Transfer case gear oil loss at high speeds (1 Viewer)

cruisermatt

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It seems that any time I go triple-digit speeds my rear hatch and tailgate (as well as most of the rear underside of the truck) ends up with a nice light coating of gear oil. Anyone else have this issue? I'd really like to cruise at 100mph without having to top off my transfer case every time. Maybe a oil cooler and pump for the transfer case itself?
 
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Sounds like the problem is too much slipstream around the axles. You just need to adjust your suspension a little bit for your preferred style of driving. Something like this outght to take care of it:

1617202648612.png
 

cruisermatt

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I’m serious guys... I want to be able to drive cross country from Florida to Colorado, Moab, California etc at least once a year, and crossing big flat states like Oklahoma, Nevada, Texas suuucks and id like to get through them faster.
I want to set the cruise control at 95-100mph.

I’m thinking it’s just too much shaft speed for the transfer case output seal to handle?

I tried out a 3.70 rear diff (with 35” tire) and had no problems at all with horsepower, I’m back to 4.11 now and putting on 37’s next week. going back to 3.70’s again with 37’s will lower driveshaft speed so that should help a little.
 
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A serious answer: you may be generating more heat in your xfer case than it was designed to dissipate at that speed. After such a high-speed run, I would check all your case temps. I would also ditch the OEM 'rubber disk in hat' xfer case vent, and run a 3/8" fuel line vent up to the firewall. You sure don't want any pressure in your t-case. Your point about the seal not being able to handle that speed may be valid, but I think it's something else.
 
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i just had my t case pack it in because of low oil. i run it 110lm/hr regularly but have had no oil puddles under the truck. sounds like my rear seal was leaking and i wasn’t aware until too late. i wonder about breather issue now and excess heat may cause it leave past the seals. and that’s at what most people would call normal speeds. ill be watching to see if you come up with anything. i don’t really want to have to keep topping mine up either if there’s actually a problem that can be fixed. it’ll be out back together this week and i might see about just running a breather tube up to the front.
 
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a direct replacement if you go with an H55 in the future, my stuff won't work.

what are your plans for a park brake?

Sounds like the problem is too much slipstream around the axles. You just need to adjust your suspension a little bit for your preferred style of driving. Something like this outght to take care of it:

View attachment 2631633
that’s what it would look like after finding terminal velocity i’d think
 
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If it is coming out of the breather, look at a vent and catch/recovery can.

If it is coming out of the seals, balance your driveshafts 😆
 

cruisermatt

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I have breathed extended into engine bay already. It’s all dry around there.
Definitely think heat is a possibility. I’ll throw a temp gauge on it.

I think it would be neat to see before/after results with a oil cooler/pump setup. And have it relay triggered with a temp. switch.
 
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Seriously then, the fastest I’ve had my BJ60 (stock NA engine, 5speed, 235/75-15 tires, 100lb roof rack, 100lb hyd winch and a some dive gear in the back) was heading east on a hwy from Santa Cruz in the evening to join up with I-5 on the way to LA.
It was purring smoothly along at about 3250rpm in 5th (w/ Peter Gabriel on the tape deck) and I noticed the Speedo was well past the end of the scale, so somewhat above the 140km/hr (88mph) scale end....
No leaks and the engine sounded so happy!
 

EscapeWagon62

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Any centrifugal oil spray lines under the rig? I had axfer case rear oil leak at the rear seawhich sprayed oil from the cataytic to the passenger side
If so, new seal and high speed drive shaft balance (if there is such a thing)
Good luck
 

cruisermatt

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High emperature isn't the culprit- race cars /trucks go way faster than 100mph. There's a leaking seal somewhere that's being aggravated by vibration at high RPMs

Perhaps that is true, I tried a new seal and new output flange a few months ago and still have same issue though.
If I’m getting a vibration it’s minor, I have some all-terrains right now and it’s really smooth at those speeds. Even with dynamat everywhere there’s still quite a burn of wind noise and drivetrain noise at those speeds. Ear buds help
 

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