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Thread: Diff Seals?

  1. #1
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    Default Diff Seals?

    So I had a bad u-joint on the front passenger side of my TJ. Taking Rubicon's suggestion I went out and bought a used axle shaft to make the job easier (It had an almost brand new u-joint on it, which was nice). When I pulled the old shaft out it was dry in there (with a bit of gunk). I checked my diff and it is dry. Looking around it looks like the seal in the back of the diff where the driveshaft goes in has been leaking.

    I tried to look on Quadratec to find what I need to replace but I couldn't figure it out. Can someone help me figure out what parts I need? Also are there seals on the shafts that should be replaced too or is it only the one on the rear of the diff?

    Help a clueless person out? At this rate I am not going to get off road this year either.....
    -You should spend 10 minutes in a hammock everyday , unless you are busy, then you should spend an hour.

    2006 Jeep Wrangler X (TJ) - Stock.... except the 31" tires... just stock...
    ...oh no, wait, I bought a new top for it and also put up a sticky led light on the interior roof as a dome light and i put my first sticker on the body.

  2. #2
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    You need a pinion seal for a D30. Very inexpensive. The job itself is pretty easy, I did it on my D30 and D35. You just have to get the pinion nut back in the right spot, for proper torque. Not going to explain it all here, but you can google it. All I did was count exposed threads.
    There are inner seals, but they are from the front. Haven't done those, sorry.
    Gone now :( -2000 Jeep Wrangler Sahara, 2" BB, 4.88's, TT F&R, 33x10.5 km2's, xrc8 winch, uniden pro xl520 cb, 4' wilson
    Gone now too :( -2008 Rubicon, uniden pro xl520 cb, 5' wilson Silver Load, JCR engine skid, JCR evap skid
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  3. #3
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    When you say the shaft was dry with some gunk, can you specify where on the shaft the gunk was? These differentials have seals just outboard of the pumpkin in the tubes that prevent gear oil from escaping down the tubes and shafts. The shaft should be dry (and likely rusty) from the sealing surface all the way out to the yokes. The shaft should be covered in oil (and clean) from the seal to the end of the splines.

    How did you confirm your diff is dry? There should be fluid just below the fill port on the front cover, reach a finger in the hole and down, or use something as a dipstick to measure the level of fluid. If there isn't and it really is dry then there may be significant damage done to the gears (having been operated with no lubrication). You may consider removing the diff cover to drain what remains of fluid, if any, and inspect the gears if you suspect there is little to no fluid in there. If anything, you will perform a fluid change which never hurts. Be sure to either pick up the cover gasket or have RTV on hand to re-seal the cover to the diff once the sealing surfaces have been cleaned down to metal. Re-fill with new fluid until it is flowing out of the fill port and cap it off.


    As for parts, I am a fan of East Coast Gear Supply. You can view the TJ Dana 30 seals HERE. Note there is a pinion seal (Stock#: PS-5778-D30/D44) and 2 inner axle seals (Stock#: AS-YMSC1003) on your axle. I would strongly recommend a thorough inspection prior to buying parts to ensure you actually need new parts.
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  4. #4
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    Sounds like a pinion seal. Depending on the year TJ, you want one of the following. I can have them to you in 2 or 3day transit depending on which.

    https://www.scerbfab.com/shop/spicer...44-rear-44895/

    https://www.scerbfab.com/shop/spicer...j-front-50660/
    ScerbFab LLC
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  5. #5
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    Quote Originally Posted by Scerb View Post
    Sounds like a pinion seal. Depending on the year TJ, you want one of the following. I can have them to you in 2 or 3day transit depending on which.

    https://www.scerbfab.com/shop/spicer...44-rear-44895/

    https://www.scerbfab.com/shop/spicer...j-front-50660/
    Holy crap, $7.86 for a Spicer seal? That's a great deal!!

