New Gear Break-In

Mudflat

Mudflat

TJ Enthusiast
Joined
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Location
Lumberton, Texas
Greetings, friends!
Well, I got my TJ back from the shop yesterday after having 4.56 gears, True Tracks, chromoly axles & new front hubs installed & I started the break-in process with 75 or so slow, easy miles on back roads. I was told to drive it for an hour or so & then let it cool down. I’ve been checking the temps with an infrared thermometer & the highest reading I ever saw was 168 degrees. This is what I saw as a baseline temperature before the work was done. Is this normal? Is a higher temperature a part of the break-in process? Is something not right here or am I worried about nothing?
Thanks in advance for your help & replies.
 
I never checked temps after my two regear experiences. I stayed off the highway and varied speed as much as reasonable for 500 miles. If you're seeing temps in the same range as before the regear, I'd say you're good to go.

From the Revolution break in guidelines:
"A new ring and pinion will initially run hotter when new and can cause extensive damage if the temperature exceeds ideal operating conditions for an extended period of time."
 
I usually check pinion temps with a laser temp gauge. 160 or so is normal for a new set up. Are you doing a break-in with big tires? That will affect temps and break-in procedure.
 
Mudflat said:
I was told to drive it for an hour or so & then let it cool down. I’ve been checking the temps with an infrared thermometer & the highest reading I ever saw was 168 degrees. This is what I saw as a baseline temperature before the work was done. Is this normal?
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No, it's not normal. I've never wasted my time checking temps with an infrared thermometer.
 
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Mrhp said:
I usually check pinion temps with a laser temp gauge. 160 or so is normal for a new set up. Are you doing a break-in with big tires? That will affect temps and break-in procedure.
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That’s nearly the temps I’m seeing with my infrared (laser) thermometer. The highest I saw yesterday (the first day of break-in) was 169 degrees, but I imagine that ambient temperatures could play a part in this as well.
I’m breaking in the gears by driving at various somewhat slow speeds with the same 33/12.50 KO-2S that have been on the Jeep since I bought it last September.
 
Mudflat said:
That’s nearly the temps I’m seeing with my infrared (laser) thermometer. The highest I saw yesterday (the first day of break-in) was 169 degrees, but I imagine that ambient temperatures could play a part in this as well.
I’m breaking in the gears by driving at various somewhat slow speeds with the same 33/12.50 KO-2S that have been on the Jeep since I bought it last September.
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Sounds like all is going well. Keep an eye on it, but you should be fine.
 
Hopefully the shop used a conventional gear lube to fill the axles. Aiming an IR temperature tester at the diff cover won't show the true temperature of the gears, especially if they used a synthetic gear lube. It's hard to measure temperature of the gears themselves without a test jig. If there's a conventional gear lube inside you're likely ok. Using a synthetic gear oil with new aftermarket gears during the break in can be bad news
 
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Jerry Bransford said:
Hopefully the shop used a conventional gear lube to fill the axles. Aiming an IR temperature tester at the diff cover won't show the true temperature of the gears, especially if they used a synthetic gear lube. It's hard to measure temperature of the gears themselves without a test jig. If there's a conventional gear lube inside you're likely ok. Using a synthetic gear oil with new aftermarket gears during the break in can be bad news
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Does aiming an IR temperature tester at a diff cover that is filled with conventional give a different reading than synthetic? It would appear so by your statement. What kind of test jig is required to measure the temperature of the gears themselves? Inquiring minds would like to know Jerry. Please enlighten the class. It appears these are mindless ramblings. Reminds me of Biden!
 
Yes you'll get different temperature readings at the exterior of the diff cover depending on if it's filled with synthetic vs. conventional. The temperature of the cover is actually very misleading where conventional vs. synthetic gear oil is concerned. But since I know you'll call bullshit out of ignorance, I'm wasting no more time on you explaining anything else. Instead, if you want to know, contact John Currie at Currie and ask how that discovery came to be. He'll be happy to attempt to enlighten you.
 
The temperature is fully believable not the synthetic vs conventional differences, but a fixture needed to check temperature on a ring and pinion is purely a fabrication. The gear cover temp has little relationship on actual ring/ pinion/ bearing temperatures.
 
