Is this differential a posi?
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From: Orlando FL
Is this differential a posi?
I just picked up a rear end that I want to switch out my current one with, but after I got home I realized its missing the springs that I always thought made it a limited slip.
It has an OH stamping on the cover which is a 78 or 79 and being after a 70 should automatically make it a posi, but I dont know the history of it. Could have been rebuilt or who knows what.
Thanks for any help!
It has an OH stamping on the cover which is a 78 or 79 and being after a 70 should automatically make it a posi, but I dont know the history of it. Could have been rebuilt or who knows what.
Thanks for any help!
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From: Orlando FL
So this is a posi unit, but just without the springs and plates?
I was reading some other threads and one said if you turn the pinion and both side axles turn the same direction then its a posi, but then another thread said the opposite. One should turn the other direction.
I was reading some other threads and one said if you turn the pinion and both side axles turn the same direction then its a posi, but then another thread said the opposite. One should turn the other direction.
Le Mans Master
Joined: May 2006
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From: League City Tx
It could still be a posi if the clutches are setup to spec (ie. tight) and not relying on springs/plates to provide preload.....
BUT if you spin the pinion or one of the side yokes, the other side yoke may spin the opposite direction because there is no springs/plates to preload the clutches....BUT once you put real torque into the pinion from the engine, the clutches will lock...
Problem is, you don't know if the clutches have been setup like that or not....Most rebuilders do not take the time to do this..... Tracdogg2 and GTR1999 both setup or "tune" the clutches like this and do not use springs/plates for preload...This is something that has to be measured out and shimmed.
Tracdogg just built my super 10 bolt and it doesn't use springs/plates....If I turn one side yoke, the other goes backwards....but I guarantee you my posi is working......I just made 5 passes at the strip....
BUT if you spin the pinion or one of the side yokes, the other side yoke may spin the opposite direction because there is no springs/plates to preload the clutches....BUT once you put real torque into the pinion from the engine, the clutches will lock...
Problem is, you don't know if the clutches have been setup like that or not....Most rebuilders do not take the time to do this..... Tracdogg2 and GTR1999 both setup or "tune" the clutches like this and do not use springs/plates for preload...This is something that has to be measured out and shimmed.
Tracdogg just built my super 10 bolt and it doesn't use springs/plates....If I turn one side yoke, the other goes backwards....but I guarantee you my posi is working......I just made 5 passes at the strip....
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Thread Starter
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From: Orlando FL
ok, just check the rotations. Pinion turns both axles the same direction. If I turn one axle the other turns the same direction. I can hold one axle still and turn the pinion and the other axle rotates.
I guess this is a definite indication that its a posi thats been 'tuned'. Did the 78 and 79s all have springs and plates?
I guess this is a definite indication that its a posi thats been 'tuned'. Did the 78 and 79s all have springs and plates?
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From: Orlando FL
ok, just check the rotations. Pinion turns both axles the same direction. If I turn one axle the other turns the same direction. I can hold one axle still and turn the pinion and the other axle rotates.
I guess this is a definite indication that its a posi thats been 'tuned'. Did the 78 and 79s all have springs and plates?
I guess this is a definite indication that its a posi thats been 'tuned'. Did the 78 and 79s all have springs and plates?
Race Director
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From: Dayton, Ohio
Race Director
Joined: May 2006
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From: Dayton, Ohio
You can solve this by looking in to see if the side gears have clutches behind them. You should also be able to see if the clutch guides are there.
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From: Orlando FL
Thanks
Race Director
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From: Dayton, Ohio
Yes inside where you have the red arrow and on the other side under the side gear.
One of the guides will be just under the point of the red arrow,its a half of of tube looking thing that holds the ears of the clutch plates.
One of the guides will be just under the point of the red arrow,its a half of of tube looking thing that holds the ears of the clutch plates.
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From: Orlando FL
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From: Orlando FL
Yep, thats mine. Seems as if someone has taken the springs out from what Ive been reading. Question is has it been 'tuned' correctly or even at all? I tried to take a better pic of the carrier to ask if its been polished. This would be a sign that its been tuned and possibly correctly??
There isnt a lot of slop in the spider gears, no rattle back and forth if I turn the axles. One interesting note is when I turn the pinion and hold the drivers side everything else rotates freely. When I hold the passenger side however it binds up and is difficult to turn. Could this mean the clutches or bearings need attention?
There isnt a lot of slop in the spider gears, no rattle back and forth if I turn the axles. One interesting note is when I turn the pinion and hold the drivers side everything else rotates freely. When I hold the passenger side however it binds up and is difficult to turn. Could this mean the clutches or bearings need attention?
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From: Orlando FL
No word yet from Gary.
I did notice that the clutches that were used were the snowflake variety so replacing them with solid clutches should give me a definite reason to start breaking it down. Whats the best brand and place to get them, and also the shim kit to?
Alex
I did notice that the clutches that were used were the snowflake variety so replacing them with solid clutches should give me a definite reason to start breaking it down. Whats the best brand and place to get them, and also the shim kit to?
Alex
