alping45

iTrader: (1)

It seems like there is some slack somewhere in the drivetrain, whenever I am coasting then hit the gas, I hear a "clunk" come from the rear end. Is this normal? This is my 4th F150 and I don't recall any of the others doing this.

I should also mention I'm running 5* tuning, could this have anything to do with the torque converter strategy set by the tune?

<-KJP->

I noticed a little bit of that on my truck, on off (gas pedal) light coasting and a slight clunk. I think you are right either little slack needs taken up or grease job.

Mine is going in for first service I will get them to have a quick look.
My truck is completely stock, but a tune could probably amplify that a bit.

sthomps

Happens all the time with my 5.0. I too run the 5* tunes. Most of the issue with their tunes is how they run a locked torque converter basically all the time with no unlocked coasting, even when crawling around a small town. You'll always get lash when you don't unlock the torque converter. It's actually a ridiculous way to tune a vehicle in my opinion. The stock tune had some lag-lash previous too. My old PHP tunes were 10x better in terms of everyday, all situations driveability.

For me, the 5 star tunes have excessively sensitive throttle at low speeds too. You barely open throttle 10% and it feels they have it tuned to open 60% or more. They are awesome if all you do is excellerate hard but other than that it's aggravating. It's made me paranoid to get back on the throttle in low speed coast situations. Personally I found the stock Ford tune to be a better strategy for towing, and it also has a better Sport strategy for driving through the mountains.

I'm not totally satisfied with the 5* tunes yet but will work with them to improve them. I'm also hoping MPT comes out with something to compare.

13.

Back in the late '90s the trucks would clunk just like you were saying if the driveshaft splines weren't lubed properly.

BoostedFx

The driveline splines need to be greased, mine started to clunk when I would accelerate from a dead stop. It's a simple fix and is covered under warranty. If Ford would put a grease fitting on the splines we could do it ourselves.

alping45

iTrader: (1)

Anyone else run into this?

birdmayon

Yes, my truck does it, and no tunes.

JAB F150

I just got a 2015 Lariat and it does it quite a bit. I previously had a 2012 and it did the same thing. It feels like something is not catching.

jdp530

My '11 5.0 clunked in front with the one-piece drive shaft but after I took it in for the TSB (after 40K), and before warranty was up, it worked smoothly for 50K more miles. The original lube wasnt enough so its a simple fix to remove drive shaft then yoke on trans and re-grease it with the correct stuff.

My '15 5.0 CC 5.5 box w/3.55 EL has a two piece drive shaft and i have a very light clunking in rear axle on occasion if i have been coasting and then accelerate away. Its not loud or hard enough to be concerned. Most every vehicle will have a bit of gear lash in rear axle.

thekevin

Look at the threads for the hard shifting into 4th gear and see if that is what you are having. On mine if I am coasting and go to apply gas it feels like it slams in to 4th gear and feels like it is going to break something. There is a TSB on the issue though.