Detroit Locker " Clunk "

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PHARAOHDISCO

Guest
I keep getting these loud "clunk" sounds from my Detroit Locker especially in U-turns or in bends. When this "clunk" sound happens it appears as if a strong spring is released and the whole rear of the truck jerks. Should I get accostumed to this sound and live with it or is there a solution to reducing it by maybe changing the rear differential oil more frequently or using an oil with a higher viscosity. I am currently using a Mobil SAE 80W-90 gear oil.
 
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ShaunP

Guest
Sounds like a detroit locker to me, that why I like air lockers.
 
hmcoleap

hmcoleap

Well-known member
Mar 26, 2005
106
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Seacoast NH
www.serious4x4.com
Sounds like normal Detriot locker behavior to me.

PHARAOHDISCO said:
I keep getting these loud "clunk" sounds from my Detroit Locker especially in U-turns or in bends. When this "clunk" sound happens it appears as if a strong spring is released and the whole rear of the truck jerks. Should I get accostumed to this sound and live with it or is there a solution to reducing it by maybe changing the rear differential oil more frequently or using an oil with a higher viscosity. I am currently using a Mobil SAE 80W-90 gear oil.
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D Chapman

Guest
No, this does NOT sound normal. Normal sounds would be a ratcheting sound in turns, with a pop or "clunk" every now and then. Not popping and jerking on a regular basis...

If he has a 5-speed truck, you have to be gentle on the gas when going into turns.

I have had my Detroit in for several years now, and drive my truck almost everyday. Maybe once a week I will get a loud pop, or "clunk". Usually while in reverse...

Pharo, I run a little thicker gear oil than you. I think its 130w. I also add about a half bottle of Lucas. I don't know if the Lucas helps or not, but I get a good deal on the stuff, and I don't think it can hurt anything..
 
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PHARAOHDISCO

Guest
The Disco is an automatic and with a 4.1 differential gear ratio. The Detroit Locker doesn't perform that way in every turn or bend, but maybe I get this loud "clunk" sound with the rear shuddering 3-4 times a week. It is not popping and jerking on a regular basis. The Disco is driven nearly on a daily basis. I am under the impression that when the differential oil is still fresh, this behaviour is less, but I am not quite sure. If heavier oil will help, I will go with the heavier. Please advise. Thanks.
 
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D Chapman

Guest
PHARAOHDISCO said:
The Disco is an automatic and with a 4.1 differential gear ratio. The Detroit Locker doesn't perform that way in every turn or bend, but maybe I get this loud "clunk" sound with the rear shuddering 3-4 times a week. It is not popping and jerking on a regular basis. The Disco is driven nearly on a daily basis. I am under the impression that when the differential oil is still fresh, this behaviour is less, but I am not quite sure. If heavier oil will help, I will go with the heavier. Please advise. Thanks.
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I was under the impression it was happening all the time....

I think I saw somewhere that the heavier the oil, the better for the Detriot, but don't quote me on that.
 
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PHARAOHDISCO

Guest
D Chapman said:
I was under the impression it was happening all the time....

I think I saw somewhere that the heavier the oil, the better for the Detriot, but don't quote me on that.
Click to expand...

Thanks Dan. I would appreciate it if anybody can add any more information to the subject concerning the use of heavier oil in the Detroit Locker differential.
 
noee

noee

Well-known member
Apr 20, 2004
1,887
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Free Union, VA
Not sure if this is helpful or not. I've had the Detroit in for over a year now, 99D2. In all that time, I've only had the "clunk" twice. This truck is not a daily driver and is generally loaded up with a few hundred pounds when it is driven. I do get the soft clicking when corning forward or reverse and I run the Valvoline Synthetic 75w/90 gear oil.
 
LostInBoston

LostInBoston

Banned
Apr 19, 2004
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Wandering aimlessly
Soft clicking is normal, sometimes it a little louder but ive only gotten the CLUNK about twice in 2 years. Scared the crap out of my gf and her sister when it happened last week, i just laughed. If your getting it often, change the oil and make sure its set up right.
 
LostInBoston

LostInBoston

Banned
Apr 19, 2004
690
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41
Wandering aimlessly
noee said:
Not sure if this is helpful or not. I've had the Detroit in for over a year now, 99D2. In all that time, I've only had the "clunk" twice. This truck is not a daily driver and is generally loaded up with a few hundred pounds when it is driven. I do get the soft clicking when corning forward or reverse and I run the Valvoline Synthetic 75w/90 gear oil.
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I run the same diff oil. Im curious what everyone else uses.
 
billb

billb

Well-known member
Nov 29, 2004
246
0
Detroit here too - racheting in corners and one or two loud "pops" in the last 3 years. Lugs on the swampers rubbing the radius arms much louder (LOL)

Running the cheapest crap gear oil I can find - 80w/90

Bill
 
greg lse

greg lse

Well-known member
Aug 27, 2004
56
0
49
long island
i have had 3 Detroit lockers running same weight oil (Mobil SAE 80W-90 gear oil) all have made difrent clunks. the worse one was from currie set up 9 inc(daily driven) but it was also the best one.bang, clunk, pop, boom all normal from detroit lockers. you will get use to it .
 
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Kyle

Guest
NO ,the banging and popping is NOT "Normal detroit behavior". The lockers that are banging are lockers that have been setup too loose. All of them are assembled by hand and most are good to go. However , 1 in 10 (Or so) is setup too loose.....
 
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PHARAOHDISCO

Guest
Kyle said:
NO ,the banging and popping is NOT "Normal detroit behavior". The lockers that are banging are lockers that have been setup too loose. All of them are assembled by hand and most are good to go. However , 1 in 10 (Or so) is setup too loose.....
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What does that mean "setup too loose". I received my complete rear differential ready assembled with the Detroit Locker from Ashcroft Transmissions in the UK. I just mounted the complete assembly in place. Should I live with this locker behaviour or is there something I can do about it? Thanks Kyle.
 
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PHARAOHDISCO

Guest
No, it's been in now for 14 months with over 12k miles. This behaviour was from day one.
 
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