    Sent from my SM-G975U using Tapatalk
    Gone now :( -2000 Jeep Wrangler Sahara, 2" BB, 4.88's, TT F&R, 33x10.5 km2's, xrc8 winch, uniden pro xl520 cb, 4' wilson
    Gone now too :( -2008 Rubicon, uniden pro xl520 cb, 5' wilson Silver Load, JCR engine skid, JCR evap skid
    Present-2012 JK Sahara-KO2's plus neat stock stuff

    Buy a Gazetteer

  6. #6
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    Quote Originally Posted by mb523 View Post
    When you say the shaft was dry with some gunk, can you specify where on the shaft the gunk was? These differentials have seals just outboard of the pumpkin in the tubes that prevent gear oil from escaping down the tubes and shafts. The shaft should be dry (and likely rusty) from the sealing surface all the way out to the yokes. The shaft should be covered in oil (and clean) from the seal to the end of the splines.

    How did you confirm your diff is dry? There should be fluid just below the fill port on the front cover, reach a finger in the hole and down, or use something as a dipstick to measure the level of fluid. If there isn't and it really is dry then there may be significant damage done to the gears (having been operated with no lubrication). You may consider removing the diff cover to drain what remains of fluid, if any, and inspect the gears if you suspect there is little to no fluid in there. If anything, you will perform a fluid change which never hurts. Be sure to either pick up the cover gasket or have RTV on hand to re-seal the cover to the diff once the sealing surfaces have been cleaned down to metal. Re-fill with new fluid until it is flowing out of the fill port and cap it off.


    As for parts, I am a fan of East Coast Gear Supply. You can view the TJ Dana 30 seals HERE. Note there is a pinion seal (Stock#: PS-5778-D30/D44) and 2 inner axle seals (Stock#: AS-YMSC1003) on your axle. I would strongly recommend a thorough inspection prior to buying parts to ensure you actually need new parts.

    Thanks for all the input. So just to be clear.
    i checked the fluid in the diff by pulling the fill cap and putting my finger in there but did not feel any fluid, so yeah, there could potentially be some in there still. My plan is to pull the plate from the from and make sure everything is clean when i replace the seal. I will probably replace it with a more heavy duty one since I have it off anyway.

    As far as the axle shafts: So I assumed that fluid was supposed to be in there as well and since it was "dry" I assumed the diff was as well. It did seem there was a fair amount of dirt that was clumped and oily on the bottom of the tube and some buildup on the shaft itself. So other than the dirt in there, I assume that is normal? The axle shaft I got from the junk yard was not oily at all, should I have oiled it up before I but it in there? Should I pull it again to oil it?
    -You should spend 10 minutes in a hammock everyday , unless you are busy, then you should spend an hour.

    2006 Jeep Wrangler X (TJ) - Stock.... except the 31" tires... just stock...
    ...oh no, wait, I bought a new top for it and also put up a sticky led light on the interior roof as a dome light and i put my first sticker on the body.

  7. #7
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    Quote Originally Posted by Dgagne View Post
    Thanks for all the input. So just to be clear.
    i checked the fluid in the diff by pulling the fill cap and putting my finger in there but did not feel any fluid, so yeah, there could potentially be some in there still. My plan is to pull the plate from the from and make sure everything is clean when i replace the seal. I will probably replace it with a more heavy duty one since I have it off anyway.

    As far as the axle shafts: So I assumed that fluid was supposed to be in there as well and since it was "dry" I assumed the diff was as well. It did seem there was a fair amount of dirt that was clumped and oily on the bottom of the tube and some buildup on the shaft itself. So other than the dirt in there, I assume that is normal? The axle shaft I got from the junk yard was not oily at all, should I have oiled it up before I but it in there? Should I pull it again to oil it?
    I must have missed it. But why did you replace the axle shaft just for a bad u joint?
    It's all gone.

  8. #8
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    Quote Originally Posted by Dgagne View Post
    ...As far as the axle shafts: So I assumed that fluid was supposed to be in there as well and since it was "dry" I assumed the diff was as well. It did seem there was a fair amount of dirt that was clumped and oily on the bottom of the tube and some buildup on the shaft itself. So other than the dirt in there, I assume that is normal? The axle shaft I got from the junk yard was not oily at all, should I have oiled it up before I but it in there? Should I pull it again to oil it?
    No oil should be in the axle tube area itself, because there is a seal on the differential side that is supposed to keep it all in the center. So if you have any oil contamination in the area that there was dirt, the seal is leaking. Please do not pull the shaft again, as it does not need to be "oiled", and every time you remove/replace could potentially damage that inner seal, plus introduce that dirt into the center differential. The splined end and where the seal rides(probably could see the line or ring where it did) is the only part that needs to be clean. Though I personally found it helpful to apply grease on that end to help prevent the previously stated possible damage to that inner seal by pushing in "dry" steel that has a spline on the end.

