Positraction Plates Popping Again And Changing Rear End Lube

[toobroketoretire]

Changing Rear End Lube

My positraction plates began popping every now and then last summer and popped a few days ago when I was down in the valley. When I installed the 3.70's several years ago I put a tube of Sta-Lube friction modifier in it and that worked okay for the first several thousand miles. Then one day it began popping again so I added a second tube. That cured the popping for the next 50,000 to 60,000 miles but with it popping again I am wondering of the Sta-Lube wears out over time. I bought two tubes of it today and tomorrow I'll change the 85W140 oil and put the two tubes into it. As my rear end has a drain plug it'll only take me a few minute to replace the oil and friction modifier. When I replace the rear end oil I drain it into a coffee can and mark the FULL level with a sharpie felt pen. Then I dump it out and put the friction modifier in first THEN the new lube into the can until it reaches the same FULL level. Then I heat it to about 200 degrees on a hot plate then gravity-feed it into the rear end with a 1/2" hose about 4 feet long from over the top of my right rear tire. Works great as there's no spillage and the pre-measured amount is exactly right.

I'll take a couple of pictures of my drain plug tomorrow so you can see how I installed it. I'll post the pictures tomorrow.

 

[LLC5]

My positraction plates began popping every now and then last summer and popped a few days ago when I was down in the valley. When I installed the 3.70's several years ago I put a tube of Sta-Lube friction modifier in it and that worked okay for the first several thousand miles. Then one day it began popping again so I added a second tube. That cured the popping for the next 50,000 to 60,000 miles but with it popping again I am wondering of the Sta-Lube wears out over time. I bought two tubes of it today and tomorrow I'll change the 85W140 oil and put the two tubes into it. As my rear end has a drain plug it'll only take me a few minute to replace the oil and friction modifier. When I replace the rear end oil I drain it into a coffee can and mark the FULL level with a sharpie felt pen. Then I dump it out and put the friction modifier in first THEN the new lube into the can until it reaches the same FULL level. Then I heat it to about 200 degrees on a hot plate then gravity-feed it into the rear end with a 1/2" hose about 4 feet long from over the top of my right rear tire. Works great as there's no spillage and the pre-measured amount is exactly right.

I'll take a couple of pictures of my drain plug tomorrow so you can see how I installed it. I'll post the pictures tomorrow.

Remember Einstein, that of course what you drain out may not always be the proper amount for the application.



What do you do if your dented coffee can doesn't have the correct amount of fluid in it to fill your differential to the proper level?

 

[toobroketoretire]

Remember Einstein, that of course what you drain out may not always be the proper amount for the application.



What do you do if your dented coffee can doesn't have the correct amount of fluid in it to fill your differential to the proper level?

I stick my finger in the fill hole first to see if it's completely full and THEN I drain it. Years ago I discovered it's easiest to use a 4 foot long 1/2" hose with a funnel on it to gravity flow the new lube into the rear end. But I heat the oil to around 200 degrees first to reduce its viscosity.

"Dented" coffee can? Uh, why would it be dented?

 

[LLC5]

I stick my finger in the fill hole first to see if it's completely full and THEN I drain it. Years ago I discovered it's easiest to use a 4 foot long 1/2" hose with a funnel on it to gravity flow the new lube into the rear end. But I heat the oil to around 200 degrees first to reduce its viscosity.

"Dented" coffee can? Uh, why would it be dented?

A finger in the hole means nothing (at least not to a automobile any way). The fluid needs to self level per the manufactures specs, Einstein.


Why wouldn't your coffee can be dented?

 

[toobroketoretire]

Changing Rear End Lube

Well, I never got around to changing my rear end lube today so maybe I'll do it tomorrow.

UPS has a cool new feature called "Following My Delivery" and it shows where the UPS truck is at any given moment from the time it leaves the distribution center. But the UPS symbol doesn't move slowly but rather in sudden jerks. I saw it about 1 mile from my house and then POOF; it was driving up to my door. The driver told me they have a BIG problem with thieves following them from a distance. A delivery is made to maybe a front porch or garage, then after the UPS truck leaves the thieves drive up and steal the packages. With Christmas approaching the problem has gotten a lot worse.

 

[Crimson Thunder]

Actually the UPS theft problem is improving with more homeowners installing motion activated cameras at their front door and garages. With all the new technology coming from companies like the "Ring doorbell" and "Nest" it won't be long before every home has cameras installed.

 

[toobroketoretire]

Changing Rear End Lube

For many years I changed rear end lube by sucking it out and squirting it back in using a suction gun. It always made a big mess on my garage floor then one day I discovered a new way to do it. First of all I began installing drain plugs in my rear ends and then I began using a 4 foot piece of 1/2" hose and pouring it in over the top of my right rear tire. By heating the oil to around 200 degrees and using a small funnel, the oil runs thru the hose and into the rear end with hardly any mess; just leaving a few little drops on the floor instead of a big puddle.

