SAAC Forum

The Cars => 1969-1970 Shelby GT350/500 => Topic started by: hurlbird on November 23, 2020, 02:50:18 PM

Title: What type of rear end do i have? LOL
Post by: hurlbird on November 23, 2020, 02:50:18 PM
Owner of 68 Shelby. This is about my 70 MACH I sorry if this is unethical to ask in this forum. BUT my pinion in leaking and I don't have a tag and have enclosed some pictures to see if they help. I need to get the correct seal. Not looking for ratio insight. Thanks ahead of time!  ;D
Title: Re: What type of rear end do i have? LOL
Post by: Greg on November 23, 2020, 02:57:38 PM
Go to Napa and tell them you need a rear end pinion seal.  They will fix you right up.  Also, go on youtube and look at "9" ford rear end rebuild" or "9" ford pinion seal installation" and you will learn a lot. 
Title: Re: What type of rear end do i have? LOL
Post by: KR Convertible on November 23, 2020, 03:02:16 PM
Check the yoke for a groove where the seal rides.  There are sleeves made to cover the groove and give you a nice fresh surface.
Title: Re: What type of rear end do i have? LOL
Post by: hurlbird on November 23, 2020, 03:02:38 PM
don't I need to know if it is a 8" or 9" ? Thanks
Title: Re: What type of rear end do i have? LOL
Post by: hurlbird on November 23, 2020, 03:03:50 PM
Sorry KR not following you....
Title: Re: What type of rear end do i have? LOL
Post by: gt350hr on November 23, 2020, 03:57:27 PM
   9" standard duty. The National seal number is 7044NA . They are the best there is.
Title: Re: What type of rear end do i have? LOL
Post by: hurlbird on November 23, 2020, 04:05:11 PM
Confirming this is a 9" correct? For my own knowledge what in the picture gives that away? thanks
Title: Re: What type of rear end do i have? LOL
Post by: Bob Gaines on November 23, 2020, 04:09:39 PM
Confirming this is a 9" correct? For my own knowledge what in the picture gives that away? thanks
The 9inch style pinion shield bolted in place is just one.
Title: Re: What type of rear end do i have? LOL
Post by: hurlbird on November 23, 2020, 04:21:52 PM
8" did not have that then? thanks
Title: Re: What type of rear end do i have? LOL
Post by: 68stangcjfb on November 23, 2020, 04:40:47 PM
A full proof way of telling an 8-inch from a 9 inch. You can fit a 9/16 deep socket on all 10 nuts of an 8 inch. On a 9-inch, you can't get the socket on the bottom 2 nuts.
Title: Re: What type of rear end do i have? LOL
Post by: Scode67FB on November 24, 2020, 03:07:07 AM
As several have confirmed, it's a nine-inch.
Being a "Mach," it had to come from the factory with a nine-inch. Of course, over the 50 years of it's life, anything could've been swapped in.
Visually, as pointed out, the bolt-on pinion snubber is a giveaway. The eight-inch rears didn't have them. Also the socket trick on the bottom two nuts. On an eight-inch rear, you  can get a socket on the bottom two nuts. On a nine-inch, no socket fits. You have to use a wrench.
Title: Re: What type of rear end do i have? LOL
Post by: hurlbird on November 24, 2020, 06:33:11 AM
thanks for the clarification.
Title: Re: What type of rear end do i have? LOL
Post by: KR Convertible on November 24, 2020, 12:09:07 PM
Sorry KR not following you....

After 50 years of usage, the machined surface of the yoke can develop a groove where the seal rides.  There are sleeves that go over the area and give you a fresh surface and slightly tighter fit in the seal.  I was surprised to learn the seal number remains the same.  Prior to using them I thought it would be a lightly larger ID on the seal, but that has not been my experience.  Below is a link to one.  Please do your own research on part numbers, I just copied the first one I found.

 https://www.randysworldwide.com/product/yms99181/
Title: Re: What type of rear end do i have? LOL
Post by: gt350hr on November 24, 2020, 12:20:51 PM
   The pinion retainer , the yoke , the case design , are my clues. As others mentioned the bolt on pinion snubber , instead of cast on , BUT there ARE 9" pinion retainers with cast pinion snubbers.
Title: Re: What type of rear end do i have? LOL
Post by: hurlbird on November 24, 2020, 01:19:00 PM
thanks KR. Seems like this could be a good practice when doing the job regardless. thoughts?
Title: Re: What type of rear end do i have? LOL
Post by: gt350hr on November 24, 2020, 02:00:48 PM
   hurlbird,
       If you are going to replace the seal yourself , take a feel of the rotational effort "before" you loosen the pinion nut. This is so you can "carefully" tighten the nut after replacing the seal itself. That is because ( unlike your Shelby) this diff has a "crush sleeve" and it is VERY easy to over tighten the nut and destroy the bearings. A slight increase in drag is OK but not too much tighter nor any looser that it was/is. Your Shelby ( nodular case /Daytona pinion retainer) is made with a "select fit" , solid spacer and can't be over tightened.
  More than likely your seal is simply worn too much and the yoke is not grooved. Don't add the seal saver unless you can actually feel the groove.
   Randy
Title: Re: What type of rear end do i have? LOL
Post by: KR Convertible on November 24, 2020, 03:17:02 PM
I usually clean the nut and the threads with brake clean, use some dyekem and scribe a line on the shaft and the nut.  Take a picture with your phone showing the threads and marks, so you can get it where it was.  I always use this procedure and assume a crush sleeve.
Title: Re: What type of rear end do i have? LOL
Post by: gt350hr on November 24, 2020, 05:29:37 PM
  You can do that but "I" would go just past your reference point. I go by feel because of my 50+ years of doing them , plus my Ford factory trainer taught me that in '68.
    Randy
Title: Re: What type of rear end do i have? LOL
Post by: pbf777 on November 24, 2020, 07:34:51 PM
   ....................., take a feel of the rotational effort "before" you loosen the pinion nut. This is so you can "carefully" tighten the nut after replacing the seal itself. That is because this diff has a "crush sleeve" and it is VERY easy to over tighten the nut and destroy the bearings. A slight increase in drag is OK but not too much tighter nor any looser that it was/is.
 


      Follow Randy's outline or you'll be sorry!        ;)

      To take this process a few steps further, one can use a dial-type or even a beam-type torque wrench for the "rotational-effort" reference, that is if you haven't done a bunch of these and have "the feel".  The factory "drag"/"resistance" effort as referenced is with the pinion assembly removed (5 bolts) from the pig (and this is the correct and best process), on the bench with new bearings and races, was 15 inch pounds in rotational resistance, that being after the increased break-away effort.  With used bearing components one should not attempt this number, but rather as Randy said: "a slight increase" is probably warranted to take-up for acceptable wear.          :)

      Should you choose to remove the pinion assembly don't toss the steel shim, as this is not a gasket to be replaced!  You wouldn't believe how many requests I've gotten from people over the years wanting a new gasket, and had thrown the odd one away!  I would just pull out the stack of shims of some twenty different thicknesses and say pick one!      ::)
       
      Also the pinion nut is intended as a one time use item, as it is a "crimp" interference fit nut for retention, and often the flange face gets damaged (galled) which makes reuse also a bad idea.  But if the nut appears to be in good condition, I would recommend the application of "Red" Loctite on final assembly.

      And to be clear, no matter what your buddy or neighbor, who knows allot about cars says, there is NOT a torque value for tightening the pinion nut!        :o

      Scott.