Diff fluid level question

[jbmoose]

For starters, it's a 2000 XJ with 5" lift, 33x12.50 KM2's, Teraflex SYE with Wood's DS. Put a Rockcrusher rear cover on 29 spline 8.25. The fill plug is a little higher than OE rubber plug. Local Shop guy with 93 XJ with 10" lift tells me that he is very familiar with Rockcrusher covers and to fill up to new fill plug level. The FSM lists 2.08 L , or 4.4 pts., as capacity for rear axle. I just put 4 quarts ( 3.8 L) in and it ALMOST made it up to the fill plug level. When is too much? I listed the specs up top so those reading would understand that the rear axle is rotated quite a bit, and I don't want to starve the pinion bearing for lubrication. I've been told that extra oil capacity is good for cooling and lubrication, and I've also been told don't overfill it (leaking seals, etc.). I have the LP 30 up front with an ARB diff cover, and I'm not sure how much to fill it. With the front axle being rotated, and same issues, any idea how much to fill????? The ARB cover has a top mounted fill plug with built in dipstick/magnet, so I could fill it to the top if I wanted. The FSM lists the LP 30 capacity at 1.2L (2.5 pints). I'm using Royal Purple 75w-140. Thanks, JB

 

[ROBZ95Xj]

i hope your prepared to be replcing every seal in that 8.25, you have way to much fluid, factory recomendation is around 2 qts

 

[cal]

with that diff cover - if you can touch the oil with your finger, its high enough.

 

[jeeperjohn]

I'd put 2 quarts in and call it good.

 

[Peregrine]

I just dealt with the same situation. If you fill the RockCrusher up the fill hole, it will most likely cause foaming and will possibly come out of the breather tube. I don't know from first hand experience about failing seals...but I wouldn't risk it.

1.5 qts in the D30 and 2.5 quarts in the 8.25 and call it done. The actual capacities are 1.25 and 2.4 respectively (if I recall correctly), but a little extra won't hurt especially if your pinion angle is greater than stock.