Eaton / Detroit locker seems like it's unlocking at 55 mph

Jerry Bransford said:
Is this happening with neutral throttle or more when starting to accelerate or decelerate? I had a Detroit Locker for years in my previous daily driver TJ that spent a lot of time on the highway.
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I've been trying to figure out if anything other than speed over 55 mph affects it and my answer is that no throttle input or lack thereof, brake, turning off/on cruise control, going up or downhill, WOT, etc. has any effect or can help create the issue. It just seems to happen randomly at speeds over 55. I've tried swerving around to recreate something like a turn and driving in between lanes to avoid the road grade offset between driver/passenger side with no affect.
In town, yes throttle input or neutrality makes it behave differently when cornering but this is at 5-15mph or so. At these speeds and driving in a city environment, it behaves exactly as I'd expect a detroit locker to behave. Occasional clunk or tire chatter but mostly civil.
 
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CherokeeKid said:
I've been trying to figure out if anything other than speed over 55 mph affects it and my answer is that no throttle input or lack thereof, brake, turning off/on cruise control, going up or downhill, WOT, etc. has any effect or can help create the issue. It just seems to happen randomly at speeds over 55. I've tried swerving around to recreate something like a turn and driving in between lanes to avoid the road grade offset between driver/passenger side with no affect.
In town, yes throttle input or neutrality makes it behave differently when cornering but this is at 5-15mph or so. At these speeds and driving in a city environment, it behaves exactly as I'd expect a detroit locker to behave. Occasional clunk or tire chatter but mostly ci
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Drop the rear driveshaft first.
 
I've not had a chance to try anything thus far as an ice storm came through and I'm not driving my Jeep in this stuff(with the lockers it has installed). I did determine that the upper rear track bar bushing is terribly worn, not sure if this could cause the axle to shift enough to cause the locker to unlock. I can't tell that it's worn driving it but found it when I was prying around trying to find any worn suspension components.
Forecast isn't showing above freezing temperatures for another week... hopefully I can't get back to this then.
 
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I got busy getting ready for Moab and Colorado trails+ life. New ball joints, front axles seals, unit bearings, axle u joints, rotors, pads, rear main, pan gasket, trailer bushings, bearings, etc. etc . Had a great time on hells revenge, fins and things, and black bear but I got plenty tired of hearing this noise and feeling the jerking on the trip so I'm back at this. I did pull the front cover and carrier to do the axle seals. No metal shavings, Richmond lunchbox locker in the front, bearings and ring/pinion all in good shape. Also upgraded to Goodyear Duratracs with correct tire pressure and the clunking jerking is still there. I did pull the front driveshaft and drove it, same behavior. Going to reinstall the front driveshaft & remove the rear driveshaft and try running it in 4 hi to see how it behaves. If it's still doing the same crap, I guess I'll pull the rear diff cover and see if it's a newer style detroit locker(full carrier replacement) or the eaton no-spin drop in locker and check for metal shavings even though it was rebuilt not long ago. If I can simply drop in a lunchbox locker and try that I probably will. If not, for the cost of replacing the carrier and the setup of gears and the fact that I really would like a selectable locker, plus it's still a Dana 35, I'll probably be looking to east coast gear supply or currie for a new 44 or 60 rear axle a$$embly.
 
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Your symptoms are certainly not what I experienced with my full case Detroit Locker which was very well behaved 99% of the. Your symptoms remind me of how a rear lunchbox locker, like I once had, behaves.
 
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I had a Detroit locker in the rear in a Dana 35 that was the old school detroit, we're talking 16-18 years ago. And this was with a Warn full floater kit on 33" & then 35" tires. Mine would pop and jolt around corners now and then but I don't ever remember it doing it just driving down the road. It might happen after going around a tight corner and then going straight but it'd pop within 300' or so I guess.

I have lunchbox lockers in a Samurai but never a Jeep so I don't know if the weight differences would matter.
 
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Maybe a longshot, but if your rear suspension bushings are worn, one side of the axle maybe pushing back due to torque under load. That may explain at 55mph. With axle slightly shifted under load, the locker will need to occasionally unlock. Just a theory, but new control arm bushings won't hurt.
 
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J Harding said:
Maybe a longshot, but if your rear suspension bushings are worn, one side of the axle maybe pushing back due to torque under load. That may explain at 55mph. With axle slightly shifted under load, the locker will need to occasionally unlock. Just a theory, but new control arm bushings won't hurt.
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Nope, no longshot, that makes sense. I've measured wheel base on each side and it's almost exact. The bushings have some light cracking but they don't make noise. I've cycled the suspension to see if I could see any movement indicative of bad bushings but no dice. Also set the frame on jack stands and had a buddy use his feet to push back and forth on each tire while I watched each control arm mount and can so no "wiggle" on anything... Though my rear sway bar bushings rattle as they're toast. Planning on savvy/currie control arms(and lift) anyways, guess i can try replacing them just to see if that helps. Will pull diff cover first to see what I'm working with and try driving with rear DS removed, though I think it'll still do it's binding/unlocking/clunk thing, just may be less noticeable since it won't be connected to TC output shaft(if all this crap is related to rear locker issue). Hopefully get some work done on it tomorrow.
 
