Driveline "Thunk"

[Ron Husak]

Hi All..
I am new to this list and have a 1997 Explorer Sport that now has 40K on it. I purchased it almost a year ago and it has always made this noise!
What happens is after a stop when releasing the brake of sightly accelerating from the stop there is a distinct "thunk" from the rear. You can feel it in the floor as well... Is this caused by the driveshaft slip joint I have read about? If so is it difficult to service? Do youuse CV joint clamps and pliars to uncover the joint and reinstall the boot?
Thanks to all for your help
Ron

 

[RadioFlyer91]

Ford TSB's and observations.

It is my understanding that several of Ford's 4x4's make this noise. Explorer and Ranger come to mind. There is a TSB that involves removing the yoke out of the transfer case output flange, cleaning the splines and output shaft and using locktite to the splines only on the transfer case yoke, not to be applied to the shaft, then reinstalling the yoke being carefull the locktite is forced away from the transfer case, then torqing the nut to 250-280 ft lbs. If the TSB has already been done you will see "Locktited, the date, and TSB 98-11-9 written on the yoke. I have not done this to my explorer, yet. However Ford says it will resolved the ping in the driveline. I have had the u-joints replaced using a different lube, I forget the type the repair was made before my technical training, this did not resove the ping. Most people take the ping as it is without making the repair. The repair is easy to make yourself if you are the shadetree type, or Ford will be glad to charge you for the service.

Hope this helps.

 

[CoreyP]

Hi all. I've been searching for an answer, but haven't found it yet. This thread is the closest I got. I've got a 99 Sport, which has a thunk when shifting into gear (automatic). I took it to my dealer and they told me that the rear driveshaft output flange was worn. They said a few other Explorers have had this problem, but it's still a pay-for-it type service. They said a new flange was around $200, and another $200 or so for labor. Ouch.

From reading this thread, it sounds like someone out there knows a work-around for this. If Loctite is the answer, what kind? The green stuff?

Also, does the flange fail after a while, or does the thunk just become more common?

Thanks.

 

['96explorereddiebauer]

Corey, I think the clunk you're talking about is a loose U-joint. I'm not very good at explaining anything mechanical b/c I don't know a lot about them. I'll let the other guys to answer your question.

 

[Ron Husak]

Corey..
The "Thunk" i am talking about in this post does not occure when shifting into gear. It is different than you mdescribe.. I am surprised that the dealer cannot positivly identify the noise if it's so easily duplicated.. If itis indeed the flange worn then the loctite would resolve the issue if o0nly for a short time..
Maybe taking it to an independant 4X4 shop would result in someone who would spend the time to properly diagnos and repair the issue.
Just my .02
Ron

 

[RON COX]

I was under the impression that the "thunk" was the limited slip spooling up and locking, or unlocking. Do you have a LS? Mine has done that for as long as I can remember. Even my Ranger does it. Nothing seems to be effected by it (yet).

 

[Ron Husak]

Ron..
Nope mine doesn't have the limited slip... The thunk is well known on the Ranger and Explorer both... That is why they came up with a TSB...
I don't think this is going to hurt anything... Just annoying..
Ron

 

[CoreyP]

The plot thickens... I do have a limited slip, but I seriously doubt I'm getting the noise there. The 'thunk' happens when I shifting between forward and reverse or from park to a gear. After I get going, I don't hear it again. I can't reproduce it by slowing down and accelerating again or anything like that. It only happens when the driveline originally receives an input.

I think the dealer correctly identified the noise- at least he has me fooled. I crawled around underneath and grabbed the driveshaft. I can reproduce the noise by twisting the driveshaft by hand with the tranny in park. I just don't know if I should worry about getting it fixed because a catastrophic failure is emminent, or if i should just turn the radio up a little more. Or better yet, if there's a work-around I can do myself...

