03 Yukon Shudder between 40 and 50 mph

[Summajet]

I am new to the forum. I have a 03 GMC Yukon 5.3 liter flex fuel with autotrak 4wd-L460E transmission.

It has 233,500 miles. Purchased in June of 2015.
Up till November 2018 it has been good with no major issues other than routine
maintenance and repairs.
It has developed a shudder between 40 and 50 mph. More noticeable when going uphill at that range and transmission is right at the spot it switches into overdrive.

Maintenance performed,
1. New filter and fluid (Ac Delco dexron 6)
2. New shift solenoids
3. Torque converter solenoid

Did not replace the pressure control solenoid.

4. Drained/filled rear diff (G80) with 80w/
90 gear oil with new gasket and added AC Delco friction modifier. After rear diff fluid change seems the shudder is worse. I know it is suppose to have the 80w/90 oil but thought 75w/90 synthetic might be better???

5. New spark plug wires and plugs.
Does not appear to be a misfire.

Based on what I read sounds like torque converter???

Local transmission shop with great reputation quoted $1,000 for torque converter and replace rear oil seal.
$2,000 for getting transmission rebuilt.

Anyone else have similar issues and/or what the cause and fix was??

I appreciate any advice.
Thnaks!

 

[rd62rdstr]

I am new to the forum. I have a 03 GMC Yukon 5.3 liter flex fuel with autotrak 4wd-L460E transmission.

It has 233,500 miles. Purchased in June of 2015.
Up till November 2018 it has been good with no major issues other than routine
maintenance and repairs.
It has developed a shudder between 40 and 50 mph. More noticeable when going uphill at that range and transmission is right at the spot it switches into overdrive.

Maintenance performed,
1. New filter and fluid (Ac Delco dexron 6)
2. New shift solenoids
3. Torque converter solenoid

Did not replace the pressure control solenoid.

4. Drained/filled rear diff (G80) with 80w/
90 gear oil with new gasket and added AC Delco friction modifier. After rear diff fluid change seems the shudder is worse. I know it is suppose to have the 80w/90 oil but thought 75w/90 synthetic might be better???

5. New spark plug wires and plugs.
Does not appear to be a misfire.

Based on what I read sounds like torque converter???

Local transmission shop with great reputation quoted $1,000 for torque converter and replace rear oil seal.
$2,000 for getting transmission rebuilt.

Anyone else have similar issues and/or what the cause and fix was??

I appreciate any advice.
Thnaks!

So what was it?

 

[Summajet]

It was the torque converter.

 

[rd62rdstr]

It was the torque converter.

Thank you

 

[Summajet]

You are welcome. I had the transmission shop rebuild it as it was 1/2 cost in just replacing the torque converter.

 

[OR VietVet]

It was the torque converter.

Thanks for the heads up. It always helps others to post the results of a fix for a problem. I know that sometimes after fighting a problem you are just glad to get it fixed and done and back to normal driving and forget about what you asked about here. Again, thanks.

 

[rockola1971]

The magic happens right around 40-50mph (depending on load) OD(4th gear) is engaged AND the torque converter locks up. Its common for people that havent been informed/trained to confuse one for the other and believe the Torque converter has locked up or OD has engaged (even though their tach is showing 2500-3200 rpm.) Shutter can destroy the front bushing of the tranny which just so happens to be installed in the pump. Walks the front seal out and then the high pressure return blows the front seal all the way out once it is blocked and now you have tranny dumping all its fluid onto the road. Then clutches are starved, vehicle wont go anywhere and the driver mashes the throttle to go 4ft forward while burning up the tranny.