4.7 gearing
Administrator
Joined: Jul 2007
Posts: 24,686
Likes: 21
From: South Georgia/East Florida
500 miles, NO Towing. The gears need to be heated and cooled repeatedly to seat and harden properly.
Rule of thumb here is:
First 200 miles, no more than 20 mins of continuous driving, followed by at least 20 mins of a cooling period. Vary your speed/rpms. No more than 45 mph.
Next 200 miles, no more than 40 mins of continuous driving, followed by at least 20 mins of a cooling period. Vary speeds. No more than 60 mph.
Next 100 miles, no more than an hour continuous, vary speeds, not to exceed 70 mph.
At 500 miles, change the fluid, as there will be small sand size filings present from break-in. Inspect the differential. There should be NO large filings present and the fluid should not appear "burnt". This change is important, not only to remove the small filings and visual inspection, but new gear sets ship with a phosphorus coating, that burns off during break-in. This coating should not be left in the gear lube for an extended period as it has shown to prematurely break down the viscosity and lubrication properties of the lubricant over time.
Contrary to what you may have heard, or what a shop may tell you, there should not be even a hint of a whine from properly installed aftermarket gears.
If all checks out well, replace the fluid and the pumpkin cover and then DRIVE IT LIKE YOU STOLE IT...
Rule of thumb here is:
First 200 miles, no more than 20 mins of continuous driving, followed by at least 20 mins of a cooling period. Vary your speed/rpms. No more than 45 mph.
Next 200 miles, no more than 40 mins of continuous driving, followed by at least 20 mins of a cooling period. Vary speeds. No more than 60 mph.
Next 100 miles, no more than an hour continuous, vary speeds, not to exceed 70 mph.
At 500 miles, change the fluid, as there will be small sand size filings present from break-in. Inspect the differential. There should be NO large filings present and the fluid should not appear "burnt". This change is important, not only to remove the small filings and visual inspection, but new gear sets ship with a phosphorus coating, that burns off during break-in. This coating should not be left in the gear lube for an extended period as it has shown to prematurely break down the viscosity and lubrication properties of the lubricant over time.
Contrary to what you may have heard, or what a shop may tell you, there should not be even a hint of a whine from properly installed aftermarket gears.
If all checks out well, replace the fluid and the pumpkin cover and then DRIVE IT LIKE YOU STOLE IT...
Last edited by HammerZ71; Jun 5, 2009 at 01:07 PM.
Professional
Joined: May 2009
Posts: 202
Likes: 0
From: Angola, NY
Figured i'd steal the thread seeing is his answer is given, and ask mine haha. I am running the 3.55's on my 4wd Ram. I have my stock 265/70R/17's on right now, and am going to ride those in the winter and 22" SRT's on the summer... Am i going to run into any issues going back and forth in size and running 4.56's?
HAHA Blue Demon4.7 we did not just ask the same friggen question... haha thats awesome
HAHA Blue Demon4.7 we did not just ask the same friggen question... haha thats awesome
Administrator
Joined: Jul 2007
Posts: 24,686
Likes: 21
From: South Georgia/East Florida
Nope, 4.56s would never be too much gearing IMO on a truck with basically two overdrive gears! You're NEVER going to find that the RPMs are too high! The ONLY downside may be a slight loss of fuel economy when traveling at high speeds on the interstate. But most won't mind this when they hit the throttle to pass someone and have the feeling like a turbo just kicked in!!!
