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Do I need a longer drive shaft?

Soylent

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69 with a 2.5” WH lift and 7* C bushings. The cap wont reach the threads. What is recommended for a new shaft? Are there off the shelf options for this lift or do I need to measure yolk to yolk. I had Reel on my heap but I think that’s all they build for.

IMG_6946.jpeg

Just dawned on me. I have an AX15 so may have shifted the D20 back some?
 

Yeller

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Yes you need a longer driveshaft. You can purchase a new shaft from one of our vendors or have a local shop retube your existing shaft longer. Sometimes the local route is less expensive and sometimes not.
 
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Soylent

Soylent

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Thanks yeller. Is the shaft length the same for D30 or D44 axles? I don’t want to invest in a nice shaft and not be able to use it if I upgrade my D30 to 44.
 

JKH67302

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It's been a while, but I seem to remember my D30 shaft being a little too long when I went to the 44. It fit, but it was too compressed.

Sent from my SM-S916U using Tapatalk
 

jamesroney

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It looks like someone put in a nv3550 or an AX15 in place of your stock transmission.

This moves the transfer case back about 1.5 inches or so. Which usually works out great for your rear driveshaft with the lift...but the front drivshaft ends up short.

As it turns out, the front driveshaft is often in perfect condition, and is serviceable, except it is too short. BUT Spicer, and Neapco make a long travel slip yoke that happens to be about 1.5-2 inches longer. You will find one currently in your rear driveshaft.

You can source a brand new 1310 slip yoke from lots of internet sources for around $53.00 (Spicer 2-3-8021KX for example) Amazon is your friend here.

If the front driveshaft is factory stock, the Spicer 16 spline, 1-3/8 diameter 7-7/8 long slip yoke will fit perfectly. You won't even have to re-balance it. The end yokes run pretty true, and your bronco front driveshaft won't ever see high speed service. (because I can see that you didn't cut and turn your inner-C's when you did your lift...)

Enjoy the savings.
 

jamesroney

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Thanks! $53 is better than $470!
...if you want to be even more frugal, I usually take the one from the rear driveshaft, and use it on the front. Then put the brand new one on the rear.

The rear one's are often worn a little bit, but moving it to the front puts it in a different location on the splines. So you get to reset the service life.

The new style doesn't use the threaded cap, but uses a press on rubber cap instead. It's actually superior for holding grease.

So for $53. You can improve the rear, and lengthen the front.

This is how the legend of "all Bronco's are different..." is perpetuated.

Here’s a link of how to measure.

Follow the directions in the link and see how long of a shaft you need. I doubt there is an off the self unit that is the right length.

If memory serves me correctly the driveshaft is the same for a D30 and a D44
Nope. There is 0ne thing that the Spicer applications engineering group is really good at. And that is convincing Ford that they need to specify power transfer components to the 1/32 inch tolerance. So you will find driveshafts, and axle shafts that are different down to the 1/32. It's completely idiotic. But yes, 9 inch rears get different driveshafts than 8 inch, and the front 44 is about 1/2 inch shorter than the front 30. So different part number, (and you have to have some way to ID them.) Eventually Ford had to put the part number in bright yellow paint about 3/4 inch tall and about a foot long. I have no doubt that a fair number of 1969-1971 Broncos with Dana 44's ended up with Dana 30 driveshafts. When you own the forge, and you are machining driveshafts at a rate of 10,000 per day, cost is king. If you can reduce material consumption by using a shorter tube, and it ends up saving $.10 per unit. Someone will claim credit for a $1,000 per DAY costs savings. I call this "Six Sigma Math." This is the kind of lunacy logic that gets you an F250 with 7 lug wheels. Economy of scale has some weird results.
 
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Soylent

Soylent

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That sounds smart to put the new one in the rear. I already have to put spring perch shims in so might as well do that as well. Do you think the rear shaft is short enough? Not sure how much it needs to “telescope” in when flexed. Looks like it has 1.5-2”.

IMG_6954.jpeg
 

toddz69

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That sounds smart to put the new one in the rear. I already have to put spring perch shims in so might as well do that as well. Do you think the rear shaft is short enough? Not sure how much it needs to “telescope” in when flexed. Looks like it has 1.5-2”.

View attachment 913385
Offhand, that shaft looks like it's too long to me. I'd want more slip yoke exposed than that.

Todd Z.
 

Oldtimer

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Might try the shorter slip joint from your front drive shaft?
And a question. . Will this affect the balance of the rear drive shaft, since it will see high speeds?
 
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Soylent

Soylent

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May be worth a drive over to a driveshaft shop to ask about flipping both once I get the truck on the road.
 

Gsxr7000

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Good information in this thread. I need to measure mine. I believe I have to much spline showing in the rear.
 
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