4x3.75 to 4x4.25 drive shaft adapter.

[arse_sidewards]

Download link for the CAD file is the green button at the top right.


Pilot on both the 3.75 flange and 4.25 flange is 2" so you can cram whatever 2" stock you want in there to provide a pilot for the yoke. I used 2x1/4 DOM tube. In retrospect I should have used something thinner wall so that the socket for the nut would fit through. You gotta clearance the stock flange. You're gonna want to make some sort of jig to make the clearance cuts some semblance of symmetrical for balance reasons. I didn't and I'm not sure how much of my vibration is from that and how much of it is from the worn out CV ball.

Your pinion flange is already 4 on 4.25 so adapting the transfer case flange up lets you run fullsize truck drive shaft components which is necessary if you want to use cheap junkyard parts to get to 1350 or 1410.

 

[arse_sidewards]

Forgot to mention. The 3.75 holes in the drawing are through holes. The 4.25 holes are whatever the tap drill for M12x1.75 is so you can either tap them or drill them depending on what you're doing.


The reason for this whole project in my case that a SCSB 4x4 drive shaft is $300 aftermarket and basically unavailable used. A 99-04 Superduty front shaft is the same on one end, less than $200 aftermarket and close enough to work (and I already had a 1350 flange yoke on hand).

 

[Curious Hound]

The 4.25 holes are whatever the tap drill for M12x1.75 is so you can either tap them or drill them depending on what you're doing.

M12x1.75 tap drill size would be;
12mm - 1.75mm = 10.25mm drill size

Or 0.40354331" a "Y" letter size drill or a 13/32" drill should work fine

 

[arse_sidewards]

The laser cutting service I used advertises +/- 5 thou. The tappable holes are .400 to ensure they don't come out too oversize. They may need to be cleaned up with a drill bit in order to run a tap through.