Who likes their 8 Speed?

TXGREEK · June 15, 2018

I just picked up my 17 from being at the service dept for the 4th time. I'm at 24k miles. Last 3 times it was there they updated to the latest software and did a trans relearn to help with the clunk, hard shifting, and shudder. This time they flushed the trans and updated the software again. Honestly it drives so much better than it ever has now. We'll see how long it lasts but I'm happy with it finally. Is it perfect? No, but it doesn't bother me anymore. If the shudder and clunk come back I'm going with a blackbear tune.

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Try adding some Lucas transmission additive and it’ll all be puuuurfecto!

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TXGREEK · June 15, 2018

I’ve got approx 6K on mine and it’s all good and maybe because I added Lucas transmission additive as soon as I got it home new from the dealership

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huntr1117 · June 15, 2018

I’ve got approx 6K on mine and it’s all good and maybe because I added Lucas transmission additive as soon as I got it home new from the dealership

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Did you actually drain any fluid or did you just add it to your existing fluid?

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TXGREEK · June 15, 2018

Did you actually drain any fluid or did you just add it to your existing fluid?

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Just added about half the jug you see there. Go on their website and see for yourself, amazing stuff. My buddy has a 1985 Volvo that ran like [emoji90] with constant transmission issues until I told him to try it out, three years later still good. I use the fuel treatment every other fuel tank cause GM stopped with the fuel filter and uses the one in fuel tank now.

Quick story: my wifes 2016 Yukon with 5.3 had a rough idle at 12K miles, dealership said that’s from bad fuel and needing $350 CleanUp (BS) which wasn’t part of warranty so I took it home added Lucas fuel treatment and the rest is history, 30K on it now and just got back from a 4K road trip and used Lucas fuel treatment every other tank during trip, true story! Lucas products are AWESOME!

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Dnt · June 16, 2018

I just added the snake oil (lucas transmission fix) into the transmission on my 18 year old kid hauler Windstar van. It has developed a torque converter seal leak. Not worth pulling the transmission to fix the seal and the lucas did seem to actually slow it down a little (or is it wishful thinking?). I cannot tell any difference in the shifts at all though. As far as pouring snake oil in a new +64k MSRP truck naw I will pass on that LOL. To each his own I guess.

Dr Awesome · June 16, 2018

Is the HP fluid folks mention here just Mobil 1 LV ATF HP? Or re-branded under a GM number? Has it helped with the clunkyness for those who have swapped the fluid out from the GM fluid? I'm thinking of having this done just because I'd rather have the better fluid, whether or not it helps. Mine is not bad, but I can feel it in some shifts depending on conditions. I have a 5.3 with the 8 speed.

Snoringbear · June 16, 2018

On 6/14/2018 at 10:30 PM, huntr1117 said:

Did you actually drain any fluid or did you just add it to your existing fluid?

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How did you add fluid? Aren’t these trannys sealed? I know mine doesn’t even have a dip stick. And, assuming you figured out how to add/drain fluid does that void your warranty?

TXGREEK · June 16, 2018

How did you add fluid? Aren’t these trannys sealed? I know mine doesn’t even have a dip stick. And, assuming you figured out how to add/drain fluid does that void your warranty?

This is the transmission dipstick For my 5.3 Yukon and for my 6.2 I’ll have to ask my mechanic. I think he used a special tube underneath while engine was running, I’ll ask

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samckitt · August 16, 2018

So I have read through some of these comments & it has gotten my blood pressure up worrying that there is no fix for the shudder I feel at light acceleration. I have a 2018 Sierra 1500 with the 8 speed. It has already been in the shop & they did the flush, service rep called me & she said it didnt fix it so they changed the torque converter. That was less than a month ago, & I don't feel any improvement, maybe a little worse. I had an apt to bring it back in today, & this morning was first I had driven it in about 2 weeks (vacation), & it drove pretty good, didnt notice it much. Told her that & she said to bring it back in when it is very noticeable. She said something like within the 2 weeks it could have (cant remember the term she used, but basically computer needed to relearn shift parameters, sounded like BS to me). Then tonight on my way home from work, I noticed it bad, & even felt like missfire while driving constant speed, but no check engine light. So I'm frustrated, pissed off, worried that I'm going to be fighting this for years (until warranty runs out), or if i sell it or trade it I am going to loose my ass on it. Beginning to regret buying it.

