clunk after easing slack out of trailer

[OldBinger]

hey guys this is my first post after months of reading. i have a 03 dmax-allie 2wd. i noticed yesterday while pulling about 7000# a clunk when pulling off. i tried to start out slowly and take all the slack out of the hitch system, but as soon as i got down on it to go it felt as if slack came from nowhere and then the clunk. i have only 11,000 miles. has anyone else had this experience and/or does anyone have any words of wisdom?

thanks
oldbinger

[JimWilson]

Is the clunk coming from the driveline or is it somewhere in the hitch/coupler area?

[OldBinger]

It appears to be somewhere in the truck. i looked at the hitch platform and could see no sign of movement. it almost feels like spring windup. i have heard of noise when the springs wind up and the stock spring bumpers are gone but mine are all intact and i had enough load so that they were in comtact anyway. i thought the allison might not be shifting into first until i asked it to go, but it feels as if suddenly there is slack in the drive train and then it catches. weird. i will be pulling through west virginia next week. i always use the tow mode as i love the way it gears down. could i have worked the ubolts loose that hold the real axle in place???

[schnier]

Do not forget ,the allison likes to have the brake applied to go into first. If you roll up a hill and coast to a stop, without hitting the brake, sometimes the tranny will not go into first until you accerate a little. If you touch the brake and let off it tells the tranny to go into first at a dead stop. I have read this before and mine will do it all the time if I really force it like this. Been working great for three years like this. It is like a little bump or clunk, if the brake is not applied at a stop.

[OldBinger]

i was leaning towards the allison not shifting into first until i pull off and it senses the load and then shifting down. i think i read somewhere that there is a spring kit that corrects the problem or maybe just a flash for the computer. it does the same thing brake on or not. i have never noticed it doing it unless hooked to a loaded trailer, but tonight i pulled to a stop going up a steep hill and as i pulled out a car came over the hill and i really had to get on it and "clunk" the same feel and the same sound. so now i know it is in the truck.

[JimWilson]

Originally posted by OldBinger:
could i have worked the ubolts loose that hold the real axle in place??? With the amount of torque applied to the rear axle under normal circumstances I can pretty much guarantee that you would know, all the time, if your u-bolts were loose. I can't see it being that.

There was a TSB for the driveshaft because of some type of slippage that caused a fairly sharp clunk/bang to happen on occasion. I believe the fix was a nickle plated yoke, but I can't find the info now so I'm not certain what it was.

[Kennedy]

Could it be delayed release of the electric trailer brakes? Could be they are due for adjustment...

[OldBinger]

thanks guys!! i'll do a lot of checking, adjusting, and testing over the week end and post what i find if anything. it's not a hard enough slip or clunk to hurt anything but it sure is annoying and on a trip it make one uneasy. i normally 1500 to 2000 miles a month.

olbbinger

ps see my website and trailer at www.oldbinger.com (http://www.oldbinger.com)

[dmaxalliTech]

I am thinking the same as Kennedy, sounds as if that may be the cause, my 5er does it if the Prodigy is on level 2 or 3.

The nickel plated yoke is only for 1/2 ton trucks

[turbowind]

Hi Guys !
I had the same problem while towing...It turned out to be my Westin step bars...As the frame of my truck flexed with the weight of the trailer, the westin bars did not flex without letting out a clunk from their mounts, I greased said mounts and that helped, but she still moans under the weight of my 15,00lbs load.. :rolleyes:

[MaxRock]

OldBinger,

One thing else to look at is the hole in the factory hitch that you install the hitch pin. If that hole is getting egg shaped, it will cause some slack in the receiver and ball mount. After 7k to 8k miles of towing an 8k TT, my receiver pin hole is starting to egg shape.

Something else to look at!

MaxRock

[OldBinger]

O.K. guys this is what i found! i could not duplicate the problem with the trailer disconnected. i rehooked and with out a load could not duplicate the problem. i took the trailer to a car wash and drenched the trailer brakes and the problem reoccured for a few stops. i am now satisfied that it is a trailer brake problem. i will have the trailer brakes adjusted this week and see if that cures the problem. i also noticed that with no boost the problem was not there. all i can say is THANKS for listening and THANKS for your answers and help

[Kennedy]

Adjust them TIGHT till you cannot move the wheels, then back off till they roll free. The square actuator cam can sometimes get close to center and start to stick...