Differential Flanges - Any Experts?

Discussion in 'Transmission & Drivetrain' started by StrongFord, Apr 20, 2019.

  1. StrongFord

    StrongFord Well-Known Member

    Vehicle(s):
    2015 GT Premium, MT, Deep Impact Blue, 401A
    Joined:
    Oct 25, 2015
    Location:
    SE Michigan
    Posts:
    274
    Likes Received:
    117
    0   0   0
    I have a 2015 GT manual with 3.31 ratio and cast iron housing. I purchased a used differential from a 2018 GT manual (verified in person) with 3.55 ratio and cast iron housing. Everything I have found indicates there are only two available flange options from Ford, one for manual and one for automatic - regardless of model year (2015-2018).

    The 2018 flange has about a 1/8" smaller inside diameter than my 2015 flange. The 2018 flange also has a taper at the top where my 2015 flange does not. The driveshaft will not press into the pinion flange. The 2018 flange has a Ford part number HR3W-4851-BA printed on it. The 2015 flange is too rusted to find a part number.

    I could swap the flanges, but since they are both manuals and supposedly they should mate, I did not want to jump into another project without knowing if it's necessary. Ultimately I put my 2015 differential back into the car.

    What the flange is going on here? Anyone encounter this issue?

    IMG_4338.JPG

    Note the taper at the top of the flange. The driveshaft and flange are hard contact. They could not be pulled together any further than this point. The driveshaft should insert as deep as the window opening.

    IMG_4345.JPG
    IMG_4341.JPG IMG_4349.JPG
    The caliper was set to the I.D. of the 2018 flange. You can see how much smaller it is than my 2015 flange.
     
    Lo Pony likes this.
  2. JohnVallo

    JohnVallo 1 5 4 8 3 7 2 6

    First Name:
    John
    Vehicle(s):
    2016 GT350, shadow black; chassis: G1245
    Joined:
    Feb 9, 2015
    Location:
    Venice, FL
    Posts:
    193
    Likes Received:
    245
    Occupation:
    Retired
    Rating:
    100%
    3   0   0
    #2 JohnVallo, Apr 20, 2019
    Last edited: May 29, 2019
    I assumed that all 2015-up differential flanges for Mustangs were categorized as either Automatic or Manual
    apparently that is not the case.
    I can offer some facts for the GT350's as I own a 2016 GT350 and have acquired 2 spare 2016 GT350 complete carriers, as well as 2 spare 2017 GT350 carriers
    All flanges on these measure right at 110mm span.
    I did purchase the new 2018 manual flange, pn: HR3Z-4851-B
    This flange has the same dimensions as all my other GT350 flanges
    One observation I have noticed is that all pre 2018 flanges did NOT come painted from the factory.
    The new HR3Z-4851-B flange comes painted black and seems to be a higher quality nicer looking piece.

    Here is the new 2018 flange HR3Z-4851-B
    IMG_0506-1200.jpg
    IMG_0507-1200.jpg

    The span on this new flange is right at 110mm
    IMG_0504-1200.jpg

    The bolt circle looks to be right at 94mm diameter

    IMG_0505-1200.jpg

    Maybe some of our Mustang GT friends can weigh-in on some 2015 manual flange measurements
    to try to clear-up this confusion about the manual flanges being of different sizes, and in what years were these differences.

    Hope this helps...
     
    Lo Pony and StrongFord like this.
  3. OP
    OP
    StrongFord

    StrongFord Well-Known Member

    Vehicle(s):
    2015 GT Premium, MT, Deep Impact Blue, 401A
    Joined:
    Oct 25, 2015
    Location:
    SE Michigan
    Posts:
    274
    Likes Received:
    117
    0   0   0
    #3 StrongFord, Apr 20, 2019
    Last edited: Apr 20, 2019
    Well, that's interesting, I measured my 2018 flange and it's right about 110mm. I can't measure the 2015 flange it's reinstalled. Judging by my estimate that it was about 1/8" larger I'd say it's around 113mm. So maybe my original 2015 flange is the odd one.

