How do I measure the length I need for a driveshaft?

[wicked93gs]

All right, here is my situation...I have a Mod Motor w/ a T45 and a 8.8" Lincoln rear end. I will be using an aluminum driveshaft from a crown vic or an aerostar, or whatever else I find thats the most convienent. Now the rear end does not have a driveshaft yoke...its got kind of a circular plate with holes if you know what I am talking about...the T45 I dont yet have a yoke for, but will be picking one up soon...so I am trying to match this "plate" on one side(which I am betting is the same setup crown vics use) to a more conventional yoke on the other and am wondering how I will need to go about taking the correct measurement. I know I can convert the rear end to a conventional yoke as well, but if there is no advantage to doing so I dont see why I should(just adds extra cost) is there any advantage?

 

[2+2GT]

All right, here is my situation...I have a Mod Motor w/ a T45 and a 8.8" Lincoln rear end. I will be using an aluminum driveshaft from a crown vic or an aerostar, or whatever else I find thats the most convienent. Now the rear end does not have a driveshaft yoke...its got kind of a circular plate with holes if you know what I am talking about...the T45 I dont yet have a yoke for, but will be picking one up soon...so I am trying to match this "plate" on one side(which I am betting is the same setup crown vics use) to a more conventional yoke on the other and am wondering how I will need to go about taking the correct measurement. I know I can convert the rear end to a conventional yoke as well, but if there is no advantage to doing so I dont see why I should(just adds extra cost) is there any advantage?

It's called a pinion flange. Even when it's a one-piece with integral yoke, it's still usually called a pinion flange. No advantage to altering the design.

Measure the driveshaft length center to center on the joint holes. Measure with no weight on the axle, this is when the slip yoke will be pushed the farthest into the trans. When weight is on the axle, it will slide out as much as 1/2"

 

[garner67]

Here's an image for measuring a slip yoke from your trans to a pinion flange.

 

[wicked93gs]

thank you, I was curious about that....I take that measurement and the driveshaft to a driveshaft shop and voila! they give me the right size?

 

[2+2GT]

thank you, I was curious about that....I take that measurement and the driveshaft to a driveshaft shop and voila! they give me the right size?

Yeah, that's pretty much it. They'll even make on new from parts.

 

[wicked93gs]

hmm, I guess this is when I need to do any final motor mount modifications(not 100% happy with the back of my valve covers being 2.5" off the firewall...was thinking of pushing it back a bit)