LOST JEEPS :: View topic - HOW TO: Diff oil change

Thanks to all the help from Diggerfreak, I just did my front and rear axles. The front is a breeze - just drain and fill. (+/- 1.3 quarts) The rear on the other hand was my first expereince with RTV. I guess I'll know how I did in a few days if it leaks....... Anyhow I can tell you that my 08 KK 4x4 has 22k miles on it and the change appeared completely unnecessary! I let a buddy of mine in the used car business talk me into it because of the number of 90's model Grand Cherokees he had seen with bad differentials. With 22k miles, both my front and rear fluids were still golden to dark brown NOT black. There were no noticeable shavings in the rear differential and only a microscopic amount of black dust size particles stuck to the magnet in the bottom of the chunk. I'll go so far as to say it probably would have gone 60k miles before it needed to be changed.

On another note I went with AMSOIL Severe Gear Synthetic 75w140 in the rear and AMSOIL Severe Gear Synthetic 75W90 in the front. Their website says it replaces GL5 80w/90. Does anyone think I screwed up on the weight change?

Total cost for two axles including 5 quarts of AMSOIL synthetics, RTV and paper towels was about $90. I think using Wal-Mart brand synthetic gear oil would have been about $20 cheaper.

Author:	Diggerfreek [ Wed Jun 24, 2009 12:08 am ]
Post subject:	HOW TO: Diff oil change
OK per request, this is the procedure to change the oil in your differentials. I will add pictures in a few weeks.. REAR 1. Place a drain pan under the diff 2. Remove all bolts from the cover minus the very bottom one and the very top one. 3. Once step 2 is done, unbolt the top bolt half way and unbolt the bottom one 1/4th of the way. 4. Using a flat pry tool of your choice, gently work it in behind the cover to break the RTV seal. If needed, loosen the bottom bolt half way. 5. Once the oil is done draining, remove the cover 6. With cover removed, remove the old RTV with a razor balde from the diff and the cover. 7. Clean both mating surfaces with brake clean, ether, ie..... and apply the RTV to the cover 8. Using your figure, spread the RTV around all of the holes 9. Tighten cover bolts in a criss-cross pattern to 41 N·m (30 ft. lbs.). 10. Remove the fill plug and add oil in tell it is at the bottom lip pf the fill hole. Replace fill plug FRONT 1. Remove skid plate if installed 2. place drain pan under the diff 3. Using a 3/8th extension, remove the fill plug 4. Using a allen driver, remove the drain plug. 5. Once drained, replace the drain plug and refill the diff 6. Reinstall the fill plug and skid NOTES Jacking the KK up is highly recommended. It can be a bear to remove the rear cover if the track bar is in the way

Author:	MtnLuvr [ Wed Jul 01, 2009 10:01 pm ]
Post subject:
Good start Digger.

Author:	Diggerfreek [ Fri Jul 03, 2009 6:43 pm ]
Post subject:
ok half updated

Author:	Diggerfreek [ Sun Jul 05, 2009 4:18 pm ]
Post subject:
Finished

Author:	MtnLuvr [ Sun Jul 05, 2009 9:50 pm ]
Post subject:
Well done and thank you Digger.

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Author:	infernicus [ Tue Nov 10, 2009 6:15 pm ]
Post subject:
Hey, this might be a dumb question.. but should the Jeep be level when filling it back up? I would assume so, but I've read elsewhere that just the front OR back was jacked up.. not the vehicle being totally level, anyway, thanks. -Dean

Author:	Diggerfreek [ Tue Nov 10, 2009 6:26 pm ]
Post subject:
Yes, the vehicle "should" however, when the vehicle is jacked up, the angle at which you are filling the diff back up is so close to level that it really doesn't make a difference. If any thing, you are slightly overfilling the diff.

Author:	infernicus [ Tue Nov 10, 2009 6:35 pm ]
Post subject:
Cool thanks for the instantaneous response, I probably will have it level, because I'll probably drive it up four of those Rhino Ramps.

