MTFCA Forum

When I tighten the rear axle nut on my 14 the wheel locks up. I put some black paint on the axle seal cap and when I tighten the axle nut it shows the back of the hub is rubbing the axle cap. What is the problem and the fix here?

You don't have a felt under that modern seal cap, do you ? Not enough room if so.

That photo doesn't show a real Ford part. Why not try doing it correctly?

Original Smith wrote: ↑

Sat Mar 21, 2026 12:24 pm

That photo doesn't show a real Ford part. Why not try doing it correctly?

I dont use those thick cast aluminum caps. If you added a felt seal it wont fit either. If you want to use a modern lip seal, Bill Bolin makes them from spun steel. Available for early & late sized caps. Also the seal cap is supposed to be a hard press fit so it cant move/rotate.

I have installed the new style seals and the old style seals and as long as everything is in the proper geometry then I have not had an issue.
When I see your picture several things come to mind.
I think the seal is installed all the way until it bottoms but I can not tell for sure.
What did the old seal look like? Was it worn heavily with the center of the cup rubbed out?
That axle surface is torn up really bad and what does the inside of the hub look like?
If the axle taper is worn and or the hub is worn it pushes the wheel further inboard towards the seal.
When (before) the wheel was removed was the brake drum outside the backing plate, lined up with it, or over the backing plate?
In other words where was the drum (and wheel) positioned before it came apart?
As the hub and axle wears the brake drum migrates inward essentially acting like a wear indicator.
Were the brake shoes touching the inside of the brake drum on the non lining faces? As it migrates inward it will start to drag the face on the drum.
Was any of the wheel and brake hardware touching anything inside the drum? I have seen plenty of worn springs and bolts from rubbing.
Do you have a set of Rocky Mountain Brake Drums on the back changing the geometry?
What is the condition of the rear axle bearings, sleeves, and thrust washers?
Were there any axle shims in there when you took it apart? A few thousandths on that long taper make a huge difference on the offset.
When these get worn all kinds of things start touching that should not be.
All of these questions are to point to the source and beginning of the problem.

So either the seal is not on far enough or the hub is on too far.
Maybe fit it up without a seal and key to see how it fits and where the drum lines up to the edges of the "backing plate" (axle flange)?
Maybe swap wheels from side to side to test?
I suspect bad axle taper and or bad hub taper is the issue but it remains to be proven.
Mike

This 14 project came with those seals on a rebuilt rear end. I usually use the original style. The only contact was with that raised part on that cap, none on the side of the shoes. I did grind some off of that raised ridge and that fixed that problem. The wheel just covers the backing plate when torqued. I will probably order some original style caps and felt. Thanks for the answers. Art

Art

FWIW - and for future readers: The brake drum is not supposed to cover the backing plate...it is designed to only cover the brake shoes and some times there is even a very tiny gap between the end of the brake drum and the face of the backing plate when everything is back to factory dimensions.

Your description validates suggestions that either or both the axle and the rear hub have significant wear.

Scott_Conger wrote: ↑

Sat Mar 21, 2026 2:29 pm

Art

FWIW - and for future readers: The brake drum is not supposed to cover the backing plate...it is designed to only cover the brake shoes and some times there is even a very tiny gap between the end of the brake drum and the face of the backing plate when everything is back to factory dimensions.

Your description validates suggestions that either or both the axle and the rear hub have significant wear.

My description was not accurate. This is the drum after installed and tight. How does it look? Art

Going on farther than when new, but I've seen worse

When everything is "as new" you can typically take a business card and insert it parallel to the backing plate and it will slide in.

Very few cases where a rebuild will meet this criteria especially if the original rear hub is used.

Original Smith wrote: ↑

Sat Mar 21, 2026 12:24 pm

That photo doesn't show a real Ford part. Why not try doing it correctly?

My research shows Ford never installed RM brakes. Will you be removing yours?

"Very few cases where a rebuild will meet this criteria especially if the original rear hub is used."
For this reason, its wise to stretch original axles to take up for wear in the taper of the axle & hub.
I lengthen axles about .090" as a matter of coarse. This why .060" longer axles are offered by our vendors.
I have yet to be sorry for extending axles on any of the many builds I have done.
Small drum brakes/hubs are close to begin with.

speedytinc wrote: ↑

Sat Mar 21, 2026 12:50 pm

Original Smith wrote: ↑

Sat Mar 21, 2026 12:24 pm

That photo doesn't show a real Ford part. Why not try doing it correctly?

I dont use those thick cast aluminum caps. If you added a felt seal it wont fit either. If you want to use a modern lip seal, Bill Bolin makes them from spun steel. Available for early & late sized caps. Also the seal cap is supposed to be a hard press fit so it cant move/rotate.

I heard Mr Bolin passed away a few weeks ago.

big2bird wrote: ↑

Sat Mar 21, 2026 3:25 pm

speedytinc wrote: ↑

Sat Mar 21, 2026 12:50 pm

Original Smith wrote: ↑

Sat Mar 21, 2026 12:24 pm

That photo doesn't show a real Ford part. Why not try doing it correctly?

I dont use those thick cast aluminum caps. If you added a felt seal it wont fit either. If you want to use a modern lip seal, Bill Bolin makes them from spun steel. Available for early & late sized caps. Also the seal cap is supposed to be a hard press fit so it cant move/rotate.

I heard Mr Bolin passed away a few weeks ago.

I hadnt heard. What a shame.

Sometimes, switching the wheels will change the clearance & both will fit......or not.

I see the vendors offer original style caps but not for the earlier cars, 09/17. Langs says they will fit but be loose and need swedged. What do you guys do? Art

I believe I still have some of Bill's early axle steel caps w/modern seal - drop me a note.

Art Ebeling wrote: ↑

Sat Mar 21, 2026 4:23 pm

I see the vendors offer original style caps but not for the earlier cars, 09/17. Langs says they will fit but be loose and need swedged. What do you guys do? Art

I split 2 sides with a hacksaw, squeeze together & weld the cuts.
Pound them on tight. They must fit tightly to compress the felt, otherwise they will leak.

RajoRacer wrote: ↑

Sat Mar 21, 2026 5:27 pm

I believe I still have some of Bill's early axle steel caps w/modern seal - drop me a note.

Steve, I sent you a message. Thanks, Art