CTS Spider

[SuperBuickGuy]

fun fact-- the "12 bolt" actually refers to the # of bolts that hold the ring gear to the carrier.
a B.O.P. 12 bolt has a 12 bolt cover....but only 10 bolts on ring gear. the chevy 12 bolt
has 12 bolts on the cover AND the ring gear.

its a known "no-no" to use the B.O.P. 12 bolt for a performance application.

fun fact, there is no such thing as a BOP 12 bolt.

the 10 bolt is different then the Chebby 10 bolt in that the BOP a semi-float design, however, there is no 12 bolt BOP... sorry.

more amazing stuff though, you can more easily shorten a 10 bolt BOP because the shafts aren't tapered

Biggest problem of the 10 bolt BOP is that Auburn is the only 'locker' available - and that's a limited slip

Sadly, differentials were the first to fall to the bean counters - when GM came up with the 12 bolt, the bean counters believed that they did not need 2 different 10 bolts and a 2 stronger 12 bolts.

And I'm pretty sure you're thinking of the 50s Oldsmobile rear... but that's a rear end for another day.

[langleylad]

fun fact, there is no such thing as a BOP 12 bolt.

the 10 bolt is different then the Chebby 10 bolt in that the BOP a semi-float design, however, there is no 12 bolt BOP... sorry.

more amazing stuff though, you can more easily shorten a 10 bolt BOP because the shafts aren't tapered

Biggest problem of the 10 bolt BOP is that Auburn is the only 'locker' available - and that's a limited slip

Sadly, differentials were the first to fall to the bean counters - when GM came up with the 12 bolt, the bean counters believed that they did not need 2 different 10 bolts and a 2 stronger 12 bolts.

And I'm pretty sure you're thinking of the 50s Oldsmobile rear... but that's a rear end for another day.

Hey how’d you get to be so darn smart at all this automobile stuff ! …. Golly!

[fatguyzinc]

the 50's old is a 9.3, got one sitting on the side of the house.
there are 12 bolt 'cover' BOP axles, but no true 12 bolt ring
gear BOP axles.

a 10 bolt chevy is either 8.2 (early) 8.5 (relatively strong with
a aftermarket carrier, axles & girdle cover, like 450hp strong
or more in a light car.) or 7.5 (late model astro,s10, camaro,
most g bodys except GN & a few 442 olds i think,etc... but
its total weak sauce. ) theres also a weird 6.5
inch 10 bolt in vegas or a 7.5 in cosworth vegas...

the 12 bolt is a 8.875, a bit bigger than a 8.75 mopar but
the mopar all were nodular center and 30 spline factory,
and a bit smaller than a 9"ford. like the 8.5 10 bolt, an
aftermarket carrier, shafts and a girdle boost it to very
good power levels, like 600hp.

it also has the benefit (passenger car axle--truck was
smaller for some reason...) of having a 1.625 pinion shaft
as does the 8.5 inch 10 bolt.

everyone loves the 9 ford, id take a 8.75 mopar over
a stock 28 spline regular cast iron 9 anyday.

and if youre already going to shorten it... dana 60.
bigger, stronger, cheaper than 9 ford.

just my .....

[SuperBuickGuy]

the 50's old is a 9.3, got one sitting on the side of the house.
there are 12 bolt 'cover' BOP axles, but no true 12 bolt ring
gear BOP axles.

a 10 bolt chevy is either 8.2 (early) 8.5 (relatively strong with
a aftermarket carrier, axles & girdle cover, like 450hp strong
or more in a light car.) or 7.5 (late model astro,s10, camaro,
most g bodys except GN & a few 442 olds i think,etc... but
its total weak sauce. ) theres also a weird 6.5
inch 10 bolt in vegas or a 7.5 in cosworth vegas...

the 12 bolt is a 8.875, a bit bigger than a 8.75 mopar but
the mopar all were nodular center and 30 spline factory,
and a bit smaller than a 9"ford. like the 8.5 10 bolt, an
aftermarket carrier, shafts and a girdle boost it to very
good power levels, like 600hp.

it also has the benefit (passenger car axle--truck was
smaller for some reason...) of having a 1.625 pinion shaft
as does the 8.5 inch 10 bolt.

everyone loves the 9 ford, id take a 8.75 mopar over
a stock 28 spline regular cast iron 9 anyday.

and if youre already going to shorten it... dana 60.
bigger, stronger, cheaper than 9 ford.

just my .....

then I have the rarest BOP axle of all... 10 bolts on the cover... 8.2 gear... semi-float.

[Deaf Bob]

then I have the rarest BOP axle of all... 10 bolts on the cover... 8.2 gear... semi-float.

