Start, Stop, CLUNK
Thread Starter
Member
Joined: Jun 2017
Posts: 39
Likes: 5
Start, Stop, CLUNK
So my 2016 3.5L Eco-boost has yet another issue. When I slow down and then accelerate without coming to a complete stop there is a loud clunk coming from under the truck in the back. I got it back from the dealership last night and they told me it is normal and I should always come to a complete stop before re-accelerating......
So i guess i cant sit in stop and go traffic either?!
Then they stated that my larger tires 35" have thrown off the shift points. Now come the F on. We all know that is not true. I cannot stand Ford Service. This truck has been to 6 different dealerships since it was purchased last January.
This seems to be known issue among others and Ford wants nothing to do with it.
Rant over.
So i guess i cant sit in stop and go traffic either?!
Then they stated that my larger tires 35" have thrown off the shift points. Now come the F on. We all know that is not true. I cannot stand Ford Service. This truck has been to 6 different dealerships since it was purchased last January.
This seems to be known issue among others and Ford wants nothing to do with it.
Rant over.
Blunt
Joined: Mar 2015
Posts: 4,034
Likes: 1,086
From: Alberta, Canada
Drivetrain play. Usually the rear diff. You get used to it. Just nudge the pedal first to let out the slack and then put it down. If you're that worried you can ask the dealership to check the lash on the diff and adjust if needed.
Senior Member
Joined: Oct 2010
Posts: 2,723
Likes: 717
From: Crossville TN
Both my 15 and now my 16b have done it since day 1. I first thought it was a problem but then I noticed it was the way I was driving. In stop and go driving you will be fine unless you are one of those people that have to get to 90 in three feet. As for the larger tires causing the shift points to be off, yup they do. Larger circumference will do it faster then you think. These are not the old trannys with gears and clutches etc. These are electronically controlled down to the temperature of the fluid will cause harder or softer shifts.
Member
Joined: Mar 2018
Posts: 84
Likes: 12
It’s driveline lash. This happens on just about every manufacturers vehicles with rear wheel drive. It’s even more pronounced with the HD 250’s & 350’s. Lubing the splines on the driveshaft will help. The shaft slides as your suspension moves up and down. Accelerating and decelerating will cause your suspension to compress or extend. At least that’s why on the HD’s. Haven’t actually crawled under the 150.
5 Year Member
Joined: Aug 2011
Posts: 2,297
Likes: 325
From: Mississippi
It’s actually the transmission doing it. These transmissions float when you let off the gas and then when you put on the gas again it locks in gear. This has been talked about many times on this thread .
Senior Member
Joined: Jun 2017
Posts: 2,336
Likes: 451
From: Memphis TN
so quite a few nuggets in the comments so far.
1) your tires are indeed throwing off the shift points - more importantly it affects the entire trans programing and part of the ECU programing. Things like commanded torque at ___ rpm is also based on veichle speed and affects the clutch transition timing. SO yes it's a great idea to get one of those tuner devices that will re-program your new wheel and tire sizing.
2) drive train slop - there is a bit between the trans and the prop shaft. and some more between the prop shaft and differential . (prop shaft - some people call it a drive shaft but it doesn't drive wheels automotive terminology differences) So as some stated some are worse than others - it's there to accommodate temp variance. and most find this worse in the winter time.
3) also stated trans jerk into gear - if the fluid is cold the trans will "slam" into gear a bit harder than normal this is due to the clutches being let out too fast because the pressures are a little high - it's also a wear item in that brand new the clutches need to work in a bit. ON your 10sp you might rarely ever use 2nd for example - and that clutch hasn't worn in as well as the 1,3 or the 4,7 etc. so it can get better with age - but this doesn't do squat for your drive line slop
1) your tires are indeed throwing off the shift points - more importantly it affects the entire trans programing and part of the ECU programing. Things like commanded torque at ___ rpm is also based on veichle speed and affects the clutch transition timing. SO yes it's a great idea to get one of those tuner devices that will re-program your new wheel and tire sizing.
2) drive train slop - there is a bit between the trans and the prop shaft. and some more between the prop shaft and differential . (prop shaft - some people call it a drive shaft but it doesn't drive wheels automotive terminology differences) So as some stated some are worse than others - it's there to accommodate temp variance. and most find this worse in the winter time.
3) also stated trans jerk into gear - if the fluid is cold the trans will "slam" into gear a bit harder than normal this is due to the clutches being let out too fast because the pressures are a little high - it's also a wear item in that brand new the clutches need to work in a bit. ON your 10sp you might rarely ever use 2nd for example - and that clutch hasn't worn in as well as the 1,3 or the 4,7 etc. so it can get better with age - but this doesn't do squat for your drive line slop