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Discussion Starter #1
Hey everyone, I absolutely love my new gear install, Its great and turns the 37's with ease :) I could power brake these meats if I wanted to! Its so weird how it locks into overdrive at such low speeds! Thanks for everyone who helped reccommend them to me!

Anyways, I am very curious to how hot the differential should be right after they are installed... I just got the truck back earlier today and I did a decent drive tonight with her... it was probably a 15 mile trip, with mixed highway and city driving... the diff cover once I got home was pretty hot actually... I could keep my bare palm on the cover for about 8 seconds and then it kinda started to hurt my hand cause it was that hot. I really hope this is normal for the first break in period... cause if its not Im gonna be sad :( Please let me know! Thanks alot!
 

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GMFS slowest truck :read:
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check the fluid level...that does sound real warm. ive never honestly checked the temp after break in, but it very well could be too little backlash in there...
 

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Discussion Starter #3
well, i actually helped the guy finish putting the axles back in and puttin back on the calipers and all... so i watched him fill it and she was full when he did it so im not too worried about that... I think it just might of been a long drive on brand new gears... the drive was about 15 miles but it probably took me 30 minutes.. and that was technically the first drive because when me and the guy finished, i went right over to a friends house that was only 4 minutes away and on that drive I didnt check how hot it was... then i did a big drive when i left to take a girl home and then back to my house... so maybe it was just alot for the first drive... i dunno
 

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GMFS slowest truck :read:
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well, i actually helped the guy finish putting the axles back in and puttin back on the calipers and all... so i watched him fill it and she was full when he did it so im not too worried about that... I think it just might of been a long drive on brand new gears... the drive was about 15 miles but it probably took me 30 minutes.. and that was technically the first drive because when me and the guy finished, i went right over to a friends house that was only 4 minutes away and on that drive I didnt check how hot it was... then i did a big drive when i left to take a girl home and then back to my house... so maybe it was just alot for the first drive... i dunno
yeah, if you know for sure that the backlash is correct (should be somewhere around .008, give or take i believe on a 10b) and its full, it prob is just the initial drive then. I didn't read deep enough into it to see it was the FIRST drive and was for 15 miles, not 15 mins. Cycle it a couple more times and see what it does after that.
 

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You're fine dude. Just don't tow, don't chirp the tires, and try not to drive more than 15-20 miles at a time for the next 500-1000 miles. After 1000 miles, change your gear oil and you'll be all set.
 

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Discussion Starter #6
well I was actually thinking about towing the boat to the ramp tommorrow, but it is literally 4 minutes away.... I've let them cool on and off twice now, but I didnt follow the advice of "not getting on it" cause Ive floored it a few times now to see what it feels like... in my mind, it seems like it should be good to go as long as its set right.. you know? I mean, im not abusing it or anything cause like I said I am doing heat cycles and Im going to change the fluid in a bit too, to get all the metal outtat there...
 

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GMFS slowest truck :read:
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You're fine dude. Just don't tow, don't chirp the tires, and try not to drive more than 15-20 miles at a time for the next 500-1000 miles. After 1000 miles, change your gear oil and you'll be all set.
after 4 or 5 heat cycles (40-80 miles usually) its fine to drive highway, etc. change the lube at 500, button it back up, and call it good.
 

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after 4 or 5 heat cycles (40-80 miles usually) its fine to drive highway, etc. change the lube at 500, button it back up, and call it good.
:word:

Don't get on it anymore. Stay under 55 for the first 500 miles then change the lube, I just went through theis with my 4.56's
 

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Clit and Tire Liquifier
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Backlash on those 5.13s should be closer .01 if they are the motives. Most of the gear installers will say to get 5-6 heat cycles ~100miles total and beat teh shit out of it. When I installed my new set of 3.73s, got the backlash right topped it off with fluid and laid 2 posi stripes out of the shop and drove like a bat out of hell but those were OEM gears too which from what I have heard tend to be a bit tougher gear. 40K later they are fine and NO noise. Go get a couple more heat cycles on them if you want to be cautious change the fluid then go have fun. All the heat is from the teeth wearing into each other most of that is done within the first 50 miles, the heat cycles are to let the diff oil cool and it also gives teh gears a kind of heat treatment, if the gears get too hot intially they will become brital when they cool because they got so hot.
 

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NCOR
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The gears are in no way going to get brittle from being cooked to upwards of 300* in gear oil, thats nowhere near hot enough to effect the state of material. The reason more so for the break in is to work harden the gear faces as the small contact points are under enormous stress and they need to be smooth and very hard. As you compress the 8620 upon itself making ultra dense pockets, you produce some heat.

The differential will always be hot after being run, thats where some of the drivetrain parasitic loss is, in trying to turn the mass as well as overcome bearing preload so don't worry about it. If it starts spitting up oil out the breather then you can worry about it getting too hot.
 

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Pat McCrotch
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Just run it the way your going to. Change the oil after a couple hundred miles or so and run it like you stole it.
 

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u might as well be careful with it...500 miles with keepin it in check is worth it so ur stuff doesnt funk up on u...
 

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Bayou Surface Drive, LLC
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Normal. after that 500 miles do what you want. DONT TOW for 500 miles man.
 

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Discussion Starter #15
well.. i did... I towed a big deep V 20' hydrasport..... maybe I shouldnt have... It was only about 3 miles though.. and I babied her... maybe theyre gonna blow up in my face i dunno....

but hey I think I have a bigger problem... the front gears... well, they make racket if your going about 35 mph or more.... they are quiet if you keep the same speed but If you give it the tiniest bit of gas they make a whirling sound.... it doesnt sound too pretty actually.... I am gonna call the guy tommorrow... oh and just to let you know its when its in 4high, what do yall think?
 

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Bayou Surface Drive, LLC
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backlash too loose. Too much water content in gear oil.
 

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That's pretty common... but you might have to adjust the backlash.
 

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EMBRACE WHAT'S LEFT
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how would you get water in the diff?
 

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Discussion Starter #19
well i know that there is no water in there... cause i just got it the other day and havent wheeled it yet... so tommorrow I will mention to him that people think the backlash is too loose.... if it helps to describe it, it only does it when going faster, when in 4 low i cant hear it... and it crawls real good...
 

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Pat McCrotch
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I can see the backlash being a bit loose but also certain brands of gears tend to whine alot more than others. Richmonds new line of gears whine more often than most from what I have seen. My 4.88s whine a little bit at highways speeds but its going to be expected with the higher numerical gear ratio you go.
 
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