2016 GMC 2500 6.0

[Motor City Rick]

^{Since there's a challenge to my position, data, and facts to back up my statements, I will cite mine below.}

 

^{We are here to help this guys jerking problem not have intellectual battle of wits to who's right, ...who's wrong. If you have an issue with my statements, ...then "prove me wrong" with actual "cited" facts (like I did) from a non-interested third parties. Don't give me "deflection statements" to look it up. Prove me wrong with your factual documentation!!! "Opinions" don't mean chit, without facts, that is how we learn things in life.}

 

^{Also, you have no clue what I have done in automotive industry, things that are not available in your neck of the woods.}

 

^{Still waiting for some answers on the 5 coefficients of drag with motor vehicles and towing???}

 

^{Now to some information on towing:}

^{...Nice calculators for towing}

^{http://changingears.com/rv-sec-calc-trailer-weight-tt.shtml}

 

^{http://fifthwheelst.com/rvtc_calculator.html}

 

^{http://www.towingplanner.com/Calculators/TowingPayloadEstimate}

^{Now to back up my statements:}

^{http://changingears.com/rv-sec-tow-vehicle-sizing.shtml}

 

^{http://www.gmc.com/trailering-towing/towing-charts.html}

 

^{http://www.gmc.com/trailering-towing.html}

[sdeeter19555]

Sounds like torque converter and/or torque converter shutter...

 

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[4wdriver]

Sounds like torque converter and/or torque converter shutter...

 

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This does feel trans related on my truck I would agree at least until the dealer finds it's not. Wonder what the original poster thinks.

[sdeeter19555]

I was thinking about this...we may be looking at the wrong culprit. Humor me...

 

If the jerking starts when the converter locks, what's to say that the torque converter IS operating normally and that it's not the transmission clutches slipping because of an underlying issue? When unlocked, the converter could slip and cushion the transmission clutches to prevent them from either slipping or being felt if they were slipping?

 

Discuss?

 

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[4wdriver]

(Quote) I was thinking about this...we may be looking at the wrong culprit. Humor me...

 

If the jerking starts when the converter locks, what's to say that the torque converter IS operating normally and that it's not the transmission clutches slipping because of an underlying issue? When unlocked, the converter could slip and cushion the transmission clutches to prevent them from either slipping or being felt if they were slipping.

 

Discuss?

 

 

 

 

Not sure which however it does happen mainly in one gear. Previously mentioned was third gear which sounds right. Why not every gear if it's just the torque converter. I have noticed that if I drive during conditions that normally cause the hesitations but instead use full throttle the hesitation is gone or at least not noticed.

Edited September 13, 2017 by 4wdriver

[grizzlyltz]

It almost sounds like the op is babying this truck while pulling

 

 

 

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[royg6677]

The jerking/bucking happens in at least 3,4 and 5th gears. I am not babying truck. I travel around 55 to 60 and if you check this is in the rpm range I talked to you about it is very annoying. I have to drive around in manual and shift to try to stay away from this situation.My truck is a 2016 GMC Sierra 2500HD DC 6.5 bed 6.0 410 gears B&W hitch and is stock with less than 6K miles. According to manual 5th wheel trailer Max weight 14100lb GCWR 21200lb

Dealer called to bring truck in for testing again dealer owner has a travel trailer they want to test with. Will let you know the out come. Test date 9/18

Thanks all RRG

[Motor City Rick]

I was thinking about this...we may be looking at the wrong culprit. Humor me...

 

If the jerking starts when the converter locks, what's to say that the torque converter IS operating normally and that it's not the transmission clutches slipping because of an underlying issue? When unlocked, the converter could slip and cushion the transmission clutches to prevent them from either slipping or being felt if they were slipping?

 

Discuss?

 

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That is why I told Red Rider a few posts back "to lightly press the brake pedal, not enough to slow down the vehicle".

 

Doing the action sends a signal back to the ECM to unlock the torque convertor clutch (TCC). If problem goes away, it's a torque convertor clutch "application issue".

 

The torque convertor is going crazy because the weight of the tow / wind resistance is reaching outside (maximum) limits. That application can be changed in the software map to come in at higher load / rpm (more torque) limits.

[royg6677]

Motor City Rick

I just got home from a trip with camper and tried several time to just touch brake pedal did not change jerking or bucking within the RPM range mentioned.

Thanks RRG

[royg6677]

Motor City Rick

When I lightly pressed brake and was on gas at the same time and converter unlocked should i have noticed a slight rpm change? I did not notice any change at all. When I took test drive with service supervisor and he unlocked converter with computer jerking stopped and rpm increased. I guess I am lost. I also do not think I am over taxing the truck. It pulls just fine except for the jerking/bucking within the 2100 thru 3200 rpm range. I hope they find the problem It feels as if the engine is missing but they do not think it is the engine.

RRG

[grizzlyltz]

What's your pin weight?

Put some water in the tanks and see if that eliminates the bucking

I find if I put more pin weight by adding water the truck rides better and smoother .

