converting to 8 3/4, support plate?

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Frank Miller

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I'm new and dumb but have to ask. In my '65 GT I am changing from the 7 1/4 to an A body 8 3/4 with a 489 third member. In the '65 Dart/Coronet tech. service manual it shows on pages 3-2 and 3-3 the two axles in full assembly drawings and I noticed the lighter 7 1/4 case doesn't have a support where the yoke meets the driveshaft whereas the heavier 489 nose out to the yoke shows a large support plate that must bolt up into the undercarriage? I'm having a suregrip installed right now and my 489 case didn't come with that support plate. What is commomly done when hanging the larger 8 3/4 to support the weight of that big case? Can the spring perches alone keep it happy?
 
Frank Miller said:
I'm new and dumb but have to ask. In my '65 GT I am changing from the 7 1/4 to an A body 8 3/4 with a 489 third member. In the '65 Dart/Coronet tech. service manual it shows on pages 3-2 and 3-3 the two axles in full assembly drawings and I noticed the lighter 7 1/4 case doesn't have a support where the yoke meets the driveshaft whereas the heavier 489 nose out to the yoke shows a large support plate that must bolt up into the undercarriage? I'm having a suregrip installed right now and my 489 case didn't come with that support plate. What is commomly done when hanging the larger 8 3/4 to support the weight of that big case? Can the spring perches alone keep it happy?
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not sure what you are referring to, the pinion snubber or the shock mount plates? The pinion snubber does not bolt to the unibody, it just bolts to the front of the hogshead and keeps the axle from winding up under hard acceleration. The shock mount plates are a must-have to mount the axle to the leaf springs, and your old ones from your 7 1/4 will not work due to the difference in diameter of the axle tubes.
-Tim
 
There is a plate with a bump stop on it that mounts to the front of the pinion. Thats the only thing I can think of.
 
I'm refering to the picture I mentioned on the '65 Dodge tech serv man. pg. 3-2 that shows a rectangular plate that bolts onto the hogshead. I see now that it's just to hold that bumpstop and doesn't attach to support anything. I guess I'm missing that part. I assume that it would be close to impossible to find. Can I live without it if I don't intend on 'gettin on it' or should I fabricate something to hold some form of rubber bumper?
 
That sounds like the pinion snubber mentioned above. I'm not running one at the moment because I'm waiting on the funds to but an adjustable one. They arent hard to find, I'm sure there are quite a few people on the forum that have one or two in their garage. They pop up on here once in a while.
 
you can buy an adjustable pinion snubber on the aftermarket, but check the junkyards because one from any 8 3/4 should work.
 
That is the pinion snubber and they are not hard to find at all. I just sold one for $10 last week. It was a stock type. as mentioned you can get an adjustable one also. You don't even have to have one at all. It just keeps the axle from winding up on hard acceleration.
 
I have one i will sell you for the same 10 plus shipping .pm me if interested
 
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