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#1 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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Rear Differential seal???
Quick Question:
My rear differential appears to be leaking at the front seal (not constant, but does cause a spray effect under the bed area). I went to the parts store to buy a simple seal, however the two seals he had did not seem to match the seal I have on my 12 bolt rear. Any suggestions? Any part numbers would be great. I have posted about a 'tink tink' noise I have that sounds like it comes from the driveshaft. Could the loose rear seal be causing this noise? Is it holding something in? I know nothing about the innards of rear ends. Thanks in advance for all of your help. I'm getting ready to put a gas tank under the bed and restain the wood floor and might as well do this while I'm at it. ![]()
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#2 |
Formerly yellow72custom
Join Date: May 2001
Location: Austin, TX
Posts: 7,531
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The seal really dosen't support anything, it just keeps the gear fluid in the diff. case.
When you go to change the seal, you must put the pinion nut on in EXACTLY the same position as you took it off. If you get the nut on in a different position, it will mess up your rear axle in a hurry. Mark the pinion nut relation to the driveshat yolk, and the driveshaft yolk to the rear axle. It would also be a good idea to take off the cover and change your gear oil too, as well as inspect the innards to make sure they appear to be in good shape. Good luck ![]()
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'72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg |
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#3 |
Watch out for your cornhole !
![]() Join Date: Jun 2003
Location: Azle, Texas
Posts: 14,162
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^ He's right, the nut needs to be torqued exactly to where it was before. The pinion bearing preload is set with the nut. Count the number of threads sticking out past the nut bfore you loosen it, and like he said, mark the nut, pinion, and yoke to make sure you can torque it to exactly to where it was. This is muy importante! You screw this up, and you will be paying to rebuild the rear end.
Too loose- bearing play, goodbye bearings Too tight- bearing wear, goodbye bearings. New bearings= remove carrier and re set up the gear set. Kevin-(man who has learned to respect pinion bearing$)
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I'm on the Instagram- @Gearhead_Kevin |
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#4 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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I changed the rear fluid about a week ago. I will admit that when I pulled the rear cover off it had maybe a handful of fluid in it. All of the gears appear o.k. with no cracks or broken teeth and there were no metal pieces in the remaining fluid. There is a gear type whining that I have been hearing lately (that's what made me check the fluid in the first place), but it didn't go away after I added fluid. Someone suggested the center support bearing and I checked mine. It appears to be loose, so I bought another today and will be replacing that tomorrow hopefully.
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#5 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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I hate to bring this up again, but the rear seal really started leaking bad today. I really need to figure this out, but I can't seem to find the right one. Please help
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#6 |
Recovering Truck Driver
Join Date: Mar 2002
Location: Orleans, NE USA
Posts: 1,883
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You might try going to your local GM dealer for the seal, they usually get the right part. or if you don't need to drive the truck to get the new seal, pull the pinion flange off and take the seal with you ( as long as you're lucky enough not to damage the part number on the seal taking it out). as mentioned above, mark the pinion flange and nut and count threads to make sure it goes back in the same place.
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67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska |
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#7 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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I didn't see a part number on the seal. Is it written in magic ink? I really appreciate your help. I wrote a suggestion in your thread. It's funny, but I hadn't even entertained the notion of going to GM dealer. I guess I should K.I.S.S. sometimes!
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#8 |
Recovering Truck Driver
Join Date: Mar 2002
Location: Orleans, NE USA
Posts: 1,883
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The part number will be stamped in the metal part of the seal, usually hidden by 30+ years of rust and barely legible if at all.
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67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska |
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#9 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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I must be crazy. My seal looks like a metal cap on the end of the differential. All of the seals I see look nothing like it. Is it a metal cap and the seal is under it? I'm sooooo confused. I drive the truck daily, so putting it out of commission is not very good for me.
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#10 |
Recovering Truck Driver
Join Date: Mar 2002
Location: Orleans, NE USA
Posts: 1,883
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There is a protective dust cover on the pinion flange, concave in shape to keep rocks and dirt out of the seal area. If you take the flange out, you will be able to see the seal.
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67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska |
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#11 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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Thanks for all the help. I will drop the driveshaft and see what I can figure out. I'll let you know.
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#12 |
Careful, they attack...
Join Date: Aug 2001
Location: Waterford, MI, USA
Posts: 1,107
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You HAVE to take the pinion nut off (good luck) to get to the seal. You can't see it with the driveshaft still on the truck. It took me an hour and some time with the torch and impact wrench to get my pinion nut off. Just pop it out and pop in the new one. Like everyone says, mark the threads and the nut. Rear ends are $$ to have rebuilt, and since you need your truck everyday, I would take the extra time to be sure it's done right the first time.
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#13 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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O.K. Pulled the pinion nut off a few Min ago (during lunch), and I can't seem to get the pinion itself off the bolt??!!! WTF? How can I get it off? I have tapped and banged, to no avail. does anyone have any suggestions?? I need to try and get this completed today. Also, how do you get the driveshaft out of the center support bearing? Thanks!!!
Shawn
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#14 |
Senior Member
![]() Join Date: Sep 2001
Location: Seattle, WA, USA
Posts: 5,817
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I'm pretty sure the seal mounts into the case like any other seal. Probably the end of the housing??? I've never removed/replaced mine. Are you having a hard time getting the pinion nut off, or you can't get the seal out?