 

[Antz81]

By heating the oil to around 200 degrees and using a small funnel, the oil runs thru the hose and into the rear end with hardly any mess; just leaving a few little drops on the floor instead of a big puddle.

Maybe it's just you that makes a mess

 

[GTR1999]

I had some hesitation posting on these threads but here is some general information that may help some.

The issue of posi chatter has been around since 1965 when GM first started using the Eaton spring loaded posi in corvettes. Now the chatter would vary from car to car because these were production built units and all depends on how they were setup and the spec is 001-008 lash on the spiders. Setting too tight and you have more chatter, too loose and the posi action isn't correct. The solution was to use the preload springs to keep tension on the clutches. While this does work it led to the chatter when they were too tight, added spring tension and old oil was involved. Its shows up when the diff is hot and usually when making a turn from a stop. Could be forward or reverse.

There were a couple of different posi additives offered by GM over the years going way back to the Whale oil days but that was 50+ years ago. The tried and true method, whether some believe it or not, was to drain the oil and replace it with fresh oil and GM additive then load each clutch pack by doing figure 8's in a parking lot. This works most of the time. The additive sold today is not the same as it was years ago so I recommend using 2 bottles instead of 1. I use Lucas 85-140 gear oil but GM 90 Wt will also work. I won't get into a oil debate on synthetic vs Dino oil, I never use Synthetic gear oil in a vette diff.

In an effort to resolve the chatter issue the clutches were slotted in 1971. I refer to these as "snowflakes" because that is what they look like to me and I see the term stuck because it's mentioned on CF all the time now. These clutches did not work, they only made them weaker and many broke in use. I have taken apart many that fell apart out of the posi case. The 65-70 used solid steels and these are the best. They are still available and all I use in the many 100's of them I have rebuilt. The current loaded posi's and some vendor units use Fiber coated clutches and they do stop the chatter but continue to wear at every turn. Some guys worn them out in drag racing applications. I never use them or recommend them.

When I build a posi I polish and tune it. Just like you can see on You Tube under Tom's posi tuning. I learned from Tom years ago. Very few rebuilder do this and even less really do them correctly. The people I trained around the world - who listened to me- know how to do them and had success doing them at home. It takes hours to do and a lot of patience from the student.

If you got 50k miles out of a posi oil change that is not bad, I believe the GM recommendation was 30k miles but I am going by memory. I also tap a drain hole in every housing, not the cover, I build. I use a magnetic drain plug as well. A 1/4 npt hole is all you need. Takes about 10 minutes cost is $8. Some vendors offer the same thing for $50 not a bad profit I must say, I would do them all day long for that. However, vendors main objective is to make as much $$ as they can as fast as they can so you will not see custom diff's offered by many and the ones I see posting pictures clearly have cut corners inside the diff but no one knows it. I was amazed at what I saw on CF from someone who is supposed to be a trusted rebuilder. Obviously his only trust was in his profit regardless of his customers trust in him- but that's another story.

Bottom line is very simple. If you have chatter- replace the oil and use the GM additive, 2 bottles. If it still chatters then the only other thing to do is take out the posi and tune it- correctly.

'nuff said. I have to go tap a housing today and setup a 77 diff.

 

[toobroketoretire]

Changing Rear End Lube

I finally got around to changing my rear axle lube today and found it was as black as midnight from oxidation. Maybe that was the reason why my friction modifier had quit working since summer. I have never heard of friction modifier going bad but maybe it can after being heated and cooled so many times and exposed to air. Well, at least I got it changed and now I can look for something else to do...........like annoying you guys.

I also found the cause of my annoying vacuum leak that has been draining my vacuum reservoir in a matter of a few minutes. It was a bad wiper door relay valve so I ordered two new ones. So this has been a successful day so far.

 

[SVO]

This past weekend, was cleaning out my parents place. Uncovered 9 bottles of the old GM whale oil posi additive. Left over from when I had a C1 autocross car. That ought to keep me chatter free for a while.

 

[GTR1999]

This past weekend, was cleaning out my parents place. Uncovered 9 bottles of the old GM whale oil posi additive. Left over from when I had a C1 autocross car. That ought to keep me chatter free for a while.

Wow that has to be pretty old stuff. I don't know what the shelf life is on that, I thought I once read where there was but who knows.

 

[SVO]

@ Gary - You know I never thought about the stuff having a shelf life. That would be my luck for it to be so old that it's worthless.

It'll go good with the C1 posi pumpkin with the 5:13 gear I dug out from under Dad's workbench. :L

 

[toobroketoretire]

I had some hesitation posting on these threads but here is some general information that may help some.

