84,000 miles and needs a new transmission

sage55 · October 13, 2021

Well this is rather annoying. Bought a 2016 Silverado with about 40,000 miles on it just a couple years ago. 84,000 miles on it now and just got a call from the dealer that the reason why it won't shift, revving, jumping and going into limp mode is because it needs a new transmission.

For only $7,500 I can get a new transmission with a 3yr, 100,000 mile warranty on it.

diyer2 · October 13, 2021

6 speed 8 speed.

No service history?

sage55 · October 13, 2021

9 minutes ago, diyer2 said:

6 speed 8 speed.

No service history?

6 speed.

Service history I typically followed the recommended 2016 silverado schedule. Oil changed every 3,000 miles and tires rotated - air and cabin filter was changed about every other oil change. Changed the brake and transmission fluid at 46,000.

Grumpy Bear · October 13, 2021

JMBX converters are junk. When they grenade so does the gearbox.

https://www.sonnax.com/tech_resources/846-transmission-report-6l80-6l90-transmission-tech-advisory-consider-an-updated-converter-in-your-next-rebuild

First paragraph page 2.

Your tech will balk and they will threaten to deny the warranty on the new transmission. So most people buckle under and use the same parts that failed the first time hoping for a different result. You know what that is the definition of, right?

BTW the Reman is just as good a a new one and several thousand cheaper.

Grumpy Bear · October 13, 2021

BTW a 3 year 100K warranty? Most people cover about 12K a year. They feel pretty safe with giving the illusion of reliable without actually delivering on it very often.

Ask how many 6L80E failures there are when mounted behind the 4.3 V6. (next to none)

They don't use the JMBX converter

And no, the V6 unit will not fit or work with the V8's

sage55 · October 13, 2021

@Grumpy Bear - So what's the actual part(s) and part number(s) that I need to have them add to this expensive bill already to ensure this doesn't happen again in 80,000 miles?

pokismoki · October 13, 2021

try and get the 6 bolt stock converter for a 2500 truck using the 6l90, direct swap, no I dont have a part number but its posted on a few youtube videos doing this upgrade

Grumpy Bear · October 13, 2021

2 hours ago, sage55 said:

@Grumpy Bear - So what's the actual part(s) and part number(s) that I need to have them add to this expensive bill already to ensure this doesn't happen again in 80,000 miles?

1 hour ago, pokismoki said:

try and get the 6 bolt stock converter for a 2500 truck using the 6l90, direct swap, no I dont have a part number but its posted on a few youtube videos doing this upgrade

This is good.

sage55 · October 14, 2021

Well just had the truck towed from the dealer over to a local mechanic who's going to throw in a rebuilt Jasper transmission.

I'm going to call around tomorrow about getting a 6L90 torque converter for the new rebuild.

Any other upgrades I should due to try to avoid this issue that is plaguing GM's?

CamGTP · October 14, 2021

Remove the transmission thermostat on the feed/return line that bolt to the side of the transmission. That will cool the temps down by 30-40 degrees at a minimum.

A tune on the transmission by someone that knows what they are doing would help a ton too. Changing the shift mph and the lock up speeds to keep the converter from working as much. From the factory it will be on in gears 2-6 and when I tune them I change it for gears 5th and 6th only.

sage55 · October 15, 2021

16 hours ago, CamGTP said:

Remove the transmission thermostat on the feed/return line that bolt to the side of the transmission. That will cool the temps down by 30-40 degrees at a minimum.

Wouldn't I be better off moving the thermostat to inside the came so it could benefit from the A/C?