Where do I get a Moser 12-bolt diff cover gasket?
11-21-2009, 10:51 AM
#1
Where do I get a Moser 12-bolt diff cover gasket? I have a Moser 12-bolt in my 2002 Z28 and it's been leaking like crazy out of the bottom of the diff cover. I'm guessing I also overfilled it because it's constantly leaking out of the breather tube, as well, even though it's placed pretty high up (strange?). I want to replace the gasket for the cover but where can I get one? Is there somewhere I can pick one up or do I have to order it? I kind of need it by Tuesday if at all possible because I have a track rental Wednesday and I don't want to get any crap for fluid leaking.
Also, when I replace it and fill it back up, what is the spec on how much fluid goes in? Any issues with Royal Purple?
Also, when I replace it and fill it back up, what is the spec on how much fluid goes in? Any issues with Royal Purple?
11-21-2009, 11:19 AM
#2
This is a reply from Bob at EPP:
You will need three bottles of 80/90 weight gear lube - non synthetic! We usually go with the Napa brand. I think your rear has an Eaton posi in it, so get posi additive (friction modifier) for it, use two of them.
Note: Bob and Moser have clearly stated. DO NOT USE synthetic as the warranty is voided if you do.
My reply and information from Moser.
If you have an aftermarket cover the fill hole is very high on the cover. However, this is NOT the oil level.
The actual fill hole and oil level hole is on the front passenger side of the rear end diff. The plug is hex so you will need a pretty big hex Allen wrench or drive adapter with a hex head to remove the plug. I don't recall the size - SAE I recall rather than metric.
Pretty easy to fill - add until gear oil starts to run out from front passenger side hole on the diff.
Or - add from the rear cover fill hole until gear oil start to run out from the fron passenger diff side add/fill hole.
Until you find a new gasket why not try silicone gasket cement. Order a gasket from Moser or EPP.
Tip: add the posi additive (friction modifier) first rather than last or mix it in your first bottle of gear oil to eliminate having to drain oil back out to allow room for the additive.
You will need three bottles of 80/90 weight gear lube - non synthetic! We usually go with the Napa brand. I think your rear has an Eaton posi in it, so get posi additive (friction modifier) for it, use two of them.
Note: Bob and Moser have clearly stated. DO NOT USE synthetic as the warranty is voided if you do.
My reply and information from Moser.
If you have an aftermarket cover the fill hole is very high on the cover. However, this is NOT the oil level.
The actual fill hole and oil level hole is on the front passenger side of the rear end diff. The plug is hex so you will need a pretty big hex Allen wrench or drive adapter with a hex head to remove the plug. I don't recall the size - SAE I recall rather than metric.
Pretty easy to fill - add until gear oil starts to run out from front passenger side hole on the diff.
Or - add from the rear cover fill hole until gear oil start to run out from the fron passenger diff side add/fill hole.
Until you find a new gasket why not try silicone gasket cement. Order a gasket from Moser or EPP.
Tip: add the posi additive (friction modifier) first rather than last or mix it in your first bottle of gear oil to eliminate having to drain oil back out to allow room for the additive.
Last edited by dlandsvZ28; 11-21-2009 at 06:35 PM.
11-21-2009, 01:45 PM
#3
This is a reply from Bob at EPP:
You will need three bottles of 80/90 weight gear lube - non synthetic! We usually go with the Napa brand. I think your rear has an Eaton posi in it, so get posi additive (friction modifier) for it, use two of them.
Note: Bob and Moser have clearly state. DO NOT USE synthetic as the warranty is voided if you do.
My reply and information from Moser.
If you have an aftermarket cover the fill hole is very high on the cover. However, this is NOT the oil level.
The actual fill hole and oil level hole is on the front passenger side of the rear end diff. The plug is hex so you will need a pretty big hex Allen wrench or drive adapter with a hex head to remove the plug. I don't recall the size - SAE I recall rather than metric.
Pretty easy to fill - add until gear oil starts to run out from front passenger side hole on the diff.
Or - add from the rear cover fill hole until gear oil start to run out from the fron passenger diff side add/fill hole.
Until you find a new gasket why not try silicone gasket cement. Order a gasket from Moser or EPP.
