Disc Brake conversion / Axle shaft binding

[Broncowilly]

I am having problems with my new axles binding when I tighten down spindle. Here are some details:
- 1971 / 72 Dana 44
- Horsepower LLC disc brake conversion that included new spindles, etc.
- New Yukon axles (upgraded 4340 w. 5-760X U-Joint) from Randy's ring and pinion. I doubled check and they are correct for 71-77.
- All the seals, thrust washer, slinger installed correctly based on everything I have read 20 times.
- I am running the NAPA premium ball joints and there is clearance
- I am also assuming that the axles should turn pretty freely subject to normal resistance.

Everything seems to be fine up until I tighten the spindle flush with the knuckle which is that last 1/16 - 1/8 or so.
The only thing that I can think is that the knuckle where the U-Joints fit the axles half's together is a bit longer then the stock and might be binding up against the axle housing.
Your advice and experience is much needed as my son and I are at our wits end.

 

[73azbronco]

Do you still have original axle to measure? I had a heck of a time getting a rear axle to work after finding the manufacturer made it one dimension regardless of year, even though they claimed they didn't. I had to prove to them the measurement was wrong with photos and such. I have not heard of a front axle issue though.

 

[Broncowilly]

Disc Brake conversion

I laid the old on and new one side by side and the length is the same. The new one is beefier and the U-Joint knuckle is a bit longer otherwise length is same.

 

[Broncowilly]

I watch more closely as I loosened and tightened the spindle and the axle didn't appear to move back into the housing so it must be something tightening against the axle from the back of the spindle.

Thoughts

 

[garberz]

Why not install the stock axles, and see if there is still an issue? Then you'll know if there is a problem with your upgraded axles, or if you assembled something wrong.

 

[bronconut73]

When I got my chromoly axles and 4340 u-joints from WH they specified whether you had the chevy disc conversion or not.
Could this be why? I haven't installed my stuff yet so I could be way off.

 

[Broncowilly]

Good suggestions. I will give the old axles a try also.

 

[904Bronco]

Do you have a locker in the front? Is everything lined up inside it, so that the axle goes all the way in?

When you lay the new and old axles together, is the inner seal surface in the same location on both?

Does it bind when you install the old axle and tighten up the spindle bolts?

 

[Broncowilly]

I just installed the original drivers side axle and tightened the spindle. While I couldn't turn the axle at the end of the spindle it will turn from the yoke. There is also a bit of in and out free play. I re-measured the axles and they are about 1/8 difference in length. It is the U-Joint knuckle that is longer than the stock.

 

[Broncowilly]

Forgot to say that the D-44 is not a locker but rather open.

 

[DirtDonk]

While an eighth of an inch isn't always enough to cause an issue, it still "can" be in some cases.
I've heard of axles being too long on the long-side, but not so much on the short outer "stub" axle.

Since your stock one seems to work, it's sounding like that little discrepancy is enough in your case.
There were indeed 2 different spindle designs about that time on the Broncos, but I don't think that either of them would cause an issue.
However, the one style that's intended to be used with a pressed-in seal on the back side might just have some extra clearance. Or not.
Are your spindles utilizing the full-seal back there (looks like a wheel bearing or rear axle seal)? Or just the little ones that come with a small seal that just sits there on top of the inner spindle bearing (looks almost like an O-ring with a squared off (v-shaped) profile)?

Also, whatever brake setup that is, is the backing plate or anything else supposed to be behind the spindle? I wouldn't think so, but thought I'd ask anyway.

And lastly, what all are you putting on the outer axle shaft before installation?
On later ones, there should only be the small "v" seal (mentioned above), the thrust washer with the beveled edge facing the u-joint, and the bellows seal floating on the larger diameter just up against the slinger.
And is the slinger pressed on all the way?

If that thrust washer (original was brass, new is usually nylon/plastic) is put on backwards, you could get some binding. Make sure the bevel faces the rounded surface of the stub axle up against the slinger's area.

And no, there's usually too much resistance to turn the tip by hand. Even when everything fits perfect. But you should be able to easily turn the shaft at the u-joint yokes and move the shaft assembly in and out a bit. Maybe up to about 1/2" or so?

Paul

 

[Broncowilly]

Well the extra grease seal on the back of the spindle was the culprit. As soon as that was removed everything seated fine, the axles turn with the yoke and I now have some end play. Thank you ClassicBroncos.