Mudflat said:
Greetings, friends!
Well, I got my TJ back from the shop yesterday after having 4.56 gears, True Tracks, chromoly axles & new front hubs installed & I started the break-in process with 75 or so slow, easy miles on back roads. I was told to drive it for an hour or so & then let it cool down. I’ve been checking the temps with an infrared thermometer & the highest reading I ever saw was 168 degrees. This is what I saw as a baseline temperature before the work was done. Is this normal? Is a higher temperature a part of the break-in process? Is something not right here or am I worried about nothing?
Thanks in advance for your help & replies.
Click to expand...
I’m no gear guru, and I’m only posting this because it makes sense to me, and it’s what I’ll be following once East Coast Gear Supply gets done building my HP30.

This info is about diff oil, mostly for break in, but mentions diff temperatures and a few other pertinent things. BTW, they do mention the issue of measuring temperature of oils as opposed to gears.

For your viewing pleasure;

https://eastcoastgearsupply.com/files/PDF Files/ecgs-gear-oil-recommendation1.pdf
At that same website they have a pretty good tech sheet on gear break in procedures if you’re at all curious.
 
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Hopper said:
I say drop the temp gauge and just follow the break in suggestions. Change the gear lubes after 500 and you will get eyes on the inside to confirm you are just being neurotic.
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I know!! I’ve been accused of being an engineer more than once. (Not true. ☺️)
Jerry Bransford said:
Hopefully the shop used a conventional gear lube to fill the axles. Aiming an IR temperature tester at the diff cover won't show the true temperature of the gears, especially if they used a synthetic gear lube. It's hard to measure temperature of the gears themselves without a test jig. If there's a conventional gear lube inside you're likely ok. Using a synthetic gear oil with new aftermarket gears during the break in can be bad news
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Conventional lube for the break-in, Jerry. I figured the infrared wouldn’t be really accurate, but I just wanted to get a trend on the temps.
The shop didn’t have the proper 39 tooth speedometer gear the day I picked up the Jeep & started the break-in. They will have it to install after the 500 mile break-in. However, the speeds show much higher & the miles are rolling up much faster than normal. When it shows 500 miles, I won’t be nearly that. I thought about taking it for the gear oil change when it’s showing 700 or 750 miles just to be sure. This will very likely be more than 500 miles. Will it hurt anything to be over 500 miles during the break-in?
Thanks in advance for your help.
 
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Mudflat said:
I know!! I’ve been accused of being an engineer more than once. (Not true. ☺️)

Conventional lube for the break-in, Jerry. I figured the infrared wouldn’t be really accurate, but I just wanted to get a trend on the temps.
The shop didn’t have the proper 39 tooth speedometer gear the day I picked up the Jeep & started the break-in. They will have it to install after the 500 mile break-in. However, the speeds show much higher & the miles are rolling up much faster than normal. When it shows 500 miles, I won’t be nearly that. I thought about taking it for the gear oil change when it’s showing 700 or 750 miles just to be sure. This will very likely be more than 500 miles. Will it hurt anything to be over 500 miles during the break-in?
Thanks in advance for your help.
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You will be fine with your gear lube change interval either way. Not that crucial to be spot on with the mileage. Short trips with little load and keeping the temps low is the key. When the lube is changed, there will be shiny material in it, that is normal break in.
 
Jerry Bransford said:
Yes you'll get different temperature readings at the exterior of the diff cover depending on if it's filled with synthetic vs. conventional. The temperature of the cover is actually very misleading where conventional vs. synthetic gear oil is concerned. But since I know you'll call bullshit out of ignorance, I'm wasting no more time on you explaining anything else. Instead, if you want to know, contact John Currie at Currie and ask how that discovery came to be. He'll be happy to attempt to enlighten you.
Click to expand...
What kind of test jig is required to accurately check the temp on a ring and pinion? I would love to purchase said jig. Is this something you had custom made? Pictures? Link to said apparatus? Help a fella out Jerry.
 
I did the temp gun thing when I did my break in. Just curious really. My readings were similar to what’s posted above.
I also used the ECGS doc for a reference.
 
It is completely normal for gears to run hot during the initial break in period. Revolution suggests first two or three times out drive for 15-20 minutes normal easy driving. You need to let the diff cool down completely after each heat cycle.

Try touching your hand to the diff cover the first time and you'll find it too hot to hold there. Try again after 500 miles and a lube change and you'll be able to hold your hand on the cover no problem.
 
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