Advice on my differential - JeepForum.com

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post #1 of 19 Old 06-11-2016, 05:11 PM Thread Starter
luggw1
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Advice on my differential

I'm working on my project Jeep, an '84/'85 CJ-7, (https://williamhlugg.wordpress.com/?ref=spelling) and I need some expert advice on the rear diff. I just cracked the thing open - it still had what appeared to by the factory gasket on it, though the identifying tag was missing. I found a fair amount of sludge and a few very small metal chips in the lube that drained out.

I've attached some photos of the cleaned up ring gear and the diff. case so you can see what I'm looking at. Consider that the Jeep has been sitting unused for several years as far as I know (I don't know it's whole history). I do know it's got a leaky pinion seal that I need to replace, but the bearings - what I can see of them look OK.

I'm planning on installing a G2 solid axle conversion, but if there are other problems I need to address I want to get those fixed before I go any further. If anybody can provide some advice on whether thy think I have some other problems looming in the dark, I'd sure appreciate it.

Thanks.
Bill Lugg

Attached Thumbnails
Ring1.jpg   Ring2.jpg   DCase.jpg  
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post #2 of 19 Old 06-11-2016, 11:16 PM
jackler
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I am by no means an expert, especially when it comes to the gears, I will let someone else tackle that. I did however use the G2 one piece axle and found the install pretty straightforward. In hindsight I wish I would have known about the potential of thrust block interference before I buttoned everything up. Your G2 direction sheet should tell you that "if upon completion of install the axles bind during rotation, or do not rotate you should call tech support". Then tech support will tell you to remove the thrust block.
Using this site, research thrust block and thrust block removal. You may decide to remove it either way prior to installing the new axle shafts.
Hope this helps somewhat
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post #3 of 19 Old 06-12-2016, 04:13 AM
HackFabrication
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I'm not an expert either, but I have seen far worse looking gears still in use today.

Can't help on the G2 axles, I have Moser in my CJ5.

"In the end...It's all Hack."
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post #4 of 19 Old 06-12-2016, 05:27 AM
predatorbass
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Seeing your going to all that work make sure you have the gear ratio you will want.
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post #5 of 19 Old 06-12-2016, 11:43 AM
TIPPEDITOVER
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So the way I'd approach this (if the gears still run quiet) is fresh fluid, stick a really strong magnet on the diff cover, run it for about 100 miles, drain the fluid and see how big a glitter beard it grew. If it's still clean, your gears will be fine awhile longer.

I do see what appears to be a considerable amount of corrosion on the ring gear teeth and that is a cause for concern.

"Societies that lose the cohesion needed for concerted, collective action collapse, either by failing to meet an external threat or from internal conflicts."


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post #6 of 19 Old 06-12-2016, 04:11 PM
OrangeCJ-5
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Where did the chips come from: ring, pinion, spider gears?
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post #7 of 19 Old 06-12-2016, 04:28 PM
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Quote:
Originally Posted by HackFabrication View Post
I'm not an expert either, but I have seen far worse looking gears still in use today.

Can't help on the G2 axles, I have Moser in my CJ5.
I've seen far worse gears run quiet also. A vehicle that sits a lot will accumulate condensation in the rearend. Water plays hell with hardened steel gears. As far as G2 axles, go, theyre not very much different than Mosers. They have to be nearly the same if they're going to run the same bearings. I have a set of Genuine Gear 1 piece axles in my CJ-5. They're the predecessor of G2. They went in same as Mosers and no problems in over 15K miles. Every time I remove my tires, I yank in and out, push sideways, etc., on the axle flanges to check for play. No problems to date
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post #8 of 19 Old 06-12-2016, 05:33 PM
TIPPEDITOVER
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Noise and amount of metal deposited on magnet after 100 miles are your two best gauges on the health of a ring/pinion. I've seen better looking gears that were trashed. Gears are strange like that. What's the backlash measurement on that set?

"Societies that lose the cohesion needed for concerted, collective action collapse, either by failing to meet an external threat or from internal conflicts."


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post #9 of 19 Old 06-12-2016, 05:54 PM Thread Starter
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OK, I think I'll try the magnetic plug idea. it seems pretty quiet just hand turning it. It didn't run (wasn't a complete vehicle) when I bought it, so I haven't hear it at speed. I'll have to look up how to measure the backlash. Also, I'll have to see if I find any surprises when I replace the pinion seal.

Thanks for the input.
Bill
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post #10 of 19 Old 06-12-2016, 06:22 PM
OrangeCJ-5
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So have you checked all the teeth for chipping? I may last a long time it there are only a few tiny chips in a spider gear.
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post #11 of 19 Old 06-12-2016, 06:40 PM Thread Starter
luggw1
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I haven't done a thorough inspection yet, but the little I've looked I haven't seen any more than the pitting (from corrosion, as others have suggested) so far. I will do a more careful inspection shortly to see what I can find. I may try screening the oil to see if I can find some of these chips and identify their source too.

Bill
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post #12 of 19 Old 06-12-2016, 06:56 PM
80cj
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A backlash measurement on high mileage gears can be inconclusive because gears will wear and the backlash will open up with mileage. Since you have the cover off and axles out, what you can do is to shove the diff side to side and spin it by hand. If there is no side play and the diff spins smoothly, then you can assume the bearings are OK. Check the pinion bearings also by shoving it in and out and side to side. Then run it and if they run quietly, don't worry about it.
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post #13 of 19 Old 06-12-2016, 08:44 PM
LumpyGrits
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Cj

Those gears got wet at one time.
Have seen worst run for many, many years with no issues.
My big concern would be what does the axle bearings look like....
LG

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post #14 of 19 Old 06-12-2016, 09:17 PM
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Quote:
Originally Posted by LumpyGrits View Post
Those gears got wet at one time.
Have seen worst run for many, many years with no issues.
My big concern would be what does the axle bearings look like....
LG
You know they got wet by looking at the pitting. Also notice that the pitting is outside of he central contact area of the ring gear teeth so they must have been run for a period after the pitting occurred. As far as the condition of the bearings, that is my reason for adivising him to feel for smoothness and play in the bearings.
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post #15 of 19 Old 06-12-2016, 09:46 PM Thread Starter
luggw1
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That's good to know. The other bit of info I forgot to mention is that I found the vent fitting missing and the hole covered with a piece of duct tape. Do y'all know if I can buy an new fitting to put in the hole and is it a press fit or threaded in? That's no doubt how the moisture got in.
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