Wanna help me build a 12 bolt rear?

307 Regal

307 Regal

Royal Smart Person
Oct 21, 2009
1,524
296
83
Northern Indiana
#1
So I'm trying to help my dad get the ball rolling on his long-stagnant '65 Biscayne (Impala (B body)) and I was asked to work on getting a rear end built. I have some (of his) 12 bolt 4-link housings to work with and a girdle cover to use. They're open-diff rears that need rebuilt. I only need one to actually install of course.

Here's what he's interested in:
-Streetable limited slip (non-spool) carrier for a 4.56:1 ring and pinion -or- 4.11 / 3.73 "in the future." (So do they make 4.56s for a 3 series carrier?)
-Strange brand axles or equivalent
--C-clip elimination (I didn't even research that for my own rear so I have no experience shopping for or installing those parts)
-Timken bearings or equivalent

Here's some info on the car and the likely direction it will take:
It's a '65 2-door post Chevy Biscayne, no fiberglass, full interior on stand-by, it will be a 4-speed car (Borg Warner Super T-10), and may be running either 8 inch pie crust slicks (reproductions) or a 275 drag radial. It will most likely be taken to a drag strip, but it's mostly being planned as a "period" tribute car with very minor resto-modding that he can take out and have fun with. He says he's "not planning on having 700 horsepower" or any boost. Engine selection is still a toss-up.

I haven't started shopping yet, but I intend to start as soon as I punch "create thread" on here. I'd love to have some good forum know-how behind me while I'm scoping out parts. Thanks ahead of time, guys.
 
307 Regal

307 Regal

Royal Smart Person
Oct 21, 2009
1,524
296
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Northern Indiana
#2
I guess I should also add:
-What size are 12 bolt carriers? 8.75" ring gear??
-What axle spline count is a good choice for a 12 bolt? 30?
-Do I need to worry about yoke compatibility when looking at ring and pinion sets?
-Is Moser just as good as Strange?
 
Last edited:
fleming442

fleming442

Comic Book Super Hero
Dec 26, 2013
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#3
I'd say Moser and Strange are both on par.
As far as I know, the same carrier will work for 3.73-4.56, and yes, you can get 4.56.
I have a TruTrac, and am a huge fan.
If you want c-clip elimination, weigh prices on the Strange 60, a Quick Performance 9", and total cost of doing your 12 bolt with Ford ends. I ditched my 12 bolt....
 
UNGN

UNGN

Comic Book Super Hero
Sep 6, 2016
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#4
My dad (78 years old) and his buddies ordered 4.56 gears in their early 60's cars because they were only running high 90's mph in the 1/4. Stock Honda Accords/Toyota Camry's run faster than this today.

3.73's would be better choice for 28" tires (275/60's) if he isn't going to run solid lifters and wants a car that doesn't hit a wall on the top end... unless he just wants to pop the clutch and pull a tire and really doesn't care who passes him at half track.
 
307 Regal

307 Regal

Royal Smart Person
Oct 21, 2009
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Northern Indiana
#5
...would...
...unless...
He's pretty old-school. I think he's mostly just wanting something he likes the idea of, and only cares if it performs well for the seat of his pants. I'm not sure how thought-out his plans are, but as far as 4.56s I think he's just more concerned about moving 4000lbs with what's more than likely going to be a mild engine. He's a small block fan and I can't imagine him going any higher than 400 horse, if that, especially with our budget, his age, and our lack of trailer & tow vehicle.

[Rambling]
I'd ask him about his engine thoughts, but my main objective is to get the car (literally) rolling (if not running with some engine) to ween him off our clapped-out 305/TH350 '71 Sprint. He only uses (let alone keeps) the Sprint because it runs and drives, and my hope is that if I can rebuild the Biscayne past the point of "it's a some-what rolling chassis with a paint job" then he'll feel like the car he actually likes is less of a mountainous project to tackle and "god willing" he'll actually get out and enjoy it before he's too old. The car's been sitting since '09. It feels bad to think that my dad is the whole reason I'm into cars, and with his help and tools we've redone almost my entire Regal short of a frame-off in his driveway, and yet there his car sits in the garage. He won't drive my car despite me offering many times, and if we'd put the same effort into his car instead of mine then it'd pretty much be done. It's disheartening and I just wanna get him out there in his own car.