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Jerry Bransford said:
Pull the diff cover and see what you're running for a differential.
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It is indeed an Eaton No-Spin/Detroit full carrier replacement locker. Ring/pinion look great, no metal in the gear oil, no signs of damage to what's visible. Guess I need to pull the carrier and tear the locker apart.

Before I pulled the diff. cover, I did re-install the front driveshaft and removed the rear. Drove around a bit in 4hi and no clunking/jerking was experienced, not even once. 99% sure its something in the rear locker.
 
CherokeeKid said:
It is indeed an Eaton No-Spin/Detroit full carrier replacement locker. Ring/pinion look great, no metal in the gear oil, no signs of damage to what's visible. Guess I need to pull the carrier and tear the locker apart.

Before I pulled the diff. cover, I did re-install the front driveshaft and removed the rear. Drove around a bit in 4hi and no clunking/jerking was experienced, not even once. 99% sure its something in the rear locker.
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Yep, could be the locker. However, I wouldn't rule out the bushings. Your friend pushing with his feet doesn't come close to the load at 55mph.
 
J Harding said:
Yep, could be the locker. However, I wouldn't rule out the bushings. Your friend pushing with his feet doesn't come close to the load
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I won't completely rule it out. This is my first TJ and I haven't searched this forum enough for issues specific to worn control arm bushings but... I'd think there'd be significant wear/play in the control arm bushings to cause the locker to unlock. Maybe I'm wrong but I'd think it would be making noise from drive to reverse or causing wandering or something if it was worn to the point of allowing the rear axle housing to misalign(in relation to front axle) to unlock a detroit when travelling straight.

I still think I'll pull the locker and see if there's anything obviously up. If not, I'll probably slap it back together and try some savvy arms. If that doesn't help, I guess I'm going to drop some coin on a new rear axle assembly.
 
CherokeeKid said:
It is indeed an Eaton No-Spin/Detroit full carrier replacement locker. Ring/pinion look great, no metal in the gear oil, no signs of damage to what's visible. Guess I need to pull the carrier and tear the locker apart.

Before I pulled the diff. cover, I did re-install the front driveshaft and removed the rear. Drove around a bit in 4hi and no clunking/jerking was experienced, not even once. 99% sure its something in the rear locker.
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Is the problem primarily during turns or primarily driving straight ahead?
 
Behavior of locker is in original message post. It hasn't changed at all since I posted about the problem.

I took the locker apart. No burrs on parts, rounded dogs/teeth, missing dogs/teeth. Absolutely nothing looks worn on this detroit; which surprises me considering it frequently unlocks at high speed. Given this, I decided I'd try new and/or heavier springs and possibly remove holdout rings. Contacted several shops around Tulsa, no one has the springs. One shop did mention having seen this straight drive unlocking behavior caused by a bent housing. Decided to revisit housing straightness again. No visual signs of anything bent from looking at it. Axle seals haven't been leaking, axles removed from carrier easily. Tried using a straight edge, again looks fine. I shined a light from one end of axle to the other. From the remaining oil in the tubes, it looks like somethings off a smidge... The edge of the oil line seems to have a mild curve. I ran a string line from each side of the backing plate flange on bottom and rear. Measured from axle tube to string line and was the same(within 1/16") across. Seems reasonable, also noticed axle tubes were welded to housing.

So... Just an update I reckon. Sounds like I've got a very rare weird problem
 
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Maybe lower the pressure on one side at the rear allot and see what happens. Force it to misbehave and see if you really are feeling the locker. Might help to intentionally try to mess it up and see if you are on the right track at all. It might be something else and tweaking things will point you in the right direction.
 
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You mentioned earlier that you're buying a suspension with new control arms. I wouldn't tear things apart any further until either you have new control arms or new bushings. Even though it's only 99K miles, 19 years can deteriorate the rubber. I still think under load your axle is shifting. Maybe have a friend drive behind you 20 mph and look fown the side of your Jeep to see if it is going straight, then go 60 mph and check the same thing. Maybe your friend can see the Jeep starting to dog-track.
 
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pagrey said:
If the tires are the same size the "dog track" doesn't matter, the tires will be spinning at the same speed. The axle could be dragging along at 45 degrees and the tires would be scraping along at the same speed.
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Well....you're probably right, so in that case...I got nothin!
 
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