Changing Rear Diff Fluid

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Mar 24, 2017 | 07:12 PM

#16

JoeF250

Tuned

Joined: Feb 2005

Posts: 478

Likes: 10

From: Minnesota

Quote:

Originally Posted by Traildust

Another thing to mention here is that the G2 rear cover's fill hole is slightly higher than a stock would be, therefore you add more fluid if you fill it to the fill hole. I asked G2 about this and they said it was for when making sharp turns that the fluid levels did not get low in opposite side of the turn.
Bill

Gear boxes are typically not a more is better situation. I'm not saying it's a problem with this product but over filling gear boxes can be disastrous. Bearings can overheat and seals can be blown out. Typically you don't want the fluid level above the center line of the bearings. If it is full to the top the bearings will act like a plugged pump and heat the snot out of the fluid. Some like to call this situation a thermal runaway.

Unless we're talking about extra 1/4" or less of oil in the diff; I don't think the added "high speed turn safety" would out weigh the added heat input that would always exist.

On a side note When I was still a mechanic for a commercial landscaping company one of our tractor driver's filled the gearboxes 3/4 of the way to the top on his 20ft field mower ( way over the top of the bearings). It caught on fire. Later that summer after forgetting this lesson he did it again, same result. Cost the company about $4500 per incident in parts. And because it happened both times on an Air Force active flight line it contributed to the loss of multi million dollar a year gov. contract. Air Force likes to spend too much to mow the grass, they don't like fire near the planes

Mar 25, 2017 | 01:51 AM

#17

Traildust

Mountain Pass

Joined: Feb 2004

Posts: 212

Likes: 11

From: Fallon, NV

Yes, I thought the same thing after I saw how much more fluid it took than the stock, I was thinking about to much oil in the axles. I could see heat and pressure build up maybe and blown seals. I added a little over what the stock rear-end should take since the G2's are a little bigger anyway.
Bill

Mar 25, 2017 | 02:04 AM

#18

BBslider001

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Joined: Mar 2012

Posts: 10,590

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From: Texas

I always wonder why people don't just buy the gasket at Napa and skip the RTV mess. Also, most synthetics come with the modifier already in the oil.

Mar 25, 2017 | 08:20 AM

#19

JoeF250

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Joined: Feb 2005

Posts: 478

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From: Minnesota

Quote:

Originally Posted by BBslider001

I always wonder why people don't just buy the gasket at Napa and skip the RTV mess. Also, most synthetics come with the modifier already in the oil.

NAPA has a gasket for the 10.5!?

Well that answers your question at least for people like me. If I'd known, I would have used one for the speed alone.

I assume you've used it, any problem with leaks?

Mar 25, 2017 | 10:16 AM

#20

BBslider001

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Joined: Mar 2012

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Likes: 382

From: Texas

Quote:

Originally Posted by JoeF250

NAPA has a gasket for the 10.5!?

Well that answers your question at least for people like me. If I'd known, I would have used one for the speed alone.

I assume you've used it, any problem with leaks?

I have always gone this route and never had any leaks or seepage over time. The last one I paid for was $7.50. It makes for a nice, clean install. I'll be doing it soon on the new rig.

Mar 26, 2017 | 11:11 AM

#21

timmyboy76

Lead Driver

Joined: Sep 2010

Posts: 7,793

Likes: 50

Changing mine today. And, will be looking into welding the npt nut if room allows... Maybe ill try the gasket route, too. Thinking though, when filling the axle to the fill hole, should the gear oil be warm to get an accurate measure, or is cold gear oil the accurate measure?