Just wondering if anyone had their Tranny Thunk problem resolved. Mine is still doing it but have not taken it to the dealer since the last time they hinted around to the "normal" explanation.

For those of you not familar with this issue try the following:

Accellerate to 25mph then coast to about 15mph then apply gas. Thunk! It is most noticeable for me around left hand turns but I have been able to consistently duplicate it going forward too.

Please sign in here if you have had it fixed or are experiencing this problem.

 

I kind of understand what you are saying...This is what is commonly refered to as excessive gear lash...

If the diff's are set loose you will get the thud...Another way to check this is to unload the driveshaft and then turn it back and forth and see how much play is in the gears...

I would rather have them set a little loose then too tight...but depends on the wear pattern...

If it is this then you have to resetup the diff gears...

This is all granted that nothing else is wrong like the u-joints...
or slip collars...

You did not mention how many miles is on your truck...as this is common with age...

 

It has been doing it since it was new. I now have about 11,000 miles on the odometer.

Has anyone explored this "reset" with their dealer?

 

kkirt,

Funny you mention this under these conditions. I wondered if I was just hearing something or it really was the tranny.

Keep me up to speed...what does the dealer say about it. I'm only into my 6th day of ownership yet and haven't asked service about it.

 

Well you guys are not alone... I have the "thunk" too... my '01 screw with barely 2000 miles has been thunking right along with no explanation since it was new...

I hope this is not the beginning of another debacle like the radiator problems ((yikes))

lets all keep in touch here........especially if someone comes up with a solution

thanks

Mike

 

Do a search on this topic. You'll find lots of background info on our histories of attempted repairs and on our particular equipment profiles (me, KKirt and others).

For my part, I gave up when I couldn't get the regional tech rep to call me back and schedule a road test. Ford QC kept telling me that the dealer was responsible for contacting the rep and setting up the appointment. The dealer told me that they had no control over the rep and that to move the issue along more quickly, they would ask to rep to contact me directly. By the way, I got as far as having the road test scheduled but the rep flaked on me and never showed! To make matters worse, neither he, the dealer nor Ford QC ever called me back on this issue.

I love my truck and have really enjoyed it. I just decided that I've got better things to do with my time and that my particular case is sufficiently documented if or when the tranny thunk turns into a major problem.

 

Sounds like you are describing sometype of driveline slop...

Check the driveshaft, u-joints, spline section and diff....

For play in these areas...

 

agree with mach1. doesn't sound like a tranny issue to me...

 

There is a post somewhere here on F150 Online where someone solved this problem on their truck. I have the same noise as well. His dealer found 3 bolts on a frame crossmember that had either worked loose or were never tightened. I have not checked mine yet, plan to later this week.

 

I thought this was just some kind of normal diferential...or overdrive unlock-lock we were feeling.....wasn't that the conclusion?

 

You are right, it may not be the tranny, I guess some one coined the phrase "tranny thunk" and it stuck. It sounds like it is coming from the middle of the truck but under-carriage sounds can be deceiving.

Also, I have read the three-bolt theory but slid under the truck with a wrench some time ago and found no loose cross-member bolts.

 

KKIRT1, Here is my opinion on the tranny thunk, I have a 2001 Screw 2 WD, 5.4L and had transmission replaced twice so far, once because of the thunk and the other because a line busted, drained fluid and caused internal damage to tranny, well thunk still there and even worse on the last tranny. I believe that the 4R70W has slop in between 2nd and 3rd gears or is some kind of time/pressure delay that causes the thunk. The reason I say this is because the thunk happens even after applying gas and all slack has been taken out of drive line. In my truck is even happening at 30 to 35 mph and I dont have to coast down and reapply gas and is only noticeble shifting down from 3rd to second. "The service department told me they do not know why". Any way I thought I shared something on this topic.

 

does anyone know if this issue is more related to 2wd s-crews? my 4wd xlt has never displayed this behaviour. however, when the truck was new, i did get a slight thunk upon initial takeoff from a complete stop. that has since disappeared.

 

Here's a link that will take y'all back to the beginnings of this "unresolved" problem.

https://www.f150online.com/forums/sh...threadid=41033

As you can see from my posts, the potential driveline (non-tranny) issues were dealt with before the dealer agreed to replace my tranny.

 

No fix for the thunking, but I am joining the club. I have a 2001 supercrew with 5.4 and 3.55 posi and mine has done it from day one. I have 4,000 miles on it. Same story, 18-20 mph stop and go get a clunk.

I had it in to the dealer last week and got the story that it is normal. They referred to a "Special Service Message 12905" Which states: Axle wind up in 4 HI and 4 Low some 1991-2001 F150/250/350 vechiles may exhibit axle wind-up and /or clunking type noises when making cornering maneuvers on vehicles equipped with a four wheel drive HI or Low range mode.

I was there for several problems and did not digest the document until I left the dealer. The notice would lead you to believe you have to be in four wheel drive going around a corner to get the clunking noises.

I sure it was the basic sluffoff. I have to go back to the dealer again next week. I will try to pin them down. They said on the work order no troble found.