rear axle locking up and popping

[lowrodderchev]

so my new daily driver slash toy is broken couples weeks back in the mountains was backing up and it kept locking up then a hard pop from the center cap wheel cover. we checked it out and everything seem fine. today i'm pulling into work and i hear it again and as i'm turning into a parking space the rear drivers wheel sounded like it was starting to drag then break loose and that loud pop happen again in the wheel cover. this is something new to me i put new u joints after the mountain incedent any ideas what it might be better yet how expensive its gonna be thanx guys

[68Timber]

It sounds like busted spider gears.

[lowrodderchev]

that sounds expensive, easy to do?

[68Timber]

I really don't know, I haven't replaced them before. I can't set up a ring and pinion, I always pay to have it done.

[lowrodderchev]

off the top of your head bruiser do you remember what it cost. sorry for all the dumb questions just need to know what i'm in for thanx

[Berg]

Off the top of your head do you know if it has a G-80 Gov-loc? I'm They are known to fail more often than not. If it is an open differential you could change the spider gears yourself. If the case isn't damaged it will cost you around $100 to do yourself and it gives you a chance to clean out the old gear oil, inspect the axle seals and refill the housing with fresh lube. What is the make and model of the truck? They are most likely C-clip axles. There will be no press or special setup tools needed. Make sure you get out all the broken chunks and shavings if there are any! If you have anything magnetic it works to take out the broken pieces. You may also want to think about upgrading from an open rear to a Lock-Right or Powertrax or something along those lines that fits into the stock carrier. )

[lowrodderchev]

No I don't its a 75 blazer 12 bolt rear end she's been good to since I bought her in January moneys tight im trying to finish my 57 Chevy truck I'm hoping she'll get me home and next week I'll pull the diff cover and check it out

[lowrodderchev]

ok well found a guy who has the front and rear axles for my truck with warner hubs new drag link and what not he updated his stuff and is selling them for $400 for both. i still havent looked in rear axle yet but it sounds pretty bad. loud pop from the drivers side wheel anything i should look for if i go for the used axles? metal shavings i know loose axles i want to rebuild mine but dont want to mess it up worst than it is and i priced possible parts i need and its looking around $300 sometimes cheaper aint better but in this case i need to figure something out

[tobiahr]

you can check the rear axle without opening it up by simply jacking the truck up and pulling on the wheels. there should be very little play when pulling the wheel away from the truck (side to side) probably less than 1/8 inch if that much. if there is more than that the c clips or spider gears have been damaged and will have to be replaced. if you have any movement up and down the outer bearing is usually the issue and can usually be replaced for under 100$. My s10 blazer just had the bushings under the spider gears fail and i found it was cheaper to get a complete axle from a salvage yard. paid 125$ from the local pick and pull plus about 50 $ for a new pinion seal, cover seal and differential oil.

[lowrodderchev]

woke up early before work and pulled the diff cover. everything looks good no metal shavings but it had some real muddy oil in it REAL MUDDY!!! i put it in gear turn the wheels and evrything seemed ok

[lowrodderchev]

the oil had alot of brown bubbles in it ive never seen that before. no play in the wheels but my bro reminded me when i put new tires on months ago the guy at the tire shop couldnt balance that wheel he said it was bend could that have caused some damage i know i should have fixed it sooner but time slipped away

[68Timber]

That looks like a G80 factory locker. I'd clean it up and try some fresh oil if everything looks OK. What is the source of the contamination?

[lowrodderchev]

when i first bought the truck the rubber breather line that goes up to the frame was ripped so i replaced it but didnt put new fluid. would that cause it to lock the rear like that? i can pull a motor apart weld a frame strip paint from a body fab parts but i'm new to rear axles so again i'm sorry for all the questions guys

[tobiahr]

the contamination looks like water in the oil. did you go through deep water recently? with the g80 lockers they will sometimes pop when cornering under hard acceleration. i've had them pop more often when the oil got contaminated ( bad axle seals, driving in river) so that may be the entire issue. make sure you get locker additive or gear oil with it already in it or you can damage the locker even more.

