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Hey all! Clueless as always. My 66 cutlass has what im led to believe is a 10 bolt rear end. Thats as far as I understand. 10 bolt chevy and 10 bolt olds sre different? And if i want to upgrade to better rear end gear I may need to change carriers? And dont get me started on traction upgrades. Lets say a yoing guy is going to pop on over and find some rear end gears more like a 3.55. Where do i find these gears, and is it a simple drop in gear replacement or not? This car is exactly 3 times as old as I am, so forgive the ignorance. Thanks all!!
^66 Gutlass... We will need pictures of the rear cover area to even begin to see what is available for the rear that is under your car.
It could be Buick Pontiac or Chevy...
Will wait for pictures then go from there.
ALL these rears you should be able to get 3.55 gears for with posi carrier and rebuild kits.
THERE is one Buick rear that could be a headache 68-70 era ...AND YES it can be under your car... 50 year old plus car anything can be swapped out as they all interchange.
Jim
JD Race
Hey all! Clueless as always. My 66 cutlass has what im led to believe is a 10 bolt rear end. Thats as far as I understand. 10 bolt chevy and 10 bolt olds sre different? And if i want to upgrade to better rear end gear I may need to change carriers? And dont get me started on traction upgrades. Lets say a yoing guy is going to pop on over and find some rear end gears more like a 3.55. Where do i find these gears, and is it a simple drop in gear replacement or not? This car is exactly 3 times as old as I am, so forgive the ignorance. Thanks all!!
It all depends on what 10 bolt you have. If it's original to the car it's probably a B/P 8.2 rear axle. That axle will accept any B/P gears or posi units. The gear break is 3.23 and numerically lower and 3.55 and numerically higher for which posi unit can be used. I looked @ Summit the other day and a 3.55 gear was the only one available from Richmond. You can search eBay for gear and posi units but must be the B/P axle. Sometimes they list them as a BOP but in reality it's eith a Buick/Pontiac,no Chevy as they are totally different.
It all depends on what 10 bolt you have. If it's original to the car it's probably a B/P 8.2 rear axle. That axle will accept any B/P gears or posi units. The gear break is 3.23 and numerically lower and 3.55 and numerically higher for which posi unit can be used. I looked @ Summit the other day and a 3.55 gear was the only one available from Richmond. You can search eBay for gear and posi units but must be the B/P axle. Sometimes they list them as a BOP but in reality it's eith a Buick/Pontiac,no Chevy as they are totally different.
Mike, can’t you just plug in a 12 bolt posi out of a chevelle pretty easily ?
My 66 cutlass has what im led to believe is a 10 bolt rear end.
Rather than being led, why not look under the back of the car and count the bolts on the rear cover. Your 66 could have come from the factory with a 10 bolt cover, 8.2" BOP axle or a 12 bolt cover, 8.5" Type O if the car was built late in the model year. Of course, the rear may not be original to the car, so a photo would end all speculation.
My W30 did but it sounded like you were saying a 12 bolt Chevy posi unit. Speak clearly and we can communicate.
my communication was solid, plug in a 12 bolt rear end.. now if you took that to mean put the guts into your 10 bolt then thats on you..I certainly don’t claim to be an oldsmobile anything but I have been around enough GM cars, tore enough apart, put enough together to know a thing or two.. and yes I am smart enough to know ya don’t just put a chevy 12 bolt ring and pinion and posi into an oldsmobile..is that clear enough?
Was the Type 'O' actually available during the '66 model year? I thought it didn't become available until midway through '67 ...?
The O type was introduced in the 66 model year. It was around April/May when it was available. It's not a rare axle but it's the only O type that had the flat spring perches & bolt on spring retainers.The O type was available for the entire 67 model year.
my communication was solid, plug in a 12 bolt rear end.. now if you took that to mean put the guts into your 10 bolt then thats on you..I certainly don’t claim to be an oldsmobile anything but I have been around enough GM cars, tore enough apart, put enough together to know a thing or two.. and yes I am smart enough to know ya don’t just put a chevy 12 bolt ring and pinion and posi into an oldsmobile..is that clear enough?
Well the other guy got the same impression,so................
The O type was introduced in the 66 model year. It was around April/May when it was available. It's not a rare axle but it's the only O type that had the flat spring perches & bolt on spring retainers.The O type was available for the entire 67 model year.
Are the springs held to the perches with a plate and bolts? If they are it's more than likely it's the original axle.
so it would appear the bottom perch is integral to the axle tube, with a center piece inside the spring bolted to that perch (retainer?), the top perch also appears to be large and integral and the shock bolts to this upper perch. Upper mount Lower mount, hard to see but bolt in center with round plate.
so it would appear the bottom perch is integral to the axle tube, with a center piece inside the spring bolted to that perch (retainer?), the top perch also appears to be large and integral and the shock bolts to this upper perch. Lower mount, hard to see but bolt in center with round plate.
That's the original 8.2" BOP axle. The number and angle of ribs on the side of the center section will tell you which it is (Type B or Type P). Parts for these are commonly available.
