Rear diff cover help

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Aug 29, 2021 | 12:36 PM

BlackLab06

Thread Starter

Mountain Pass

Joined: Nov 2017

Posts: 117

Likes: 2

From: Baltimore

Rear diff cover help

So I decided to finally do my rear differential gasket because it was leaking like a sieve when I found a pin hole in the plate…I’m wondering if I can use some jb-weld to temporarily patch the hole while I wait for a new plate to come…the tags on the bolts say “fw-140 syn oil only” and also “3 s 136 H….73 10 5 0 J19” so I know what type of gear oil to use and I know this is not a limited slip and it’s got 3.73 gears as well as a 10.5” ring gear…my question is and I’ve seen conflicting answers…will a plate that says 10.25/10.5 work? Must it say both ring sizes? I also mistakenly got valvoline 80w-90 because that’s what I was told…but after looking at the tags on the diff I want this done correctly and I don’t have the means to spend a couple hundred dollars on a fancy plate right now…any and all help would be greatly appreciated!! Oh and I need to know exactly how much gear oil I’m going to need because I was told to get 3 quarts, but I’ve heard it holds as much as 6…

Aug 29, 2021 | 02:23 PM

WWR

Cargo Master

Joined: Dec 2015

Posts: 2,911

Likes: 504

Sure you can use JB Weld. Not sure how well it'll work but worth a shot.

I'd be surprised if a 10.25 diff cover wouldn't fit a 10.5 but I can't be certain.

This is not relevant to your exact repair but funny because I just happened upon it this morning --- a JB Weld repair to a 3V timing cover at ~42:30. Worth a look and a chuckle to ANY gearhead out there:

Aug 29, 2021 | 04:16 PM

leadmic

Fleet Mechanic

Joined: Feb 2002

Posts: 1,483

Likes: 273

From: Tulare U.S.A.

You can buy a cheap cast aluminum diff cover from ebay or amazon. I think I paid $55 for the one I bought. It fit good, holds more oil, and has a drain plug in it. Its been on their 3 years so far no issues.

Aug 29, 2021 | 09:43 PM

PJWhelan

Laughing Gas

Joined: Jan 2019

Posts: 868

Likes: 84

From: Florida

Look up "parts.lakelandford.com". Stay away from the "Cheap" stuff. You wouldn't buy a cell phone plan from "Consumer Cellular", don't buy cheap stuff from Amazon or Ebay...I got my Diff Cover from Lakeland Ford and it was under $50, for sure. Yours holds about 3 quarts of oil. Make sure you bead the gasket silicone correctly and don't cut corners.

Aug 29, 2021 | 10:04 PM

BlackLab06

Thread Starter

Mountain Pass

Joined: Nov 2017

Posts: 117

Likes: 2

From: Baltimore

Thanks, I had some JB weld high temp steel weld leftover from putting an insert in my cylinder head…the epoxy seems to have patched the hole and I tested to make sure no leakage…I have a fel pro gasket and diff sealant so I’m doing both, I was just worried about the difference in oil..I’ve got 75-90 and 3 quarts of it…I’m gonna go ahead and try it…thanks for the help

Aug 29, 2021 | 11:12 PM

R&T Babich

Fleet Mechanic

Joined: Feb 2011

Posts: 1,812

Likes: 88

From: Thousand Oaks, CA

Quote:

Originally Posted by BlackLab06

JB Weld should hold fine, clean the surface well, a friend sealed a crack in his manual trans case after hitting a rock which worked well.
Checkout the Dorman 697-725 Finned Aluminum Differential Cover which is a copy of the Ford '99-'11 cover.
I drilled and tapped mine to provide a drain plug.
Also, look for a video on Youtube about aftermarket diff covers and how the diff cover shape affects oil flow over the gears when thrown off the spinning gear.
The large boxy covers add oil capacity, but may decrease oil flow over the gears.

Aug 31, 2021 | 08:22 AM

nydiver

More Turbo

Joined: Jun 2009

Posts: 661

Likes: 186

From: Lakeland, MN

Quote:

Originally Posted by R&T Babich

Also, look for a video on Youtube about aftermarket diff covers and how the diff cover shape affects oil flow over the gears when thrown off the spinning gear.
The large boxy covers add oil capacity, but may decrease oil flow over the gears.

Gale Banks made that video and showed how not only do the expensive flat aluminum covers inhibit proper oil flow, they also do a worse job of cooling the gear oil than even the steel covers.