Slant Six Forum :: 8 3/4 axle running too hot?

: My newly installed 8 3/4 rearend seems to be
: running awfully hot. How hot do these things
: normally get? It's hot enough that I can't
: hold my hand on the case for more than 2
: seconds after running the car 30 miles or 5
: miles, it doesn't seem to matter.
:
: I am using 85w140 gear oil, which seems to be
: leaking slightly from somewhere. I haven't
: been able to tell where. The gear oil is
: filled to the bottom of the filler plug. By
: the way, this has 3.55 gears and a sure
: grip.
:
: Also, I don't have the proper axle vent valve
: yet. I've been using a bolt with a hole
: drilled in it. Is it possible that the axle
: isn't venting enough?
:
: Any help would be appreciated. Thanks.

:
: The venting should not cause overheating, poor
: venting will cause leaks.
:
: Did you have the center section (pumpkin) out?
: How did the unit spin, real easy or with
: some drag? (newly rebuilt ones will have
: some drag due to the bearing preloads, they
: "break-in" and loosen-up after
: some use)
:
: These units do get hot, especally at high
: (freeway) speeds, that why the NASCAR boys
: have to run an oil pump / cooler on the rear
: axle.
: DD

: Thanks for the replies Bud and Doug.
:
: I did forget to mention that this is a new,
: rebuilt third member. I just never knew that
: these things got this hot when breaking them
: in (and I'm paranoid since it is new). I
: probably never even felt the back of my 7.25
: aftering running it.
:
: I am going to re-check my axle endplay tomorrow
: as Bud suggested, just in case.
:
: Thanks again.

Author:	Patrick Devlin [ Fri Aug 02, 2002 5:22 am ]
Post subject:	8 3/4 axle running too hot?
My newly installed 8 3/4 rearend seems to be running awfully hot. How hot do these things normally get? It's hot enough that I can't hold my hand on the case for more than 2 seconds after running the car 30 miles or 5 miles, it doesn't seem to matter. I am using 85w140 gear oil, which seems to be leaking slightly from somewhere. I haven't been able to tell where. The gear oil is filled to the bottom of the filler plug. By the way, this has 3.55 gears and a sure grip. Also, I don't have the proper axle vent valve yet. I've been using a bolt with a hole drilled in it. Is it possible that the axle isn't venting enough? Any help would be appreciated. Thanks. pwd22@drexel.edu

Author:	bud L. [ Fri Aug 02, 2002 7:44 am ]
Post subject:	Re: 8 3/4 axle running too hot?
Quote: : My newly installed 8 3/4 rearend seems to be : running awfully hot. How hot do these things : normally get? It's hot enough that I can't : hold my hand on the case for more than 2 : seconds after running the car 30 miles or 5 : miles, it doesn't seem to matter. : : I am using 85w140 gear oil, which seems to be : leaking slightly from somewhere. I haven't : been able to tell where. The gear oil is : filled to the bottom of the filler plug. By : the way, this has 3.55 gears and a sure : grip. : : Also, I don't have the proper axle vent valve : yet. I've been using a bolt with a hole : drilled in it. Is it possible that the axle : isn't venting enough? : : Any help would be appreciated. Thanks. Sure, that's possible. I'd look for a bad brg or improper axle shaft end play setting. A little less likely, dragging brakes.

Author:	Doc. [ Fri Aug 02, 2002 9:40 am ]
Post subject:	Re: 8 3/4 axle running too hot?
Quote: : My newly installed 8 3/4 rearend seems to be : running awfully hot. How hot do these things : normally get? It's hot enough that I can't : hold my hand on the case for more than 2 : seconds after running the car 30 miles or 5 : miles, it doesn't seem to matter. : : I am using 85w140 gear oil, which seems to be : leaking slightly from somewhere. I haven't : been able to tell where. The gear oil is : filled to the bottom of the filler plug. By : the way, this has 3.55 gears and a sure : grip. : : Also, I don't have the proper axle vent valve : yet. I've been using a bolt with a hole : drilled in it. Is it possible that the axle : isn't venting enough? The venting should not cause overheating, poor venting will cause leaks. Did you have the center section (pumpkin) out? How did the unit spin, real easy or with some drag? (newly rebuilt ones will have some drag due to the bearing preloads, they "break-in" and loosen-up after some use) These units do get hot, especally at high (freeway) speeds, that why the NASCAR boys have to run an oil pump / cooler on the rear axle. DD

Author:	Patrick Devlin [ Fri Aug 02, 2002 4:55 pm ]
Post subject:	Re: 8 3/4 axle running too hot?
Thanks for the replies Bud and Doug. I did forget to mention that this is a new, rebuilt third member. I just never knew that these things got this hot when breaking them in (and I'm paranoid since it is new). I probably never even felt the back of my 7.25 aftering running it. I am going to re-check my axle endplay tomorrow as Bud suggested, just in case. Thanks again. Quote: : : The venting should not cause overheating, poor : venting will cause leaks. : : Did you have the center section (pumpkin) out? : How did the unit spin, real easy or with : some drag? (newly rebuilt ones will have : some drag due to the bearing preloads, they : "break-in" and loosen-up after : some use) : : These units do get hot, especally at high : (freeway) speeds, that why the NASCAR boys : have to run an oil pump / cooler on the rear : axle. : DD pwd22@drexel.edu

Author:	bud L. [ Fri Aug 02, 2002 7:23 pm ]
Post subject:	Re: 8 3/4 axle running too hot?
Quote: : Thanks for the replies Bud and Doug. : : I did forget to mention that this is a new, : rebuilt third member. I just never knew that : these things got this hot when breaking them : in (and I'm paranoid since it is new). I : probably never even felt the back of my 7.25 : aftering running it. : : I am going to re-check my axle endplay tomorrow : as Bud suggested, just in case. : : Thanks again. Ah, that puts a different spin on things. Yeah, Doc hit it right on the head, or rear end, so to speak. It's probably the pinion brg preload your feeling. They have different settings for new, and for used brgs. They require a higher torque value, when you're using new brgs. When they wear in together, the torque required to spin the pinion will decrease. In the meantime, you'll see increased friction(heat). fglmopar@aol.com

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