My 2010 F-150 with 170,000 miles - 6R80 Transmission is starting to chatter while shifting into overdrive. It lasts about two seconds and then all is well. I'm sure it will get worse. Any suggestions will be appreciated.

 

How old is the ATF? Old fluid can cause this. So can old spark plugs and/or ignition coils.

 

The transmission oil & filter have 63,000 since the last change. The spark plugs have 30,000 miles on them. The coils are original at 170,000 miles.
The chatter does not happen if I put the transmission in Tow/Haul mode.
Thank you for the help

 

I recommend changing the ATF first. If that doesn't fix it, consider the possibility that one or more coils is getting weak.

 

There have been a few reports of torque converter problems with the 2009-2010 f150's. These years are programmed with a very soft torque converter clutch engagement which appears to be very hard on the fluid and clutches.

That being said, you should notice the chatter slightly after the 2-3 shift as the truck will lock the converter very early in 3rd gear.

As a test, you can start the truck out in 3rd. This will let the truck take off in 3rd and eliminate all the other variables in the trans except the torque converter clutches. The truck will lock the converter very early in 3rd even with the pedal to the floor, so if it is the clutches going bad, you should notice it when it tries to lock up. If it is there all the time, then it is probably something else like an ignition problem as mark mentioned. If you only feel the chatter when the converter locks up, then a fluid exchange might fix it.

If all they did was drop the pan and refill, then you only got about 1/3 of the old fluid out when they changed the filter. 2 more pan drops and refills will get 90% or better of the old fluid out. Being as this truck has a thermostat in the cooler circuit, a line off exchange at home wont work, so the only other practical way to get the fluid exchanged is with a heated flush machine.

There are some quickly lube places that have a machine that hooks up to the filter inlet and exchange the fluid that way, so that might be another option.

Just some things to try and think about.

 

I can make the problem go away by putting the transmission in Tow/Haul Mode or by driving around in 3rd gear. Does that suggest what it might be?

 

Im far from an expert, but that would tell me the torque converter is probably not your issue.

Tow haul changes shift points so it would go into 6th later than normal.

I'd probably Change fluid and hope that's it, but i wouldn't rule out ignition issues.

 

I took it to the local transmission shop. They tell the 6R80 Ford transmission is a good transmission although they have seen a few torque converter issues.
They want $1,100.00 to replace the torque converter, new filter and fluid change. Fair enough I'm going to let them do it. I'm hoping to drive that truck at least 250,000 miles. My 1998 F150 made it that far. Time will tell.
Thanks for all the advice