Re: 1" pullout for driveshaft measurement?
[Re: BDW]
#3151251
06/13/23 03:50 PM
06/13/23 03:50 PM
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Joined: Dec 2018
Posts: 88 IL
83hurstguy
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member
Joined: Dec 2018
Posts: 88
IL
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When I ordered my new driveshaft from Mark Williams, they will go down to 3/4" slip yoke travel (and their tech support recommended that). I think I ended up on the short side of the 3/4" due to rounding measurements.
I converted from a driveshaft with around 1-5/8" slip yoke travel and noticed a vibration improvement from the 1-5/8" to the 3/4". Leaving the U-joint hanging out there too far can be felt, at least with a four speed it can be felt in the shifter. The MW tech confirmed it's a common issue, too. People get worried about the output shaft seal dust boot, make the driveshaft too short, then have a vibration issue.
Last edited by 83hurstguy; 06/13/23 03:52 PM.
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Re: 1" pullout for driveshaft measurement?
[Re: BDW]
#3151406
06/14/23 07:45 AM
06/14/23 07:45 AM
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Joined: Jun 2019
Posts: 744 Almost Heaven
Bob Stinson
super stock
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super stock
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Posts: 744
Almost Heaven
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You don't mention your setup but if the factory built the same body style with the same transmission and rear end, the easy way to get it right is to use the length from the FSM.
69 road runner A12 ex-racer 71 Duster w/ a 400
Shiny paint causes stress.
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Re: 1" pullout for driveshaft measurement?
[Re: BDW]
#3151739
06/15/23 11:59 AM
06/15/23 11:59 AM
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Joined: Jan 2003
Posts: 25,910 Rio Linda, CA
John_Kunkel
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Too Many Posts
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Posts: 25,910
Rio Linda, CA
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So is it better err on a longer DS, 1/2" pulllout? Keep in mind that the u-joint cups are are 1"+ in diameter and the cradle in the rear yoke that they sit in is a little over half that deep, so you need at least that much in order to push the shaft forward during installation before pulling it back into the yoke. 3/4" should cover all bases.
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Re: 1" pullout for driveshaft measurement?
[Re: BDW]
#3151831
06/15/23 04:51 PM
06/15/23 04:51 PM
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Joined: Jan 2003
Posts: 4,741 Moved to N.E. Tennessee
GomangoCuda
master
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master
Joined: Jan 2003
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Moved to N.E. Tennessee
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The two different size or different brands of front yokes might be different lengths. Best to get the yoke and then measure for drive shaft. No guessing here.
Last edited by GomangoCuda; 06/15/23 04:53 PM.
In theory, there is no difference between theory and practice. In practice, there is.
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Re: 1" pullout for driveshaft measurement?
[Re: GomangoCuda]
#3152002
06/16/23 11:03 AM
06/16/23 11:03 AM
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Joined: Dec 2005
Posts: 11,645 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,645
Fulton County, PA
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3/4" here.
Some kind of weird pinion angle, leaf spring setup may need more.
If the results don't match the theory, change the theory.
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Re: 1" pullout for driveshaft measurement?
[Re: BDW]
#3152005
06/16/23 11:10 AM
06/16/23 11:10 AM
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Joined: May 2005
Posts: 4,748 Florida
BDW
OP
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OP
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Appreciate the input, another question
Would changing the front yoke to 1350 from 7290 and using a conversion u-joint change the DS length? 1350 is a little larger, so maybe only 1/16 or 1/8" ?
Thx I’ll answer my own question on this part, 1350 has 1/16” larger cup size compared to 7290. So 1/2 of that 1/16” would make it 0.030” longer, nothing to worry about. I’m going 3/4” when I get around to getting this done.
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Re: 1" pullout for driveshaft measurement?
[Re: BDW]
#3152026
06/16/23 12:23 PM
06/16/23 12:23 PM
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Joined: Dec 2005
Posts: 11,645 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,645
Fulton County, PA
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Appreciate the input, another question
Would changing the front yoke to 1350 from 7290 and using a conversion u-joint change the DS length? 1350 is a little larger, so maybe only 1/16 or 1/8" ?
Thx I’ll answer my own question on this part, 1350 has 1/16” larger cup size compared to 7290. So 1/2 of that 1/16” would make it 0.030” longer, nothing to worry about. I’m going 3/4” when I get around to getting this done. True. But the hole is bigger. The C/L doesn't move. Does a larger or smaller crank pin journal change the stroke?
If the results don't match the theory, change the theory.
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Re: 1" pullout for driveshaft measurement?
[Re: CMcAllister]
#3152064
06/16/23 02:29 PM
06/16/23 02:29 PM
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Joined: Jan 2003
Posts: 4,741 Moved to N.E. Tennessee
GomangoCuda
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master
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Moved to N.E. Tennessee
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Yes but is the bottomed out length the same on all yokes? Different brands, different materials, oem, aftermarket forged or billet. All the same?
In theory, there is no difference between theory and practice. In practice, there is.
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Re: 1" pullout for driveshaft measurement?
[Re: GomangoCuda]
#3152102
06/16/23 06:07 PM
06/16/23 06:07 PM
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Joined: May 2005
Posts: 4,748 Florida
BDW
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Florida
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Yes but is the bottomed out length the same on all yokes? Different brands, different materials, oem, aftermarket forged or billet. All the same? Very good question, I have 2 different yokes, 1 aftermarket cast, and a factory forged that came with the 518 when I pulled it at JY.
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