    Hope this eases your worries Dean. Wish I was closer to help.
    Traction, articulation, and gearing make a good off-road rig. Just a big lift, wide mud tires, and a winch simply do not.
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  9. #9
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    Quote Originally Posted by GSSFC View Post
    I must have missed it. But why did you replace the axle shaft just for a bad u joint?
    Dean sometimes lacks the tools and experience to perform his own repairs 100%, but does not have the extra cash to pay professional shop labor costs, thus asks for assistance here. Since the shaft has to be removed anyways, I suggested that for the price of a brand new u-joint, especially if paying for labor to install, he might be able to find a good used shaft and do the work himself to save money, plus gain knowledge ;)

    I offered to help him with this, but it was just too far of a drive(time + gas).
    Last edited by Rubicon; 08-04-2019 at 07:30 AM.
    Traction, articulation, and gearing make a good off-road rig. Just a big lift, wide mud tires, and a winch simply do not.
    ~Shawn(the correct spelling ;)

  10. #10
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    As stated, there is a seal at each side of the diff that the shaft goes through to keep oil in the diff. As these wear, oil can leak into the tubes. I wouldn't worry about it at all until oil starts leaking out the tubes onto the knuckle. Those seals are a little more difficult to replace.

    If you are concerned with the dirt in the tubes (which is the leading cause for the axle seal wear) you can install these: https://www.scerbfab.com/shop/dana-3...axle-and-gear/
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  11. #11
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    Quote Originally Posted by Rubicon View Post
    Dean sometimes lacks the tools and experience to perform his own repairs 100%, but does not have the extra cash to pay professional shop labor costs, thus asks for assistance here. Since the shaft has to be removed anyways, I suggested that for the price of a brand new u-joint, especially if paying for labor to install, he might be able to find a good used shaft and do the work himself to save money, plus gain knowledge ;)

    I offered to help him with this, but it was just too far of a drive(time + gas).
    I guess that makes sense. Now he can learn how to replace the bad u joint and have a spare.

    Ive never used anything special to change a standard u joint other than a vice and hammer. BFH if necessary. Good to know how to do it.
    It's all gone.

  12. #12
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    I once had CV joints fail on my Mazda 323 FWD sedan. A friend told me to replace the axle shafts, not only was it cheaper but way easier. So I call the dealer, ask about the price and availability and the parts guy says, "Just how did you break the axles?" I told it was easier and cheaper, he said he would run the numbers both ways.

    It saved about $200! He was shocked.
    --
    Agnes - 1995 Jeep Wrangler (YJ) - 4 cylinder 35" MTRs, SM465, RockTrac, 3.5" Black Diamond Suspension SUA, Ford 8.8, HPD30 w/vacuum disconnect w/4.88s, ARB lockers front and rear, front shackle reversal, rear revolvers, lotsa skids, Bullet Proof steer modified, flat belly, engine relocation, Mastercraft seats with PRP 5 point harness
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  13. #13
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    Quote Originally Posted by GSSFC View Post
    I guess that makes sense. Now he can learn how to replace the bad u joint and have a spare.

    Ive never used anything special to change a standard u joint other than a vice and hammer. BFH if necessary. Good to know how to do it.
    Same here ;)
    Traction, articulation, and gearing make a good off-road rig. Just a big lift, wide mud tires, and a winch simply do not.
    ~Shawn(the correct spelling ;)

  14. #14
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    Did you get this done? Asking for a friend with a leaking diff seal...
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  15. #15
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    Quote Originally Posted by Ivoryring View Post
    Did you get this done? Asking for a friend with a leaking diff seal...
    Sorry for the delayed answer, no, i haven't gotten it done yet. Going to order the part this week though. Will update when done.
    -You should spend 10 minutes in a hammock everyday , unless you are busy, then you should spend an hour.

    2006 Jeep Wrangler X (TJ) - Stock.... except the 31" tires... just stock...
    ...oh no, wait, I bought a new top for it and also put up a sticky led light on the interior roof as a dome light and i put my first sticker on the body.

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