detroit chatter

[NEWMEXICOK5]

alright, i have a 89 jimmy. 350 slightly hopped up, 700,231, 35's and 10 bolts. i have auburn pro w 4:56 front and a detroit w 4:56 in the rear. both have superior axles. detroit is awesome but im getting chatter when going any speed over 20 miles an hour. the chatter is only on coast,any amount of throttle shuts it up. sounds to me like the detroit is ratcheting. i talked to eaton and they told me the detroit wont make noise going straight. Im not a stupid man i know its making noise. And its not normal. its making the same ratcheting noise as it would in the air and you manually unlock one axle. ive spent the last hour or so surfing the deroit noise search and am not finding anything. ya, i know they are ten bolts! and i love em this is just a trail/hunting truck no big rocks. i just got tired of getting stuck in the mud so i built em. i took the cover off, nothing seemed out of place or broken. fluid is still cherry, only about six months old. ive been running valv synthetic in both boxes. would that make a difference?

 

[tRustyK5]

I'm with Eaton, in a straight line it should be dead silent. A Detroit has to be forced to differentiate, spring force needs to be overcome as one side or the other 'overruns' ring gear speed. Unless you're running a 31" tire on one side and a 35" tire on the other this isn't gonna happen going in a straight line.

I'm thinking it may be a noise caused by the synthetic fluid. A Detroit is fine with regular old 80W90.

 

[blazinzuk]

I doubt it is your detroit, if there is no metal in the bottom of the diff, for it to make a noise like that something inside the diff would be broke.

Check u joints and pinion bearings. Also slip yoke on the driveshaft

 

[4X4HIGH]

Sounds to me like a gear set-up issue because of the fact it only makes the noise on coast. Like was already said a detroit will not make any noise going straight.

 

[nvrenuf]

Any changes in lift or anything that might effect driveshaft angle? Based solely on the noise description it sounds like the pinion angle is wrong.

 

[Chaddy]

U-joints, & or bad pinion angle. I had this problem years ago.

 

[TheBeast_88K5]

My detroit ratcheted as described, but only when I let off the gas around 15-20 mph.
It stopped after the about a week....

Just sayin'.

But, I would pull the diff cover, and check everything.
Just to be safe.

 

[pblaze725]

Check to see how much backlash you have on it. You may have too much. Also it wouldn't hurt to make sure your center pin is not damaged and has been properly hardened.
It it cold there right now? Your fluid may be too thick. I have no problem w/ 80W90 either.

 

[72blazerguy]

I doubt it is your detroit, if there is no metal in the bottom of the diff, for it to make a noise like that something inside the diff would be broke.

Check u joints and pinion bearings. Also slip yoke on the driveshaft

Any changes in lift or anything that might effect driveshaft angle? Based solely on the noise description it sounds like the pinion angle is wrong.

U-joints, & or bad pinion angle. I had this problem years ago.

I would check your driveshaft angles and u-joints. I had a howl (coast only, throttle stopped it) after switching from 3.08 to 4.56 gears. At first, thought it was the gear set up. Checked that out and it was ok. Then thought maybe the Detroit was the problem. Turned out that my driveshaft angle was too steep. A CV driveshaft fixed the problem.

 

[NEWMEXICOK5]

ok, update. opened up the diff....again. looks good. checked driveshaft alignment, 6* off. shimmed rear diff to 3* off, noise still there. rear ujoint had a little play, drive shaft a little too short so i had one built complete, noise still there. checked all again....about to burn truck to the ground.remembered i had to replace a tire, checked tread depth. left rear 12/32 right rear 9/32 rotated bigger tire to the front found one of the fronts to be 9/32. noise gone! $%^&, @#$@!
3/32 difference im getting noise? are you kidding me?
but the noise is gone, and i have new parts ive needed so i guess its all goodnow i have a pull cuz of that damn tire