I finely got posi unit for my Omega.Can anyone tell me anything about setting the back lash.Is there any videos or books info of any kind.
railguy

 

Rail guy if you've not done this before do a lot of homework.
First determine if you have part compatibility. Will the carrier fit the ring gear? A 2 series carrier will not fit a 3 series with out a spacer to bring the gear towards the pinion. That also means new carrier (ARP) bolts.
The pinion depth as well as gear lash needs to be spot on or you will destroy something in short order.
You didn't mention what type of rear you have but I will assume its a GM 7.5 or an 8.2 corporate rear. In other words the pinion and the carrier both pull out from the rear of the housing.
You will need a shim pack kit for the carrier and pinion and a bunch of crush sleeves and a a new pinion nut for final torque. You will need a good (not harborjunk) dial indicator with a mag base. Gear contact paste (lash paste). A micrometer helps to determine the shim thickness. You need a way of holding the rear from rotating while you have a 3/4" drive breaker bar on the pinion nut to achieve proper crush sleeve spec. You should have a foot pound and an inch pound torque wrench...see where Im going...Have I scared you away yet?
For $100 you could find a local (speed) shop to do it for you. I usually recommend this unless your willing to learn and buy tools; or are already well versed...in which case I just wasted your time.
YouTube Im sure theres plenty of info there. Some of the better manuals will have good info and specs too.

 

My experience has been that when replacing the carrier only, all you need to do is ensure the backlash is within tolerance. A quick web search shows there are 2 possibilities:

http://www.crawlpedia.com/ring_pinion_setup.htm
2-cut = .003"-.006"
5-cut = .006"-.010"

I have no idea what 2-cut and 5-cut means or how to determine which one you have.

The web provided this meaningful information:
Older "5-Cut" face milled gears have different set up specifications than the newer "2-Cut" face hobbed gears.

 

Should be. Corp 8.5" 10 bolt. Reusing existing ring and pinion its best to check backlash before swapping ring to other carrier. Also note how much preload is on the bearings (how firm it is in there after you pull axles and caps) often the factory cast single shims can be retained or atleast tried first and see how it measures up and the preload is adequate. Plan on buying a shim kit anyway. Good to have one regardless. I like to go for .007" plus or.minus a thou. Of course ensure your pinion is good (not loose or leaky) you may need to reseal it too and put a new nut. Axles seals while your in there.

 

I saw one video that made it look a lot easier then I had previously thought.The pinion has the bearing on it and has only 20 k on it. I'm going to put it in and check the contact pattern .If it's good I'm going to use the old bearings.Maybe I'll post a pic for other's opinions.We have a pretty long winter here even if the roads are clear there's still a lot of sinders and salt.So I have plenty of time.
railguy