Looking for input on posi, gear, and axles - Chevy Nova Forum
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Old 19th-March-2017, 09:40 PM   #1
Mwilson904
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Looking for input on posi, gear, and axles

About to pull the rear end out of my project, the axles have "value line" cast on the end, so I'm guessing they're not the best, the posi unit was posted earlier and determined it needed to be changed. I plan on dropping it off somewhere to just have it done. Plan to have it as a street/weekend car. Has a 502 in it with approx 520 hp (allegedly) has a th400 trans.

Please give me recommendations on good but reasonable:
Posi unit
Gear ratio
Axles

I'm guessing it's a 8.5 but don't think that matters if I'm having them change everything, here are some pics.

Any input will be appreciated

Thank you
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Old 19th-March-2017, 09:58 PM   #2
sbc1320
 
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Eaton 30 spline posi
Moser 30 spline axles
3.73 gears if it's a weekend warrior
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Old 20th-March-2017, 07:54 AM   #3
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Eaton limited slip rear differential. Great bang for the buck.

Richmond gears. Do not cheap out on gears- pay a little extra for the good stuff.

Moser axles. With the kind of power and torque that 502 will be turning out, good axles are good insurance.
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Old 20th-March-2017, 06:24 PM   #4
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The Value Line axles are a little better than original factory axles or so they claim. I have installed a few over the years and have not had any issues but they are on the cheap end of the spectrum. I would run either Moser, Dutchman, Toms or Sierra axles. Eaton posi units are very good and as for gears I prefer US Gear (not USA STD), Motive, Sierra, or something along those lines, not a huge richmond fan except for drag applications.

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Old 21st-March-2017, 08:07 PM   #5
Mwilson904
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Eaton 30 spline, moser axels, and a decent 373 gear is the route I'll go.
I believe the housing has been powder coated, or painted very well, I found a local shop online and called them, they seemed to really want me to upgrade to a 12 bolt, but I think the 8.5 is fine for what I need.
I would have them purchase the parts, when I told the guy I wanted the eaton posi, moser axles, and a some decent 373 gears, he said the gears come with the Eaton posi unit? I've never heard of this before, maybe with the moser axles, or he misunderstood so I'll wait until he calls me back with pricing and info.

I would be bringing the shop the unit.
I'm guessing in the $1500.00-1600.00 range?
Posi 500, axles 250, gears 250, bearing etc 50, 450 labor?

Does that sound about right? +/- $100 or so.
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Old 22nd-March-2017, 10:02 PM   #6
70chevybb

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rear end

Quote:
Originally Posted by sbc1320 View Post
Eaton 30 spline posi
Moser 30 spline axles
3.73 gears if it's a weekend warrior
I j u st installed this exact set up I n my 72 the 396 4 speed. Great combo
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Old 22nd-March-2017, 10:43 PM   #7
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Quote:
Originally Posted by 70chevybb View Post

I j u st installed this exact set up I n my 72 the 396 4 speed. Great combo
I did the 4.11's, but that 3.73 gear is hard to beat. My buddy did a 3.90 gear. You can get a good deal on the posi on Ebay at times. I want to say I paid $420 for my Eaton posi.
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Old 25th-March-2017, 12:26 AM   #8
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Ugh.
I pulled the rear and took it to a local shop, the guy pulled the case off and said that he'd just run it, no need to change.
I went by a classic restoration shop and they didn't pull the case and just said that I will shatter it, so I should just sell it and buy a Ford 9"
He Said I could find a new one, moser or Currie for about 2k.
I called moser, they're about $2,700.00
Soooo, I'm putting it back in for now, measure for a drive shaft and get that ordered (don't have one) and I'm going to stick with the plan for the Eaton, Moser and gears, utilize the casing and order the parts when I find someone local that comes recommended, I need to make some local connections and find a shop.
Oh well, I wanted to pull the leafs to put on the (Camaro) new spring eye brackets anyway.
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Old 25th-March-2017, 12:33 AM   #9
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Garage
I purchased new Ford 9 from Quick Performance nice set up.
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Old 25th-March-2017, 12:52 AM   #10
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Being an old Ford mechanic I go with the 9in. No laying on your back to work on it, easy to set up and it's stronger than any 10 bolt
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Old 26th-April-2017, 05:39 PM   #11
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Currently I have a one wheel wonder right and want a posi rear end. If I'm going to light up the tires, I want to see two marks on the road. It's a weekend driver in town and highway. I have an 8.5" diff.

Can someone help me understand the difference in the following rear ends I see on Eaton's website? Also gear set up for highway driving. Right now I have the original transmission, 3 speed automatic, but I'm thinking about swapping that out as well down the road for lower rpm's on the highway. I'm guessing I may want a different set of gear once I swap out the transmission. And then what is a good transmission and how many speeds, 4, 5, 6, overdrive?

Detroit Truetrac
Detroit Automatic Lockers
Eaton Posi (limited-slip)

Thanks,
Rob
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Old 26th-April-2017, 09:46 PM   #12
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Your not going to shatter a 8.5 that is built with what you have. Especially with street tires.

Way to many people over build rear ends thinking they need to.


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Old 27th-April-2017, 01:11 PM   #13
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True trac is a worm gear style posi unit originally developed for road racing. they work very well.

detroit locker is a locker so under power they will be locked and you will drag tires around the corners. they will unlock off throttle and under lifght acceleration only.

Eaton clutch posi is basically an updated version of the old 12 bolt style posi units from the 60's. now they run carbon fiber clutches, 400lb springs, and chromolly spider gears.

I agree that many people over build their rearends. Some do it planning on further upgrades down the line, others do it because someone else told them to. For your use a build 8.5 will be plenty strong.

Miles
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Old 27th-April-2017, 04:19 PM   #14
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Eaton posi, Stock 28 spline axles with 2.5" studs, girdle.
I will probably get better axles.
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Old 27th-April-2017, 08:24 PM   #15
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What does weekend warrior mean ? Light to light dragging around town ? Then ok on the 3.73 maybe , but if you do any highway cruising at all my advice is to be careful.

What is the diameter of your rear tires ?

I have a 3.55 and hate it on the highway, ended up putting on bigger rear tires to give it more leg. I have 26.1 " tall tires with overdrive and it's liveable on the highway now.

Also don't believe all the free gear ratio calculators you find on the internet. They are theory, not real world. I higher stall convertor is not going to give you the same 1:1 ratio in drive that a stock convertor will.

I also agree you are not going to necessarily hurt your existing rear end if the tires don't hook hard.

my 2 cents.
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