If your torque converter or trans was acting up you would think your truck would be throwing codes.

 

Does this truck buck and jerk with out the trailer ?

 

 

 

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Edited September 14, 2017 by grizzlyltz

[XSKIER]

A couple of points that I have noticed in the 2017 CCSB 6.0 Z71 of mine while towing. The torque converter clutch does apply in third while accelerating and holds through the 4 5 6 shifts. All bumper pull towing I've done has been smooth, 1000 to 12,000 lb trailer weight. I did have a goose neck 21k tri-axle torsion spring flatbed for a while. It probably weighed 6k empty. When that trailer was empty I would get some annoying shudder on certain road conditions, but it definitely wasn't the transmission.

 

On the other hand, the torque converter suddenly failed in my 2015 SS Sedan last month. It let out a couple of grumbles then was gone completely. I'm not sure if the 6L90E uses the same converter or not, but there is a long list of 2015-2016 6L80E owners that have had converter failure.

 

 

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[Motor City Rick]

When the torque convertor unlocks, yes the rpm's will slightly climb on any vehicle.

 

It's somewhat the same principal as a stick shift. When the clutch is not depressed on a stick, you have direct mechanical connection. When you depress the clutch, rpm's slightly rise, and no mechanical connection.

 

Now with a torque convertor clutch system, you have a "fluid" mechanical connection which constant slippage is occurring in the torque convertor at all speeds (like a slipping mechanical clutch).

 

When certain specified requirements are met in the ECM, the torque convertor clutch solenoid engages the torque convertor in a direct 1 to 1 mechanical engagement. Listening to all your input, the 2 areas I would look at is torque convertor solenoid engagement / disengagement at a "mechanical level". The other is, ...the dealer is clueless to correct, the input / output values already set in the software map for transmission torque convertor solenoid activities.

 

Another test not mentioned put on a "much lighter trailer" (under 6,000 pounds) and see if the jerking is still present. If the jerking is greatly reduced / or gone, ...I will stand by my argument. If it's still there, head for the "mechanical operation" of the torque convertor clutch solenoid.

Edited September 16, 2017 by Motor City Rick

[Sledge8]

A couple of points that I have noticed in the 2017 CCSB 6.0 Z71 of mine while towing. The torque converter clutch does apply in third while accelerating and holds through the 4 5 6 shifts. All bumper pull towing I've done has been smooth, 1000 to 12,000 lb trailer weight. I did have a goose neck 21k tri-axle torsion spring flatbed for a while. It probably weighed 6k empty. When that trailer was empty I would get some annoying shudder on certain road conditions, but it definitely wasn't the transmission.

 

On the other hand, the torque converter suddenly failed in my 2015 SS Sedan last month. It let out a couple of grumbles then was gone completely. I'm not sure if the 6L90E uses the same converter or not, but there is a long list of 2015-2016 6L80E owners that have had converter failure.

 

 

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Just my opinion and maybe my driving style. If the converter is locking while accelerating in 3,4,5 you are babying the truck. While I am pulling I do not see converter lockup until I am up to speed and pull back on the throttle for cruising speed. I have never seen or felt my truck lock the converter in any gear under 5th. By letting the converter lock that early and trying to accelerate from there is not utilizing what the convert is for in the first place. Multiplying the torque output of the motor. These 6.0 motors are designed to spin. They don't make full power until 4 - 5000 rpm. This issue does sound like a converter / TCM torque Management issue. I will be curious what they find.

[sdeeter19555]

A couple of points that I have noticed in the 2017 CCSB 6.0 Z71 of mine while towing. The torque converter clutch does apply in third while accelerating and holds through the 4 5 6 shifts. All bumper pull towing I've done has been smooth, 1000 to 12,000 lb trailer weight. I did have a goose neck 21k tri-axle torsion spring flatbed for a while. It probably weighed 6k empty. When that trailer was empty I would get some annoying shudder on certain road conditions, but it definitely wasn't the transmission.

 

On the other hand, the torque converter suddenly failed in my 2015 SS Sedan last month. It let out a couple of grumbles then was gone completely. I'm not sure if the 6L90E uses the same converter or not, but there is a long list of 2015-2016 6L80E owners that have had converter failure.

 

 

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2012, I know, but the only gear the converter won't lock is 1st.

 

All other gears lock and shift while locked under most circumstances. Only very rarely and for no reason will I get the converter to unlock and drive down the road for any length of time unlocked (usually a small grade and very little throttle) without downshifting and locking up.

 

Once up to temperature (i.e., above 68F), it goes 1st, 2nd (converter locks), 3rd locked, 4th locked, 5th locked, and 6th locked. Sometimes on a down shift, mine will unlock for a moment before reapplying and you can feel that.

 

I think that's how they keep the trans temperature within reason...it's also why I feel mine doesn't pull as good as it could if the converter would stay unlocked for even a brief period of time and let the engine stay in higher RPMs within any given gear.

 

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