ram and then drive it like ya stole it. That is a true medium duty transmission and the duty cycle is very high. You wonít hurt the tranny.

I remember it was like 15000 miles before I felt my Aisin was smooth and I think that was with a reset the dealer did for another issue.
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Old 12-08-2021, 03:50 PM   #11
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3500

My 17 3500 does the same thing but only when Iím just easing around, never under heavy load. They flashed the trans and it helped for a week or so.
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Old 12-08-2021, 04:49 PM   #12
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Another RAM 3500

I have a 2014 RAM 6.7L ISB Cummin's, with the Aisin trans., mine does it in normal mode at about 35mph, I never really tried to figure out if this is 2 to 3. Mine jumps about 200 RPMs and quickly goes back to normal after it shifts, it does not do this in tow/haul mode, like another poster said, they flashed mine and it lasted maybe 7 to 14 days and started doing it again the dealership looked at it several more times but couldn't find anything and pretty much said if it gets worse to come back, now I am out of warranty so there is no way I am going back.
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Old 12-08-2021, 04:53 PM   #13
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this is a "learning transmission" that learns how you drive. When they flash them they remove all that data the trans has learned.



I used to find that when I first loaded the camper in spring the truck would shift strange, but the more I drove it the better it felt. than in fall it would shift hard when camper was taken off for winter.


I think it was Buick that actual experimented with a "his and her" mode in the 90's. It had different trans learning memory dedicated to which key unlocked the door.
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Old 12-08-2021, 05:35 PM   #14
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At almost 53K miles I think mine has learned all it"s going to learn ;-)
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Old 12-09-2021, 03:15 PM   #15
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At almost 53K miles I think mine has learned all it"s going to learn ;-)
Perhaps but often they revert to factory defaults when battery is disconnected and the process of "learning" how YOU drive begins again.
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Old 12-09-2021, 10:47 PM   #16
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Thanks for all the info guys. I have been on another trip since I posted this and it's been fine. Runs like a beast.
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