Dana 20 Front Output Shaft Won't Turn With Nut Tightened

[ILikeBond]

I'm completing the rebuild on my Dana 20 (including Terralows and the Wild Horses/AA HD output). Spec is to tighten front output shaft yoke nut to 240-250 ft lbs, but before I get even close to that, tightening the nut down I can no longer turn the yoke/shaft by hand or otherwise (for example, by turning the rear output yoke/shaft).

I don't appear to have any end play. I don't have a gauge, so I can't really tell, but I can't seem to pry any movement in either direction on the shaft. Could this be the issue, and if so do I need to remove a shim from the rear cover? I used the same 3 shims I took off, and I put a thin layer of RTV in between each. Maybe this was a mistake?

Should I remove a shim, or remove them all and scrape the silicon off before re-installing--or is something else possibly going on?

Also, when tightening down the yoke nut, what's the best way to keep the shaft from turning so as to have some resistance? I can't see being able to tighten to 250 ft lbs just holding the yoke with my left hand...

Thanks!

 

[Viperwolf1]

Where did you get the spec of 250 ft-lbs? Should be about 130.

You won't be able to hold the yoke by hand. Make a tool to fit in the yoke bolt holes to hold it.

You need to make sure the bearings are fully seated on the shaft. You can do this by removing the yoke and smacking the inner race of the bearing with a hammer and section of pipe. If you still don't have enough play you need to add more shim thickness.

 

[bknbronco]

make something like this

 

[ILikeBond]

Thanks, Viperwolf (was hoping you'd answer!).

The spec comes from the Terralow installation instructions. Here's the link. Check out the last page. Is it just wrong?

http://static.summitracing.com/global/images/instructions/tmi-002102000.pdf

 

[Viperwolf1]

I think the spec for the jeep D20 is where that may come from. Technically it is 3/4"-16 thread and should be fine at that torque but Ford specified 125-150.

 

[ILikeBond]

Got it. Thanks!

 

[70_Steve]

Maybe some instructions would help.
www.classicbroncos.com/dana20/dana_20_manual.html

 

[ILikeBond]

Maybe some instructions would help.
www.classicbroncos.com/dana20/dana_20_manual.html

Yes, thanks, that's what I primarily used for the rebuild, of course, but it doesn't have the answer to the specific issue I raised.

 

[70_Steve]

Saw where you were using the TeraLow instructions. Been a while since I did mine, but I found the TeraLow instructions confusing and in some cases just plain wrong when compared to the Bronco Dana 20 manual. Pay attention to what Viperwolf1 suggested and check the front output shaft end play. FWIW, the manual says set the end play to .003-.005, but I like to get it closer to .001...

 

[ILikeBond]

Fair enough. I was using a combo of the two, but agree, except for a few key places, the manual is far better.

 

[66BlueGoose]

Just set mine up a few months ago, used this manual. http://www.oldcarmanualproject.com/manuals/Bronco/ I set it at 150lbs with .003 backlash. Did not have the nice tool shown above but was able to use a really large pipe wrench to hold the flange.