The big problem is that my dad is very particular and wants to do things "exactly right" the first time. The whole reason the 307 Chevy in the car hasn't run since '09 is because my brother borrowed the headers for the then-his Sprint. And "I need a set of headers for my '65" turned into "which engine should I use" turned into "I should have it built first" turned into "every bolt on this car needs redone" turned into "I just don't have time."
[/Rambling]

All that being said, I could probably sell him on 4.11 gears. I get the feeling he wants something "old-school drag-racey" for gears. What do you think would be good for ~350-375hp in a 4000lb car? Just out of curiosity.

Also, he says if it's too costly or complicated we can skip the c-clip eliminators. So that's about how serious we are about racing it at the moment.
 
TURNA

TURNA

Comic Book Super Hero
Jul 24, 2009
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Socialist NY
#6
Ford 9 "
















:banana:
 
pontiacgp

pontiacgp

Canadian Prime Minister
Mar 31, 2006
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#7
I would skip the c clip eliminators, they have a tenancy to leak.
 
UNGN

UNGN

Comic Book Super Hero
Sep 6, 2016
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Southlake, TX
#8
On of my dad's favorite stories was they convinced one of their friends to order a 60 chevy with a 348 tripower, a 4 speed and a 4.56 gears and then they "deleted" the mufflers. They were piled in it terrorizing the town one night, doing launches and going through the gears.

Even with two people in the back seat, the car would be all over the road through first and second. The cops eventually pulled them over and told them to "come with us". During one of their runs, their rear bumper snagged the bumper off a parked car, tore it off and flung it into a house. They had no idea.

The owner of the house called the cops when he was startled from a car bumper hitting his house.
 
lilbowtie

lilbowtie

Royal Smart Person
Jan 7, 2006
2,110
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Canton Mi
#9
If you google it you will find there is a lot of info & vids on set-up and building a 12 bolt. If it helps here are some different gears ratios and what you will be turning at different rpms (28 in tall tire) Before you pic a gear your engine combo is going to dictate what should be back there.

3rd GEAR RPM
2500 2750 3000 3250 3500 3750 4000 4250 4500 4750 5000
3.42 61 67 73 79 85 91 97 104 110 116 122 M.P.H
4.11 51 56 61 66 71 76 81 86 91 96 101
4.30 48 53 58 63 68 73 78 82 87 92 97
4.56 46 50 55 59 64 69 73 78 82 87 91
4.88 43 47 51 55 60 64 68 73 77 81 85

360 HP will give him a respectable 13.0 et in a 4000 lb car. (my spread sheet didn't copy well)
 
307 Regal

307 Regal

Royal Smart Person
Oct 21, 2009
1,524
296
83
Northern Indiana
#10
Updates:

Well, We've settled for 4.11s. In short, it seems that he's not going to be bothered with optimization. The most I got out of him is that he probably won't be turning more than 6000RPM and doesn't have any horsepower goals. He just wants something playful to drive. I appreciate the numbers regardless, lilbowtie, and look forward to hearing what you might have to say the day I finally post an ET slip for my Buick 350. (This spring???)

C clip elimination has been dropped at this point. We should be fine with a good quality axle set.

As predicted, even the passing mention of a Ford 9" was met with flaring nostrils and a shaking head, practically before the words even got all the way out of my mouth. lol

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Is there any merit behind using an "adjustable" pinion sleeve (think "shims") versus using a standard crush sleeve to set the pinion depth? If it's a reliable alternative then I really wouldn't mind using one.
 

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