Thanks, this is my first corvette and this forum has been great in assiting me
75 Corvette Diff. Service
Thread Starter
Instructor
Joined: Mar 2013
Posts: 126
Likes: 2
St. Jude Donor '14
75 Corvette Diff. Service
How difficult is to change the diffential fluid and add the the additive? I read that to remove passenger tire and suck fluid out. I was going to use the Trans-X brand additive, any feed back on that? My car has sat for almost 9 years and I have just got in on the road and this is the last thing I need to do. Power Steering Control Valve changed, new crate 5.7L vortec engine 96-00, transmission TH40 serviced modulator and governor replaced along with fluid change, new exhaust, edelbrock 1406 carb, aluminum radiator and electric fans. Thanks in advance for your help
Drifting
Joined: May 2012
Posts: 1,353
Likes: 44
From: Calgary Alberta
There's no need to pull wheels off for this one, just need a syringe or similar to suck out the old fluid and put new stuff back in.
Just go to your local GM dealer and get a couple of bottles of 75-90 synthetic gear lube and a tube of GM posi additive.
Just go to your local GM dealer and get a couple of bottles of 75-90 synthetic gear lube and a tube of GM posi additive.
Burning Brakes
Joined: Apr 2013
Posts: 926
Likes: 2
From: Castle Rock CO
Thanks for the information on which weight fluids to use. Instead of starting a new thread asking the same question I read this one.
I have a pump for changing Gear and Manual Tranny fluid that I purchased at the local auto parts store for another car. Works great for refilling the fuilds and fits right on the Gear Oil Bottle. Than you just pump it in till it is full on the top Filler.
My question was also on draining the old Diff Fluid out and it was answered. Thinking I can use this same pump to drain it out since I do not see a drain plug anywhere.
I generally use Valvoline Syn Power 75W-90 Synthetic Gear Oil on my other car for the rear diff and Manual Transmissions.
I have a pump for changing Gear and Manual Tranny fluid that I purchased at the local auto parts store for another car. Works great for refilling the fuilds and fits right on the Gear Oil Bottle. Than you just pump it in till it is full on the top Filler.
My question was also on draining the old Diff Fluid out and it was answered. Thinking I can use this same pump to drain it out since I do not see a drain plug anywhere.
I generally use Valvoline Syn Power 75W-90 Synthetic Gear Oil on my other car for the rear diff and Manual Transmissions.
Last edited by MakoJoe; May 21, 2013 at 09:59 PM.
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Safety Car
Joined: Mar 2005
Posts: 4,255
Likes: 82
From: Brampton Ont.
Will 2 Qt of the Mobile One Synthetic 75-90 Limited Slip and one GM posi additive fill a bone dry 75' differential?
EDIT;
Is this the GM Additive?
Genuine GM Fluid 88900330 Limited Slip Axle Lubricant Additive - 4 oz.
EDIT;
Is this the GM Additive?
Genuine GM Fluid 88900330 Limited Slip Axle Lubricant Additive - 4 oz.
Last edited by Maymyvetteliveforevr; May 21, 2013 at 10:17 PM.
Burning Brakes
Joined: Apr 2013
Posts: 926
Likes: 2
From: Castle Rock CO
One of the reasons I use Valvoline is
Detailed Description
Valvoline SynPower Gear Oil is a full synthetic, thermally stable, extreme-pressure gear lubricant designed to operate and protect in both high and low extreme-temperature conditions. SynPower Gear Oil is specially recommended for limited-slip hypoid differentials.
•Contains additives to assist in protecting gear teeth
•Maintains excellent low temperature fluid protection down to -50°F (-46°C)
•Provides outstanding thermal stability for cleanliness and longer service life
•Contains special additives to reduce chattering in limited-slip differentials
•Recommended for (conventional and limited slip) manual transmissions where an API GL-5 or MT-1 fluid is specified
•Protects parts from rust and corrosion
•Compatible with conventional gear lubricants
Detailed Description
Valvoline SynPower Gear Oil is a full synthetic, thermally stable, extreme-pressure gear lubricant designed to operate and protect in both high and low extreme-temperature conditions. SynPower Gear Oil is specially recommended for limited-slip hypoid differentials.
