Is there any kind of break in period for a newly installed posi? Swapped my 2.56 non posi in my 71 Skylark for a 3.08 posi along with a B&M tyranny shift kit.
After I installed my freshly rebuilt 8.5 rear with Eaton Posi, I did figure 8's in a parking lot for about 10 minutes. After I put about 100 miles on the car, I drained and refilled the gear oil. I used regular dino oil and a container of the GM additive. Don't know if all that is necessary, but that is what I did. BTW, Eaton said no synthetic or it would void the warranty.
Interesting about the synthetic voiding the warranty. You would think it would be recommended. I used a Auburn unit.
The only break-in procedure i know of is drive for 15-20 miles then let diff cool for 2 hours or so....then no heavy accelleration/towing and stay under 55mph for 500 miles then change oil
Are those the same break-in procedures that came with the car when it was new? What would be different about installing an aftermarket setup?
If the gears are new, Richmond's recommendation for break-in is "normal street driving speed for approximately 1 miles,then stop and let cool for 30 minutes. Do this 2 to 3 times". I use 55mph as a "normal street driving speed".
My Auburn set up has Richmond gears. Don't recall seeing any warning / break in procedures. Nothing either regarding regular vs synthetic fluid.
It's not a big deal. Use some common sense. Just drive it normally. Give it 100 miles before you romp on it.
This thread has me concerned..I have an Eaton posi with about oh,300-500 miles on it that I have been driving on Sundays when possible. I get 2nd gear rubber pretty easy with the old stock 350 2bbl. due to a shift kit on my TH400...what gear oil do I use? How much? I just e-mailed the guy that built it (rear end)for me, wish he had told me about this BUT at times like this...you guys serve as great advisors. Best Regards, 455nGLIDE
I'm not sure what you are asking? Are you saying you have synthetic oil in the rear? I use Valvoline 80W/90 with one container of GM posi additive. How much? As with any rear, you fill it until it just dribbles out of the fill hole. That takes more than one container of gear oil, but less than 2
I'm not sure what you are asking? Are you saying you have synthetic oil in the rear? I use Valvoline 80W/90 with one container of GM posi additive. How much? As with any rear, you fill it until it just dribbles out of the fill hole. That takes more than one container of gear oil, but less than 2 My bad...specifically: I am wondering/asking if I have damaged my new posi unit since I have 3-500 miles on it with NO oil change. I have followed up with the guy that built it for me...but in the mean time I am checking in here. I appreciate the reply. Regards, 455nGLIDE
OK, I say you shouldn't worry at all. 3-500 miles is nothing. If you are worried, change the fluid, it's easy.
Larry70GS, Thanks you for your comments...gonna change the oil today, and Eagleguy...thanks for starting this thread...this topic has been helpful. Best Regards To All, 455nGLIDE
This board and its members have saved me a lot of time and $$. I've found that the only foolish question is the one you don't ask. Have yet to get bad information and as always its better to be safe than sorry . Thanks for all the input!
Any good GL-5 rated gear lube will work for you. Gear lube change after breakin is more important if you have a new set of gears, vs. a new or rebuilt posi case. As new gears break in, they will in fact shed some material, and it's a good thing to get that out of there. I typically tell my customers to change it after 100 miles, and some hard use. The clutch type posi-traction, as used in the Eaton Style 8.5" and 12 bolt, does require a friction modifier, or additive, to allow the discs and plates to slip a bit, to allow chatter-free turns. Some lubricant brands have this built into the product, some require the extra additive to be added. The GM supplement has long be held as the best additive for this, and a similar product is offered by a number of suppliers. Generally speaking, any quality GL-5 rated 80-90WT oil, with the additive, will work just fine in our street driven cars. As far as synthetics, for most applications, they simply are not required, and some manufactures don't want them on the friction materials of their posi units, as you have seen. Posi units do require friction to function properly. It is possible to over-lubricate a posi unit, and glaze the friction discs. The only application that I typically use a synthetic gear lube in is a drag race car with a spool. I will typically use an Synthetic in those vehicles. Mainly because the non-dino oil is more temperature consistant, from the first pass to the last, after a proper warm up. I've had good results with Richmond, Amsoil, and Redline gear oils. JW
Just as additional info for posi addatives I have used the Amalie posi addative concentrate (available at CarQuest among other places) and it did not give me the best results. Sometimes it helped other times it did not. I no longer use it. NAPA sells posi lube addative in a white and blue toothpaste looking tube. Called TRANS-X Posi Trac limited slip gear oil addative by K&W. About $10, and it indicates it is suitable for use in place of GM#1052358, Ford #M2C118-A etc. IT WORKS GREAT. I use this because the NAPA is closer to me than the GM dealership. I hear the GM addative works very well.
so youre saying change it at 100 miles rather then 500mis jim w? and i just realized my rearend guy put in posi additive looking at the invoice paper ..but i have a detroit tru-trac...should it still be fine...dont think it'll damage/wear it faster but can't hurt to ask
True trac does NOT require the additive...DO NOT waste your money. It is a gear to gear helical sliding gears. So synthetic is ok and probably recommended for these units as they will tend to increase heat in the rear. HAve fun. Jim J D Race.com :3gears: :3gears: :3gears: :3gears:
