2014 - 2018 5.3 6 speed downshift jerks

[Grumpy Bear]

3 hours ago, Josh Powell said:

It may be normal and there may be a reason for it. All I know is that out of all my vehicles this is the first that I really feel the downshifts. I can live with it and I've even gotten used to it. Some days it still catches me off guard and feels unusual. Especially , like I said, when I'm just trying to go around 30-35 it's very noticeable.

I am not doubting you Josh and it may indeed have some issue. Please, have it checked out.

 

This whole statement of mine is more of a comment to the masses that think Zebra instead of Horse every time they here hoof beats. That said a couple of ideas. Trucks will never be as smooth as cars. They are heavier and built overall looser for a variety of really good engineering reasons. Not just curb weight but rotating weights. They are stiffer and that translates into a more direct 'feel' of the vehicle. Gearing overall is normally much lower and the lower it is the more you feel the gear changes going down. There are others but I just wanted to present some other reasons besides mechanical damage. Your other vehicles are cars? Smaller trucks? 

 

Are you geared 3.42? Slightly rolling terrain or light on/off pedal? That's about 5 mph slower than my 3.23 geared truck will on occasion have the AFM and the transmissions search for 4th or 5th gear freak the TCM out a bit. Especially if I have it in cruise control and tap it back in when I match the speed limit. This is where there are three systems trying to be top dog. Happens on the same road entering the same town every time. . Moving my set speed up just 1 mph stopped it. People...we are the biggest difference. 

[Bill Reinhardt]

There are a few comments suggesting a TCM tune. With the problem as you describe it, I'd like to point out that a tune, for me at least, exasperated the downshift problem as-described. To me, it feels like a less aggressive "engine brake" that cannot be disabled. The TCM tune I received from Diablew, while great on the upshifts and around-town driving, did NOT help with the downshift feel while braking.

 

Since the shift pressure was increased, it only increased the feel of the downshifts. I will contact Lew and see if there is something that can be done to change that, but with how many of these trucks he has tuned, I'm surprised it's not a part of the default package.

Edited October 5, 2018 by Bill Reinhardt

[nluchau]

3 hours ago, Bill Reinhardt said:

There are a few comments suggesting a TCM tune. With the problem as you describe it, I'd like to point out that a tune, for me at least, exasperated the downshift problem as-described. To me, it feels like a soft "engine brake" that cannot be disabled. The TCM tune I received from Diablew, while great on the upshifts and around-town driving, did NOT help with the downshift feel while braking.

 

Since the shift pressure was increased, it only increased the feel of the downshifts. I will contact Lew and see if there is something that can be done to change that, but with how many of these trucks he has tuned, I'm surprised it's not a part of the default package.

This is interesting.  And maybe it has that feeling of a soft engine brake to me too but it occurs as a jerk, I can replicate the feeling when I tap the brake pedal too.  Keep us posted 

[Bill Reinhardt]

17 minutes ago, nluchau said:

This is interesting.  And maybe it has that feeling of a soft engine brake to me too but it occurs as a jerk, I can replicate the feeling when I tap the brake pedal too.  Keep us posted 

I changed the verbiage in my original statement to say a "less aggressive engine brake" as I felt that there was nothing soft about it, lol

[300 Blackout]

After I replaced my u-joints I noticed downshifting was much smoother and less noticeable. Might not work for everyone but it certainly worked for me.

For anyone experiencing this problem I would keep a log of as much data as you can gather and see if there is a pattern. (Outside temp, trans temp, engine temp, RPM, MPH, etc... )

[Grumpy Bear]

^{Line pressure has less to do with it than clutch release/apply percentages and timing.}

[BlackBearPerf]

On 10/4/2018 at 2:04 PM, nluchau said:

My 2016 5.3 6 speed has me very frustrated to say the least.  I know I've brought this up before but I need to again. I am still getting the jerk downshifts when coasting/slowing to a stop.  I don't hear any clunk but it literally jerks at each downshift from 4-3, 3-2, 2-1.  If I am a little heavier on the throttle it may get better for a while but rarely does it feel like a normal downshift with a blip of the RPM's.  I currently have 27k miles

 

What's been done: I've complained about this day 1.  I love the truck but this just doesn't seem right and is a bear to drive in stop and go traffic.  