Derby guys call them BIA... Bolt In Axles..
kid did burnouts with his before I gave him a 65 Elky rear and put in 3:40’s and limited slip

saw one “12 bolt” in an Electra. Was given $500 for it. Then hada hell of a time making up a 10 bolt to work in it.

[fatguyzinc]

then I have the rarest BOP axle of all... 10 bolts on the cover... 8.2 gear... semi-float.

remember the camel cigarettes tag line, "turkish gold"?
you, my friend, have turdish gold. hah hah....

[SuperBuickGuy]

Turkish gold, just for you.... how many bolts are in that rear cover?

now remember, Sal, it comes from God to me then to you

I am curious, though, is Sal short for Salad? or are you a few croutons short of a salad, thus, sal? I know it isn't because of a healthy diet

so let's add some info - there are 2 10 bolt BOP rears, the 64 to 66 version then a 70-72 version - the 64 version is a 8.2 ring gear size and has scallops on the sides of the cover, the later one, doesn't have scallops and is an 8.5 10 bolt - but nothing inside interchanges with the Chevy.. this is NOT the 8.5 Chevy 10 bolt. Apparently the one I have is pretty rare, but that and 5 bucks will get you a drip coffee - rare doesn't equal valuable in either of the BOP rears because there is very little aftermarket support for them.

I know of the differential you're thinking - iirc it's some version of the pickup truck 12 bolt... I dunno, never dealt with them because there's 14 bolts....

[Captain]

remember the camel cigarettes tag line, "turkish gold"?
you, my friend, have turdish gold. hah hah....

I thing you all have been "Smokin' Something - Something"....sounds like a parts matching "Nightmare" to me......

From Dat Dissident Ford Guy.......LOL

[Deaf Bob]

Turkish gold, just for you.... how many bolts are in that rear cover?

now remember, Sal, it comes from God to me then to you

I am curious, though, is Sal short for Salad? or are you a few croutons short of a salad, thus, sal? I know it isn't because of a healthy diet

so let's add some info - there are 2 10 bolt BOP rears, the 64 to 66 version then a 70-72 version - the 64 version is a 8.2 ring gear size and has scallops on the sides of the cover, the later one, doesn't have scallops and is an 8.5 10 bolt - but nothing inside interchanges with the Chevy.. this is NOT the 8.5 Chevy 10 bolt. Apparently the one I have is pretty rare, but that and 5 bucks will get you a drip coffee - rare doesn't equal valuable in either of the BOP rears because there is very little aftermarket support for them.

I know of the differential you're thinking - iirc it's some version of the pickup truck 12 bolt... I dunno, never dealt with them because there's 14 bolts....

Pickup 12 bolts are stand alones..

[SuperBuickGuy]

Pickup 12 bolts are stand alones..

I think, also, the ring gear in them is 10 bolt. Once FGZ stops goldbricking, he can pop under his Blazer and check this out for us (get well, buddy!)

[fatguyzinc]

I think, also, the ring gear in them is 10 bolt. Once FGZ stops goldbricking, he can pop under his Blazer and check this out for us (get well, buddy!)

the pickup 12 bolt has 12 bolt ring gear, i know only because
i once got a car gearset by accident and ring went on carrier fine...
but the pinion bearings were way too small to fit pinion.
as for looking at blazer--cant.... got 8 lug remember?

[SuperBuickGuy]

the pickup 12 bolt has 12 bolt ring gear, i know only because
i once got a car gearset by accident and ring went on carrier fine...
but the pinion bearings were way too small to fit pinion.
as for looking at blazer--cant.... got 8 lug remember?

point is I've heard of the differential that you're talking about - this just isn't that differential.

[Loren]

I may be headed to the LA area of California after the new year because of my wife's bloodhound stuff... that would be an interesting build.... tempting

Let me know if you want that 300 by the 15th (iron block, alum heads, 2bbl, inner condition unknow, a buck-a-cubic-inch) and I can shuffle it to a friend's up the 14 from Santa Clarita where it could be picked up whenever. Otherwise it can sit here waiting to see if its' original intended use ever happens along with 20 other "spare" (hah) motors...

[SuperBuickGuy]

Let me know if you want that 300 by the 15th (iron block, alum heads, 2bbl, inner condition unknow, a buck-a-cubic-inch) and I can shuffle it to a friend's up the 14 from Santa Clarita where it could be picked up whenever. Otherwise it can sit here waiting to see if its' original intended use ever happens along with 20 other "spare" (hah) motors...

will do and thank you. I thought, for a moment, that it might not happen because my wife found a pup in Idaho but that fell through so we're still in the market.

I was watching some autocross stuff last night - and guys who gutted Datsun Fairladys and thought "you know, with a simple turbo 4 cyl I could do that.... granted the 124 is 1/3 larger then a fairlady.... but still....