    Do your flanges taper in near the top like black one in the 2nd picture?

    Thanks!
     
    Lo Pony likes this.
  4. Lo Pony

    Lo Pony Well-Known Member

    First Name:
    Take me home
    Vehicle(s):
    86 GT, red; 88 LX 5.0, black; 95 GT black; 99 Cobra with mods (still own); ‘16 GT, PP, manual, Ruby, drivetrain vibration!; Traded for ‘19 GT, A10, velocity blue, love it.
    Joined:
    Dec 17, 2015
    Location:
    W. VA.
    Posts:
    296
    Likes Received:
    111
    Occupation:
    Mountain Momma
    0   0   0
    Because of the drivetrain vibration issues from the 15 to 17 cars, the 18 and ups have a revised pinion flange and different driveshafts. The older shafts will not work with the newer flanges.
     
  5. BmacIL

    BmacIL Enginerd

    Vehicle(s):
    2015 Guard GT Base, M/T
    Joined:
    Sep 21, 2014
    Location:
    Naperville, IL
    Posts:
    14,152
    Likes Received:
    8,086
    Garage Profiles:
    1
    Rating:
    100%
    3   0   0
    Also, PSA: GT350 diffs also have a different, and smaller flange (looks like the same as the 18 manual one you posted here) that I am not able to bolt up my 2015 manual driveshaft too. Bolt circle and flange ID are smaller. This came as a real surprise bummer today for me.
     
    Lo Pony and StrongFord like this.
  6. mindys

    mindys Well-Known Member

    First Name:
    Mindaugas
    Vehicle(s):
    2015 GT Premium PP DIB | 2006 Mazdaspeed 6 GT
    Joined:
    Jul 15, 2015
    Location:
    Chicago Suburbs
    Posts:
    431
    Likes Received:
    161
    0   0   0
    Yup can confirm what BMac said above. I was there with him and did the measurements. 2015 pinion flange has a approximately 112mm ID while the GT350 had about 110mm ID. Tried to pull it in with bolts on opposite sides of the driveshaft but i could not get the second bolt started because the holes did not line up when the first screw was started.
     
    Lo Pony, BmacIL and StrongFord like this.
  7. OP
    OP
    StrongFord

    StrongFord Well-Known Member

    Vehicle(s):
    2015 GT Premium, MT, Deep Impact Blue, 401A
    Joined:
    Oct 25, 2015
    Location:
    SE Michigan
    Posts:
    274
    Likes Received:
    117
    0   0   0
    I haven't shared to the forum yet, but some lessons learned from this experience. A driveshaft is required to accomplish the swap. Contrary to the online information I was able to find, the driveshaft and pinion flange changed for 2018. Likely for the GT350 too.

    Here's the 2015 GT driveshaft compared to a 2018 GT that I bought. I installed the 2018 3.55 differential and driveshaft yesterday.

    Driveshaft compare.JPG Driveshaft CV.JPG CV Joint.JPG
     
    Lo Pony, mindys and BmacIL like this.
  8. Catfood

    Catfood Member

    First Name:
    Dean
    Vehicle(s):
    2016 Mustang PP
    Joined:
    Apr 26, 2019
    Location:
    Georgia
    Posts:
    8
    Likes Received:
    1
    0   0   0
    I am running into this same issue today. I bought a 3.15 pre-2018 diff with the correct manual flange but the flange was damaged in shipping. I bought a used one online but it turned out to be the smaller diameter one. I checked with an oem online system and it shows the same part number for the pre and post 2018 flanges (FR3Z-4851-B). The larger diameter flange from my car has a part number of FR3W-4851-FC but I can't find that part number online. Very aggravating!
     
    Lo Pony likes this.
  9. BmacIL

    BmacIL Enginerd

    Vehicle(s):
    2015 Guard GT Base, M/T
    Joined:
    Sep 21, 2014
    Location:
    Naperville, IL
    Posts:
    14,152
    Likes Received:
    8,086
    Garage Profiles:
    1
    Rating:
    100%
    3   0   0
    I will probably be swapping flanges instead of buying a new driveshaft. More economical.
     
