C4 transmission - No reverse or 1st gear

[High Pressure]

Forward Hub ID spline stripped!

Back home from India... Just completed the partial teardown of the transmission to remove the forward hub. Below are the pictures. The ID spline is stripped! The input shaft spline seems to be fine. I can't see any obvious cracks in the hub. It looks like I need to purchase a new forward hub.

Of course the obvious question is why did it fail? I did install a new hardend input shaft when I installed the transmission.

Should I purchase a basic stock version forward hub for 5 frictions or upgrade to 6 frictions or a welded hub since I have to replace it? Or are the upgrades truly only needed for racing transmissions.

Should I perform any other upgrades while have the transmission apart?

Is Broader a good supplier?

http://www.broaderperformance.com/C4 trans and parts-A.htm

 

[High Pressure]

Purchased a used forward hub & rebuilt it today

Purchased a used forward hub and new thrust washers from Transpartsonline to replace the stripped hub. I could not find a "new" hub. In addition, I purchased an ART CARR manual shift reverse pattern valve body from WH. All of the frictions & bands were new from an earlier rebuild. Not sure I like the fluid pickup compared to the original bronco filter/pickup. I rebuilt the transmission today and it is ready to install back into the Bronco. Of course, I don't need the modulator valve now but... I guess I will just use it to plug the hole!!

 

[Broncobowsher]

I missed the cummins in the original post.
Now I better understand why the hub died.
I hope that the new one lives. I worry that the pounding torque of the 4BT may be too much for it.

 

[PaulS]

You are going to be going through those hubs until you install a hardened input shaft and a sleeved or welded hub. You can get both pieces from Art or Broader performance.

 

[High Pressure]

Broncobowsher & PaulS,

Thanks for the feedback... This truly might be the case...too much pulsed torque from the little 4bt. I have no clue about the original hub ID spline condition. It might have had an issue that would have failed under somewhat normal conditions. I did speak with the man at Broader. He was not sure if his welded hub would have prevented this specific issue... He stated the welded hub was to prevent splitting. I do have a hardened input shaft. So, if this next one fails...I will take a look at a hardend ID splined sleeved hub..

I'm not planning anything radical for the 4bt... currently it is still around 120Hp and 250 ftlbs of torque... I do have some planned performance improvements.. but have no plans to make it SMOKE!

 

[PaulS]

I wish you the best with it. I hope it works for you extremely well.