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About Bigmac

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    2018 Sierra 6.2 Max Tow

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  1. Shudder/Vibration Issue

    Maybe I can lend some info here on this issue. I’m an ex tech and for 25 years a factory field service rep ( not Gmc) so have been around the block. I had a 2017 6.2 8 speed and we replaced 2 converters and 3 flushes. Not to bad driving but pulling an rv was a dog 💩 peach seeds it shook so bad. It did settle down after 10 k miles but always there. Family member bought it so I purchased a 2018 identical truck Max tow 6.2 8 speed end of production vin thinking this was it and all the problems cured. Wrong. Same thing. IMO it is a tq modulation and the fluid breaks down. Instead of me getting upset I just lowered my expectations of a Gmc truck. Waiting for fluid fix and I don’t think you’ll get a rental as it is still drivable unpleasant as it is. You might be lucky especially if a good customer. I’m as anal as anyone on this problem ( ton of posts) but sitting back waiting to see if it really is repairable I understand the 2019 8 speeds do not have this condition but I believe a different converter is used. End of my rant 😀😀
  2. Bring an ex non GM factory rep, Warranty will not cover this problem. The dealer might but as you said many mikes away. I have found on occasion the dent and scratch repair guys the dealers use for u/c touch up can do a great job of fixing and blending. I have witnessed some good work and very reasonable. But like everything else in life the repair is only as good as the person was trained to do.
  3. Curious how you scored wi if for $10/ month. Thought it was $20.
  4. Coming from a 2017 6.2 max tow to a 2018 6.2 max tow ( end of production built) the trans shifting is much better. Haven’t had 1 bad shift yet in 4 k mikes. Seems it holds in gear longer when you let off the throttle and doesn’t upshift so quick. Drove the 17 the other day ( family member bought it) and it is night and day different. Still have t/q shudder on 2018? Oh yes especially when towing but is better in all other aspects. Waiting for tq upgrade as noted above before even addressing it.
  5. My 2017 and 2018 6.2 max tow both did it when towing. 2015 5.3 did not get that high towing a smaller trailer. It goes to certain point then 2nd fan kicks on. All good.
  6. Wondering how to install since there is no trans dipstick? Worth a try 😀😀. Disconnect trans cooling return line on radiator or cooler I would think. Anybody figure it out?
  7. What Weight Do You Tow?

    Before I got my 2018 6.2 max Tow I pulled a 6000lb trailer across the us for 3 months and 10,000 Miles with a 2015 5.3 6 speed Silverado. 3:42 Did great and ended up 10 mpg total. West coast to Maine - Down the east coast then back home to NW.
  8. Real world experience. I tow a 8000 lb 5th wheel. Using an Anderson Ultimate Hitch ( 42 lbs). I have towed all over nw and all thru west coast and spend time in Arizona in the winter and it works great. Never a problem and will get 10 mpg towing and I love it. Since 90% of the time it is used as a DD a 3/4 ton was not considered. I do have disc brakes on rv which makes all the difference but more of an afterthought then necessity but will never have another rv without them. It tows straight and have been in some severe windstorms but have never had a “ white knuckle” tow. Only added air bags to level but didn’t really need them. It works great for my application.
  9. Could you do the swap using a SLT grille instead of the Denali?
  10. My friend - you have a bigger pair then I do for attempting this. Good luck and watching. Liking the direction you are going.
  11. Good luck. Been there done that with my 17 8 speed. It’s inherit I believe with these trans and the converters they use. My understanding is 2019 8 speed has a different type of converter. My 2018 does it also so I just lowered my expectations of a fix from GM. Let me know what they figure out please. Try and tow a trailer and watch the shudder magnify to the 10th power 😀😀
  12. 2019 6.2 emblem

    Thank you 😀😀
  13. Any one working parts that would have the part # for the 2019 emblem? My local store has a blank look since I do not have a vin number. Thanks in advance.
  14. Hey Bigmac, I believe you when you said you have been all over the shudder issue. I am experiencing the same with a 2016 Yukon Denali with a 6.2. I bought it a month ago with 20,000 miles. I've had motor mounts replaced, but am definitely feeling the shudder under light acceleration as described in 16-NA-175. It seems like the most common dealership response it "Can not duplicate"


    1. Show previous comments  3 more
    2. Elew


      I made a visit to the dealership, they are very aware of the problem. I am told that there was some sort of update coming next month. I am also told that GM has bought back several

    3. Bigmac


      Let me know please how it works out. The 2019 8 speed have  a new and different converter possibly to address this issue. I would be surprised they continue to make updates for the 2014-2018 8 speeds.  As noted I love my truck and tows my rv very well except for tq chatter.  Stay in touch please with updates 😀😀

    4. Elew


      Maybe they will use that torque converter on the 2015 and 2016. I will let you know what they come up with. As it stands, the vibration and trembling is not acceptable for a 75+K SUV.


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