    Lo Pony likes this.
  10. OP
    OP
    StrongFord

    StrongFord Well-Known Member

    Vehicle(s):
    2015 GT Premium, MT, Deep Impact Blue, 401A
    Joined:
    Oct 25, 2015
    Location:
    SE Michigan
    Posts:
    274
    Likes Received:
    117
    0   0   0
    Not having the proper tools or experience torquing the pinion nut, nor wanting to pay a shop to do the swap led me this way. This way I still have my factory differential fully intact in case I needed to swap back or consider selling it.
     
    Lo Pony and TX-Ripper like this.
  11. BmacIL

    BmacIL Enginerd

    Vehicle(s):
    2015 Guard GT Base, M/T
    Joined:
    Sep 21, 2014
    Location:
    Naperville, IL
    Posts:
    14,152
    Likes Received:
    8,086
    Garage Profiles:
    1
    Rating:
    100%
    3   0   0
    Yeah I'm planning on the same, but buying a new flange (or used if necessary), nut, seal and crush spacer, and changing out the one on the new diff, leaving the current one intact. I'll have someone do that for me and then I'll install it myself.
     
    Lo Pony likes this.
  12. OP
    OP
    StrongFord

    StrongFord Well-Known Member

    Vehicle(s):
    2015 GT Premium, MT, Deep Impact Blue, 401A
    Joined:
    Oct 25, 2015
    Location:
    SE Michigan
    Posts:
    274
    Likes Received:
    117
    0   0   0
    So, did you reinstall your original differential while you get more parts? I did, I pulled the original and mounted the new one only to find it didn't fit :facepalm:. Then reinstalled my original for a few weeks and did the whole job again, now with a driveshaft.

    Just for good measure check your rear wheel bearings. My driver's side was totally shot, those got changed too.

    Good luck
     
    Lo Pony likes this.
  13. BmacIL

    BmacIL Enginerd

    Vehicle(s):
    2015 Guard GT Base, M/T
    Joined:
    Sep 21, 2014
    Location:
    Naperville, IL
    Posts:
    14,152
    Likes Received:
    8,086
    Garage Profiles:
    1
    Rating:
    100%
    3   0   0
    Yes, I did have to reinstall my OE 3.31. I was very unhappy about that. While I was in there I did check wheel bearings and both seemed fine. I did change to the new axle nuts with the 150+1/8 turn spec and some red loctite. They were popping a lot before.

    My least favorite part of it is that the exhaust has to come off. I love the sound, but damn the corsa catbacks are a PITA to install/remove.
     
    Lo Pony likes this.
  14. BmacIL

    BmacIL Enginerd

    Vehicle(s):
    2015 Guard GT Base, M/T
    Joined:
    Sep 21, 2014
    Location:
    Naperville, IL
    Posts:
    14,152
    Likes Received:
    8,086
    Garage Profiles:
    1
    Rating:
    100%
    3   0   0
    Scratch my above post. I think I'll end up getting a 2018+ one piece driveshaft. Just need to confirm that this GT350 flange is the same as the 2018+ flange. Looks identical and the measurements I took mirror what you found. If I'm going to swap out the shaft, might as well get something with an upgrade.
     
    Lo Pony and GregO like this.
  15. OP
    OP
    StrongFord

    StrongFord Well-Known Member

    Vehicle(s):
    2015 GT Premium, MT, Deep Impact Blue, 401A
    Joined:
    Oct 25, 2015
    Location:
    SE Michigan
    Posts:
    274
    Likes Received:
    117
    0   0   0
    Awesome, you’re always going the extra mile.

    The OD of the driveshaft CV was 108mm and the pinion flange ID was 110mm. The overall driveshaft length between 2015 and 2018 is the same or at least really close. An exact measurement was tough with CV movement.

    I would think a 2018+ one piece driveshaft would be a direct fit with this flange.
     
    Lo Pony and BmacIL like this.
Loading...

Share This Page