how much movement in slip yoke?

Chuckman

Chuckman

Well-Known Member
Joined
Oct 9, 2005
Location
Huntersville
dodge slip yoke transfer case. measuring for new rear driveshaft. after bottoming out in the case, how much should should I back it out to measure for length? -assuming sitting on tires and springs compressed.
 
^ yeah not making that mistake again
 
I'd probably shoot for the middle. I guess it all depends on how far the suspension travels. Kinda curious why you didn't go with a fixed rear yoke!
 
It's all in the geometry, you are working in triangles. A drive shaft shop will have you do some simple measurements under the vehicle to figure it out. It helps to know how many inches the suspension can compress and extend from ride height (with all the weight on the vehicle). The ratio of compression/extension versus the total will tell you approximately how much of the working length of the yoke should be exposed at ride height.

Say you have 6" of compression and 10" of extension at ride height. Of the total compression is 6/16 or 3/8 of total travel. The extension would be 10/16 or 5/8 of total travel. If you have 2 inches of slip available you would set it at 3/8 x 2 or 3/4" away from bottoming out at ride height. You may want to hedge with a little more room for full bumpstop compression, because jacking your driveshaft into the t-case from a hard hit is bad ju-ju. It helps to know the working length of the slip-yoke, but I don't know that I have ever seen that measurement on any documentation I have ever read. That must be the drive shaft shop "magic".

Obviously, I have over simplified this because true hotchkiss leaf spring suspension or a typical link suspension locates the axle in an arc, my example above assumes travel in the vertical plane only.
 
^ what he said
 
Ahhh, I was thinking it was his NV4500 project :D
 
justjeepin86 said:
This is on a Dakota, not a wheeling rig. Swapped to the larger available rear.
9 1/4
Click to expand...

In that case simply measure both axles from center line of the tubes to the end of the pinion yoke. The difference is what you should have cut out of the original driveshaft and have it re-welded and spin balanced.
 
OnlyOneDR said:
In that case simply measure both axles from center line of the tubes to the end of the pinion yoke. The difference is what you should have cut out of the original driveshaft and have it re-welded and spin balanced.
Click to expand...
Can't cut the original, the new one is a flange, the old one has straps. That makes perfect sense if they had the same yoke set up.
OnlyOneDR said:
In that case simply measure both axles from center line of the tubes to the end of the pinion yoke. The difference is what you should have cut out of the original driveshaft and have it re-welded and spin balanced.
Click to expand...
 
justjeepin86 said:
Can't cut the original, the new one is a flange, the old one has straps. That makes perfect sense if they had the same yoke set up.
Click to expand...

The math is still the same, the only change is the added length for the flange. All he should have to do is get a flange and have the shaft shortened (maybe a conversion u-joint if necessary). Do you have the part number for the flange? Dana/Spicer has a great website with all the dimensions and drawings for their parts.

The Expert - Dana Holding Corporation Product Information for driveshafts, driveshafts, axles, and Drivelines.
 
As I research this it looks like you can just buy a normal strap-type pinion yoke for the 9.25 for $85. That seems like an easier solution if the length is really close. It looks like you can get conversion u-joints from the 7260 to 7290 for $26 if the stocker is a 7260 style joint on the existing driveshaft.
 
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