Getting ready to open up the rear end.
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
Getting ready to open up the rear end. I was told a 1994 Z28 has no drain plug for the rear end. I have never had the fun of seeing what is in there. But I do know it is time to change the gear lube. Can you all give me a clue on what I am getting into. What I am looken for and how to find out what has been done in there if anything. I have found a few surprizes working on my new project car/ DD.
yeah they don't have a drain plug so you have to remove the diff cover to drain then fill through the side of the diff. Make sure to get a new gasket and a little bit of RTV goes a long way 
When you take it off i always leave one bolt in loose at the top then pop the bottom off with a screw driver so it wont go everywhere. If you think it might have gear turn the drive shaft and count how many times it takes for the ring gear to make one full revolution. As JB said above get a new gasket and i usually put a few miles on it and then recheck the bolts because the gasket tends to shrink
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
Ok I can do that it sounds easy. How do I tell if gears have been changed? What do I look for when looking for wear, and how do I know what kind of gears are in there.
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
When you take it off i always leave one bolt in loose at the top then pop the bottom off with a screw driver so it wont go everywhere. If you think it might have gear turn the drive shaft and count how many times it takes for the ring gear to make one full revolution. As JB said above get a new gasket and i usually put a few miles on it and then recheck the bolts because the gasket tends to shrink
that will determine what gears are in there. Hence 3.23:1 is a ratio of how many times the pinion spins compared to one revolution of the ring gear. So if you have 3.73 gears it will take 3 and 3/4 turns of the driveshaft to make the ring gear revolve once.
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Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
Ok that sounds simple thanks bigj2717 and JB_97ws6TA. Now how do I tell if there is a lot of wear and tear in there?
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Verdad Gallardo chunks haha a lot of metallic contamination in the gear lube, look the gears over real good looking for wear such as knife edging or barreling. If you wanted to get crazy you can check backlash and but chances are if the are not making noise or giving you any grief a simple fluid change should suffice, don't forget the limited slip additive.
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
chunks haha a lot of metallic contamination in the gear lube, look the gears over real good looking for wear such as knife edging or barreling. If you wanted to get crazy you can check backlash and but chances are if the are not making noise or giving you any grief a simple fluid change should suffice, don't forget the limited slip additive.
All these cars need limited slip additive. If the fluid say it already has it, which some synthetics like royal purple have, then you don't need it. If it doesn't say make sure you add it or else you will be replacing the rear end.
you dont need a gasket just use rtv thats what we use at the dealer. and to check what gear ratio you have it is usually stamped on the ring gear, if not count the teeth on the ring gear and the pinion gear and divide the two and you will get your gear ratio.
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
Oh ok got ya. I thought limited slip an posi were types of rear ends.
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
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From: Winter Haven, Florida
Thats a good one two I will look into that also. Thanks
Yeah they are but there require a friction modifier to be add to the fluid and that if what the limited slip additive is its a small tube of fluid that you add to your regular rear end fluid
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
Likes: 0
From: Winter Haven, Florida
Thread Starter
Launching!
Joined: Jan 2010
Posts: 281
Likes: 0
From: Winter Haven, Florida
Just want to do it right the first time and make sure I under stand thats all. And find out what I have. The guy I bought it from gave no info on the car.