G80 Test Procedure
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G80 Test Procedure - 12/18/2007 9:03:06 AM
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jcheil
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How can I test if my G80 is "working as designed".
I got hung up the other day (frame hung, see-saw) and I swear I only had one-wheel wonder action going on out back.
Thanks,
Jay
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RE: G80 Test Procedure - 12/18/2007 10:39:53 AM
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rriddle3
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It's not a locker and if I remember correctly the design of it makes it work kind of like a variable limited slip. Unless one tire is sensed as slipping, the other tire won't lock in. I believe it was designed to keep your rear end from coming loose and sending you sideways on things like a gravel road (which I had happen to me once with a true limited-slip axle.)
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RE: G80 Test Procedure - 12/18/2007 12:09:56 PM
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swartlkk
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Correction, it is a locker. It is a gov-loc assembly that is used. It will act somewhat like a light limited slip under normal conditions and once one slip on one wheel is sensed, it will lock the diff up, turning both wheels. This may result in the back end getting loose, but is to be expected with anything but an open diff.
As far as testing goes... That is a tough one. Given that there must first be a speed differential between the two wheels, it presents a problem for testing. While you are out and about, try getting onto a loose surface and just mash it in 2wd. See if one wheel spins or two...
< Message edited by swartlkk -- 12/19/2007 12:15:24 PM >
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RE: G80 Test Procedure - 12/18/2007 1:14:50 PM
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rriddle3
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quote:
ORIGINAL: swartlkk
Correction, it is a locker. It is a gov-loc assembly that is used. It will act somewhat like a light limited slip under normal conditions and once one slip on one wheel is sensed, it will lock the diff up, turning both wheels.
I dunno, I've grown up calling an axle that turns both wheels at the same time, all the time, a locker, activated either manually, electrically, or by pneumatics. GM can call the G80 what it wants to, but to me it's a form of limited-slip axle.
Just found this short article on this subject:
http://www.4x4abc.com/4WD101/locking.html
< Message edited by rriddle3 -- 12/18/2007 1:20:39 PM >
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RE: G80 Test Procedure - 12/18/2007 1:28:59 PM
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swartlkk
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From the link above:
quote:
Now here is a twist to the locking differential story: When Chevy advertises its trucks with an optional rear locking differential - it indeed is a differential that locks up (automatically). In the 80's it was sold as a Gov-Lok for a while named Command-Traxx and is available in some Chevy trucks as G80 option. It is not manually activated as in Dodge, Jeep and Mercedes - it locks up automatically. It is a hybrid of a clutch type limited slip unit combined with a flyweight governor that is able to lock up 100%.
< Message edited by swartlkk -- 12/18/2007 1:32:11 PM >
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RE: G80 Test Procedure - 12/18/2007 1:35:59 PM
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rriddle3
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quote:
ORIGINAL: swartlkk
From the link above:
quote:
Now here is a twist to the locking differential story: When Chevy advertises its trucks with an optional rear locking differential - it indeed is a differential that locks up (automatically). In the 80's it was sold as a Gov-Lok for a while named Command-Traxx and is available in some Chevy trucks as G80 option. It is not manually activated as in Dodge, Jeep and Mercedes - it locks up automatically. It is a hybrid of a clutch type limited slip unit combined with a flyweight governor that is able to lock up 100%.
Yeah, I read that. It's the last line that counts. Even a limited-slip 'locks' up at some point. I'm still gonna call our's a limited-slip.
I know, I'm just hard-headed.
< Message edited by rriddle3 -- 12/18/2007 1:40:09 PM >
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RE: G80 Test Procedure - 12/18/2007 1:38:06 PM
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swartlkk
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The difference as I see it is even if a limited slip will 'lock-up' at some point, it will not lock as soon as the automatic locker that the G80 is. Weakness aside, the G80 is the best of both worlds, limited slip around town so you don't wear your tires out prematurely and a locker when things get messy.
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RE: G80 Test Procedure - 12/18/2007 1:40:45 PM
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rriddle3
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Awright, now we're gettin' closer! I love common ground.
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RE: G80 Test Procedure - 12/18/2007 5:19:58 PM
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drperry
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The G80 is supposed to lock up at something like a 200RPM difference...
The G80 in the new style GM pickups works MUCH better...
I'm not a fan of the G80 in my Blazer... it might as well be an open diff, for how often it locks, lol.
There's a Volvo board somewhere, where the guys are modding their G80's for full lock 100% of the time... Which means you can probably get the G80 to lock earlier...
< Message edited by drperry -- 12/18/2007 5:23:44 PM >
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RE: G80 Test Procedure - 12/18/2007 5:38:47 PM
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jcheil
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quote:
ORIGINAL: drperry
I'm not a fan of the G80 in my Blazer... it might as well be an open diff, for how often it locks, lol.
There's a Volvo board somewhere, where the guys are modding their G80's for full lock 100% of the time... Which means you can probably get the G80 to lock earlier...
