Limited Slip Additive

[Snagglefoot]

Here is a limited slip additive readily available in Canada at Canadian Tire. I'm trying to find out out how much to add and so far I hear about two to three oz per quart. Anyone have some guidelines on that? I left a message with CRC since there is no suggested dosage. And yes, I know there are some diff fluids that already have some mixed in. My application is a 14 Bolt 10-1/2 inch LS Chev diff.

 

[MolaKule]

For clutch type posi's my experience and recommendation is to add 1/4 tube and then do circle 8's in a parking lot. If chatter still exits, then add another 1/4 tube until it stops.

In my view most people over treat with this stuff and then when torque bias is needed the clutch slips.

 

[Snagglefoot]

Thanks, this tube is 7 oz, so a quarter would be almost 2 oz for the 3 quarts in my case.

 

[Donald]

In the past I have bought OEM additive and went with what was on the Amsoil website.

 

[69GTX]

2-6 oz should normally be enough to get it done. 3-4 oz is probably the norm. Most mechanics will just dump the entire tube in.

 

[propuckstopper]

I have always been confused on this issue as well. I have aftermarket posi units in both of the old GTOs. One is an Auburn, and one is an Eaton. Each of them are about five years old, as both rear ends were gone through completely at that time. The reason for the aftermarket posi units is because the factory Pontiac cone-style posi units are not really rebuildable. One guy claims he can do them, but it is not a popular choice among those in the know.

Anyway, I am using dino-based gear oil in both rear ends with Ford (!!!) posi additive as per the recommendation of Eaton. I always wanted to try Amsoil Severe Gear as Amsoil claims to have the posi additive already built in. Yet, they too sell a posi additive.

The truth is, these cars see very little miles and very little tire spinning activity, so I have never really determined if these posi units work "right". There is no clunking in the turns, so I know I am good there. I think the Severe Gear is likely a superior fluid than what I am using, but with these cars seeing about 500 miles per year I can't really justify the use of synthetics. It is not a cost thing, but I can't imagine any of these rear ends failing any time soon given the mild usage and limited miles.

Similarly, I use a dino-based gear oil (Sta-Lube GL-4) in the Muncie 4 speed. The "rumor" out there is that synthetic gear oil does not have the correct coefficient of friction necessary to keep the syncros happy in the Muncie.

For the record, I do use Amsoil Z-Rod 10W-30 in both engines, and have had good success. Again, I would like to try the synthetics elsewhere, but apparently I don't want to try it bad enough to pull the trigger.

 

[CharBaby]

I've always just bought the gear oil with the LSD additive already in it.

 

[MolaKule]

Originally Posted by propuckstopper


...Similarly, I use a dino-based gear oil (Sta-Lube GL-4) in the Muncie 4 speed. The "rumor" out there is that synthetic gear oil does not have the correct coefficient of friction necessary to keep the syncros happy in the Muncie...



I think you have heard the wrong rumors. Dedicated MTF's, whether mineral-based or synthetic, are the ones formulated to have the correct FM's and not Sta-Lube.

 

[MolaKule]

Originally Posted by propuckstopper
I have always been confused on this issue as well...



I don't know why there should be any confusion.

Even hypoid gear lubes with the LSD additive already in them sometimes requires extra LS additive to reduce chatter.

It's due to different friction materials and the differences in spring loading.

 

[propuckstopper]

Hi MolaKule. Thanks for your reply. I have attached pictures of exactly what I am using in the Muncie 4 speed manual transmission. I was told to stick with this product due to the GL-4 specification, as GL-5 is corrosive to brass components. Is this true?

If something like Amsoil MTG would be a better choice, I would be all over it. They do claim it is OK for Muncies, but some Muncie guys say no synthetics.

Your view?

 

[MolaKule]

Look at the choices from Amsoil and Redline.

The last Muncie I had required a 75W90 so Amsoil MTG or Redline MT-90 or MT-75W85 would work.

I have no idea what their latest spec might be but there should be a match out there.

 

[MolaKule]

Originally Posted by MolaKule
Now GL-4 does not necessarily refer to MTF's, as there are some gear lubes in the
Market place that are GL-4 rated, but are not MTF's. GL-4 is an SAE wear protection rating.

as stated in:
Last Post

 

[propuckstopper]

Originally Posted by MolaKule
Originally Posted by MolaKule
Now GL-4 does not necessarily refer to MTF's, as there are some gear lubes in the
Market place that are GL-4 rated, but are not MTF's. GL-4 is an SAE wear protection rating.

as stated in:
Last Post


Hi MolaKule. I just ordered some Amsoil MTG for the Muncie, and even went as far as getting the 75W-110 Severe Gear for the posi rear end. I will do the swap next week, and I will be sure to come back here and let you know what my results are. Thanks again.

 

[Snagglefoot]

Originally Posted by Snagglefoot
Here is a limited slip additive readily available in Canada at Canadian Tire. I'm trying to find out out how much to add and so far I hear about two to three oz per quart. Anyone have some guidelines on that? I left a message with CRC since there is no suggested dosage. And yes, I know there are some diff fluids that already have some mixed in. My application is a 14 Bolt 10-1/2 inch LS Chev diff.

Thanks everyone. I received some input from Yukon Gear and Axle to use 8 oz of LS additive. I used my entire 7 oz tune of CRC Positrac along with my 75w-90 synthetic gear lube. All is fine and running smooth. Here is a final shot of my new AC Delco Diff cover bolted in place. (Painted black).

 

[propuckstopper]

Originally Posted by propuckstopper
Originally Posted by MolaKule
Originally Posted by MolaKule
Now GL-4 does not necessarily refer to MTF's, as there are some gear lubes in the
Market place that are GL-4 rated, but are not MTF's. GL-4 is an SAE wear protection rating.

as stated in:
Last Post


Hi MolaKule. I just ordered some Amsoil MTG for the Muncie, and even went as far as getting the 75W-110 Severe Gear for the posi rear end. I will do the swap next week, and I will be sure to come back here and let you know what my results are. Thanks again.


So, I received my Amsoil MTG in the mail today, and did the swap in the Muncie. I then took the car for a ride and I tried to remain as skeptical as possible in terms of improved shift quality.

As skeptical as I tried to remain, I could not believe how well the Muncie seemed to "pull" itself into the next gear. Before with the Sta-Lube, the gear box had a very notchy feel, but being that this has been my only Muncie, I thought that it was normal. Not so. There is a dramatic difference now, and I wish I had of used a dedicated MTF in the first place.

Next up will be the Severe Gear in the rear end, although I don't think I will be able to "feel" anything with this change.

 

[BlueOvalFitter]

I have always added 4 oz. for every 3 quarts. And, my differentials never made any noises. YMMV