Differential Leak?

[BigBrakeFuelie]

Hey everyone.I had a question to ask some of are knowledgable members.I just had my car to the shop and they told me that I had a leak where the driveshaft goes into the differential.He said it was pretty bad.He was kind of vague with the details.Just that a seal needed to be replaced.
First of all does that make sense?Secondly is that a big job labor wise if I need to take it into a Corvette Shop?Can anyone give me a ballpark estamite of what it SHOULD cost me? Maybe someone on here has already done this.
Thanks
BBF

 

[JohnZ]

Replacing the pinion seal is about a 2-3 hour labor job, seal itself costs about $5.00.

 

[BigBrakeFuelie]

Thanks JohnZ-Is that a job for an experiance Mechanic or is it somethin a relative novice like myself could tackle with the help of my freind who is a shade tree mechanic?I like to save $ but I want it done well.

 

[JohnZ]

I'd recommend you leave it to a professional; takes MAJOR torque tools to get the companion flange nut off, and when you re-install it after replacing the seal, the torque and compression has to be set precisely to avoid changing the pinion bearing preload. Make sure the shop uses non-hardening sealer around the forward end of the splines and packs it in the recess under the washer before installing the nut and washer, or it'll leak through the splines, not the seal.

 

[cruzer99]

Hey BBF,
There is a rearend shop over on Sunrise that is OK. Check the phone book for the number.

 

[Stallion]

I've learned a lot here from my stay on parts of automotives and such, but one thing that I'm still always shady on (this might sound odd) is places in which requires a "fluid". What kind of fluid is needed in the differential? I know there is a lot of friction and I know the basics of them, but what kind of liquid is in them? Or is it just basic oil for lubrication?

Thanks and good luck with the fix, BigBrakeFuelie!

TR

 

[DDLS3]

TR
Most if not all, differentials usually take EP-80/90w gear lube, which a heavy oil. In the positrac differential like is used in the corvette an additive is also used to help with the smooth lock-up and un-locking of the clutches that are used to transfer power to the opposite wheel when the primary drive wheel losses traction. 80/90 gear lube is also redily available in a synthetic oil. Many standard shift transmissions also use this same gear lube.

 

[BigBrakeFuelie]

The guy at the shop said the term "differential" So I crawl underneath and to take a look and all I see is a leak where the driveshaft goes to the transmission.The differential is in the rear only correct?So now I am talking about a tranny seal?If I`m right this is a bad sign.One of those situations where it could be a simple seal or a major teardown.:eek

 

[cruzer99]

If it is the tranny's rear seal, it is still a simple seal to change. Most tranny shop's will do it quick and cheap......just call around.

 

[BigBrakeFuelie]

Let me ask you guys this,What does it mean when you first put your car in drive(auto) and the car makes a sound kinda like CLUNK!Is this a sign the tranny is worn out?The car runs and shifts smoothly.
Cruzer-I hope your right and it`s just a simple fix.

 

[cruzer99]

Bad or loose u-joint somewhere in the drivetrain or something with the ring and pinion.

 

[BigBrakeFuelie]

So the U Joint? Is that the connection between the driveshaft and the tranny?So it doesn`t necessarily mean the tranny itself is going south.Is this a major job laborwise? Big $$ for a shop to do?

 

[cruzer99]

You need to get the back of the car in the air and check the drive and half shafts. I think there are 6 u-joints and it is most likely one or two that are bad. They are somewhere around 25.00 each.

 

[Stallion]

TR
Most if not all, differentials usually take EP-80/90w gear lube, which a heavy oil. In the positrac differential like is used in the corvette an additive is also used to help with the smooth lock-up and un-locking of the clutches that are used to transfer power to the opposite wheel when the primary drive wheel losses traction. 80/90 gear lube is also redily available in a synthetic oil. Many standard shift transmissions also use this same gear lube.

So there is this fluid right in the differential and the transmission then. But, where is it stored? Is there a little resourvoir (sp?) like, say, the oil pan in the engine? And like the steering fluid? Or is it just "on" the gears?

Thanks!

TR

 

[JohnZ]

The differential case (where the ring and pinion gears and Posi unit are) contains about 4 pints of hypoid lube (75W90 or 80W90 heavy gear oil) which is splashed around by the rotating ring gear to lubricate the gears, posi unit, and carrier bearings. There is a seal at the front for the pinion shaft and one on each side for the side yokes.

 

[Stallion]

Okay, I see what you mean. Is this the kind of fluid in which you have to change every x amount of miles?

Thanks!

TR

 

[JohnZ]

It's a fairly long-life lubricant - depends on the car, but generally they recommend changing it at 30,000 miles or more, or some recommend no changing at all. Not a regular maintenance item.

 

[Stallion]

Okay, I see. Thanks, John!

TR

 

[BigBrakeFuelie]

Turns out it was my rearend.The local Corvette shop checked it out and they told me it looks like it hasn`t been serviced.....ever.So I`m biting the bullet and having my rear rebuilt.It was chewed up pretty bad,filings pretty ugly in there.The leak in front was from the valve covers.

 

[Stallion]

About the valve cover leaks, what the previous owner did to my Vette (which I think is pretty ingenious) was put a sort of shim and make-shift bolt so that there was no leak on the covers. If you would like me to post a pic of what I'm talking about, I would be more than happy to.

TR