Author:	Diggerfreek [ Tue Nov 10, 2009 6:41 pm ]
Post subject:
infernicus wrote: Cool thanks for the instantaneous response, I probably will have it level, because I'll probably drive it up four of those Rhino Ramps. no problem

Author:	cgreen [ Wed Nov 11, 2009 12:47 pm ]
Post subject:
Thanks to all the help from Diggerfreek, I just did my front and rear axles. The front is a breeze - just drain and fill. (+/- 1.3 quarts) The rear on the other hand was my first expereince with RTV. I guess I'll know how I did in a few days if it leaks....... Anyhow I can tell you that my 08 KK 4x4 has 22k miles on it and the change appeared completely unnecessary! I let a buddy of mine in the used car business talk me into it because of the number of 90's model Grand Cherokees he had seen with bad differentials. With 22k miles, both my front and rear fluids were still golden to dark brown NOT black. There were no noticeable shavings in the rear differential and only a microscopic amount of black dust size particles stuck to the magnet in the bottom of the chunk. I'll go so far as to say it probably would have gone 60k miles before it needed to be changed. On another note I went with AMSOIL Severe Gear Synthetic 75w140 in the rear and AMSOIL Severe Gear Synthetic 75W90 in the front. Their website says it replaces GL5 80w/90. Does anyone think I screwed up on the weight change? Total cost for two axles including 5 quarts of AMSOIL synthetics, RTV and paper towels was about $90. I think using Wal-Mart brand synthetic gear oil would have been about $20 cheaper.

Author:	Diggerfreek [ Wed Nov 11, 2009 3:19 pm ]
Post subject:
cgreen wrote: Thanks to all the help from Diggerfreak, I just did my front and rear axles. The front is a breeze - just drain and fill. (+/- 1.3 quarts) The rear on the other hand was my first expereince with RTV. I guess I'll know how I did in a few days if it leaks....... Anyhow I can tell you that my 08 KK 4x4 has 22k miles on it and the change appeared completely unnecessary! I let a buddy of mine in the used car business talk me into it because of the number of 90's model Grand Cherokees he had seen with bad differentials. With 22k miles, both my front and rear fluids were still golden to dark brown NOT black. There were no noticeable shavings in the rear differential and only a microscopic amount of black dust size particles stuck to the magnet in the bottom of the chunk. I'll go so far as to say it probably would have gone 60k miles before it needed to be changed. On another note I went with AMSOIL Severe Gear Synthetic 75w140 in the rear and AMSOIL Severe Gear Synthetic 75W90 in the front. Their website says it replaces GL5 80w/90. Does anyone think I screwed up on the weight change? Total cost for two axles including 5 quarts of AMSOIL synthetics, RTV and paper towels was about $90. I think using Wal-Mart brand synthetic gear oil would have been about $20 cheaper. Nope, you did fine there are only a few company that produce a 75w140 for sale at cheaper places..... You could have gone longer, but with as hard as I wheel mine, I'm going to stick with the 15K service interval....

Author:	infernicus [ Tue Nov 24, 2009 12:05 am ]
Post subject:	Sludge in Rear Differential
Heyyyy, me again, lol. So I changed my Front & Rear Differentials for the first time in 50k miles.. I don't use 4 wheel drive too often so I'm not too worried about the front, but when I opened the Rear there was a nice amount of sludge back there.. Since it was late on a Sunday night (and I had to drive it), I just closed it back up and refilled it with new oil. I'm assuming thats not supposed to be there, lol. What is the best way to clean it up, or should I just leave it alone.. I do have an '07 so my gas tank is in the way, because I cant take it out like you can your spare, lol, so it's a little tight back there. Anyway, I just want to kind of start fresh, and if there is a way to clean it up back there it would be great. Again, Thanks in advance.