* On 1 occasion at 16k miles Dealer replaced valve body and TCM. Shift adapts were reset.  

* At 26k miles the shift adapts were reset again. 

 

Does anyone have advice or any remedy for this without voiding my warranty?  I've tried the range technology device, its great for disabling V4 but it doesn't resolve the downshift jerk.  I've tried disabling grade braking to no avail.  I've tried M5.  I've tried tow/haul. Where it seems slightly better at times I still get the jerk.  

 

I need fire power for the dealer before my bumper to bumper is up.  I have just under a year or 36k miles whichever of the two comes first.  Guessing miles.  

 

Thank you for listening!

 

If you would like, send us an email, [email protected], and the tuner can review your situation.

 

On a 6 speed, the shudder with the transmission is very common, as is a downshift clunk coming to a stop.  We are able to help address both of those issues for you.  We would tune your vehicle with our AutoCal. The AutoCal as mentioned above will allow us to see your specific vehicle data and provide you custom tune files via email. 

Edited October 10, 2018 by BlackBearPerf

[nluchau]

On 10/10/2018 at 2:35 PM, BlackBearPerf said:

If you would like, send us an email, [email protected], and the tuner can review your situation.

 

On a 6 speed, the shudder with the transmission is very common, as is a downshift clunk coming to a stop.  We are able to help address both of those issues for you.  We would tune your vehicle with our AutoCal. The AutoCal as mentioned above will allow us to see your specific vehicle data and provide you custom tune files via email. 

Will this in any way shape or form void my warranty?  

[BlackBearPerf]

2 hours ago, nluchau said:

Will this in any way shape or form void my warranty?  

With the AutoCal one of the features is that you can put it back to factory settings when you take it in for service. We use every effort to ensure that there is no trace of the tune using GM's current method of tune identification.  To date, we haven't had any issues with warranty on these trucks.

 

Plus there is the Magnuson–Moss Warranty Act that protects you as well, they have to prove beyond a reasonable doubt that whatever modification you made is exactly what caused the damage, to deny your claim. 

[nluchau]

On 10/24/2018 at 10:58 AM, BlackBearPerf said:

With the AutoCal one of the features is that you can put it back to factory settings when you take it in for service. We use every effort to ensure that there is no trace of the tune using GM's current method of tune identification.  To date, we haven't had any issues with warranty on these trucks.

 

Plus there is the Magnuson–Moss Warranty Act that protects you as well, they have to prove beyond a reasonable doubt that whatever modification you made is exactly what caused the damage, to deny your claim. 

My understanding is they can see if the ECM was flashed and how many times.  I really don't want to get into a pissing match with the dealer.  I understand you guys could potentially remedy some of my issues it just isn't worth the hassle of going to court over if it came down to it.  I'll continue pressing the dealer for potential remedies until my warranty expires.  

[Bill Reinhardt]

On 10/5/2018 at 2:55 PM, nluchau said:

This is interesting.  And maybe it has that feeling of a soft engine brake to me too but it occurs as a jerk, I can replicate the feeling when I tap the brake pedal too.  Keep us posted 

I got a new TCM tune from Diablew that has nearly eliminated the engine brake feel during downshifts as the truck comes to a stop. So with the Diablo tuner and a custom tune, it can be fixed. I'd assume the same with Blackbear.

 

However, the occasional driveline "clunk" is still present. I think this is more of a driveline slack problem rather than a transmission problem. Worn parts are most likely the culprit for me.

Edited October 31, 2018 by Bill Reinhardt

[crushNchowda]

On 10/5/2018 at 10:39 AM, Grumpy Bear said:

I am not doubting you Josh and it may indeed have some issue. Please, have it checked out.

