GM Drivetrain & Suspension Chassis | Transmission| Driveshaft | Gears/Rear End/Differential | Traction Aids

went to the track last night g80 not working right

Old Jun 23, 2012 | 05:14 PM
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Default went to the track last night g80 not working right

Well I went to the track last night and I noticed that there is only rubber on my passenger side. I have been questioning if it was locking up because sometimes it would feel like its not and when I watch the tire it will lock in. When a G80 locks in does the driver side lock in 100%? The rear end has almost 200k on it so I wouldnt doubt it could be going out. If it is going out it worth rebuilding or how about them dura grip rear posi they seem like a good value how do they hold up?
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Old Jun 23, 2012 | 05:53 PM
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As far as I know the factory G80 is not re-buildable at all. As far as aftermarket carriers are concerned, I feel the intended use of your vehicle should dictate which is the most appropriate, with price being factored in as well. So many people automatically say the TruTrac and while I feel it’s a good unit, I also feel it works well for daily street use and instances where you would be applying power coming out of or through corners such as a road course or slalom event. I personally like the regular old Eaton LSD “clutch type posi” for street driven 4WD’s, where if you were to take it off road and one tire leaves the ground you still have traction being applied to the other wheel. I also like the regular Eaton LSD for moderate track duty, especially when upgraded to the 800lb springs and Kevlar clutch plates. There is good and bad with everything though, as the 800lb springs really are a little much for daily use and will cause the tires to want to stay locked going through corners on anything but dry pavement and will require more frequent oil changes to keep the clutches from locking up. The TruTrac can also be made to somewhat function in an offroad environment by applying the brake to allow the load to redistribute the torque bias. Once you get past what these two units can typically handle, you would really be looking at needing a locker of some sorts or spool. Of course with all of these units there is some overlap in capability and secondary options at a lower cost for units of similar function to each.

Last edited by 1Bear; Jun 24, 2012 at 02:01 PM.
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Old Jun 23, 2012 | 11:47 PM
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If you pop it past 30MPH the Gov-Lock (G80) rearend does not engage both tires. The only times it is supposed to lock up if if the drive input is going to average to less than 30mph or so. So if you start spinning instantly rather than rolling into the spin I'd say the G80 is doing what it's supposed to do to keep from blowing up.

Description and Operation
Locking Differential Description and Operation
The locking differential consists of the following components:

  • Differential carrier
  • Locking differential spider
  • 2 clutch discets
  • Locking differential side gear
  • Locking differential clutch disc guide
  • Differential side gear shim
  • Locking differential governor
  • Latching bracket
  • Cam plate The locking differential allows for normal differential function as indicated in the standard rear axle description. Additionally, the locking differential uses multi-disc clutch packs and a speed sensitive engagement mechanism that locks both wheels together if 1 wheel spins excessively during slow vehicle operation. Under light loads, the clutch plates alone tend to lock the axle shafts to the differential case, and therefore, locking each other. This is due primarily to the gear separating the load developed on the right clutch pack. This induced clutch torque capacity resists motion between the side gear and the axle differential case. The differential allows the wheels to turn at different speeds while the axle shafts continue to transmit the driving force. Heavier throttle application will cause an axle speed difference. This action starts the full-lock feature of the unit. You can accomplish full-lock through the use of a heavyweight governor mechanism, a cam system and a multi-disc pack. The flyweights on the governor mechanism move outward in order to engage a latching bracket whenever the wheel-to-wheel speed varies by approximately 100 RPM or more. This action retards a cam, which, in turn, compresses the multi-disc clutch packs locking both of the side gears to the case. The 100 RPM wheel-to-wheel speed allows for cornering with the differential lockup. At vehicle speeds above approximately 32 km/h (20 mph) , the latching bracket overcomes a spring preload and swings away from the flyweights. At this vehicle speed, or greater, the differential is designed not to lock since added traction is generally not needed. The axle parts of the vehicles equipped with the locking differential are interchangeable with those equipped with the conventional differential, except for the case assembly.
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Old Jun 24, 2012 | 10:43 AM
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When my G80 dissolved in my rear end case, it stopped locking and starting clicking and clucking a few days before it let go. I would be careful so it doesn't take out your ring and pinion.
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Old Jun 24, 2012 | 06:18 PM
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From: JunkYard
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I believe they can be partial rebuilt. I know for the 9.5 they offer new clutches the problem is there so expensive it's cheaper to buy a new one and if you have any hard parts that are damaged forget it...

The G80's work ok for what they are. But they were never designed to handle the abuse we put them through. Your best bet would be to open it up and check condition of everything else. You may get away just Replaceing whats needed but at 200,000 miles you might want to replace everything.

If that's not in the budget then look for the best condition replacement you can find.
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