Lets Roll
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I put this drive shaft in a driver and it looks a little close to the 727 what do you think?
Is this driveshaft to long?
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With the full weight resting on the suspension, how far forward will the yoke go into the trans? Hard to tell from the pic. You need 3/4" at the minimum..
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That rubber boot is probably over an inch long. You can be closer to it than if you were comparing it directly against the seal with no boot.
Technically, the diff moves back as the weight goes onto the springs. Since they are mounted solid at the front and swinging at the back, they transfer rearward. Subtle, but mechanical.
Does it equal the up / down difference? Not sure.
Technically, the diff moves back as the weight goes onto the springs. Since they are mounted solid at the front and swinging at the back, they transfer rearward. Subtle, but mechanical.
Does it equal the up / down difference? Not sure.
Last edited:
Bb70charger500
Well-Known Member
We can probably do this a bit more intelligently.
Can you tell use year mand model motor trans then how long that shaft is center of u joint cap to center! If it's been cut and played with we will know if it's not for the car again we will know!
Can you tell use year mand model motor trans then how long that shaft is center of u joint cap to center! If it's been cut and played with we will know if it's not for the car again we will know!
Lets Roll
Well-Known Member
Yes, The full weight is on the suspension.
1969 Roadrunner, 51 1/2 drive shaft,727 18" tail shaft, 1974 440 regular mounts, Mopar performance springs.
Lets Roll
Well-Known Member
Its a close one.
Beware if this is a 1965 trans. The output shaft has a ring limiting how far the driveshaft will go into the trans. Also be aware that depending on where the rear suspension sets the drive shaft can be closer at ride height than at droop. Needs to be cheked through out it travel. Never thought about it until I broke a converter at the track. A friend offered up his drive on hoist in his stacker trailer to swap it. When my race car sets on the wheels the drive shaft is closer to the trans. So close there wasn't enough room to remove it without letting the rear axle hang. That led me the the discovery of the dellema with the output shaft. It pays to check.
Doug
Doug
gdrill had it right in post #4 when he said the drirveshaft the farthest away from tailshaft when full weight is on suspension. If you jack up the car and let suspension hang the driveshaft gets closer to tailshaft. The rear springs go in an arc not straight up and down.
Is the end of the ruler actually where the yoke butts against the trans? It's so close if I were you I'd take the rear straps off and slide the driveline all the way in and note exactly where it stops. The yoke may bottom out sooner if it stops against the inside of the trans, as dvw Doug alluded to. That big bushing-looking thing on the end of the tailshaft...that is a pre-66, yes?
Is t
hat with weigh on the suspension?
Bb70charger500
Well-Known Member
My professional driveline guy that has been doing this for 30+ years says that is the correct length shaft ! You should have no issues unoess there's worn out susp parts or something like that !
Not true, depends on where the pinion C/L sits verses the front pivot (spring eye/ladder bar/4 link instant center). If the axle C/L is above the spring eye the center to center distance will close up at droop. Granted most car don't do this. But checking throughout the range is the proper way to test. As stated, mine is closer at ride height than at droop.
Doug
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