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Rear diff fluid capacity accurate?

Brem95

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First off I would like to thank everyone who’s offered great advice and helped me with my new project.


1997 Ford Explorer sport with 4.10

I’ve searched the forum and google but can’t find the specific information I’m looking for. I drained my rear diff fluid and the axle tubes, painted and sealed it up. After the sealant cured I starting pumping in gear oil. Expecting to use up 2.75-2.8 quarts I was confused when I used almost 3.5 give or take with 4 oz of friction modifier. I’m assuming it’s the same as any other diff I’ve filled which is fill until it spills out and self levels.

Would draining out axle tubes account for the extra fluid I had to add in the end?


Thanks!

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Runnin'OnEmpty

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I changed my rear diff recently, and it took 2.5 quarts to refill. I didn't do anything special
to drain the axle tubes, just let it drip out the diff until it stopped. As long as the vehicle
wasn't tilted toward the right, I don't see how you could overfill it. You're right, it's a "fill
and spill", filling until it spills out the fill hole.

The Haynes specs says 5.3 to 5.8 pints for the rear diff.

One other thought; even an extra quart wouldn't raise the oil level much, considering the
surface area in the diff and both axle tubes.
 




donalds

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Took me 3 quarts as @Runnin'OnEmpty said you fill till it spills then plug it

The difference may be the angle of the diff on our individual rigs may be different
 




J_C

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Time for new brake lines?
 




Brem95

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Time for new brake lines?
I’ll be looking into doing the brake lines in the spring. I know they look gross in the rear but at least the fronts are fairly new.
 




koda2000

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With the vehicle as level as you can get it, you put the fluid in until it begins to drip out the fill hole. Put your friction modifier in first and then add the gear oil. If you have limited slip the it might take slightly less than 3 qts, w/out LSD it will take about 3 qts. It's not important that the amount of fluid in the diff be "accurate". The quantity needed is "approx" 3 qts +/-. When it leaks out the fill hole it's full.

BTW - I wouldn't wait until spring to replace those rear brake lines. You don't want to be laying on you back in the snow replacing them in February, in Canada, dealing w/minus temps.
 




Brem95

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With the vehicle as level as you can get it, you put the fluid in until it begins to drip out the fill hole. Put your friction modifier in first and then add the gear oil. If you have limited slip the it might take slightly less than 3 qts, w/out LSD it will take about 3 qts. It's not important that the amount of fluid in the diff be "accurate". The quantity needed is "approx" 3 qts +/-. When it leaks out the fill hole it's full.

BTW - I wouldn't wait until spring to replace those rear brake lines. You don't want to be laying on you back in the snow replacing them in February, in Canada, dealing w/minus temps.
Thanks for the reply. Do the rears really look that bad? Haha luckily I have a heated garage. Still wouldn’t be ideal but at least I couldn’t be cold.
 




koda2000

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Thanks for the reply. Do the rears really look that bad? Haha luckily I have a heated garage. Still wouldn’t be ideal but at least I couldn’t be cold.

They look pretty bad to me.
 




Brem95

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They look pretty bad to me.
I’m checking around trying to find pre bent, I see what you mean. Not worth having them blow out in winter.
 




koda2000

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I wouldn't waste the money on pre-bent brake lines. They're easy to bend in your hands and over your knee. Auto parts stores sell brake line in multiple sizes and in rolls. Estimate how long a piece you need, get a piece at least that long and bend it to match the piece you're replacing.

Tip: If you need to connect multiple pieces of line together, do not use compression fittings. Always use unions.
 




J_C

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Thanks for the reply. Do the rears really look that bad? Haha luckily I have a heated garage. Still wouldn’t be ideal but at least I couldn’t be cold.

I don't recall the depth of my garage, but it's single vehicle deep and when I did the front to rear brake line I had already unrolled the coil of new line (or as you would do if you had pre-bent) and had to have my garage door open to feed it in during installation.

I don't even think it's reasonably possible to do a front to rear line with pre-bent, though across the rear axle might be possible but as Koda stated it is not hard to bend the line by hand, especially if you get CuNi line which is also more corrosion resistant than steel, though locally you can probably find steel that's nylon(?) coated which splits the difference and is pre-flared.

For example I used this on my '98 rear axle:
https://www.napacanada.com/en/p/BLQ8135456

It's slightly shorter than stock so the bends aren't quite as dramatic but the next longer piece they offer is too long and would need creative bends to take the slack out if not cut and re-flared on one end.
 




koda2000

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OP - The roll of line might seem easier to work with, but then you need to cut it, add the fittings, and double flare the ends. What I've done is use various lengths of auto parts store line (using unions to connect them when I need longer lengths) and if I end up an inch or two too long I can just add a bend to the line to shorten it the perfect length.

I've also used a roll of tubing, added the fittings and double flared the ends, but if you've never done this before there will be a learning curve and wasted brake line plus you need a pipe cutter and a good flaring tool. You need to do the double flare because a single flare will crack and leak. Steel line is easy to work with. Plastic coated steel line is preferred. Stainless steel line is much harder to bend and flare.
 




Brem95

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I wouldn't waste the money on pre-bent brake lines. They're easy to bend in your hands and over your knee. Auto parts stores sell brake line in multiple sizes and in rolls. Estimate how long a piece you need, get a piece at least that long and bend it to match the piece you're replacing.

Tip: If you need to connect multiple pieces of line together, do not use compression fittings. Always use unions.


I bought poly armor which has a coating and bends easier. I searched the forum and found out that the 51 and 60 inch pieces will fit the rear hard lines. The flares and fittings should be plug and play. Thanks for the help everyone, I knew the lines were rusted but didn't think about how compromised strength would be. Always learning something new and I love it.

Cheers

PS. forgot to mention that the hard lines at the front were rust free when I inspected them during the front end work I did.
 




koda2000

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OP - I should have mentioned that you use line-wrenches to avoid rounding off the fittings.
 




Brem95

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OP - I should have mentioned that you use line-wrenches to avoid rounding off the fittings.

When unbolting the line it cracked, thanks for the heads up I would have overlooked it. We should be good to go for the upcoming winter. Installing warrior shackles tmrw.

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