Front drive shaft

• May 3, 2023

• #1

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brentcovey

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Can someone please tell me what size bolts I need for the flange of the front drive shaft on my 79 K20?

 

• May 3, 2023

• #2

bucket

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They are 7/16", course thread. About 1.25" long.

^going off of memory here^

 

• May 3, 2023

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SquareRoot

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bucket for the win!

 

• May 3, 2023

• #4

bucket

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SquareRoot said:

bucket for the win!

Click to expand...

I don't know about that, lol. I'm not home and can't verify the accuracy of my memory.

 

• May 3, 2023

• #5

SquareRoot

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It's accurate, I got one laying on the bench at the moment.

 

• May 4, 2023

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brentcovey

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Thank you!

 

• May 4, 2023

• #7

mtnmankev

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7/16" head size, or threaded shank size ?
There's a slight difference.

 

• May 4, 2023

• #8

SquareRoot

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mtnmankev said:

7/16" head size, or threaded shank size ?
There's a slight difference.

Click to expand...

First off, Bucket and I were both wrong. The correct bolts are 7/16-20 (fine thread), 1-1/4 long and a 5/8 head. Sorry, carry on. My shaft is at the drive line shop getting shortened and rebuilt. These are the correct bolts.

 

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• May 5, 2023

• #9

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brentcovey

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Thanks for the update!

 

• May 5, 2023

• #10

bucket

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SquareRoot said:

First off, Bucket and I were both wrong. The correct bolts are 7/16-20 (fine thread), 1-1/4 long and a 5/8 head. Sorry, carry on. My shaft is at the drive line shop getting shortened and rebuilt. These are the correct bolts.

Click to expand...

Interesting. I'm still fairly certain that the ones I've had were course thread.

But yeah, 7/16" bolt size, not head size. Head size of any bolt can vary with different manufacturers. For some reason, the 7/16" size seems to be the most inconsistent.

 

• May 7, 2023

• #11

bucket

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Yep, all my 205's and 208's use a course thread bolt. It looks like my 203's do as well, but I didn't pull a bolt to confirm.

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• May 7, 2023

• #12

SquareRoot

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Interesting,They must have changed pitch at some point. Mines an 85, OE and definitely fine thread. I guess if I were the OP I would just buy both. It's not like it's gonna break the bank.

 

• May 8, 2023

• #13

bucket

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SquareRoot said:

Interesting,They must have changed pitch at some point. Mines an 85, OE and definitely fine thread. I guess if I were the OP I would just buy both. It's not like it's gonna break the bank.

Click to expand...

I'm thinking it must have depended on the supplier for different plants? My 88's original was course thread. The replacement was as well, but I don't recall what year it was made.

 

• May 8, 2023

• #14

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brentcovey

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I will definitely get both. Never can have too many extra bolts around.