Gear break-in: cooling differential

[Strizzo]

Apologies if this info is here somewhere, but a search has not pointed me to it.

After trying to do my own regear I had issues and lost confidence, so have had a garage do it for me. Places that will work on 20 year old Jeeps are few and far between in the UK, so when I pick it up tomorrow I will have a 250 mile drive home.

The Revolution Gear break in process requires a number of short drives at low speed, with the need to let the differential cool in between. I will need to do this as part of my drive home. However, I have been unable to find any info on how long I need to let the differential cool for. I understand this may depend on a number of factors, so my plan is to go no faster than 35mph for the first few 20 mile stints and to allow time to cool between. Forecast says temperature will be about 60 degs in the UK tomorrow. Any rough indication of how long I need to stop to allow the differential to cool would be much appreciated.

My guy told me his standard break in process is 5, 15 minute drives at 55mph, with 45 minutes of cool down, then changing the fluid after 500 miles.

He recommended 85-140w conventional Lucas for fluid.

This was a shop that does 10-20 Jeep rehears a month for the last 25ish or more years.

 

[hosejockey61]

It's real simple. This is a video I made in consultation with Revolution Gear. Almost all the gear manufacturers use the same process. You only need to make two short trips to cycle them. Then you can drive home normally.

 

[OldButStillJeeping]

Yeah, plan your route via pubs...

-Mac

Yep, By the 4th stop you'll forget why it's taking so long to get home. Seeing double you'll wonder why you are under your jeep holding on to the pumpkin.

The Constable will too.

If you're that concerned, have it flatbed hauled home.

 

[LONGJP2]

I've bought new vehicles and have not had to endure this level of break-in... Why is this process necessary for replacement gear sets, and not factory new axles? Are the replacement gears made from a lesser grade steel?

I thought it had something to do with factory gears being 'finish lapped'.
Whatever that is?

 

[UKTJ]

It's real simple. This is a video I made in consultation with Revolution Gear. Almost all the gear manufacturers use the same process. You only need to make two short trips to cycle them. Then you can drive home normally.

Perfect, thanks Mike. Any thoughts on how long it takes to cool completely? Is an hour enough?

 

[UKTJ]

My guy told me his standard break in process is 5, 15 minute drives at 55mph, with 45 minutes of cool down, then changing the fluid after 500 miles.

He recommended 85-140w conventional Lucas for fluid.

This was a shop that does 10-20 Jeep rehears a month for the last 25ish or more years.

Really helpful, thanks. I'll probably go with an hour for cool down, just to be sure.

 

[hosejockey61]

Perfect, thanks Mike. Any thoughts on how long it takes to cool completely? Is an hour enough?

More than enough

 

[Rut Row]

Perfect, thanks Mike. Any thoughts on how long it takes to cool completely? Is an hour enough?

Given your expected outside temps, 10-15 min may be enough. When I did it the temps were around 30F and they never got too hot-no cool down required.

 

[JMT]

Really helpful, thanks. I'll probably go with an hour for cool down, just to be sure.

“Cool” means cool to the touch, which means you can keep your hand on the pumpkin. It doesn’t mean cold or like it would be after sitting on the garage for several hours.

 

[jjvw]

Given your expected outside temps, 10-15 min may be enough. When I did it the temps were around 30F and they never got too hot-no cool down required.

Ambient temperatures where humans typically live will make no meaningful difference in how quickly a differential will heat up or cool down.

 

[Rut Row]

Ambient temperatures where humans typically live will make no meaningful difference in how quickly a differential will heat up or cool down.

that makes no sense. When I did mine, I used a pyrometer to measure temps before and after. Cold days did make a difference.

 

[jjvw]

that makes no sense. When I did mine, I used a pyrometer to measure temps before and after. Cold days did make a difference.

Emphasis on meaningful.

 

[OldButStillJeeping]

To get out of the semantics of posts.... I don't see a valid argument there. Just headstrong pushing for no reason except for maybe pride. Chill out. Find a better victim of your welled up anger. Take it out on your lawn. No body gets offended or hurt, except your lawn which doesn't squeal and fight back. Good Lord on High, let me tell you.... "There is no verbally realized or emotional infection in the written word. None". You all probably agree more than you don't!

Shifting gears: I have regeared a few diffs in my days and the goal is to heat and then cool a few times. Which has its merit. In my history after regear I just 'baby it' for the first 1,000 miles. Then I drive it normal.

As some suggested earlier, just drive it normal but give it a few resting periods. Carry a therm gauge and use it if... if you must. And climb under you Jeep and touch the diff if you feel better.