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86-95 Trucks & 4Runners 2nd/3rd gen pickups, and 1st/2nd gen 4Runners with IFS

Junkyard 4.88 IFS front 3rd member checkup help

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Old Oct 24, 2010 | 05:26 PM
  #1  
hgill's Avatar
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From: San Jose, CA
Junkyard 4.88 IFS front 3rd member checkup help

So I was at the local Pick ' n' Pull today to pickup some 63" Chevy springs when I noticed a 94 Runner w/ Axle code G144 ... I got a lil greedy as I could really use some 4.88 Gears as opposed to stock 4.10. I already had 4.88 3rd member for the rear that I had bought on craigslist. So, I just had to pull the front IFS assembly so I have the full set.

So .. to cut to the point.. I got the front 4.88 IFS home .. how do I check if it is in good condition? I dont know how these things work yet. I know it has the factory "white" color code. im such a n00b..lol

Here is what I notice (using FSM terminology .. so dunt laugh):
#1 After disconnecting the CV Drive Shafts at the junkyard, there was a release of vacuum or hissing sound.
#2 If I turn the "Companion Flange", It causes the "RH Side Gear Shaft" to turn slightly, but its no synchronous. "LH Side Gear Shaft" does not move at all.
#3 "LH Side Gear Shaft" moves freely. No sounds .... smooth
#4 "RH Side Gear Shaft" is tricky, it makes a bearing sound when I turn it... its like Im turning a rough gear.

Here's the pictures ...




BTW, I dont have ADD, but rather Asin hubs! Also, I was pretty amazed at my self for pulling this thing off with just simple tools and a breaker bar .. its a *&^%^ PITA to take it out with no floorjack or other goodies as mentioned in the article: http://www.gearinstalls.com/ifs.htm

.. I was a total mechanical n00b before I joined YT ... but im glad im catching up. Thanks everyone :-) I also manned to get the chevy leaf springs from a 94 chevy 1/2 ton ... What a crazy day .. reminder to self: bring a buddy along coz you never know what you will find at the junkyard .. also holla at me if your in the bay area n need a second hand
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Old Oct 24, 2010 | 05:47 PM
  #2  
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Nothing you've stated sounds out of the ordinary. The hissing sound isn't something that I've heard before while removing cv's from a front axle, but it wouldn't be any cause for alarm IMO. It seems possible to me that the air caught between the side gear shaft/stubshaft flanges and the inner cv assemblies was not equal to atmospheric in pressure when they were removed. That hissing would then be attributed to the sudden pressure equalization within that small cavity between them.

Everything else sounds like normal operation for an ADD front axle. Remember the driver's side stubshaft isn't connected to the side gear, or therefor the rest of the differential assembly, without vacuum applied to the actuator. So it's not supposed to move relative to anything else unless it is. The sound heard while turning the pass. side stubshaft is just the sound of the side gears engaging the spider gears, and is perfectly normal.

To gauge the condition of the internal components with any certainty would require tearing it apart and inspecting it further. Other than having a general idea, felt by hand when turning the companion flange back and forth, for how much ring gear backlash is acceptable. Which, if you've not had enough experience doing so with these differential assemblies, would be near impossible. And isn't something that can be verbally explained in sufficient detail as to be a safe procedure. I've done it many times, so have some idea what I'm looking for when I do an initial inspection of a 3rd member/differential.

BTW, it's not really important, but generally speaking the right and left hand sides of the vehicle and it's components are described as seen from the front of the vehicle. So you have that backwards. I was able to make those distinctions, based on your description of them and knowing which is actually which, even before you added the captions to the top photo(which are technically incorrect). You'll notice how I used the terms "driver's side" and "pass. side" so as to not further the misunderstanding. Driver's side = Right hand side, Passenger's side = Left hand side. So it may not be such a bad idea to keep that in mind for the future. It'll take some confusion out of understanding how automotive terminology is used to describe the various parts and components of a vehicle, and the vehicle as a whole.

Last edited by MudHippy; Oct 24, 2010 at 06:42 PM.
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Old Oct 24, 2010 | 06:15 PM
  #3  
hgill's Avatar
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From: San Jose, CA
Thanks for your input MudHippy ... I feel much relaxed about my investment now... Now to think about it ... the vacuum sound might have been from the ADD actuator because it started when I removed the passenger stubshaft.. but im not entirely sure.

Last edited by hgill; Oct 24, 2010 at 06:16 PM.
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Old Oct 24, 2010 | 10:06 PM
  #4  
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From: Penn Valley, CA
hissing...

I've heard it too! It was the CV boot pushing air past the seal on the shaft when I was yanking on it.

As for ADD, you can disable it (take off front cover, engage the shaft, and use a hose clamp to keep it that way) or just swap long-side axles with your current setup. The only real trick is getting the axle shaft out of the center!

Good luck!
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