That's the original 8.2" BOP axle. The number and angle of ribs on the side of the center section will tell you which it is (Type B or Type P). Parts for these are commonly available.
How are these things past stock? Mild 330 put through a th350, wont be much power.
So from the pictures it can be a Pontiac or a Buick 8.2 rear end with BOLT in 28 spline axles.
It appears it is a true 1966 rear original to your car.
NOW if this all correct the 8.2 B-P in this year are the same ring and pinion 1964-1967 were all the same 27 spline pinion 1.438 pinion shaft inner bearing land OD.
You can get these gears in 3.36 3.55 3.73 3.90 and if you look really hard there are still 4.10, 4.33 GM and (repop aftermarket fabcraft) 4.56, 5.13 ratios
3.36 3.55 3.73 3.90 are your most common to find at most diff outlets.
THE only difference in the Buick to the Pontiac 8.2 from 64-67 is the pinion Yoke seal surface diameter. Buick is smaller and Pontiac is bigger 1.94"
So a GOOD master bearing kit will have all the parts ...our kits have 3 pinion seals in them to cover any B P set up you might have.
Posi unit are available 3 or 4 series - 4 series being more common as all the 3.36 - 5.13 fit the 4 series.
3 series fits the 2.93 3.08 and 3.23 ratios which you will likely have to find good used.
Hope this info helps.
The whole rear swaps can be 12 bolt olds 66-70 direct
10 bolt buick 1966-1970 direct
10 bolt pontiac 1966-1972 direct
12 bolt chevy 1968-1972 u joint swap only
10 bolt chevy 1968 -1972 u joint swap only
Remember the bottom of a bolt in retained spring factory is slightly larger than the 67 - 72 pig tail but still can work depends on how crazy **** you want to be.
1964 1965 B and P axle assembles are 1" narrower and will fit they will just be a 1/2' narrower on each side
1964- 1967 12 bolt and 10 bolt 8.2 chevy same deal they are narrower by a 1/2" on each side and you will also need a u -joint converstion swap to mate the driveshaft.
Jim
JD RAce
1
Last edited by monzaz; March 8th, 2023 at 10:01 PM.
So from the pictures it can be a Pontiac or a Buick 8.2 rear end with BOLT in 28 spline axles.
It appears it is a true 1966 rear original to your car.
NOW if this all correct the 8.2 B-P in this year are the same ring and pinion 1964-1967 were all the same 27 spline pinion 1.438 pinion shaft inner bearing land OD.
You can get these gears in 3.36 3.55 3.73 3.90 and if you look really hard there are still 4.10, 4.33 GM and (repop aftermarket fabcraft) 4.56, 5.13 ratios
3.36 3.55 3.73 3.90 are your most common to find at most diff outlets.
THE only difference in the Buick to the Pontiac 8.2 from 64-67 is the pinion Yoke seal surface diameter. Buick is smaller and Pontiac is bigger 1.94"
So a GOOD master bearing kit will have all the parts ...our kits have 3 pinion seals in them to cover any B P set up you might have.
Posi unit are available 3 or 4 series - 4 series being more common as all the 3.36 - 5.13 fit the 4 series.
3 series fits the 2.93 3.08 and 3.23 ratios which you will likely have to find good used.
Hope this info helps.
The whole rear swaps can be 12 bolt olds 66-70 direct
10 bolt buick 1966-1970 direct
10 bolt pontiac 1966-1972 direct
12 bolt chevy 1968-1972 u joint swap only
10 bolt chevy 1968 -1972 u joint swap only
Remember the bottom of a bolt in retained spring factory is slightly larger than the 67 - 72 pig tail but still can work depends on how crazy **** you want to be.
1964 1965 B and P axle assembles are 1" narrower and will fit they will just be a 1/2' narrower on each side
1964- 1967 12 bolt and 10 bolt 8.2 chevy same deal they are narrower by a 1/2" on each side and you will also need a u -joint converstion swap to mate the driveshaft.
Jim
JD RAce
1
You can't use a 67 and later spring in a 64-66. The 64-66 spring is open @ the top where the 67 up pig tail down.
No. I was talking about the BOTTOM of the spring pig tail. The 1964-1966 lower spring pig tails are slightly larger than the 1967-1972 pig tails WHERE they meet the spring perch. IF you install a 67-72 rear in a 66 the lower perch will be sloppy on the raise spring perch.
Here is the sentence - Rememberthe bottom of a bolt in retained springfactory is slightly larger than the 67 - 72 pig tail but still can work depends on how crazy **** you want to be.
No. I was talking about the BOTTOM of the spring pig tail. The 1964-1966 lower spring pig tails are slightly larger than the 1967-1972 pig tails WHERE they meet the spring perch. IF you install a 67-72 rear in a 66 the lower perch will be sloppy on the raise spring perch.
Here is the sentence - Rememberthe bottom of a bolt in retained springfactory is slightly larger than the 67 - 72 pig tail but still can work depends on how crazy **** you want to be.
March 6th, 2023, 11:37 AM