Tip: add the posi additive (friction modifier) first rather than last or mix it in your first bottle of gear oil to eliminate having to drain oil back out to allow room for the additive.
You will need three bottles of 80/90 weight gear lube - non synthetic! We usually go with the Napa brand. I think your rear has an Eaton posi in it, so get posi additive (friction modifier) for it, use two of them.
Note: Bob and Moser have clearly state. DO NOT USE synthetic as the warranty is voided if you do.
My reply and information from Moser.
If you have an aftermarket cover the fill hole is very high on the cover. However, this is NOT the oil level.
The actual fill hole and oil level hole is on the front passenger side of the rear end diff. The plug is hex so you will need a pretty big hex Allen wrench or drive adapter with a hex head to remove the plug. I don't recall the size - SAE I recall rather than metric.
Pretty easy to fill - add until gear oil starts to run out from front passenger side hole on the diff.
Or - add from the rear cover fill hole until gear oil start to run out from the fron passenger diff side add/fill hole.
Until you find a new gasket why not try silicone gasket cement. Order a gasket from Moser or EPP.
Tip: add the posi additive (friction modifier) first rather than last or mix it in your first bottle of gear oil to eliminate having to drain oil back out to allow room for the additive.
My rear does have an Eaton posi, by the way, so when I replace the gasket I'll make sure to go with the nonsynthetic gear oil and additive.
11-21-2009, 02:15 PM
#4
If most of the oil dripping to the ground is from the vent tube you want to position the tube and tie in place so it vents just the gases from the diff rather than gear oil. Obviously you might have to lengthen the hose if the current one is cut too short.
If the tube is positioned correctly any gear oil forced into the tube should gravity flow back into the diff instead of letting the tube hang down so oil in the tube will gravity feed out of the tube and to the ground.
If it's overfilled you will smell the fluid more readily than if the level is correct. At least that's what happened when I overfilled mine.
Now that the level is correct I smell no gear oil at all.
If the tube is positioned correctly any gear oil forced into the tube should gravity flow back into the diff instead of letting the tube hang down so oil in the tube will gravity feed out of the tube and to the ground.
If it's overfilled you will smell the fluid more readily than if the level is correct. At least that's what happened when I overfilled mine.
Now that the level is correct I smell no gear oil at all.
11-21-2009, 02:44 PM
#5
If most of the oil dripping to the ground is from the vent tube you want to position the tube and tie in place so it vents just the gases from the diff rather than gear oil. Obviously you might have to lengthen the hose if the current one is cut too short.
If the tube is positioned correctly any gear oil forced into the tube should gravity flow back into the diff instead of letting the tube hang down so oil in the tube will gravity feed out of the tube and to the ground.
If it's overfilled you will smell the fluid more readily than if the level is correct. At least that's what happened when I overfilled mine.
Now that the level is correct I smell no gear oil at all.
If the tube is positioned correctly any gear oil forced into the tube should gravity flow back into the diff instead of letting the tube hang down so oil in the tube will gravity feed out of the tube and to the ground.
If it's overfilled you will smell the fluid more readily than if the level is correct. At least that's what happened when I overfilled mine.
Now that the level is correct I smell no gear oil at all.
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11-22-2009, 08:45 PM
#8
Thanks for the advice, guys. After fixing the breather tube issue, I wiped everything down, then drove the car HARD all last night and parked it in the garage. I went out there tonight to check under it and there's not one drop of fluid on the floor or dripping from the rear, so it almost looks like maybe it was fluid traveling down from the breather tube that made it look like the gasket was the issue. I'll keep an eye on it but it looks like I may have been barking up the wrong tree with the gasket.
11-14-2011, 07:40 PM
#12
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I have to bring this back from the dead, I have a moser 12 bolt thats leaking, I am in the process of changing my gasket on my 12 bolt and before i opened the rear I decided to hold the gasket up the the rear to make sure its right. It seems like my gasket is alot smaller then my rear in the car. My bolt holes measure from very top hole straight down to bottom hole is about 10 1/4". The Gasket 12 bolt I bought at Discount Auto measures 9 1/2". So it seems to be off 3/4". Any ideas??