Author:	Boiler [ Tue Nov 24, 2009 2:06 am ]
Post subject:
Are the bolts the same as in the KJ? KJ have 5/16-18 grade 5 bolts. I used a lubelocker gasket which called for a 35 ft-lb torque. The bolts supplied with my Riddler differential cover also were 5/16-18 grade 5. They broke under 30 ft-lbs. Breaking a bolt in the differential can be a real pain in the rear. Grade 5 bolts have 3 radial lines on the heads, in a "Y" pattern. Grade 8 bolts have 6 radial lines on the heads, with the extra 3 lines spaced evenly between the portions of the "Y". I would suggest lowering the torque values. 30 ft-lbs is a lot of torque and uneccesary. I looked at a bunch of charts, most all of them were different, some included "tightening torque" etc. All of them showed a lower suggested torque than 30. I think a good safe average of the charts would be: If the KK have grade 5 bolts, I'd recommend specifying 17 ft-lbs. If the KK have grade 8 bolts, I'd recommend specifying 25 ft-lbs. Remember to reduce this torque by 15-25% if the bolts are oiled. If they went to 3/8 bolts, disregard all of this, they're fine at 30 ft-lbs regardless of being grade 5 or grade 8.

Author:	Diggerfreek [ Tue Nov 24, 2009 3:49 pm ]
Post subject:
The KJ and KK share the same 8.25 chryco diff......... infernicus, try jacking up your KJ from the hitch of diff an then place two jack stands on the "frame rail" to as to let the diff hang down. This should help a little with space issues. You can do one of two things, one, drop the oil in it now and then refill it or two, when you dump the oil again, spray the inside of the diff out with some brake cleaner. The new oil will have a detergent additive in it that will help to clean it out.... Personally, I would drive it for 3K and then do your engine oil and diff.... then change your diff again at 15K.........

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Author:	cgass [ Sat Oct 01, 2011 5:08 pm ]
Post subject:	Re: HOW TO: Diff oil change
I've found that brillo pads are really good at removing RTV as well

Author:	Gageraid [ Wed Mar 13, 2013 2:02 pm ]
Post subject:	Re: HOW TO: Diff oil change
Thank you, Digger. If I have time, I'm going to do my rear differential in the morning. If I can find it, I think I'll for the synthetic. I'm more hesitant to do the transfer case (Command trac) and front differential since my last car only had a rear differential. Any specific tips for the front and transfer?

Author:	Ted15 [ Wed Mar 13, 2013 11:34 pm ]
Post subject:	Re: HOW TO: Diff oil change
Gageraid wrote: Thank you, Digger. If I have time, I'm going to do my rear differential in the morning. If I can find it, I think I'll for the synthetic. I'm more hesitant to do the transfer case (Command trac) and front differential since my last car only had a rear differential. Any specific tips for the front and transfer? The front diff has drain and fill plugs, real easy to do. I'm pretty sure the transfer case does too.

Author:	khalilw [ Tue Mar 19, 2013 5:51 pm ]
Post subject:	Re: HOW TO: Diff oil change
How many Quarts of 75w140 should I buy to do the rear diff oil change?

Author:	JeepMorrison [ Tue Mar 19, 2013 7:13 pm ]
Post subject:	Re: HOW TO: Diff oil change
khalilw wrote: How many Quarts of 75w140 should I buy to do the rear diff oil change? Id buy three, just changed my front and rear and used obe gallon and quart...plus a lot on me..lol dawn dish soap Sent from my SPH-L710 using Tapatalk 2

Author:	khalilw [ Tue Mar 19, 2013 8:22 pm ]
Post subject:	Re: HOW TO: Diff oil change
khalilw wrote: How many Quarts of 75w140 should I buy to do the rear diff oil change? Oh I see! Thank you Im only at 11.000 Kms but my rear axle shafts have been extracted from the axle housing few times because of a car crash. I extracted them today again and a bit of black fluid came out of the housing, probably its time to change the oil. By the way, here in Venezuela the KK's have a dana 44 rear differencial, not a 8.25.