The issue of posi chatter has been around since 1965 when GM first started using the Eaton spring loaded posi in corvettes. Now the chatter would vary from car to car because these were production built units and all depends on how they were setup and the spec is 001-008 lash on the spiders. Setting too tight and you have more chatter, too loose and the posi action isn't correct. The solution was to use the preload springs to keep tension on the clutches. While this does work it led to the chatter when they were too tight, added spring tension and old oil was involved. Its shows up when the diff is hot and usually when making a turn from a stop. Could be forward or reverse.

There were a couple of different posi additives offered by GM over the years going way back to the Whale oil days but that was 50+ years ago. The tried and true method, whether some believe it or not, was to drain the oil and replace it with fresh oil and GM additive then load each clutch pack by doing figure 8's in a parking lot. This works most of the time. The additive sold today is not the same as it was years ago so I recommend using 2 bottles instead of 1. I use Lucas 85-140 gear oil but GM 90 Wt will also work. I won't get into a oil debate on synthetic vs Dino oil, I never use Synthetic gear oil in a vette diff.

In an effort to resolve the chatter issue the clutches were slotted in 1971. I refer to these as "snowflakes" because that is what they look like to me and I see the term stuck because it's mentioned on CF all the time now. These clutches did not work, they only made them weaker and many broke in use. I have taken apart many that fell apart out of the posi case. The 65-70 used solid steels and these are the best. They are still available and all I use in the many 100's of them I have rebuilt. The current loaded posi's and some vendor units use Fiber coated clutches and they do stop the chatter but continue to wear at every turn. Some guys worn them out in drag racing applications. I never use them or recommend them.

When I build a posi I polish and tune it. Just like you can see on You Tube under Tom's posi tuning. I learned from Tom years ago. Very few rebuilder do this and even less really do them correctly. The people I trained around the world - who listened to me- know how to do them and had success doing them at home. It takes hours to do and a lot of patience from the student.

If you got 50k miles out of a posi oil change that is not bad, I believe the GM recommendation was 30k miles but I am going by memory. I also tap a drain hole in every housing, not the cover, I build. I use a magnetic drain plug as well. A 1/4 npt hole is all you need. Takes about 10 minutes cost is $8. Some vendors offer the same thing for $50 not a bad profit I must say, I would do them all day long for that. However, vendors main objective is to make as much $$ as they can as fast as they can so you will not see custom diff's offered by many and the ones I see posting pictures clearly have cut corners inside the diff but no one knows it. I was amazed at what I saw on CF from someone who is supposed to be a trusted rebuilder. Obviously his only trust was in his profit regardless of his customers trust in him- but that's another story.

Bottom line is very simple. If you have chatter- replace the oil and use the GM additive, 2 bottles. If it still chatters then the only other thing to do is take out the posi and tune it- correctly.

'nuff said. I have to go tap a housing today and setup a 77 diff.

When I read the part about running figure 8's I began laughing my butt off and quit reading right there. Just a single right or left hand turn coats the clutch plates with the new lube so there is no point in running figure 8's unless you want to look like a total fool.

 

[toobroketoretire]

Remembering The Old Days

As I am thinking back I am realizing this '71 is very different from the past G.M. cars I owned with positraction. Whereas they saw limited mileage before I sold them this '71 is the first to be driven over 100,000 miles in 5 years. As the rear axle lube was as black a midnight I am sure it's the age and mileage that finally rendered the friction modifier ineffective. I had originally installed a single 4 ounce tube of Sta-Lube friction modifier and that seemed to be enough until it began popping several months later. So I added another 4 ounce tube and that did the trick for the next 45,000 miles or so.

The Sta-Lube friction modifier is odorless and a very light yellow color whereas the G.M. friction modifier I had used many years ago stunk like REAL strong sulfur and that's all I remember about it.

 

[Crimson Thunder]

Calling Gary a fool is when the membership should get revoked.

 

[Antz81]

Calling Gary a fool is when the membership should get revoked.

Probably should have been revoked long before then.

 

[toobroketoretire]

Calling Gary a fool is when the membership should get revoked.

I didn't call anybody a fool. I said running figure 8's is a good way to make yourself look like a fool because it accomplishes nothing. You guys really need to take a college course on reading comprehension. Or did you already but you couldn't comprehend what the textbooks said?

 

[Crimson Thunder]

You may want to Google GTR1999 or Gary Ramedi before you question something he suggests or call it foolish. You may actually learn something.

 

[kpic]

When I read the part about running figure 8's I began laughing my butt off and quit reading right there. Just a single right or left hand turn coats the clutch plates with the new lube so there is no point in running figure 8's unless you want to look like a total fool.

You have a lot of butt to laugh off. In fact, IMO shared by others you're all butt..

You may want to Google GTR1999 or Gary Ramedi before you question something he suggests or call it foolish. You may actually learn something.

TBTR learn something; surely you jest...