Dana 20...how much gear oil?

supersport126 · 03-31-2010, 05:20 PM

I pulled the cover and drained the rear axle today. Filled it back up with ONE QT. of GL5 but it never started overflowing. Do I need more then ONE QT.

**SlikRic** · 03-31-2010, 05:29 PM

It's an AMC 20 rear axle and it takes almost 3 QT. I just finished mine for the 3rd time in 4 days due to leaks the first 2 times. I finally found a few small indentions and had to tap them flat, now no leaks.

**D-BO** · 03-31-2010, 05:39 PM

I always thought you filled it up to the plug. Once it reaches that hole then you are done. 3 sounds like how much I remember putting in.

**Trapshooter** · 03-31-2010, 06:35 PM

X2....Fill the diff until you get a dribble at the fill plug.

foggybottombob · 03-31-2010, 06:47 PM

Quote:

Originally Posted by Trapshooter

X2....Fill the diff until you get a dribble at the fill plug.

This is not really a good way to determine how much oil to put in a differential since the amount you put in a diff using this method will vary with the pinion angle and the height of the fill plug using this method. You should always put in the amount of fluid specified for your particular differential.

supersport126 · 03-31-2010, 08:12 PM

Quote:

Originally Posted by SlikRic

It's an AMC 20 rear axle and it takes almost 3 QT. I just finished mine for the 3rd time in 4 days due to leaks the first 2 times. I finally found a few small indentions and had to tap them flat, now no leaks.

Thanks, guess I need a couple more, lol.

jeepsarecool · 03-31-2010, 08:23 PM

Wait............ nevermind.

**Trapshooter** · 03-31-2010, 08:37 PM

Just pulled out my CJ7 manual and it states under Axles, Fluid Check, "The level should be up to the filler hole. When you remove the filler plug, the oil should start to run out. If it does not, replenish the supply until it does". (Pg. 1-38, Chilton, Jeep CJ/ Scrambler 1971-86 Repair Manual).

CSP · 04-01-2010, 08:13 AM

Quote:

Originally Posted by Trapshooter

Just pulled out my CJ7 manual and it states under Axles, Fluid Check, "The level should be up to the filler hole. When you remove the filler plug, the oil should start to run out. If it does not, replenish the supply until it does".

That's fine for a stock axle in that has not been modified. Swap in a CV driveshaft and you point the yoke up, which lowers the level of the fill hole. Suddenly you can't put as much gear lube is as before, which is not good.

Modifications in equipment require modifications in other areas.

I'd much rather rely on a fluid spec. out of a real factory manual over a Chiltons any day of the week anyhow.

**Trapshooter** · 04-01-2010, 08:50 AM

The original post does not mention any mods.

I don't disagree with your point of view but we are talking about a 26 year old axle. Things were much simpler back then.

**JeffreyCharles** · 04-01-2010, 10:40 AM

Quick question: when you replaced your diff cover, did you use an actual gasket or some RTV?

MrWills · 04-01-2010, 12:21 PM

I do both, a new gasket and a little RTV.

TDHofstetter · 04-01-2010, 12:33 PM

Quote:

Originally Posted by CSP

Swap in a CV driveshaft and you point the yoke up, which lowers the level of the fill hole. Suddenly you can't put as much gear lube is as before, which is not good.

That's begging for other problems anyway - point the yoke back forward and save yourself grief.

CSP · 04-01-2010, 12:42 PM

Say what???

TDHofstetter · 04-01-2010, 12:53 PM

Yup, for real. BEGGING for troubles.

Your rear u-joint is pointed directly into the differential when the Jeep's at rest, isn't it? Cool - so there's no velocity shift.

What happens when the Jeep's NOT at rest, though? When the axle actually articulates? Under load? Answer: Your u-joint no longer points directly into the differential, and you get velocity shifts. Depending upon how much the axle has articulated, you may get SEVERE velocity shifts. Beats the chit out of everything between the clutch pressure plate and the rear tires unless you're on the highway with a specific amount of fuel in the tank.

If you're out wheeling, the rolled axle also exposes that sheetmetal rear cover to rocks & such.

Much better to keep the axle pointed straight ahead and keep u-joints on both ends of the driveshaft. If you have to, clock the transfer case to get a lower u-joint angle.