Noise Help (1 Viewer)

[sxp]

'96 with 3" Dobinsons coils, Delta arms, rear adjustable uppers, DC front shaft, 35's.

I've had the suspension dialed in now for several years, but now I'm getting a noise upon deceleration. The noise starts like a heat shield rattle, but turns into a banging as I slow down. The banging is like a hammer on metal. I've isolated the exhaust to rule that out. The u joints seem tight too.

The noise seems rpm specific. As I slow down, if I put the transmission into 2 or L, it'll go away until the rpms drop down. Unfortunately I'm several hours away from my house so I can't do a full diagnosis. It drives fine when accelerating. There is a little vibration through the steering wheel when slowing down, but not sure if that is new or me overanalyzing it.

Any help is appreciated. The shop I normally use is down the street so looking for insight before I drag it over there.

 

[leonard_nemoy]

Noise on decel is often a pinion bearing or transfer case output bearing.

First thing I would do is pull the front driveshsft and see what happens.

 

[sxp]

Noise on decel is often a pinion bearing or transfer case output bearing.

First thing I would do is pull the front driveshsft and see what happens.

Thanks. I was afraid of something like this. I didn't have enough tools or space to pull the front shaft where I was so I dropped it off at the shop. I'll report back with what they find.

 

[tmxmotorsports]

Have a side picture?

 

[sxp]

This pic is a few years old, but it is the best side shot I have.

Here it is currently. Suspension and drivetrain are the same.

 

[tmxmotorsports]

Cool my rig has j springs with no weight so has stink bug stance. Recently started trying to figure out grinding/ gear noise on deceleration put a Tom woods dual cardin front drive shaft in it noise was almost completely gone then got some garden bricks at Walmart for my girl to do some garden stuff. With that weight in the back of the truck zero noise. Can pull front drive shaft out ... you have cdl button?

 

[sxp]

The sound wasn't a u joint grind sound. I have a Landtank front DC shaft, and it is within a degree or two of perfect. I've also run without a front shaft before (I had a custom shaft before the Landtank one), and yes, I have a CDL button.

My stance is 1" different front to back. I have no middle or rear seats so the back is fairly light. I'm running Dob's linear coils rated for plus 220 pounds.

 

[tmxmotorsports]

Well that rules out the front drive line angle

 

[sxp]

My shop replaced the u joints in my rear shaft. I'll be picking it up tomorrow so I'll know then if it is truly fixed.

I assume that since I wasn't able to park on a flat enough surface when I was inspecting the drive line that I was not able to take enough pressure off the rear shaft to notice any play. That is also a really long sentence.

 

[LandLocked93]

If the sound resembles a sword fight but with metal bats instead of swords...mine did that till I got the ds phases correct.
Beyond that...when was the last time the yoke was greased?

 

[sxp]

If the sound resembles a sword fight but with metal bats instead of swords...mine did that till I got the ds phases correct.
Beyond that...when was the last time the yoke was greased?

My drive shaft phases are correct. The rear shaft is the original, and it is going on 320000 miles. It was most likely due for u joints anyways. The u joints get greased with every oil change.

 

[LandLocked93]

My drive shaft phases are correct. The rear shaft is the original, and it is going on 320000 miles. It was most likely due for u joints anyways. The u joints get greased with every oil change.

Assuming the yoke is greased at the same time?

 

[mudgudgeon]

when I was inspecting the drive line that I was not able to take enough pressure off the rear shaft to notice any play.

IMHO you can't effectively check uni joint condition with the shaft in the truck.

With it out, you want to be able to rotate the ini joint spider freely in every direction. If it's stiff, or notchy, or sloppy, time for new ones.

 

[BILT4ME]

My DS has 346k miles on it and the yoke is worn out but the u-joints are not.

Just a point of reference.

 

[sxp]

Assuming the yoke is greased at the same time?

Yes.

Picked the LX up today, no more noise. Once I get it home (I'm currently 2 some hours south of home for the night) I'll recheck the flange angles to make sure everything is correct.