Detroit Noise

[BGKYK5]

Anybody have a Detroit that goes "thunk"? I am trying to track down a drivetrain noise - please describe when you hear the Detroit what it sounds like and how loud it is.

BTW, the axle is a 14BFF.

 

[Merv]

I had mine in a shortbox with a 4 speed and 1tons. When it would engage/dis-engage going around a 90deg. turn and then speed up it. It would make it throught the turn go ahead some and then clunk BANG!.( it was fairly loud, sounded bad. But not like somethings breaking bad, If that makes sense?) sometimes it would just clunk. Fawcker can be noisy.

Prolly made worse with manual, and i could hear it better cause i didn't have doors or rear window.

 

[toomany]

I'm voting that it's just the normal Detroit noises that you are hearing. I had one that was fairly silent. But that was in a Suburban with small (31") tires and an auto. Swapped that axles into a K5 with a stick and put some 38''s on it...got allot louder.

 

[tacoma]

I have one in a K5, 14blt in back, if I don't get off the gas through a turn it will bang or thunk when it shifts up (700r4). Not a big deal. Other than that the locker itself is pretty quiet.

 

[colbystephens]

I had mine in a shortbox with a 4 speed and 1tons. When it would engage/dis-engage going around a 90deg. turn and then speed up it. It would make it throught the turn go ahead some and then clunk BANG!.( it was fairly loud, sounded bad. But not like somethings breaking bad, If that makes sense?) sometimes it would just clunk. Fawcker can be noisy.

Prolly made worse with manual, and i could hear it better cause i didn't have doors or rear window.

i agree. the detroit has a distinct bang that sounds like something's popping into place - not breaking apart. i've got one in my 14bolt (running a 465 as well), and when that sucker binds up, you hear it.

 

[BGKYK5]

I don't hear it in corners - but I'm not usually in the throttle much in corners anyway - I hear it accelerating straight. The rear u-joint was making noise under braking, but I ground the yokes and repainted - no more contact marks in the paint. I'm gonna check tire pressures and drive it some more and see if I can narrow it down.

My truck details are in my sig if it makes a difference.

 

[colbystephens]

i'm betting tire pressure is the culprit. gotta be the exact same, ya know? accelerating straight forces me to the left a bit sometimes - i can imagine that dissimilar tire pressure would cause some stuff in addition to that.

how are your u-joints?

 

[BGKYK5]

I don't think the tire pressure is off, much, but I definitely plan to check it and adjust as required before the next test drive. Just had the rear driveshaft out a couple days ago (Monday?). The u-joints seem fine. The rear one has maybe 50 miles on it. The front (t-case end) is not original, but I have no idea how old it is. They both felt the same - smooth with no play. There is less slip yoke engagement than I would like so I lowered the t-case 1" and got back about 1/2" of engagement (I think it is about 2.5" now).

 

[k5floyd]

the first detroit i had in my 10 bolt made that lound clunk and then one day durring normal driving something happened to it and only had power to one side essentially giving me only one wheel drive. drove it like that around town for a couple weeks and then the thing locked back up again and wouldnt unlock acting like a spool. had it replaced and the new one never made any noise. weird.

 

[Thunder]

I dont know about a "Thunk". That could be serious. But IDK.
Mine always went clunk and Bang. But i never heard a Thunk.
But after i sat down and thunk about it a while. Its prolly ok.

 

[Leper]

Every time I let off of, or get on, the gas. If the gas pedal moves up or down, I hear and feel it locking/unlocking. People following me get worried.

 

[BGKYK5]

Surprise surprise, it was the tire pressure. The tire pressures were 14 and 16 (it has gotten cold here in the last few weeks). Set them both back at 20psi and the "thunking" is 95% gone. Still have some weird noises, and I think the u-joint angles aren't helping, but it is much better.

BTW, I would describe the noise as somebody whacking the underside of your truck with a hammer.

 

[colbystephens]

i bet it was one tire binding up on the ground and then "popping" over that bound up section. glad it was an easy fix.

 

[BGKYK5]

I think the different wheel speeds due to the different pressures/diameters were causing the Detroit to lock/unlock.

 

[sandawgk5]

I think the different wheel speeds due to the different pressures/diameters were causing the Detroit to lock/unlock.

I agree. Mine will get a bang that sounds like something hit the bottom of the truck sometimes but it takes specific conditions to get it to happen. I think it has only done it 3 or 4 times in 5 years.

I do get a little swagger when getting off and on the gas that is about the only way I know mine is locking and unlocking. Mainly noticeable while coasting down hill and then getting back on the gas at higher speeds like on the highway.

Dik