How hot is too hot?

[F150hybred]

Just got finished installing new 4.88 gears and I was wondering just how hot is too hot for a differential to be with new gears? As it is now, if I take it for a short drive (as per the instructions) the differential gets real warm to the touch... not a burning hot, but warmer than warm and cooler than hot. I took my time installing the ring and pinion and crossed my t's and dotted my eyes. The pattern is correct and yes, I did put gear oil in it. Any thoughts???

 

[dangerranger83]

Mine gets warm but nothing that I cant touch, was that way when i put my gears in the front of my D30 and my rear hasnt been touched and its the same way.

 

[t0x1k]

If your concerned about heat, buy a new diff cover, one with a higher fill hole, and cooling fins. More oil will allow more cooling and the fins will disperse the heat. An aluminum cover will do that best.

 

[dla]

If you can touch it without burning a white mark into your skin, it's not too hot. The differential fluid can go 275* or more before it cooks into road tar. As you continue to break it in the temps won't rise so much.

 

[4x4junkie]

Mine gets pretty warm, even with 32K miles on it now. I'd say about 2-3 seconds or so is about the max time I can hold my hand on it after 20 or more miles on a freeway doing 65.

 

[F150hybred]

Well, I guess I'll just run it and if something fails, I will deal with it then. Though I must say, switching from 3.73's to 4.88's sure gives my Explorer a different feeling of acceleration.

 

[F150hybred]

UPDATE: Well, I ran the differential as it was following the "break in" procedure as described in the guide from Yukon Gear. Drained the fluid (85w140) and filled with 80w90. All is good... the temperatures came down to a tolerable level.


Only one problem now... Since I have this new found power, I have found myself going a little heavy with the skinny pedal... to the extent that I believe my lunchbox locker has crapped. What's happening is... and I hope I'm saying this rite... When under heavy throttle (pavement or loose gravel) I get a steady popping and pulling to one side or the other when popping. It's feeling like it's letting loose and engaging again... violently. Is it possible that it's crapped out or is this just normal for a lunchbox running 35's and 4.88 gears?

H E L P!!!

4x4junkie... your "oh so wise" wisdom is required!

 

[Hahnsb2]

What locker? Did you notch the ring gear and use a full cross-pin or did you use a notched cross-pin? Was the locker in spec when installed?

 

[4x4junkie]

Definitely not normal.

I'm not as familiar with the lunchbox units as say the ARB or a Detroit, though I do know if they are not shimmed to the proper clearance, you can get popping like that (or if like said you tried to use a dreaded notched crosspin in it).

 

[F150hybred]

No notched cross pin...I ground the gear and it's a richmond gear locker (Lockrite). As for the spec... it was working fine before I swapped gears... and as far as the spec, if some jacka$$ on here would have returned my manual as he said he would (BLOODY LIAR), I would know if it was in spec or not.



EDIT: I'm wondering of maybe it's the springs and pins. If not, I'm most likely gonna save the cash and get a Detroit locker.

 

[t0x1k]

Check your tire pressure? Uneven pressure and wear will cause engagement/disengagement while driving.
Anyway, I would never run a lunch box with anything bigger than 33s, thats IMO. I love me detroit.

 

[strvger]

^^ x2 on the Detroit.

 

[F150hybred]

Well, the plan is (when I get a free moment) I'm gonna pull the cover and take a look see at the insides. If the springs and pins are the issue, I'll deal with it and save the cash for a detroit. If the locker is crapped and broken, I'll get some factory spiders and run them for time being. If there doesn't seem to be any problems, I will put the cover back on and save the cash. I guess either way, I'm saving cash.
Oh, t0x1k, the tires are new (not new to me, brand spankin new Goodyear MT/R's) and measure out under a quarter inch of each other (diameter not radius). Tire pressures are exactly the same.

 

[F150hybred]

Well, I don't know what the hell is going on, but I removed the cover and took it apart to find nothing wrong. I checked the space between the drivers and it was well within spec... Inspected all parts and came up with nothing. Figuring I still needed to drive this thing, I assembled it and now it works!
I have no idea what I did... but it works.

 

[strvger]

guess we won't be seeing any pics of your fix then. lol
glad it's all working for you!