Thanks for all the great info. Here is my full problem:
I opened the diff about 2 months ago to change the fluid and by luck, the carrier was in a position in that it only showed the spider gear side of the carrier, not the "locking" side (you will know what I am talking about if you have ever opened up a G80). In any event, again, at that time I did not know it was a G80 (nor did I even know what a G80 was - I just saw spider gears ans said "open") ... so I bought a mini-spool to put in (I am ONLY 100% off-road use). Now, I am wondering:
1) Can I still put the mini-spool in and just remove the guts of the "locker assy"?
2) Does anyone know how to mod the existing G80 for full time locking or should I just look to swap the axle for an open and put the mini-spool in?
Thanks,
Jay
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RE: G80 Test Procedure - 12/18/2007 5:45:00 PM
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swartlkk
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I'm not sure if you are going to like a mini spool... Even lockers unlock for turns. You could buy an open carrier and install a 'lunchbox locker' which just fits inside of the standard open carrier. This would allow you a diff that would ratchet when necessary to allow the wheels to turn at different speeds but lock when under power.
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RE: G80 Test Procedure - 12/18/2007 6:05:36 PM
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drperry
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quote:
ORIGINAL: jcheil
quote:
ORIGINAL: drperry
I'm not a fan of the G80 in my Blazer... it might as well be an open diff, for how often it locks, lol.
There's a Volvo board somewhere, where the guys are modding their G80's for full lock 100% of the time... Which means you can probably get the G80 to lock earlier...
Thanks for all the great info. Here is my full problem:
I opened the diff about 2 months ago to change the fluid and by luck, the carrier was in a position in that it only showed the spider gear side of the carrier, not the "locking" side (you will know what I am talking about if you have ever opened up a G80). In any event, again, at that time I did not know it was a G80 (nor did I even know what a G80 was - I just saw spider gears ans said "open") ... so I bought a mini-spool to put in (I am ONLY 100% off-road use). Now, I am wondering:
1) Can I still put the mini-spool in and just remove the guts of the "locker assy"?
2) Does anyone know how to mod the existing G80 for full time locking or should I just look to swap the axle for an open and put the mini-spool in?
Thanks,
Jay
To full time lock the G80, you've gotta fiddle with the springs that control the locking... You can probably find more info if you search the web...
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RE: G80 Test Procedure - 12/18/2007 6:18:50 PM
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jcheil
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OK, I found some info:
This vid shows how the G80 works...now I understand
http://www.youtube.com/watch?v=KbMZ9vcYVSg&NR=1
This thread talks about modding the weights because the diff will not normally lock above 20mph.
http://forums.turbobricks.com/archive/index.php/t-25829.html
(it even has full step-by-step pictures)
But honestly, this thing is used 100% off road so I am OK with the spool. It is always in the swamp.
I guess I would just like an opinion or 2 - try to install the mini-spool (if it can it be done on a G80) or try the mod they were talking about?
-- also, if anyone is familiar with this mod they are talking about is there any reason you could not just simply REMOVE the weight rather than making it smaller. It would seem that by removing it then it would allow locking at all speeds.
Thoughts anyone?
< Message edited by jcheil -- 12/18/2007 6:45:16 PM >
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RE: G80 Test Procedure - 12/19/2007 5:37:45 AM
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drperry
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For anything other than a straight line drag strip, you do NOT want a fully locked differential... It wears out tires faster, and there's control issues in slippery conditions at highway speeds...
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RE: G80 Test Procedure - 12/19/2007 11:19:15 AM
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jcheil
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Like I said before, 100% off-road.
In any event, I have spent 6 hours reading everything possible on the internet to come to the conclusion that there is nothing I can do with the G80 other than the volvo mod and the problem with that is that my axel is 18 years old and the clutches are surely work out. The carrier won't even accept the mini-spool.
Therefore, I am bringing my axle to Modifications Unlimited (West Palm, FL) tomorrow and they have an old non-G80 carrier they are gonna replace with mine and install the mini-spool that I bought that would not go in the original G80 carrier.
So in the end, I will still get my mini-spool installed ($100) and also learned WAY MORE than I wanted to know about lockers, etc.
Thanks for all the help everyone!
Jay
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RE: G80 Test Procedure - 12/19/2007 2:21:05 PM
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drperry
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Most aftermarket diffs, don't fit into the G80 carrier...
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RE: G80 Test Procedure - 12/20/2007 8:22:19 AM
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jcheil
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quote:
ORIGINAL: jcheil
-- also, if anyone is familiar with this mod they are talking about is there any reason you could not just simply REMOVE the weight rather than making it smaller. It would seem that by removing it then it would allow locking at all speeds.
Thoughts anyone?
Ok, after more investigations, answered my own question, you cannot remove that piece because that is the piece that slides over and locks the clutch plates together -- so removing the weighted part of that piece is the only option.
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