[lowrodderchev]

No deep water maybe from previous owner I got it in January im gonna add fluid and try it out hopefully its ok thanx guys

[68Timber]

Posi lube should never be used with the G80. There is a GM TSB on this:

LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109
SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)
VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS
Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.
This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.
To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 10950849).

The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

VEHICLES/COMPONENTS INVOLVED: ------------------------- ---- Some light duty trucks equipped with locking rear axles, RPO G80.
SERVICE PARTS INFORMATION:
Part Number Description ----------- ------------------ 10950849 Lubricant, Rear Axle (1 litre)
Parts are currently available through CANSPO.
WARRANTY INFORMATION:
As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
© Copyright General Motors Corporation. All Rights Reserved.

[lowrodderchev]

I'm crossing my fingers hoping its the oil

[Berg]

yeah best to get some brake cleaner and get all that contamination and crap out of there. Some fresh gear oil and you will be back in business. The G80 has centrifugal weights which engage the clutches so maybe the weights are getting stuck out which will keep it locked.

[lowrodderchev]

excuse me for opening up this book but this morning i went to the local 4 wheel drive place and he told me 85/90 oil with limited slip additive. i know a few people say yes some say no. keep in mind this is a 1975 axle. im not sure if that makes adifference to the new ones

[68Timber]

Get regular dino 80/90 gear oil. No lsd additive. The G80 is a locker, not a limited slip.

[motornut]

sounds like good info to remember thanks bruiser, thought about changing my rear oil,my 79 has the 3.4 ratio 1G80 locker ,tested on the weekend ,no noise

I had my 88 Pro rebuilt for about $1200. offset berrings,bunch of new stuff 2 days on the hoist,no worries,no regrets,still solid

[lowrodderchev]

So just got done scraping the old gasket and thought I would check the gears again so started spinning the wheel real fast then bam the wheel stop it self and bounce back is that correct? Or all bad

[motornut]

Originally Posted by lowrodderchev

So just got done scraping the old gasket and thought I would check the gears again so started spinning the wheel real fast then bam the wheel stop it self and bounce back is that correct? Or all bad

in park?how many turns parking pawl/pinlocking in?

[lowrodderchev]

In drive diff cover off

[Berg]

The locking action is correct. When there is a difference of a few mph between the drivers side axle and the passengers side axle the weights will fly out and lock the spiders. Use 80-90 GL5 rating gear oil. As far as the additive, GM says no. The following is a General Motors Corporation Technical Service Bulletin (TSB) for the G80 Gov Loc:
LOCKING DIFFERENTIAL LUBRICANT (SERVICE INFORMATION) #91-4-109
SUBJECT: LOCKING DIFFERENTIAL (G80) LUBRICANT - (SERVICE INFORMATION)
VEHICLES AFFECTED: ALL LIGHT TRUCKS EQUIPPED WITH G80 REAR AXLE ALL YEARS
Some light duty trucks equipped with locking rear axles (G80) may exhibit rear axle chatter, especially when turning a corner from a stop.
This condition of alternate engagement and disengagement of clutches in differential assembly is usually caused by contaminated axle lubricant.
To correct this condition, drain and refill the rear axle with SAE 80W-90 GL5 (P/N 10950849).

The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

VEHICLES/COMPONENTS INVOLVED: ------------------------- ---- Some light duty trucks equipped with locking rear axles, RPO G80.
SERVICE PARTS INFORMATION:
Part Number Description ----------- ------------------ 10950849 Lubricant, Rear Axle (1 litre)
Parts are currently available through CANSPO.
WARRANTY INFORMATION:
As specified in Light Duty Truck Maintenance Schedules, locking rear axle fluid drain and refill is required owner maintenance at the first engine oil change. Failure to drain and refill the rear axle as specified may contribute to a later axle chatter condition. Refer to the appropriate Light Duty Truck Maintenance Schedule or service manual, section OB, for further details on change intervals.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
© Copyright General Motors Corporation. All Rights Reserved.