 

This whole statement of mine is more of a comment to the masses that think Zebra instead of Horse every time they here hoof beats. That said a couple of ideas. Trucks will never be as smooth as cars. They are heavier and built overall looser for a variety of really good engineering reasons. Not just curb weight but rotating weights. They are stiffer and that translates into a more direct 'feel' of the vehicle. Gearing overall is normally much lower and the lower it is the more you feel the gear changes going down. There are others but I just wanted to present some other reasons besides mechanical damage. Your other vehicles are cars? Smaller trucks? 

 

Are you geared 3.42? Slightly rolling terrain or light on/off pedal? That's about 5 mph slower than my 3.23 geared truck will on occasion have the AFM and the transmissions search for 4th or 5th gear freak the TCM out a bit. Especially if I have it in cruise control and tap it back in when I match the speed limit. This is where there are three systems trying to be top dog. Happens on the same road entering the same town every time. . Moving my set speed up just 1 mph stopped it. People...we are the biggest difference. 

So which is it guy? Are they "looser" or are they "stiffer"??? Sounds like more excuses for piss poor engineering & lazy Mexican manufacturing teams - sounds like big cuts & savings in R&D/Engineering/OEM parts suppliers/labor to help pad the balance sheet after borrowing our tax dollars to prevent bankruptcy.

 

That's pretty much how I look at these piles of trash we all gut suckered into buying under the assumption GM would continue to @ least produce trucks that will match the reliability/durability of their previous offerings - instead they went backwards, probably intentionally & willfully as a business decision to put them in better financial shape - they 10000000000% KNOW These '14-'18 trucks are junkboxes, & the most unfortunate thing I'm starting to realize is that if you expect to get anywhere near a good deal on trade for a new one its gonna have to be @ a GM/Chevy dealer b/c I've already been told from multiple Dodge dealers they "know these are the chevy trucks that shake on the highway or rough trannies because 50% of the time that's why people are trading them in"

 

GM trucks, the gift that keeps on giving!!!!!!!!

[nluchau]

I thought I'd bump this again, anyone else dealing with it?  I'm at almost 30k and if its something I can have fixed under the bumper to bumper the time is now.  Only thing they have done is reset taps a couple of times, replaced valve body and TCM and that is all.   

[300 Blackout]

Mine does the exact same thing. Seems more noticeable to me in the winter but that could all be in my head. When I switched to 4.56 gears it became much, much more noticeable.

Everyone has different expectations of their truck. I drove a friend’s EcoBoost F150 not too long ago and I’d be lying if I didn’t say I was a bit jealous of how smooth the ride was. Suspension primarily but the driveline and powertrain were also smooth.

When I bought my truck, I wanted a “truck” and was willing to accept a rougher ride in exchange for a tough platform. I think you’d be hard pressed to find a better 6 speed OEM trans (at this price point) than the 6L80.

A couple ideas if you really think something is wrong. You can get a Zip Kit from Sonnex and rebuilt your valve body. Pretty easy to do if you’re willing to drop your pan.

You could flush your trans fluid to see if things improve.

You can add a bigger trans fluid cooler and replace the thermostat with one that opens at lower temperatures.

You can get a trans tune, HOWEVER, watch what you wish for because there are at least a few people on here who have tuned the trans for the same issue and experienced problems later on. The clutch plate engagement is calibrated by GM for a reason. If you tune it, you may be trading the longevity of your clutch plates for a smoother downshift.

Im pretty happy with my truck. One of these days I’ll overhaul my trans as part of an aggressive routine maintenance schedule and while I’m in there I’ll upgrade a few parts but none of them will be to give it a smoother ride.

[Mozzer]

This is the part I don't get...

"The clutch plate engagement is calibrated by GM for a reason. If you tune it, you may be trading the longevity of your clutch plates for a smoother downshift."

Shifting gears like a ham fisted gorilla with a manual transmission results in the same driveline clunk as this auto, surely that can't be good for longevity.

I never had an auto before leaving the UK for Canada, the auto in the 300,000 kms Jeep Cherokee I bought when we moved over was much nicer than this truck. The 2008 Dodge Ram I traded for this truck was great after adjusting the shift points with a Superchips.

Just seems like laziness on behalf of GM.


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