rear diff fluid recommendations
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Senior User
Joined: Feb 2004
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rear diff fluid recommendations
I have 4.10 rear end in my f350.
I usually tow my boat and have my camper on.
What fluid should I be using for the rear diff???? Axle code is 35.
I found a buliten regarding the use of 75-140 synthetic for extreme conditions. Should I use that???
Also, I bought the ford additive for the rear because I wasn't sure if it had a limited slip. Do I dare install that?
Lastly, is the fill hole the bolt on the front driver side of the pumpkin? It looks really low. Just fill til it runs back out?
Sorry for all the questions, its just the first time I've had to service the rear end.
I usually tow my boat and have my camper on.
What fluid should I be using for the rear diff???? Axle code is 35.
I found a buliten regarding the use of 75-140 synthetic for extreme conditions. Should I use that???
Also, I bought the ford additive for the rear because I wasn't sure if it had a limited slip. Do I dare install that?
Lastly, is the fill hole the bolt on the front driver side of the pumpkin? It looks really low. Just fill til it runs back out?
Sorry for all the questions, its just the first time I've had to service the rear end.
Senior User
Joined: Sep 2007
Posts: 317
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From: Snohomish, WA
If you are servicing you rear end, be sure to pull the cover off to drain the old fluid. Clean out any crap in there, and the old RTV off the case and cover. While the cover is off you should be able to tell if you have the Trac-loc or not. If you have more that 50,000 miles on your rear end, it won't matter anyway because the clutch discs in the trac-loc are probably worn enough not to matter, so you won't need to add the Ford additive.
Put 1/4" bead of new RTV on the diff-cover and re install the bolts to 30 ft-lbs.
I would run 75-140 synthetic if I were you given your loading. It's pretty cheep insurance.
Yes, the bolt in the middle of the cover with the 3/8" socket head is the fill hole. Fill the diff until oil is to the bottom of that hole. Depending on your work environment you should be able to knock the whole thing out in about an hour.
Put 1/4" bead of new RTV on the diff-cover and re install the bolts to 30 ft-lbs.
I would run 75-140 synthetic if I were you given your loading. It's pretty cheep insurance.
Yes, the bolt in the middle of the cover with the 3/8" socket head is the fill hole. Fill the diff until oil is to the bottom of that hole. Depending on your work environment you should be able to knock the whole thing out in about an hour.
Elder User
Joined: Aug 2007
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the 3/8 square drive hole in the center is stripped out
if so the only way you will be able to remove it is to drill out the center of teh plug to relieve the tension on the threads and use a large easy out to remove it but you will get metal shavings in the diff so you may need to remove the carrier to remove all of it
most likely someone installed it with an impact , that is a no-no
if so the only way you will be able to remove it is to drill out the center of teh plug to relieve the tension on the threads and use a large easy out to remove it but you will get metal shavings in the diff so you may need to remove the carrier to remove all of it
most likely someone installed it with an impact , that is a no-no
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I think I'm just going to leave the fill bolt alone and buy a rear diff cover that has a drain and fill hole already in it.
The only other thing I was thinking was to weld a 3/8 square drive onto the nut and then
try to remove it. But, it's not leaking now, and the rear diff cover is an easy, but expensive option.
The only other thing I was thinking was to weld a 3/8 square drive onto the nut and then
try to remove it. But, it's not leaking now, and the rear diff cover is an easy, but expensive option.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 16
From: Nutter Fort, WV
That very well could work, and the heat from welding could help break it loose.
But I would wait till it cools before I tried to turn it out.
The plug expansion from the heat is going to make it even tighter while it is hot.
But I would wait till it cools before I tried to turn it out.
The plug expansion from the heat is going to make it even tighter while it is hot.
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Laughing Gas
Joined: Aug 2007
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From: Baldwin, ND
If its was me......I would look into getting a new cover. I have been eyeballing the large capacity ones in the 4x4 mags for awhile anyway......
Thad
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Posting Guru
Joined: Mar 2005
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From: KY
You can grease the drill bit up good and it will catch allot of the drillings. Drill slow though.
Most likely stripped because somebody use a 3/8 ratchet and the ball that holds the socket kept it from going all the way and it rolled out of the plug. Pipe plugs are pretty soft.
Most likely stripped because somebody use a 3/8 ratchet and the ball that holds the socket kept it from going all the way and it rolled out of the plug. Pipe plugs are pretty soft.
Post Fiend
Joined: Nov 2004
Posts: 5,638
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From: Manitoba
They came from the factory with synthetic 92/93+ If you have a limited slip use the additive cheap insurance check the axle code on the door post.....
https://www.ford-trucks.com/article/...de_Chart_.html
Automotive What is my Ford rear end ratio, do I have positraction
https://www.ford-trucks.com/article/...de_Chart_.html
Automotive What is my Ford rear end ratio, do I have positraction
Senior User
Joined: Sep 2007
Posts: 317
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From: Snohomish, WA
I don't know why you guys are even discussing drilling the plug out installed. Risking metal shavings in the diff seems silly when the cover is so easy to pull.
I would pull the cover and try any of the good plug removal ideas suggested.
chewyjackson, what part of WA are you in? I have a spare 10.25 with a good cover that you can have if you need it. I would need your to replace it, but we could swap them in my drive way pretty quickly.
I would pull the cover and try any of the good plug removal ideas suggested.
chewyjackson, what part of WA are you in? I have a spare 10.25 with a good cover that you can have if you need it. I would need your to replace it, but we could swap them in my drive way pretty quickly.
