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The community here at 355nation.net urges you to please use caution and seek professional assistance when performing modifications to your vehicle. Before attempting any modification it is advised that you refer to your Colorado or Canyon service manual or contact a certified mechanic as not all GMT355 trucks are the same. The staff and the associated members are in no way responsible for any damages, injuries or other harm inflicted to your vehicle or yourself which may result in attempting these modifications. The posts and content presented on this site reflect in no way the views of 355nation.net or it’s ownership.




A 355nation How To presented by
burn

Project Description
Changing your own rear differential fluid

Skill Level
easy

Project Vehicle
Make: Chevrolet
Model: Colorado
Year: 2006
Engine: 3.5L
Transmission: Auto
Power windows: No
Sun Roof: No

Note: The V8 Colorado's have a AAM860 rear differential... here is the procedure:
http://www.355nation.net/forum/how-performance-maintenance/18190-how-change-your-rear-dif-fluid-4.html#post2463562


I started by picking up 2 quarts of Amsoil 75w-90 severe gear oil, along with some RTV & a pump since I was not sure what to expect.



Since GM are cheap a$$-hats and dont include drain plugs, you have to pull the dif cover off. Heres a pic with the rear cover off:



The old oil was a murky-black and looked like crap. I only have 75,0000km on my truck - and GM says that under normal conditions the fluid is good to 160,000km but there is no way! It looked past-due! Anyways - Turns out the gasket is rubber reinforced steel - so I wont need any RTV sealant with it:




Then I cleaned up the dif cover. Fortunately there was not any metal shavings on the magnet:




NOTE: The gasket looks symmetrical - but its not. It actually fits when its "wrong" and you can get about 6-7 of the bolts in, but the other 3-4 are off by like 1/8". I figured that by the way things were going that there must be a problem so I took it off and had a good careful look and noticed a tiny deviation in one of the corners of the gasket. I got the gasket straightened out, and installed with the cover. Torqued all the bolts to 20 ft-lb and put a dab of red loc-tite on each bolt.

NOW the real fun begins! Take out the fill plug,get a funnel with a flexible spout and put it in the fill hole. carefully & slowly pour the fluid in.
 

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Discussion Starter #3
yes, sorry I just copied everything over from CF and some of these threads (including this one) are pretty old. My server crapped a few weeks ago and I have been gradually restoring pics as I find whats missing. I will try to get these back up tonight.
 

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Discussion Starter #4
pics fixed
 

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CHEEZEDOODLE
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did you use all of both bottles of fluid in the diff?

wheres the fill plug? how does it come out?

did you have to jack the truck up to get the pumpkin far enough from the bed to fill it?

did you feel or hear a difference after the fluid change?
 

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Going Deaf
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ya apparently you have to vacuum it out, the people at oil exchange told me to do it between 60,000 - 75,000 miles... but the more people i talk to say its a waste of money...?
 

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YOU DO NOT HAVE TO VACUUM IT OUT.


Just pop the cover. The fill plug for the rear diff is on the front ( driveshaft side ) of the differential, above the axle line, on the passenger side of the driveshaft. The rear does not require a full two bottles.
 

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I just did this at my last oil change and it was over 400 dollars. Each diff was 110, transfer case was 90, oil change was 60. It says they used 3 quarts in the back and 2 in the front, I think they are quarts, it doesn't actually say. I was at 80k km and they told me it needed to be done, I saw it and it was pretty nasty.
 

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Discussion Starter #12 (Edited)
did you use all of both bottles of fluid in the diff?

wheres the fill plug? how does it come out?

did you have to jack the truck up to get the pumpkin far enough from the bed to fill it?

did you feel or hear a difference after the fluid change?

Sorry, this was never intentionally to be a how-to, it just evolved into one. I answered most of these questions on CF - they just never made the copy when I put the info here.

The rear holds 3.4 - 3.6qt. The bottles are 2qt each so you do not use all of it. I just removed 0.3qt from one of the bottles before I started.

the fill plug is on the passanger side of the dif, just above the middle. It has a square hole in it - just stick the end of a 3/8" extension into the hole - you dont use a socket to remove it.

I put the front up on ramps then jacked the rear from teh frame. Originally I lifted from the axle but coudlnt get to the dif. lifting by the frame allows the axle to hang down.

yes, I felt a difference, and it quieted it down quite a bit.
 

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Code:
Manual Transmission, 2WD..........5.1 pints
Manual Transmission, 4WD..........5.3 pints
Differential,  Front..........3.2 pints
Differential,  Rear..........3.4 pints
Transfer Case,Isuzu T150..........2.7 pints
 

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do we need any friction modifier if we have a g80. i have a 94 explorer with a lsd and its a must so i just want to clear that up if we need it.
 

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Only LSDs need friction modifier. And not all of them.

The G80 does not need anything besides the proper lube.
 

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CHEEZEDOODLE
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if yall dont start talkin english im gonna go apeshit in this motherfucker!!!!!!!!

dhua, the g80 is a pumpkin with a locker.

lsd?

friction modifyer?
 

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Limited Slip Differentials sometimes need a friction modifier fluid. We don't. End of story.
 
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