Differential - 1991 Chevy Caprice 5.0l Automatic

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Hearing a little whine , I think from the differential ( 46,000 + miles ) . I replaced the pinion seal 2 - 3 years ago & used no name brand dino 90W gear lube from O'Reilly .

I realize something coming out of a bottle is not going to repair anything , but I am hoping you all can recommend a gear oil that would help it run a little quieter ?


Thanks , :)
 
You could try 75W140. I'd use Valvoline Synpower myself only because I used it in the rear diff in a WRX I once owned with good results. No need to say that Caprice is an automatic. Thats a given.
 
If it whines only on decel, your pinion nut is coming loose. Did you replace the crush sleeve the first time? did you use locktite on the pinion nut?
 
It also whines on acceleration .

No , I did not go into it that far .

I replaced the seal and tightened the pinion nut with a 24" break over bar .

Thanks , :)
Wyr
God bless
 
Originally Posted By: CT8
The whine is from replacing the pinion seal. Try a heavier oil.


Can you please explain ?

I am thinking about a heavier / synthetic gear lube .

Thanks , :)
Wyr
God bless
 
Originally Posted By: skyactiv
You could try 75W140. I'd use Valvoline Synpower myself only because I used it in the rear diff in a WRX I once owned with good results. No need to say that Caprice is an automatic. Thats a given.


Synpower , I take ir , is a synthetic ?

May give that a try .

Will it mix OK with the dino gear lube that may remain in the banjo housing , after I evacuate all I can ?

Thanks , :)
Wyr
God bless
 
There is no reason replacing a pinion seal will create whine unless the pre-load got goofed up while reassembling. You say you tightened the pinion nut with a 24" breaker bar? How did you know when to stop?

You also have whine on acceleration? I'm willing to bet the cause of this is because you over-tightened the pinion nut, which crushed the crush sleeve slightly more increasing your pinion bearing preload.

oil does not exist that will help this situation.

You need to install a new crush sleeve. You then tighten the pinion nut little by little (this crushes the crush sleeve) and creates the pre-load on your pinion bearings. You need to measure the force in inch/lbs it takes to turn the pinion (wheels off the ground) You are looking for about 15-20 inch/lbs of force to turn the pinion once pre-load is correct. (if carrier is removed you usually want 8-12 inch/lbs on the pinion only with used bearings)

There's quite a bit that goes into all this, I suggest you do some research and get it right, otherwise you will never have a silent diff.

Let me re-iterate, oil does not exist that will fix too much pre-load on the bearings to the point they whine. You may already have destroyed the bearings and races depending on the severity.
 
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Best I remember , I had to use the electric impact wrench to originally remove the pinion nut .

When I went to tighten the nut , with only 1 side of the car jacked up , I think I used a 24" break over bar . But I had to use my foor to try to hold the tire / wheel from rotating .

OK , lets say I remove the drive shaft ( both wheels off the ground ) , locate the appropriate socket and any needed adapters . Using an inch pound torque wrench , set to your recommend specification , try to rotate the pinion yoke . If the wheels rotate before the torque wrench clicks , I have not tightened the pinion nut sufficiently ?

If it clicks at the specification you gave , then it is correct ?

It it takes more torque to rotate the wheels , than the specification you gave me , I have it too tight ?

Can not remember if it is a 2 piece drive shaft with a carrier bearing ? Perhaps I should look ? It just occured to me , that bearing may be noisy , too ?

If I tightened the crush sleeve too much , can that be changed out , with the seal removed , with out going into the differential from the " back side " ?

Thank you very much for the information , :)

Wyr
God bless
 
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Yes that makes sense that you would have to use a impact to remove the pinion nut. There is some thread locker on it from the factory.
Did you replace the crush sleeve when you did the seal? It sounds like you didnt.

And yeah, thats pretty much how it works. If it clicks before it starts turning, it is too tight.
I dont believe a caprice would have a 2 piece. They aren't long enough to require it. You usually only see that on long bed quad cab pickups.
 
