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Rear Pinion Seal #2791996
07/02/20 07:18 PM
07/02/20 07:18 PM
Joined: Feb 2015
Posts: 222
Philadelphia, PA
GTXKARL Offline OP
enthusiast
GTXKARL  Offline OP
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Joined: Feb 2015
Posts: 222
Philadelphia, PA
Hello. What are the steps to replacing a rear pinion seal on a Dana rear of a 1970 Plymouth GTX? What kind if gear oil do I need to put in it? What gear oil for a 4 speed transmission? TY for any help!


Working on cars teaches you patience... and every curse word imaginable.

1970 Plymouth GTX -- A true gentleman's coupe, but a serious muscle machine.
Re: Rear Pinion Seal [Re: GTXKARL] #2792037
07/02/20 08:58 PM
07/02/20 08:58 PM
Joined: Jan 2003
Posts: 27,245
Oregon
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AndyF Offline
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Oregon
That job is easy if you have the right tools. If you don't have the right tools then all you can do is lay under the car and stare at it. The torque on the pinion nut is around 250 ft-lbs so you need a big cheater bar or a big impact wrench. You'll also need a way to hold the pinion. Once you pull the pinion yoke off (takes another tool) then you just pry the old seal out and install the new seal with the correct installation tool. Then you put it back together. Takes about 20 minutes for a good mechanic with all the right tools and a lift. If you don't have any tools then you can work on it for the rest of time and never finish the job. I'm in the middle of changing the gears in my Dana 60 myself. Here is the tool I used to hold the pinion while I'll removed the nut.

DSC_4234 (Large).JPG
Re: Rear Pinion Seal [Re: GTXKARL] #2792106
07/02/20 11:08 PM
07/02/20 11:08 PM
Joined: Aug 2003
Posts: 35,270
Bend,OR USA
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Cab_Burge Online content
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Cab_Burge  Online Content
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Joined: Aug 2003
Posts: 35,270
Bend,OR USA
I use a big pipe wrench on the pinion yoke, tighten it up so it holds well and then use 1/2 inch or if you can a 3/4 inch breaker and socket to break the pinion nut loose. I use a brass drift, punch, to drive the pinion yoke off of the pinion shaft hammer
as far lube I like and use 75x90Wt non synthetic gear oil with a posi additive for the posi units up
On the 4 speed look for Pennzoil synchromesh gear oil and use it up
Summit and probably other hi Po warehouses stock and sell it if you can't find it locally like me scope


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Rear Pinion Seal [Re: Cab_Burge] #2792182
07/03/20 07:05 AM
07/03/20 07:05 AM
Joined: Jan 2003
Posts: 5,413
Abilene, Texas
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fastmark Offline
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I think Andy is a machinist so he has nice tools. I did the pipe wrench thing for years. I final grabbed a piece of scrap 2” angle iron and drilled some holes to bolt on the yoke. I then used a torch to cut out the center slightly to get a socket on the nut. I’ve got a big Matco torque wrench that will go to 250. It was not cheap.

Re: Rear Pinion Seal [Re: fastmark] #2792253
07/03/20 10:33 AM
07/03/20 10:33 AM
Joined: Aug 2011
Posts: 2,019
KATY TEXAS
csk Offline
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KATY TEXAS
Here is how I break mine loose, it keeps from damaging the gears with an impac

103854713_3112138312178190_8471341047009670912_n.jpg104429837_3112138252178196_3958849205188835337_n.jpg

[img]https://live.staticflickr.com/65535/49699175113_7f39889fbc.jpg[/img]87379033_2843330729058951_8904448720599252992_o by Charlie Keel, on Flickr
1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 3.54gear A518 OD 4100lb,11.04@123 full street car trim
Re: Rear Pinion Seal [Re: GTXKARL] #2792261
07/03/20 10:51 AM
07/03/20 10:51 AM
Joined: Jan 2008
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None
71rm23 Offline
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I just did this in February. I had to take the whole axle out because I had to change the housing, because one tube was leaking(long story). Anyway, AndyF is spot on with his reply. My rear end oil is a Amsoil racing(?) brand that my friend who had rebuilt it. I know it is VERY thick stuff, not sure of the weight tho.

Re: Rear Pinion Seal [Re: csk] #2792266
07/03/20 11:00 AM
07/03/20 11:00 AM
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nowhere
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Sniper Offline
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That's called working smarter, not harder.


Originally Posted by csk
Here is how I break mine loose, it keeps from damaging the gears with an impact

Re: Rear Pinion Seal [Re: GTXKARL] #2792287
07/03/20 11:35 AM
07/03/20 11:35 AM
Joined: Jan 2003
Posts: 27,245
Oregon
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Oregon
Originally Posted by GTXKARL
Hello. What are the steps to replacing a rear pinion seal on a Dana rear of a 1970 Plymouth GTX? What kind if gear oil do I need to put in it? What gear oil for a 4 speed transmission? TY for any help!


Mancini has the adapter for the yoke. You'll still need a 3/4 breaker bar to fit in the tool and then a big socket and a big breaker bar for the nut. Then you'll need a big torque wrench to tighten the nut back up.
https://www.manciniracing.com/yoinreto.html

Re: Rear Pinion Seal [Re: AndyF] #2792308
07/03/20 12:19 PM
07/03/20 12:19 PM
Joined: Jan 2003
Posts: 28,794
Hamtramck, PA
Alaskan_TA Offline
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Hamtramck, PA
Mine was fabricated using a broken torsion bar from a Superbird.

Details at https://www.hamtramck-historical.com/NostalgiaAndOldCars.shtml

Re: Rear Pinion Seal [Re: Alaskan_TA] #2792336
07/03/20 01:23 PM
07/03/20 01:23 PM
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Posts: 1,512
Michigan
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Transman Offline
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Michigan
So the parking brake won’t hold the yolk? Just asking, I never tried.

Re: Rear Pinion Seal [Re: Transman] #2792341
07/03/20 01:56 PM
07/03/20 01:56 PM
Joined: Jan 2003
Posts: 14,040
Eagle, Idaho
Neil Online content
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Posts: 14,040
Eagle, Idaho
FWIW I was told by a guy at a differential shop that occasionally pinion seal leaks can also be from oil migrating down the pinion gear, thru the splines, and out between the washer and or pinion nut. Once everything is wet with oil it's hard to tell where it's coming from exactly.

Re: Rear Pinion Seal [Re: Neil] #2792342
07/03/20 01:59 PM
07/03/20 01:59 PM
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Michigan
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Transman Offline
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Michigan
Originally Posted by Neil
FWIW I was told by a guy at a differential shop that occasionally pinion seal leaks can also be from oil migrating down the pinion gear, thru the splines, and out between the washer and or pinion nut. Once everything is wet with oil it's hard to tell where it's coming from exactly.


True, and this also applies to the crank bolt and washer. Always use a dab of RTV on the yolk splines and most of the times on the damper slot for the key. I think we even issued an ASN in the early 80’s for the 318/360 damper leaks.

Last edited by Transman; 07/03/20 02:00 PM.
Re: Rear Pinion Seal [Re: GTXKARL] #2792464
07/03/20 10:17 PM
07/03/20 10:17 PM
Joined: Jan 2003
Posts: 27,245
Oregon
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AndyF Offline
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Once you remove the pinion nut you'll need a way to pull the pinion off since it is a slight press fit on the splines. Here is a home made puller that I use but a two jaw puller will also work.

DSC_4235 (Large).JPG




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