85 3/4 Ton with Clunky Front End

[uberschall]

Howdy.

The steering in my 85 C2500 has never been great - can't tighten slop out of the steering gear any more, but recently I've developed another concerning issue.

I've noticed a pronounce "click" noise when I get on OR off the brakes. At an idle, a deliberate stop will produce a clunk, and subsequently releasing the brakes will result in another clunk, like something's flopping back and forth.

Anybody have an idea where to start?

Thanks in advance.

 

[MadOgre]

Take your front wheels off and take a look. spin your calipers. push pull on things. look at your pads to see if there still there or worn or separating from backings. Cant really do much if you don't look.

 

[MadOgre]

Could also be worn suspension bushings.

 

[chengny]

Many people report a noticeable noise that occurs in the situation you describe However, there is another cause that emanates from that area. The splined interface between the driveshafts and the transmission/transfer case. It is generally the rear drive shaft.

When you come to an abrupt stop, the front brakes (as designed) do most of the stopping and the front of the truck slows much faster than the rear. The rear end eventually catches up and slows to the same speed. But what happens during that period of time is that the entire driveline compresses, due to the different rates of deceleration. When you accelerate again the drive train relaxes and stretches back out. That is one of the reasons the drive shaft is splined.

If the splines are dry, as they return to there stretched out length, they will make a groan or squeak. This is the faces of the splines as they slide along each other. There is usually a grease fitting ( or a tapped hole to accept one) in the splined area.


Yeah, I know - it is counter intuitive. But it is true - a vehicle's driveline actually elongates during acceleration after a stop (even with rear wheel drive). And at some point I knew why.


It’ll come back to me. Here is Popular Mechanics on the issue:

Many RWD cars and trucks exhibit a clunk when accelerating from a dead stop. It’s caused by friction in the splines that couple the transmission tailshaft to the driveshaft front yoke. Friction keeps the splines from sliding as the axle moves fore and aft slightly when transitioning from stopped to under way. When the truck starts moving, it all sorts out with a clunk as the splines slide longitudinally.

I think that may be happening here. The fix, or at least the diagnosis for clunking splines is to remove the driveshaft, and lubricate the splines with Motorcraft PTFE lubricant (Ford p/n D2AZ-19590-A).

 

[uberschall]

Didn't take me long to find the problem - one of the G-D sleeve nuts on the upper control arm shaft (the DS, specifically) is COMPLETELY MISSING.

I've never touched those, how on earth could it have come off?

Just ordered a shaft assembly, but worried that the threads on the control arm may have gotten boogered up.

Has anybody seen this before?