Getting a vibration that comes and goes while cruising at 55-60

NonTypicalCPA · August 12, 2020

My truck is an ‘18 Sierra crew with the 5.3. Just started noticing this vibration that feels like driving over small rumble strips. It comes and goes for a few seconds while I’m maintaining around 55-60mph. As soon as I give it a little gas it goes away. You can feel the vibration in the steering wheel. I’m thinking it’s a transmission issue, or maybe bearings? I’ve got around 55,000 miles on it. Thoughts?

papageoff · August 12, 2020

Wheel balance?

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Jmanson6262 · August 12, 2020

In the same boat still. Have had numerous road force balances done. Have swapped tires out just to rid a variable. I believe mine is the converter but cannot get any dealer to feel what I feel. They check everything out and say its good. Mine happens from 68 thru 75. Some days its more noticeable than others. Also have had shaft checked for balance, all good.

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papageoff · August 12, 2020

My neighbor has a 17 and says he has the same thing. He paid for some magical flush and it helped but they said if it comes back, that he'll need a transmission.

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Jmanson6262 · August 12, 2020

Thats what I'm afraid of hearing from the dealer when they decide something Is wrong. I've read from quite a few people that they have flushed and threw in amsoil with great success. But I'd really like a tech to see this first before I start changing up on fluid.

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papageoff · August 12, 2020

Thats what I'm afraid of hearing from the dealer when they decide something Is wrong. I've read from quite a few people that they have flushed and threw in amsoil with great success. But I'd really like a tech to see this first before I start changing up on fluid.
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Well, hopefully if it does come to that your power train warranty will cover it. Mine paid for a 4k AFM Lifter job about 10k miles ago.

My transmission worries me a bit, too. I've noticed that if I get on it from a stop I sometimes get at least a full second of slip on the 1-2 shift. I'm worried it's gonna give up the ghost one day while towing my camper.

Good luck. I hope the warranty covers you if the tranny is bad.

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Jmanson6262 · August 13, 2020

Well, hopefully if it does come to that your power train warranty will cover it. Mine paid for a 4k AFM Lifter job about 10k miles ago.
My transmission worries me a bit, too. I've noticed that if I get on it from a stop I sometimes get at least a full second of slip on the 1-2 shift. I'm worried it's gonna give up the ghost one day while towing my camper.

Good luck. I hope the warranty covers you if the tranny is bad.

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In the back of my mind hovers the dod system and the potential failure of it. But for now it seems fine. I baby it to keep it outta 6th gear if I can as to not engage 4 cyl mode. But on state to state trips in the 80 mph zones that 6th gear really helps.

I'll just keep pushing the dealers around here and hopefully one day they'll break and take me seriously about the converter.

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NonTypicalCPA · August 13, 2020

My warranty is good to 60,000 miles, and I’m at 55. I’m looking into the cost of an extended warranty. What’s a new transmission cost installed at the dealer?

Jmanson6262 · August 13, 2020

My warranty is good to 60,000 miles, and I’m at 55. I’m looking into the cost of an extended warranty. What’s a new transmission cost installed at the dealer?

I'm not sure about labor costs, but you can get a reman 6l80 for about $2500. But i have seen from Monster Transmission a built up one for around $5500. Somewhere around that price anyways. I would suggest if you are thinking about a new trans, if budget allows, get a built up one and never have to worry about it again. If I run into this down the road I will probably go this route.

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papageoff · August 13, 2020

My warranty is good to 60,000 miles, and I’m at 55. I’m looking into the cost of an extended warranty. What’s a new transmission cost installed at the dealer?

They told my neighbor it'd be about 4k for his 8-spd. You sure your power train warranty is only 60k? It's not the same as the bumper to bumper... Mine is good to 100k and I'm at about 86.

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bsprtsgrp · October 19, 2020

Geezz, mine is doing this now (rumble strips/braille driving) and it thought it was the road pavement. I'm a 17' with only 19K mileage.

martinto · October 20, 2020

2016 Sierra 6.2. At 30K miles I would have a periodic shudder (like rumble strips). Got the TSB, took it to my dealer,. The TSB calls to change out the Dextrose tranny fluid with special Blue Mobil 1 fluid. It works...no more shudder and-last week, I pulled a 6500 lb travel trailer in the mountains, with no reoccurrence of the shudder. May consider changing out the tranny fluid every 30K miles given I pull a travel trailer.

Fishbait · October 25, 2020

On 10/20/2020 at 5:33 PM, martinto said:

2016 Sierra 6.2. At 30K miles I would have a periodic shudder (like rumble strips). Got the TSB, took it to my dealer,. The TSB calls to change out the Dextrose tranny fluid with special Blue Mobil 1 fluid. It works...no more shudder and-last week, I pulled a 6500 lb travel trailer in the mountains, with no reoccurrence of the shudder. May consider changing out the tranny fluid every 30K miles given I pull a travel trailer.

Same issue with mine. Did the flush 60k ago. No problems since. Best $200.00 spent on this truck.