Positraction Plates Source

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AZScott
Posts: 105
Joined: Mon Aug 15, 2016 11:57 am
Location: Tucson, Arizona

Positraction Plates Source

Post by AZScott »

I am getting ready to do a tear down on a 1964 positraction trans axle. I am getting no movement when I put it up on blocks in netural and spin one wheel, so I am fairly certain I will need to replace the plates. I called Clarks and they no longer sell the plates. Can anyone tell me where I can find a set? Thanks
63 Monza Coupe (164-4 carb)
64 Spyder Convertable
62 MGA Roadster
74 Norton Commando
69 Triumph Bonneville
notched
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Joined: Wed Jul 25, 2012 8:13 pm
Location: Southern New Jersey

Re: Positraction Plates Source

Post by notched »

Used is your only option right now as they are not reproduced. When you say the wheel doesn't move do you mean the opposite wheel doesn't spin? Are you sure the differential definitely has positraction?
1966 Corsa turbo
1969 Monza convertible
1987 Buick Grand National
AZScott
Posts: 105
Joined: Mon Aug 15, 2016 11:57 am
Location: Tucson, Arizona

Re: Positraction Plates Source

Post by AZScott »

Well,... I was relatively certain, its a '64 Spyder with a HJ numbered case, which means it should have a 3.55 Posi in it. I popped the cover and it looks like an open differential.
Image
I would have expected a boxier dif cover so it looks like it may have been swapped at some point in its past. Would appreciate it if someone can positivily identify it. I thought the Posi would be cool, however in Arizona with no chance of snow, a posi may be more of a PIA than its worth.
63 Monza Coupe (164-4 carb)
64 Spyder Convertable
62 MGA Roadster
74 Norton Commando
69 Triumph Bonneville
notched
Posts: 674
Joined: Wed Jul 25, 2012 8:13 pm
Location: Southern New Jersey

Re: Positraction Plates Source

Post by notched »

We need a better picture of the side of the carrier that has the bolts in it. That is the side that holds the clutches on a posi. I wouldn't be surprised if it was removed as the early style 6 bolt positraction covers are known to catastrophically fail.
1966 Corsa turbo
1969 Monza convertible
1987 Buick Grand National
AZScott
Posts: 105
Joined: Mon Aug 15, 2016 11:57 am
Location: Tucson, Arizona

Re: Positraction Plates Source

Post by AZScott »

Here is a better photo of the side of the carrier. It has 32 teeth, so it is a 3.55 rear end.
Image
63 Monza Coupe (164-4 carb)
64 Spyder Convertable
62 MGA Roadster
74 Norton Commando
69 Triumph Bonneville
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bbodie52
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Re: Positraction Plates Source

Post by bbodie52 »

I believe these pictures show the external differences in the Corvair Positraction side of the carrier...
Posi (2).jpg
Posi (2).jpg (94.62 KiB) Viewed 400 times
Posi (3).jpg
:link: http://s1273.photobucket.com/user/1964M ... 9.jpg.html
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
AZScott
Posts: 105
Joined: Mon Aug 15, 2016 11:57 am
Location: Tucson, Arizona

Re: Positraction Plates Source

Post by AZScott »

Thanks again guys, so it appears that what I have is a standard good working 3.55 open axle (non-Posi). I see enough differences between what BBodie52 was good enough to post and what I have to demonstrate that. If any of you experts disagree please let me know.
63 Monza Coupe (164-4 carb)
64 Spyder Convertable
62 MGA Roadster
74 Norton Commando
69 Triumph Bonneville
66vairguy
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Joined: Tue Dec 21, 2010 3:44 pm

Re: Positraction Plates Source

Post by 66vairguy »

Brad - Your pic. looks like the later Posi unit, which had a more robust end cover.

AZscott - even a worn posi will turn both wheels in the same direction. Typically it takes 50ft.lbs to slip one wheel vs. the other on a "GOOD" posi., but even worn there will be some resistance.

If you turn one wheel (axle) and the other rotates in the opposite direction then it's an open (non-posi).

In a rear weight Corvair a posi is of little use unless you plan on driving in a lot of snow and mud. The EM open differentials were stronger than a posi.
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