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No , did not replace the crush sleeve .

Is it removed & replaced from the carrior side or pinion nut / yoke side ?

Once upon a time I had a Chilton and / or Hayes manual . Do not seem to be able to fine it ! Frustrating ........

Thanks , :)
 
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Originally Posted By: CT8
The whine is from replacing the pinion seal. Try a heavier oil.

The pre load likely was changed when the seal was done and a heavier oil isn't going to do much for that. If the nut was tightened more than it was before, disassembly, replacing the crush sleeve and torqueing to specs is the only way to quiet it down.
 
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OP, have you ever checked the external housing temperature at the pinion lock nut end as well as the bell housing (at LHS and RHS sides ) with an IR gun or palm fingers immediately after say, 20 - 30 miles of high-speed drive ?
If it's cool, there is no big deal even if you 'really' over-tightened pinion bearing.
If lock nut end is disproportionately hotter than bell housing temperature, then the pre-load at pinion is unaccepateble.
You may want to verify with housing temperatures.
 
Crush sleeves are accessed from the yoke side. Once you pull the pinion seal out you will see the tapered roller bearing, pull that out too. The crush sleeve is located between the two pinion bearings. The crush sleeve is what adjusts the distance between the two bearings.

You will probably need to pull the diff cover too though because once you remove the yoke side bearing the pinion will want to move all over the place.

Crush sleeves are super cheap, any parts store should have one, you just need to figure out if you have the 7.5" 10 bolt or the 8.5" 10 bolt. Since you car originally came with a V8 it probably has the 8.5".
 
Originally Posted By: zeng
OP, have you ever checked the external housing temperature at the pinion lock nut end as well as the bell housing (at LHS and RHS sides ) with an IR gun or palm fingers immediately after say, 20 - 30 miles of high-speed drive ?
If it's cool, there is no big deal even if you 'really' over-tightened pinion bearing.
If lock nut end is disproportionately hotter than bell housing temperature, then the pre-load at pinion is unaccepateble.
You may want to verify with housing temperatures.



Sounds like you are saying , if it is not running hot , then it is OK , as long as I am willing to put up with the Whine ?

We used to have an IR " gun " at work . May need to check that out .

Getting cooler , will that cause inconsistencies , as long as I get it jacked up quickly , after the drive ?

Thanks , :)
 
I'm not suggesting the whine is ok.

But a preload resulting in abnormally higher operating temperature as like 80-90 ish degrees Celsius shall be detrimental to components longevity, which will require immediate remedial action on your part.

Should your operating temperature is 'cool' as like 45-60 ish degrees Celsius, after say a 30 mile high speed travel, then this so called 'overdone' preload is not detrimental to differentials. In this scenario, as someone suggested above, select a higher KV@40*C in xW140 to mitigate the whine ,and move from there.
 
So 80C = 176F to 90C - 194F Bad
45C = 113F to 60C - 140F Tolerable ?

It is currently 43F . Is that going to theow me off enough to matter , after a 20 - 30 mile frive at , say , 65 - 75 MPH ?

Thanks , :)
 
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43F ambient won't matter as it only influlence oil grade recommendations ......
so you might get 35 - 45*C ..... which is too cold ..... then drop a grade or two of gear oil grades in use.
So 43F won't throw you off really ....
as the saying goes, the test of the pudding is in the eating , whatever oil grades in use or differential designs/rebuilt etc.In this context, it's about operating temperatures.

Btw, what's the oil grade in use ?
 
Best I remember , 75W-90 dino oil .

I was concerned the 43F ambient would skew the results of using temperature after a 20 - 30 mile drive , to diagnose the situation .

As far as general operating conditions , best I remember , some sort of 90 weight lube is " normal " in this climate .

Thanks , :)
 
Do you mean to say this differential gear set was replaced new at 46,000 miles ago ?
And since then has been using 75W90 (brand?) till todate ?
 
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