Brake upgrade; issue with hubs

[UKTJ]

Looking for any advice anyone can provide. Recently did a WJ Knuckle swap (late XJ hubs, WJ discs redrilled to 5 on 4.5, cross over steering) on my TJ. After about 1,000 miles I found the studs had worn the holes in the hubs to the point the wheels were lose. We removed the 30mm wheel spacers as they were not fitting tightly on the hub and changed both hubs. Now 1,500 miles later can clearly feel one of the wheels is coming lose, so expecting issue is repeating itself even without the spacers.
Anyone ever had anything similar happen? Any thoughts or suggestions as to what the cause may be much appreciated.

 

[Obi-Wan]

@mrblaine would be the best person to give advice on this subject.

 

[mrblaine]

@mrblaine would be the best person to give advice on this subject.

That is not a brake problem.

 

[macleanflood]

That is not a brake problem.

Correct it's a break problem...

-Mac

 

[mrblaine]

Looking for any advice anyone can provide. Recently did a WJ Knuckle swap (late XJ hubs, WJ discs redrilled to 5 on 4.5, cross over steering) on my TJ. After about 1,000 miles I found the studs had worn the holes in the hubs to the point the wheels were lose.

You have some mechanical retardation going on and some descriptive retardation as well.
Is the wear at the lug stud to the hole interface in the unit bearing flange or something else?
Are the holes for the lug studs in the wheels losing the battle or were the lug nuts just loose?

We removed the 30mm wheel spacers as they were not fitting tightly on the hub and changed both hubs.

Are you trying to say that the wheel spacers were lug centric and not hub centric and that is why you removed them? If so, that wasn't your problem and won't be since we run bazillions of lug centric wheels with zero issues.

Now 1,500 miles later can clearly feel one of the wheels is coming lose, so expecting issue is repeating itself even without the spacers.

Precisely. The lug centric condition (if present) is not your problem.

Anyone ever had anything similar happen? Any thoughts or suggestions as to what the cause may be much appreciated.

Clarify a few things so we aren't chasing our collective tails.

 

[UKTJ]

Thanks for your help.

You have some mechanical retardation going on and some descriptive retardation as well.
Is the wear at the lug stud to the hole interface in the unit bearing flange or something else?

Yes, the wear is at the interface of the lug and the hole in the bearing flange.

Are the holes for the lug studs in the wheels losing the battle or were the lug nuts just loose?

It is not an issue between the lugs and the wheels, the looseness is between the studs and the holes in the bearing flange.

Are you trying to say that the wheel spacers were lug centric and not hub centric and that is why you removed them? If so, that wasn't your problem and won't be since we run bazillions of lug centric wheels with zero issues.

Yes, clearly as issue recurring with spacers removed that is not the issue, we were just hoping I guess.

Precisely. The lug centric condition (if present) is not your problem.

Clarify a few things so we aren't chasing our collective tails.

Having just pulled and replaced another hub we have noticed something else. Where the WJ discs have been re drilled for a 5 on 4.5 hub pattern we now wonder if the re drilled holes are fractionally too small. The threaded part of the studs comes through the discs, but it looks like the hole is too small for a small shoulder at the end of the studs to go into the disc. The result seems to be that there is a small gap between the disc and the hub when the wheel nuts are tightened to torque. Could this allow play in the whole assembly that could cause the stud and the holes in the hub flange to wear enough for them to enlarge the holes and / or where the knurl off the stud?

 

[mrblaine]

Thanks for your help.

Yes, the wear is at the interface of the lug and the hole in the bearing flange.


It is not an issue between the lugs and the wheels, the looseness is between the studs and the holes in the bearing flange.


Yes, clearly as issue recurring with spacers removed that is not the issue, we were just hoping I guess.



Having just pulled and replaced another hub we have noticed something else. Where the WJ discs have been re drilled for a 5 on 4.5 hub pattern we now wonder if the re drilled holes are fractionally too small. The threaded part of the studs comes through the discs, but it looks like the hole is too small for a small shoulder at the end of the studs to go into the disc. The result seems to be that there is a small gap between the disc and the hub when the wheel nuts are tightened to torque. Could this allow play in the whole assembly that could cause the stud and the holes in the hub flange to wear enough for them to enlarge the holes and / or where the knurl off the stud?

Folks mistakenly assume that hole size in the rotor for the lug studs has to be precise. It does NOT. They are merely clearance holes that allow the rotor to fit over them without any contact. Those holes can be 1" in diameter and as long as they don't cut into the center bore, no issue whatsoever. The rotor ceases to care about the holes once the wheel it tightened down and the lugnuts torqued properly. The clamping force developed via that process is what stops the rotor from moving under braking, nothing else.

 

[machoheadgames]

The threaded part of the studs comes through the discs, but it looks like the hole is too small for a small shoulder at the end of the studs to go into the disc. The result seems to be that there is a small gap between the disc and the hub when the wheel nuts are tightened to torque. Could this allow play in the whole assembly that could cause the stud and the holes in the hub flange to wear enough for them to enlarge the holes and / or where the knurl off the stud?

This is absolutely your issue. Drill your rotor holes larger so they can sit flush against the unit bearings. Currently right now everything is bottoming out on the stud knurl shoulders and then the lugs work themselves backwards out of the hole and become loose. As blaine says, the holes only need to fit over the studs, and don’t need to be any more precise than that. The holes definitely can’t be smaller than the studs.

 

[mrblaine]

The holes definitely can’t be smaller than the studs.

Oh, they can be, it just doesn't work very well.

 

[UKTJ]

I counter bored the back of the brake discs to give enough for the studs, letting the discs sit flush to the hubs. I didn’t want to declare victory too soon, but I have done about 1,000 miles since doing that with no further issue, so I am hopeful.

I just wanted to say thank you to everyone who provided helpful input. This forum really is an unparalleled source of information and support for TJ owners.