4.88 installed...break-in suggestions?
Thread Starter
JK Enthusiast
Joined: May 2008
Posts: 152
Likes: 0
From: Corinth, Mississippi
4.88 installed...break-in suggestions?
Finally had the gears swapped. The shop gave me guidelines but what are your suggestions for a successful break in period? Have any of you "screwed the pooch" by returning to aggressive driving too early?
Last edited by bmcqueen; Oct 30, 2008 at 01:07 PM.
JK Super Freak
Joined: Jan 2008
Posts: 1,835
Likes: 0
From: The Deep Dark Woods of Texas!
On the Jeeps I've had that we re-geared ourselves we always put about 200 miles minimum on the gears city/hwy driving, nothing hard. In my racecar I had the shop who did my gears professionally on the 9" had me do the same thing before I hit the track.
JK Jedi Master
Joined: Feb 2008
Posts: 12,907
Likes: 185
From: Maine
What SASQUATCH said is basically correct. I would add:
Drive for about 10 miles conservatively, with easy accelerations and deceleration, then stop to let the gears cool down. Do this several times on your initial run. Be easy for a few hundred miles, no need to let them cool if you don't beat them. Overheating when new is the quickest way to shorten the life of your gears. This is most important on the rear end because the front end will most likely see conservative use on your first few 4wd runs (if you keep in mind the gears are new).
In a few thousand miles, drain the diffs and refill with synthetic. You will see fine steel filings in the used oil from the gears lapping in.
Drive for about 10 miles conservatively, with easy accelerations and deceleration, then stop to let the gears cool down. Do this several times on your initial run. Be easy for a few hundred miles, no need to let them cool if you don't beat them. Overheating when new is the quickest way to shorten the life of your gears. This is most important on the rear end because the front end will most likely see conservative use on your first few 4wd runs (if you keep in mind the gears are new).
In a few thousand miles, drain the diffs and refill with synthetic. You will see fine steel filings in the used oil from the gears lapping in.
Last edited by ronjenx; Oct 30, 2008 at 02:52 PM.
JK Jedi
Joined: Feb 2008
Posts: 7,215
Likes: 10
From: Georgia
Drive that sumbitch like you stole it. Them NASCAR boys don't break in crap...just like them NHRA boys and ARCA boys and on and on and on. You think Ivan "Ironman" broke in gears when he was BAJA racing? Hell no. He jumped in and hauled ass. The only thing the gears need is to set up a "working" pattern. They are gonna do that no matter how you drive it.
JK Jedi
Joined: Feb 2008
Posts: 7,215
Likes: 10
From: Georgia
What SASQUATCH said is basically correct. I would add:
Drive for about 10 miles conservatively, with easy accelerations and deceleration, then stop to let the gears cool down. Do this several times on your initial run. Be easy for a few hundred miles, no need to let them cool if you don't beat them. Overheating when new is the quickest way to shorten the life of your gears. This is most important on the rear end because the front end will most likely see conservative use on your first few 4wd runs (if you keep in mind the gears are new).
In a few thousand miles, drain the diffs and refill with synthetic. You will see fine steel filings in the used oil from the gears lapping in.
Drive for about 10 miles conservatively, with easy accelerations and deceleration, then stop to let the gears cool down. Do this several times on your initial run. Be easy for a few hundred miles, no need to let them cool if you don't beat them. Overheating when new is the quickest way to shorten the life of your gears. This is most important on the rear end because the front end will most likely see conservative use on your first few 4wd runs (if you keep in mind the gears are new).
In a few thousand miles, drain the diffs and refill with synthetic. You will see fine steel filings in the used oil from the gears lapping in.
What for? They're already heat treated. They ain't gonna cure any more than they already are.
JK Jedi Master
Joined: Feb 2008
Posts: 12,907
Likes: 185
From: Maine
Drive that sumbitch like you stole it. Them NASCAR boys don't break in crap...just like them NHRA boys and ARCA boys and on and on and on. You think Ivan "Ironman" broke in gears when he was BAJA racing? Hell no. He jumped in and hauled ass. The only thing the gears need is to set up a "working" pattern. They are gonna do that no matter how you drive it.
I figured the OP was looking for suggestions on how to do it properly.
Nothing I suggested in my post can be singled out as improper or not needed.
JK Junkie
Joined: Oct 2008
Posts: 2,118
Likes: 1
From: Twain Harte, CA
Don't haul or tow any heavy loads, keep your speed down for at least 100 miles, and do not drive very long in each instance. Your dif cover will get hot to the touch for the first 25 miles or so as the gears break in in most cases. Over heating them is the single easiest way to damage them.
Trending Topics
JK Jedi
Joined: Feb 2008
Posts: 7,215
Likes: 10
From: Georgia
"Them NASCAR boys" have sponsors who will pay for anything to come in first. No such thing as being easy on the equipment.
Sure, they are heat treated. Overheating will unheat treat them. Heat in the initial few runs is the enemy of long life.
I figured the OP was looking for suggestions on how to do it properly.
Nothing I suggested in my post can be singled out as improper or not needed.
Sure, they are heat treated. Overheating will unheat treat them. Heat in the initial few runs is the enemy of long life.
I figured the OP was looking for suggestions on how to do it properly.
Nothing I suggested in my post can be singled out as improper or not needed.
