Bad limited slip?

4C FED

4C FED

Absolutum Dominium
Tonight when I went to the store I noticed that when making a left hand turn when I hit 2nd the axle locks and both tires break loose.
But when I make a right hand turn only the inside wheel spins.

What's up with that?

I just recently changed the rear end fluid & added 4oz. of limited slip additive. It still crabs quite a bit when making tight slow turns, like parking turns.
 
J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: Bad limited slip?

Well, the factory limited slip IS a POS.

The limited spin (its not really a limited slip) diff in your truck is an Eaton Gov-Loc. Needs about 100 rpm difference in axle speeds to activate. Which means one tire has to be spinning before it'll grab. Also, it has certain criteria for engagement. If you're doing above 25mph and start spinning, it won't do anything. Only way it'll be "locked" above 25mph is if you get it to lock up below 25mph and don't lift (has to have power applied to stay locked). Once you lift it'll unlock and won't activate again until you're below 25mph.

What I'm not sure about is whether the Gov-Loc needs the limited slip additive. I know certain limited slips (like Zexel Torsens / TruTrac's) don't need it.

Long story short, if you're consistently spinning one tire (hard enough to exceed the 100rpm difference criteria) below 25mph, then I'd say you probably need to figure on replacing it (I'd suggest something better than stock). I personally like the gear type limited slips (Zexels & TruTrac's) but that's just me.

'JustDreamin'
 
B

big gear head

axle builder
Re: Bad limited slip?

I don't use the additive in rear ends with the Gov. Lock because the only time the clutches are applied is when you spin a tire and it locks up. Then you don't want the clutches to slip. Anyway, when you turn right is it at low speed?

A car with a standard differential will almost always spin the right tire because of the way the drive shaft torques the rear end housing. When turning left you are loading the right tire and lifting the left, which somewhat equalizes the load on both tires and makes it easier to spin the left tire with the right. When you turn right you load the left tire and make it easier to spin the right tire, which is already too easy to spin. Your differential might not be locking up enough to overcome this.
 
4C FED

4C FED

Absolutum Dominium
Re: Bad limited slip?

big gear head said:
I don't use the additive in rear ends with the Gov. Lock because the only time the clutches are applied is when you spin a tire and it locks up. Then you don't want the clutches to slip. Anyway, when you turn right is it at low speed?
Click to expand...

Yes. I stop at the corner & punch it making the right hand turn. Only inside tire spins, very easy to predict attitude/direction I'm going.

When making left turn at stop, same technique but a larger radius turn. When I hit 2nd, both wheels break loose & things get interesting.

I just want consistency, preferably having the axles lock instead of free-wheeling one side.
 
Loeryder

Loeryder

New member
Re: Bad limited slip?

I don't use the additive in gov locks either.

There was a TSB posted on this some time ago.
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: Bad limited slip?

4C FED said:
So when you installed this did you need to setup the ring & pinion clearance?
Click to expand...
I had it installed by a local service place, I do not remember the invoice mentioning any changes to the clearances. As far as I know it was a straight bolt in swap
 
B

big gear head

axle builder
Re: Bad limited slip?

I also recommend the Eaton. The backlash will have to be checked and adjusted, but the pinion depth stays the same. Here is some informationn on changing the differential. This is for the 8.5, but it also allpies to the 7.5. http://www.nastyz28.com/forum/showthread.php?t=19773&highlight=install+posi You need to know the number of splines on your axles. Before '89 they had 26 splines and then they were upgraded to 28 splines. Summit's price is too high on these.
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: Bad limited slip?

big gear head said:
Summit's price is too high on these.
Click to expand...
I agree, but at the same time I can't talk because I got mine at Eaton direct employee pricing :tup:
 
M

motorhead

New member
Re: Bad limited slip?

4C FED said:
<cough>bad info</cough>
http://www.syty.net/forums/attachment.php?attachmentid=790&stc=1
Click to expand...

91chevy16

GMC NUMBER: 91-4B-124

GROUP: 4B Rear Axle

DATE: July, 1991

CORPORATENUMBER: 964201R

SUBJECT: LOCKING REAR AXLE CHATTER

MODELS: ALL LIGHT DUTY TRUCKS EQUIPPED WITH LOCKING REAR AXLES, RPO G80


THIS BULLETIN CANCELS AND REPLACES GMC TRUCK SERVICE BULLETIN 90-4B-30 (CORPORATE NUMBER 964201) DATED JANUARY, 1990 TO ADD WARRANTY INFORMATION. ALL COPIES OF 90-4B-30 SHOULD BE DISCARDED.

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 the clutches in the 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 1052271). 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
1052271 Lubricant, Rear Axle (24 oz.)
See Appropriate Gasket, Rear Axle Housing
Parts Manual Cover

Parts are currently available through GMSPO.

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. For those vehicles repaired under warranty, which have had the axle fluid changed at the first oil change and have experienced rear axle chatter use:Labor Operation: F2010, Locking Differential - Flush

Labor Time: 0.9 hr. (All Models)











© 2007 ALLDATA LLC. All rights reserved.
Terms of Use
 
J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: Bad limited slip?

jjorgensen52 said:
I agree, but at the same time I can't talk because I got mine at Eaton direct employee pricing :tup:
Click to expand...
Still have a connection there? I'm looking to replace the 7.625" 10-bolt in my Bravada with a 8.5" 10-bolt with a True-Trac.

'JustDreamin'
 
jjorgensen52

jjorgensen52

NHSTE - I'm the only one!
Re: Bad limited slip?

JustDreamin said:
Still have a connection there? I'm looking to replace the 7.625" 10-bolt in my Bravada with a 8.5" 10-bolt with a True-Trac.

'JustDreamin'
Click to expand...
Nope, unfortunately not
 
4C FED

4C FED

Absolutum Dominium
Re: Bad limited slip?

motorhead said:
91chevy16

GMC NUMBER: 91-4B-124

GROUP: 4B Rear Axle

DATE: July, 1991

CORPORATENUMBER: 964201R

SUBJECT: LOCKING REAR AXLE CHATTER

MODELS: ALL LIGHT DUTY TRUCKS EQUIPPED WITH LOCKING REAR AXLES, RPO G80


THIS BULLETIN CANCELS AND REPLACES GMC TRUCK SERVICE BULLETIN 90-4B-30 (CORPORATE NUMBER 964201) DATED JANUARY, 1990 TO ADD WARRANTY INFORMATION. ALL COPIES OF 90-4B-30 SHOULD BE DISCARDED.

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 the clutches in the 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 1052271). 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.
Click to expand...

I wasn't doubting you, just pointing out sytyauthority.net is incorrect/out dated, which is where I went to get the gear oil info, and why I added the additive.
 
J

'JustDreamin'

Dream: 6LV8 Turbo Bravada
Re: Bad limited slip?

There is no Limited Slip Differential available for the front axle. Its an open diff. Only thing that was ever available was a Lock-Rite locker. I've heard that locker is not readily available anymore, but not sure whether that is accurate or not.

'JustDreamin'
 
You must log in or register to reply here.
Top