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'69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA. |
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#15 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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I got the nut off easy. I can't get the part that te driveshaft connects to off of the bolt the nut screwed on to. Does this make sense? The seal is under the flange that I am trying to remove.
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#16 |
Watch out for your cornhole !
![]() Join Date: Jun 2003
Location: Azle, Texas
Posts: 14,162
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You have to tap it off with a hammer. Some times, not too gently either.
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I'm on the Instagram- @Gearhead_Kevin |
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#17 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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Wow, I guess I will bang a little harder. My Chilton says there is some kind of removal tool? Any Idea what they are talkin about and if it is necessary? Thanks again for the quick replies!!!
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#18 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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O.K., I beat the crudd out of it and I can't get it to budge!!! Is this really how it comes off?????
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#19 | |
Registered User
Join Date: Mar 2002
Location: Agua Dulce, Ca. usa
Posts: 179
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Quote:
I have gotten them off with hits with a rubber mallet but yours is like the one described in the magazine. Ed ke6bnl
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Ed ke6bnl Agua Dulce 70 S.E. Los Angeles 70 Chevy short bed 1948 F3 ford pu 1949 F1 stock V8 flathead 3 on floor 1950 F1 pu street rod 1948 F6 Ford Dually/350sbc no bed stock trans&rear 1972 El Camino 4" chop 1953 Chevy 3100 2b daily driver 1970 SB 4X4 400ci 6in lift |
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#20 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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Looks like it's tool fabricating time!!!!
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#21 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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Yeahhhh!! I got the pinion off!! What I did (in case anyone ever has this problem) is used the straps that hold the u-joint to the pinion and strapped in a hammer so that it protruded from the top a bit, but went through both straps. Then I tapped (insert beat the crud out of) the hammer on the side with a rubber mallet. This worked the pinion off. Slowly at first then it quickly came off. The seals I bougt from kragen auto parts didn't fit (go figure). When I tried to give tem the numbers that were atamped on the side of the seals they said they couldn't cross reference them(Kragen Sux). Autozone did it without a problem. I will be buying my parts from them from now on!!!!!
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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#22 |
Finish the'71..or bust!
Join Date: Jun 2003
Location: Nashville, TN.
Posts: 441
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Sounds like you have it under control now. GREAT!
I'm sorry I did not see this thread earlier as I just replaced my pinion seal and cover gasket on my Corp. 12- bolt. The pinion seal I used is a: NATIONAL (Federal-Mogul) 8460N Do like the other guys said....marking the pinion nut relation to the driveshaft yolk, and the driveshaft yolk to the rear axle....and counting the threads for good measure. But if you get overly concerned about the torque on the pinion nut: Get an INCH-LB 'beam style' torque wrench, jack the rear wheels off the ground, remove the brake drums (to relieve all resistance on the axles), and check to see that it takes 15 to 20 INCH-LBS to cause the pinion to turn. Remember...what to look for here is 'resistance'. My manual says that 15 inch-lbs is spec (if new bearings and crush sleeve are installed), but if you are not replacing bearings and crush sleeve that 20 is recommended to reset pre-load and compensate for worn bearings and sleeve. I filled my differential with Royal Purple...and so far it all is working like a charm. No clunking, whining, or anything else wierd. Plus...no big oily spot on the driveway! ![]() I hope I've explained this right.... |
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#23 |
Watch out for your cornhole !
![]() Join Date: Jun 2003
Location: Azle, Texas
Posts: 14,162
|
That is the correct way to determine bearing preload, the torque wrench way. But, that way is only intended for use when the carrier isn't installed yet. When the carrier bearings and axle bearings are added into the picture, they give the wrong reading.
That said, it's probably pretty close doing it that way. When I worked at the Chevy dealer, GM taught us to use the mark the yoke method. Kevin
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I'm on the Instagram- @Gearhead_Kevin |
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#24 |
Registered User
Join Date: Mar 2003
Location: Wichita, KS
Posts: 137
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If you still have the whinning sound, check the carrier bearing, as well. I was real close to taking mine to the rear end shop, when I decided to take a chance and check the bearing. When I got it out, it would not turn by hand at all. Installed new u-joints, and carrier bearing, and most of the whinning went away. Probably still need rear end work, but it is not near as bad as before.
By the way...I now have the tink sound comming from the driveshaft, when I stop completely or take of from a stop. Sounds like the front shaft, because I tapped on the shafts and the tone is exactly like the front. Go figure.
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![]() 350/350 3.73 Next; 335hp GM Crate |
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#25 |
Registered User
Join Date: Jul 2003
Location: Cypress, Tx
Posts: 4,005
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Update:
I got the rear differential seal in today, and the tranny seal. I am trying to replace the carrier bearing also, but I'm having a hard time getting the u-joint out to take the old one off. Any suggestions would be great!!!. There is a bolt under the u-joint, do I need to remove that to take the two drive shafts apart?? Can I reuse the u-joint that holds the 2 shafts together, or do I need to buy anoter one? Thanks for everyones help! I know it takes time to respond, so thanks!!!
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1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE |
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