[990]

This has occured to me on two instances, so allow me to go into a little detail here.
No.1: Sunday. At light waiting to turn left. Light turns green, i step on gas, and about a half second later i hear this god awful thump come from the back of the truck. It was so loud i actually pulled over to make sure i didnt break anything. Thought it was a freak coincidence involving the detroit.

No.2: Leaving work yesterday. Back out of parking spot, and shift into drive. About a half second later i get that same thump!

The truck drives fine before and after. Infact, the first instance was on sunday, when i was still 200+ miles from home. (all highway miles) The thump hit hard enough for me to feel like someone kicked the underside of the truck.

This morning i climbed under the truck to inspect the driveshaft. Upon closer inspection, i found that i could wiggle the double cardan. That is, theres play in it. Both of those ujoints were replaced about a year ago now. The double cardan is most likely the one that came from the factory.

My question is, should there be any play in the double cardan? Or should i go out tomorrow and get a new one?

other info that may/may not be important:
the rear was rebuilt 3k miles ago with 4.10's and a detroit. About a thousand miles ago i changed the fluid/filter for the tranny/t-c (but i doubt that second one has any impact on it)

 

[Guest]

There should be no play.

I know Detroits are different, but my old EZ Locker used to give some really weird sounds, even when practically going straight.

How's your slip shaft?

 

[953]

go have the CV head rebuilt. i get mine done for $45(new ball weldded on, new insert in the CV head, and new seals put in, including parts cept u joints) a pop, but i got a running deal going with him.

 

[muddybronco]

make sure there's no slack in the slip joint too, mine sounded very similar to yours when it needed grease.

 

[WD40]

I "second" the slip-joint.
However, I'd get the double cardan joint rebuilt as well since you found it's loose.

 

[990]

Its a little late now, (after 2am) so ill check into this in the morning. Perhaps monday i will pull the driveshaft and take the double cardan in, seeing as the truck will be in the shop getting the front axle re-geared. Cant drive it with an axle missing anyway, right?

 

[Guest]

I have the same " problem " as you have, but i have this " bumping " or " clunking " noise everytime i come to a complete stop and when i take of again it`s there again sometimes i even get two " clunks ' after eachother ! I also get the same kind of noise when i go over speed bumps or just some bumps in the road, as soon as the rear end of my bronco go over some bump or anything i get this noise, and it`s the same if i drive on an uneven surface like a big field and the car starts to " sway ' sideways i get this noise.

I have been under the car and looked at everything and everything looks and feels ok, so i really whonder what it could be.

 

[Steve83]

\"Car\"

We frown on the use of THAT word to refer to a Bronco...

It's a truck!

 

[633]

If the bronco has the problem then why were you looking under a car?

 

[Guest]

I guess this is a common problem. Mine does the same thing..."clunk" at complete stop and "clunk" a start, other than that it's fine. I guess I should slide under the truck and check for play (side to side) in the drive shaft. If I understand correctly some twisting play is okay, it's the side to side stuff I need to worry about correct?

Is this normal wear?

 

[Steve83]

Twisting

Twisting is not OK - it's worse than side-to-side slop. The whole idea of the driveshaft is to transmit exactly the same rotation sent by the trans/t-case to the rear end with [no[/b] slop, especially rotational.

The noise might be a worn engine mount hitting the limit bolt when the engine torques over, or it might be worn radius arm bushings allowing the radius arm washers to hit the brackets, or it might be worn diff internals. ...or a hundred other possibilities.