I didn't mention it before, but in case it matters, I'm at 39.5k miles. I also had a t-case repair a few months back. I found that the front output shaft seal was leaking, so I took it in under warranty. When they got the case apart, they found one of the teeth from the chain sprocket in the bottom of the case. Pretty cool. There wasn't any other damage I saw or they reported. They replaced the broken sprocket and I haven't had any trouble since, except the noise. I'm pretty sure the tooth was broken from the factory, because I assume that I would notice something like a tooth breaking off if it got caught in the chain or other gears.

 

[Ron Husak]

Corey,
In and of itself a liomited slip doesn't make any noise.. Save sometimes "chattering" when going around corners slowly..
The noise you are picking up particularly if it can be duplicated by hand should be attended to.. There is something REALLY loose somewhere...
The broken tooth.. who knows.. Could have happened at assembly or anytime since.. You would not necessarily hear it untill the gear let go totally..
Good luck with it..
Ron

 

[HuiDaddy]

I GET THE THUNK TOO!!!! it feels like someone just bumped me from behind. nothing massive, but friggin annoying!!! my passengers think someone bumped me from behind too. They look back and are like, "dude, did someone just hit you?" This is when it occurs. When i stop at like a red light or stop sign, and usually when i make a harder stop that normal. then when i lift up the brake to drive on again, the THUNK occurs. i have always thought it to be my brakes for some reason like a sticky caliper or some sort, but dude, DRIVE SHAFT?!!? aw man!!!

 

[yob_yeknom]

Never worried about it before...

I've always had a small 'thunk' when starting off and a louder 'thunk' when putting it in gear. I never thought twice about it. Now after reading all this I'm beginning to think again...

Let me know what you guys do and how it turns out. I might do the same things.

 

[Robert]

Originally posted by HuiDaddy
I GET THE THUNK TOO!!!! it feels like someone just bumped me from behind. nothing massive, but friggin annoying!!! my passengers think someone bumped me from behind too. They look back and are like, "dude, did someone just hit you?" This is when it occurs. When i stop at like a red light or stop sign, and usually when i make a harder stop that normal. then when i lift up the brake to drive on again, the THUNK occurs. i have always thought it to be my brakes for some reason like a sticky caliper or some sort, but dude, DRIVE SHAFT?!!? aw man!!!

Yours sounds like your rear driveshaft slip yoke. My '97 did the same thing until I lubricated the slip yoke. Since it is part of routine maintenance, if you haven't had it done recently that is where I would start.

This is not to be confused with the other "clunk" posted here. That sounds more like U-joints or something related.

 

[steveissteven]

Hello!

I had the same problem with my '93 Sport... As for the output flange, this only contributes about 15-20% of the THUNK you are experiencing. What is a more accurate term for this THUNK is commonly known as Rear Axle Wrap. I took my truck to a spring service shop and had them add a leaf to the rear leaf springs. The annoying thunk is now gone. Hope this helps. By the way, having the rear leafs added cost around $200.00

 

[Ron Husak]

Guy's...
Axle flange.. Slip joint... Spring leaf.. All adds up to the infamous "Thunk"!
I have had luck with the TSB fix 98-11-9 and lubing the slip joint... Haven't had to add a leaf..
That seemed to take care of the problem for me..
Ron

 

[Frisckey1]

Instead of a "Thunk"

What do you make of a rubbing sound? Sort of like a tire is rubbing...but I know that's not it. It usually happens when I first put it in gear (automatic) or when I put it in reverse. It is definately NOT a thunk though. I know that sound, and I get it to occasionally, but this is different. It doesn't continually rub, just for a second. And it won't do it if I put it in drive after reversing. Only from park to drive, or drive to reverse...etc. Any suggestions?

 

[01EB5.0]

Ok, here's my thunk. it happens in forward or reverse. I mostly notice it when backing upo the driveway or backing inot the garage. when the tire stops on ther bump to go up into the garage i ease on the gas. As i start giving it gas I hear a clunk of thump from the rear. I bought the truck with 72K on it and now is has nearly 100K. I just wan to know if this sound is normal or if it may be a potential problem?