Ford 1710 FWD Driveshaft Issue

[tedward4]

I thought I'd post this and see if anyone else had a similar failure. The MFWD quit working a few months ago and I finally got to fixing it. On the 1710, the front drive shaft is splined on either end with a coupler on each end (one coupler on the transmission output and one on the front axle input). It turned out that the splines were sheared off one end of the drive shaft. The first picture is what the splines should look like, and the second is the damaged ones.



Rather than buying a new shaft and coupler, I welded the coupler onto the shaft (there was still ~1/4" of spline engagement). We'll see how long that holds.

 

[jones6780]

My concern now would be that the coupler has 1/4 less engagement now. I have a 1700 and never had a problem, but I don't have a FEL

 

[JC-jetro]

I thought I'd post this and see if anyone else had a similar failure. The MFWD quit working a few months ago and I finally got to fixing it. On the 1710, the front drive shaft is splined on either end with a coupler on each end (one coupler on the transmission output and one on the front axle input). It turned out that the splines were sheared off one end of the drive shaft. The first picture is what the splines should look like, and the second is the damaged ones.

View attachment 348218 View attachment 348219

Rather than buying a new shaft and coupler, I welded the coupler onto the shaft (there was still ~1/4" of spline engagement). We'll see how long that holds.

View attachment 348220

Good job Ted,

I too am concerned with engagement and more stress on little soling that is left. I know those shaft are hardened and difficult to drill.. but nit impossible. I'd probably use the coupler that you had and would weld the coupler to other shaft if only I can slide out the axle connection. I know the coupler is sliding so shafts can be connected without moving the axle and transmissions side is also fixed. FWA is an option so the final output gear/assembly for the fwa can be loosened and lowered to maybe make the connection. Drill out a hole on coupler and shaft might be okay as then you have a shear pin in the front wheel drive shaft. Did you tig or mig the new coupling?

JC,

 

[RickB]

I'd be darn certain to put the welded coupler against the drop box and not the front diff pinion shaft. Last thing you want to do is squeeze nickels until you trash the front ring & pinion. (not welded straight, not enough spline engagement, etc, etc)

 

[Jerry/MT]

The question I have is why did the shaft splines fail like they did? It's almost as if something locked up and the torque exceeded the ultimate strength capability of the splines. Could the shaft have been defective?

 

[RickB]

The question I have is why did the shaft splines fail like they did? It's almost as if something locked up and the torque exceeded the ultimate strength capability of the splines. Could the shaft have been defective?

Apparently it didn't exhibit any obvious defects or design flaws in the first 25 years.
If that joint was originally at the front end of the driveshaft, worn axle pivot bushings(which are non-relube style) will cause spline misalignment & failure in fairly short order if 4WD is used a lot.

 

[tedward4]

Did you tig or mig the new coupling?

I TIG welded the shaft to coupler. There is actually some play in the coupler to allow for very slight misalignment. In order to get the coupler welded straight on the shaft, I tacked it in place and checked run-out using a lathe. Then fully welded and re-checked the run-out. Definitely don't want a wobbly coupler.

 

[tedward4]

I'd be darn certain to put the welded coupler against the drop box and not the front diff pinion shaft. Last thing you want to do is squeeze nickels until you trash the front ring & pinion. (not welded straight, not enough spline engagement, etc, etc)

The drop box end of the driveshaft is the side that had the sheared off splines, and I did put the welded end back on there. I'm fairly confident that weld/remaining splines will fail before the other parts fail...

 

[tkrlyon1]

I ran into the exact same pronblem, the splines on the pinion shaft were stripped and the coupling was damaged beyond repair.
I am curious if the keeper ring were to break and fail on the pinion shaft, could that cause the axle shaft and pinion shaft to collide in the coupling during a turn..... Causing this problem?