rear end break in
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Senior User
Joined: Dec 2000
Posts: 342
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rear end break in
1990 E350, 460 FI, E4OD, Dana 70 w/4.10; When I bought this vehicle, the rear end was going out of it. Had the local Ford dealership rebuild the rear end. They finished at noon, we left for Iowa at about 5PM that evening, (700 Miles) pulling a 12K 5th wheel. Stopped for supper about 40 miles down the road, and I smelled hot oil. The dif cover was HOT. Called the dealer, and they said they would cover it, Go. Coming back it stared making a high pitched whine now & then.
Got back and had them check it out. They replaced the gears again. This fall, it started making the whine again. I've read different places, about breaking in the rear end after a gear swap. Ford says they never have. Now, the main part of my quest. This is a tow rig, not a dailly driver. If the mechanics, change gears in a local truck
that is driven every day, those gears would(?) be automaticly broken in by the time they tow something. (at least more than my 1 mile home). I'm starting to think that I need to go out and drive it solo for a few hundred (?) miles before I start towing. Is there any logic in what I'm thinking? Thanks, Elliott
Sorry for the long post, but to ans the ? I figured you needed some backgound.
Got back and had them check it out. They replaced the gears again. This fall, it started making the whine again. I've read different places, about breaking in the rear end after a gear swap. Ford says they never have. Now, the main part of my quest. This is a tow rig, not a dailly driver. If the mechanics, change gears in a local truck
that is driven every day, those gears would(?) be automaticly broken in by the time they tow something. (at least more than my 1 mile home). I'm starting to think that I need to go out and drive it solo for a few hundred (?) miles before I start towing. Is there any logic in what I'm thinking? Thanks, Elliott
Sorry for the long post, but to ans the ? I figured you needed some backgound.
Junior User
Joined: Oct 2001
Posts: 67
Likes: 0
From: Colorado
rear end break in
After I had the Dana 60 rebuilt in my 72 F250 the shop said NO TOWING for 500 miles, after 500 change the oil and wipe out the housing...After that your good to go...Dosen't matter if the gears are new or used... Gears never go back in the exact same way they came out... but the major concern with the 500 mile break in according to the shop that did mine is not the gears but the bearings...Don't load the bearings until they run in...
Metro2
Metro2
Senior User
Joined: Dec 2001
Posts: 304
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From: san diego usa
rear end break in
Here's what I've heard from my pro-gear shop and many others:
Drive for 20 to 30 minutes with no load, at normal speeds. Freeway speeds are ok. Then stop, let the diff cool down completely. Do this again 3 or 4 times. This helps remove the phosphate coating and cold work the contact surfaces without overheating the oil. Don't tow or accelerate hard for at least 500 miles.
When you do tow, don't pull hard (like up a long grade) for more than 10-20 minutes at a time until you get another 500 miles on the set. When you tow, the gear teeth flex and new material will be making contact, that's why you have to take it easy the first 500 when towing.
I've never had them tell me to change the diff oil, but I don't see any reason why it would hurt. If you did, at least you could visually check for problems. I've always broken my gear sets in this way, and never changed the oil after break in, and I've never had any problems.
Drive for 20 to 30 minutes with no load, at normal speeds. Freeway speeds are ok. Then stop, let the diff cool down completely. Do this again 3 or 4 times. This helps remove the phosphate coating and cold work the contact surfaces without overheating the oil. Don't tow or accelerate hard for at least 500 miles.
When you do tow, don't pull hard (like up a long grade) for more than 10-20 minutes at a time until you get another 500 miles on the set. When you tow, the gear teeth flex and new material will be making contact, that's why you have to take it easy the first 500 when towing.
I've never had them tell me to change the diff oil, but I don't see any reason why it would hurt. If you did, at least you could visually check for problems. I've always broken my gear sets in this way, and never changed the oil after break in, and I've never had any problems.