•Contains additives to assist in protecting gear teeth
•Maintains excellent low temperature fluid protection down to -50°F (-46°C)
•Provides outstanding thermal stability for cleanliness and longer service life
•Contains special additives to reduce chattering in limited-slip differentials
•Recommended for (conventional and limited slip) manual transmissions where an API GL-5 or MT-1 fluid is specified
•Protects parts from rust and corrosion
•Compatible with conventional gear lubricants
Thread Starter
Instructor
Joined: Mar 2013
Posts: 126
Likes: 2
St. Jude Donor '14
Diff
Can someone tell me where the plug is fill the diff, is it in the rear or on the side? I took off the rear passenger tire and saw a square plug about center is this it? Thanks for your help
Pro
Joined: Apr 2013
Posts: 749
Likes: 56
From: Northern VA
It's on the right side of the diff housing when facing the diff from the rear of the car. The drain plug is directly under the diff in the center. You don't need to remove the tire at all. Just make sure you have your car level when jacked. Both the fill plug and drain plug use the same size Allen socket. Easier to drain from the drain plug and leave no question that you got it all out IMHO. Make sure you remove the fill plug first. Would really suck to remove the fill plug then later find out you have a problem removing the fill plug. I just did my trans fluid and diff fluid today. I used AMSoil Torque Drive Synthetic trans fluid and their Severe Gear 75W-90 gear oil with a tube of their Slip Lock gear oil additive. The procedure was pretty simple and straight forward. Toque has a pretty well explained procedure he posted that I followed. http://www.toquez06.com/diff.html
Last edited by MAJ_Charlie; May 25, 2013 at 10:55 PM. Reason: Additional information
Burning Brakes
Joined: Apr 2013
Posts: 926
Likes: 2
From: Castle Rock CO
If you cannot fully lift the car in the air on a 2 post or 4 post lift the easiest way to get to it is to remove the passenger side right rear tire and reach in.
If you can use a lift then you can just reach up to it and remove the fill plug.
A Transfer Fuild pump like this works so much better then a turkey baster to fill the diff. I bought one of these for another car to fill my manual transmission and differential
http://www.oreillyauto.com/site/c/de...&keyword=pumps
Thanks guys I am going to look for the drain plug at the bottom of the differential but have not seen it yet.
Thread Starter
Instructor
Joined: Mar 2013
Posts: 126
Likes: 2
St. Jude Donor '14
My 1977 is on the passenger side and is the same for most early model year corvettes. Nice thing mine also has a red tag on the filler that states only use Limited Slip Fluid still on it from the factory.
If you cannot fully lift the car in the air on a 2 post or 4 post lift the easiest way to get to it is to remove the passenger side right rear tire and reach in.
If you can use a lift then you can just reach up to it and remove the fill plug.
A Transfer Fuild pump like this works so much better then a turkey baster to fill the diff. I bought one of these for another car to fill my manual transmission and differential
http://www.oreillyauto.com/site/c/de...&keyword=pumps
Thanks guys I am going to look for the drain plug at the bottom of the differential but have not seen it yet.
If you cannot fully lift the car in the air on a 2 post or 4 post lift the easiest way to get to it is to remove the passenger side right rear tire and reach in.
If you can use a lift then you can just reach up to it and remove the fill plug.
A Transfer Fuild pump like this works so much better then a turkey baster to fill the diff. I bought one of these for another car to fill my manual transmission and differential
http://www.oreillyauto.com/site/c/de...&keyword=pumps
Thanks guys I am going to look for the drain plug at the bottom of the differential but have not seen it yet.
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 113
From: Michigan
Anyways after sucking my old fluid out the best I could, I then just used the bottle the new lube comes in and proceeded to squeeze the heck out of it when it got low. Well I poured the bottles best I could then combined the leftovers, poured and then squeeze to heck.