Pearl2017 · August 17, 2018

Took mine in last Friday and picked it up Saturday after a flush and filter and it drives perfectly smooth once again. Convinced the chuggle issue is the TCC intentional % slippage strategy being employed and the TCC clutch material contaminating the fluid from the slippage. Adding oversize and heavier tires is not helping either. The grabbiness you feel as a chuggle feels like the popping of limited slip rearend that needs friction modifier. Putting in some trans additives may help i look forward to someones actual results on that idea.

samckitt · August 17, 2018

This chugging/shudder I feel happens when I apply slight acceleration in the 45-70mph range. Do this without it downshifting, it feels like driving a manual transmission & you need to downshift. When it does downshift, it goes away. Could it be just that? That maybe a tune to change shift point would resolve it....?

Bigmac · August 17, 2018

1 hour ago, samckitt said:

I chased this shutter problem last year on my 2017 6.2 max tow till I was nuts. It will not go away and it got very bad when towing. It feels like t/q modulation. I changed fluid twice and installed a new t converter. Finally gave up as GM rep said normal. It did get better after driving 15k or so but will always be there. Had a chance to sell it ( long story) and buy a 2018 exact truck since the incentives where so good. Very little money difference $3k so made sense. I would have kept it as I got used to the chuggel as I call it. The 2018 does exactly the same thing but the trans shifting in the 2018 is night and day different. . Instead of shifting at a light load ( throttle) and banging into gear it will hold and shift smooth. I have read the tq has been changed in the 2019 and thinking the vibration issue might be one of the reasons. It is not bad except when towing and then it will shake very hard. Love the truck otherwise and that’s why I got another new one. I’m an ex tech and factory rep so I know the industry inside and out but lowered my expectations and live with its idiosyncrasies

Srode1 · August 18, 2018

I had shudder fixed by the dealer with a fluid flush and filter change - they were aware of the problem and that was the standard fix they were using and it seemed to work great until recently when I am starting to get a hint of it doing the same thing again. Could be road texture deceiving me, I will certainly wait till it get's more obvious. I have a 100,000 mile warranty since it's a 2015 and 2.5 years till the 5 years is up (bought a left over 2015 NHT Package truck with the 6.2) so I can afford to wait a while for it to get worse if it's going to. Love the truck otherwise, it still has an occasional clunky shift but its pretty rare and I can live with that - got a lot better with the fluid service for the shudder.

The jury will be out for me on the new 10 speed for at least a year though to see if it does any better or has other annoying habits.

Edited August 18, 2018 by Srode1

CounterMeasure · August 20, 2018

I get about 12K miles on the fluid before mine starts really banging and clunking around often. I get the tranny serviced at the dealer, and there's an immediate improvement. Much smoother and way fewer bangs and clunks. Then it goes downhill as the miles add up and I rinse and repeat at the dealer.The dealer has told me many customers have commented on improvements after the service. The fluid isn't really discolored and no metal in the filter, so the transmissions are just susceptible to when the fluid or additives starts to break down a little bit.

samckitt · August 20, 2018

On 8/17/2018 at 10:17 AM, Bigmac said:

I chased this shutter problem last year on my 2017 6.2 max tow till I was nuts. It will not go away and it got very bad when towing. It feels like t/q modulation. I changed fluid twice and installed a new t converter. Finally gave up as GM rep said normal. It did get better after driving 15k or so but will always be there. Had a chance to sell it ( long story) and buy a 2018 exact truck since the incentives where so good. Very little money difference $3k so made sense. I would have kept it as I got used to the chuggel as I call it. The 2018 does exactly the same thing but the trans shifting in the 2018 is night and day different. . Instead of shifting at a light load ( throttle) and banging into gear it will hold and shift smooth. I have read the tq has been changed in the 2019 and thinking the vibration issue might be one of the reasons. It is not bad except when towing and then it will shake very hard. Love the truck otherwise and that’s why I got another new one. I’m an ex tech and factory rep so I know the industry inside and out but lowered my expectations and live with its idiosyncrasies

With my 03 Silverado, applying the brake disengages/unlocks the torque converter. So with this truck with the 8 speed, is that still true? I ask because I applied slight brake while applying slight acceleration & feel the shudder. So i'm thinking its not the torque converter.