2018 Chevy Silverado 1500 8 speed transmission problem

[Captainmc]

Bought a brand new Silverado 2018 1500 with 8 speed and having shifting issues at low speeds. Highway speeds runs perfectly, but low speeds I can only describe as:

Clunky.

Jerky.

Rough.

Hard occasional bump or shift.

Accelerating or lurching forward causing me to hit the brakes hard.

Havnt had any check engine light yet.

Has anyone heard of a fix for this? Or am I going to be another unhappy GM statistic?

Edited March 25, 2019 by Captainmc

[JimCost2014]

3 minutes ago, Captainmc said:

Bought a brand new Silverado 1500 with 8 speed and having shifting issues at low speeds. Highway speeds runs perfectly, but low speeds I can only describe as:

Clunky.

Jerky.

Rough.

Hard occasional bump or shift.

Accelerting or lurching forward causing me to hit the brakes hard.

Havnt had any check engine light yet.

Has anyone heard of a fix for this? Or am I going to be another unhappy GM statistic?

Welcome to the site. There are quite a few threads on this topic. I would start with your dealer, maybe open a claim with GM to see what they can do for you. It is unfortunately a problem that some trucks seem to have. 

 

 

 

 

[Captainmc]

17 minutes ago, JimCost2014 said:

Welcome to the site. There are quite a few threads on this topic. I would start with your dealer, maybe open a claim with GM to see what they can do for you. It is unfortunately a problem that some trucks seem to have. 

 

 

 

 

Thanks. I know all too well about the whole dealership fiasco. With all the issues I had with my 2005 suburban and 2005 Silverado you would think I would have learned by now but here I am. I do still have my 2005 Silverado 2500 HD. Other than the pump rub and gauge cluster repairs, it’s an amazing running vehicle (160,000 miles). I’m thinking of keeping it in case this new Silverado leaves me stranded. Pretty pathetic to feel better about driving your old truck.?Interesting enough is that I have a 2015 Yukon and it’s been awesome so far. Shifts perfect with no issues yet. Does do the lugging deal in V4 mode but we are used to it now.  Just thought I would see if anyone actually found a real fix or had any advice  before I take the Silverado in?

Edited March 25, 2019 by Captainmc

[1SLOW1500]

This has been addressed but I would look at the service record. I understand it's new but that doesnt mean there isn't a service bulletin on it. 

I say all the time the 8speeds have issues. I was told not to buy one by GM. Anyways again it's new so may not be what you want but can be fixed with tune.

[Captainmc]

4 hours ago, 1SLOW1500 said:

This has been addressed but I would look at the service record. I understand it's new but that doesnt mean there isn't a service bulletin on it. 

I say all the time the 8speeds have issues. I was told not to buy one by GM. Anyways again it's new so may not be what you want but can be fixed with tune.

I sure hope so. Love everything else about the truck except the terrible shifting. I heard that tuning it can void the warranty?

 

Anyways, just made an appointment to have the software updated so hopefully it

can help like I’ve heard it has from some other guys.  I’ll repost what happens 

Edited March 25, 2019 by Captainmc

[jaijason]

Would love to hear updates.  I'm in denial but thinking I could be in the same boat.  Not even 2k miles

[Mstangr]

Bueller? Anything more? I have been experiencing the same issues with 2018 8 speed. 

 

[Randy Daggett]

I have been rebuilding transmissions for over 30 years and I just bought at the time a new 2020 Chevy Silverado 5.3L and I love it except for all of the little features that I really didn’t want but anyway let’s get to the 8 speed Chevy transmission, I have found that most of the time when the transmission is clunking or shifting hard at lower speeds is due to a faulty Valve body and THECM unit, or internal clutch packs that are leaking or just burnt clutches can cause clunking at low speed, the valve body is one of the most common reasons for clunking at low speed, but there can be burnt clutches or a defective one way clutch assembly, pump assembly not producing the correct pressures.

When ever I rebuild a newer 6,8,10 speed automatic transmission I always get a remanufactured Sonnax valve body, they are all dyno tested for internal leaks that cause clunking and many other issues!

 

 

[dgstarr63]

I have a 2021 Silverado 1500 4wd, 5.3, 8 speed. Every 500 or so miles it would clunk on a downshift to low when slowing up to a stop for about 1 to3 days and then quit for another 500 miles and start over. At 5000 miles my dealer installed a new valve body. It has been about 500 miles since the repair and is shifting perfectly. I hope this repair will be permanent.