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How-To: Bleed/Fill rear differential and hydraulic system service + specs
The following How-To covers the explanation of the Rear Differential Bleed/Fill and Hydraulic System Service and includes specifications, schematics, etc.
These How-To guides are neither endorsed by or property of Corvette Forum or myself in any way/shape/form. All liability stemming from any actions taken in relation to these guides is solely placed upon the user.
I'll admit I'm a bit confused - I have a '15 Z51 that I'll need to change the differential fluid at the end of the year since I track the car. I'm assuming that's just the first part and not the Rear Diff Service Bleed, right? Also, what exact fluid should I be using to refill? Just the DEXRON LS Gear Oil or the DEXRON VI (as it has an eLSD)?
I'll admit I'm a bit confused - I have a '15 Z51 that I'll need to change the differential fluid at the end of the year since I track the car. I'm assuming that's just the first part and not the Rear Diff Service Bleed, right? Also, what exact fluid should I be using to refill? Just the DEXRON LS Gear Oil or the DEXRON VI (as it has an eLSD)?
You can follow the Differential Oil Replacement doc from the second post - that's the change you're referring to.
Did mine for the first time a week ago, and wondering why I didn't do it sooner. Aside from being completely contaminated with (large) chunks of metal, it has cleared up a few issues (and not in a placebo sense).
I used Royal Purple Max Gear 75W90 fluid on the recommendation of a few members here. I can't give any sort of endorsement, nor would I want to with the fluid arguments everyone has here. I'm satisfied with that fluid's performance, though.
The factory fill is, from post 4, Dexron LS Gear Oil. Three quarts and a hand pump (I use a cheap 4cc pump from Amazon) will work great. Just combine the extra from each bottle at the end, and it will take right at 3qt.
Theta, do you know the tool you need to open the two plugs? Also, how do do get to the fill plug (pictured)? Just looking at it, I don't see how to get a wrench up there, much less a torque wrench.
I just had the dealer drain and fill mine for the new HPDE track season. It wasn't too expensive and I don't think I could have done it without tearing something up, probably including my hands. The $$ are definitely worth the savings in hassle, IMHO.
Theta, is there any way to bleed the elsd without the engine running? I just installed a new diff and don't have the engine running yet- that's another long story with me trying to program the modules with this global A architecture. Anyways, it would be easier to do without the exhaust on the car.
Theta, is there any way to bleed the elsd without the engine running? I just installed a new diff and don't have the engine running yet- that's another long story with me trying to program the modules with this global A architecture. Anyways, it would be easier to do without the exhaust on the car.
Theta has been worryingly absent since early September 2015. Given his medical issues mentioned at times, I do hope he replies some day.
I am obviously not Theta but I drained and filled my 15 Z51 with new GM LS gear oil after a couple thousand miles and a few track days and it can be done with a socket wrench and flex extension. The plugs are just a square fitting on a 1/2" extension. You gotta work at it to get access. There may be a fancy tool for it but I did not need it. My fluid had just real fine grit that was normal for a rear axle just breaking in. I've seen a few in my day. Most of the grit was on the magenetic plug.
[QUOTE=Jedi-Jurist;1591715707]Theta, do you know the tool you need to open the two plugs? Also, how do do get to the fill plug (pictured)? Just looking at it, I don't see how to get a wrench up there, much less a torque wrench.
Theta, do you know the tool you need to open the two plugs? Also, how do do get to the fill plug (pictured)? Just looking at it, I don't see how to get a wrench up there, much less a torque wrench.
A flex-head 3/8" drive ratchet works perfectly. I did my differential and transmission fluids yesterday and completed the entire project in about 2 hours including set-up and clean-up. I plan to type up a DIY thread on it later today.
Theta, do you know the tool you need to open the two plugs? Also, how do do get to the fill plug (pictured)? Just looking at it, I don't see how to get a wrench up there, much less a torque wrench.
Thanks!
So after doing the change with Royal Purple, I get a knock from the diff when starting out (forward or reverse). I was told I need to add "Positraction Lubricant Additive." Can anyone confirm? How much do I need?
Last edited by Jedi-Jurist; 05-26-2016 at 10:14 PM.
Man thanks for all of your help in here on how to do stuff. I did this job a few months back just put the car on the 4 post and wasn't bad at all. Robert
So after doing the change with Royal Purple, I get a knock from the diff when starting out (forward or reverse). I was told I need to add "Positraction Lubricant Additive." Can anyone confirm? How much do I need?
I used Redline Gear lube. I didn't have to add anything, no issues here.
06-15-2014, 01:56 AM
How-To: Bleed/Fill rear differential and hydraulic system service + specs
