Different drive shaft?

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Snake

Snake

Mopar Nut
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69 dart with 7 1/4 going to the 8 3/4.I have read that if I install an 8 3/4 I will have to chandge my drive shaft.says axel centerline to yoke centerline is greater. on the 8 3/4 than the 7 1/4 I know I need dirrerent shock plates and thought my drive shaft would have to shortened thats it.Any thouights.
 
Yes you will need to change the length of your driveline. I ran into the same thing when i swapped my rear. And yes you are correct that you will need different shock plates. this is also a great time to replace your u bolts and u joints.
 
Just changed mine on my 65 valiant.. Measured to be sure but they cut 2 inches off... fits perfect 1 inch free play on the front yoke.
 
Snake said:
69 dart with 7 1/4 going to the 8 3/4.I have read that if I install an 8 3/4 I will have to chandge my drive shaft.says axel centerline to yoke centerline is greater. on the 8 3/4 than the 7 1/4 I know I need dirrerent shock plates and thought my drive shaft would have to shortened thats it.Any thouights.
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As long as you're not changing the position of the tranny, I'm pretty sure your drive shaft will have to be shortened because the 8 3/4 pumpkin is longer (pinion yoke centerline to drive axle centerline) than the front end of the 7 1/4 and 8 1/4.
 
Well thats good news just what i thought.Now from what I also read I should stay away from cone type pumpkims.are all non sure-grip pumpkins cone type.I have found a 8 3/4 rearend with the sb axels not sure grip its a 489 case.Great price 250 for everything.Any outher thoughts here guys.
 
not sure but I think
7 1/4 to 8 1/4 is minus 1 1/2 inches
7 1/4 to 8 3/4 is minus 2 inches
also 7 1/4 uses 3 1/2 inch shock plates and U-bolts
8 1/4 and 8 3/4 use 4 inch shock plates and U-bolts
 
489 is the preferred case over the 741, & 742
sure grip units will interchange between cases, ring & pinion will not
sure grip are cone type and clutch type both will fit clutch type is preferred
 
caferacerx said:
also 7 1/4 uses 3 1/2 inch shock plates and U-bolts
8 1/4 and 8 3/4 use 4 inch shock plates and U-bolts
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7.25 uses 2.5" u-bolts and the 8.25 & 8.75 use 3" u-bolts.

FWIW, you can elongate the holes in the 7.25 shock plate 1/4" to the outside and use them on the 3" axle tube of the 8.25 or 8.75. I have been running this way for over 40K miles now.
 
oops my bad on the dimension's 2 1/2" and 3" not 3 1/2" and 4"
thanks I will try elongating the holes if I cant find a pair of 3" plates when I install an 8 3/4

cone type applies to one style of sure grip if it is open it has no sure grip there for is neither cone type or clutch type just open
 
Snake said:
Ok are all non sure grip cone?
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No, Cone refers to a type of sure grip if there is nothing in the housing other than side gears it is referred to as open. There is also the clutch disc type which is the prefered because it can be rebuilt easier. The cone type has wear areas within the housing that can be machined if wore. Here's a writeup on the 2.

http://www.moparts.org/Tech/Archive/axle/13.html
 
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