Powder coat Warning

Gathering
Just a little something to think about if you powder coated your wheels. And if you want to know what a catastrophic bearing failure looks like, look no further. I made a rookie mistake that will cost me plenty. When I disassembled my wheels for powder coating I asked the guy if the center section of the wheel had to be masked off where the hub bolts on and he said no he has never had a problem. Well something I did not consider was this adds about .010 to the length to the center section of the wheel. So when I put it back together I did not think to to add that same amount to the center squish tube. So after torquing the axle down it put that force on the bearing race. So after only 4500 miles on brand new bearings this is what happens. The worst part is that since this wheel was an option for big dog in 04 neither them or pm make the hubs any more. Pm said they would custom make me one for $400 and I say fuck that. The bore area for the bearing looks good but I was a little concerned about the wall thickness where the grooves are in the hub. So I having those welded up. I have been down for almost 2 weeks trying to locate a hub and give up.


 

Gas Man

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WTF! What was the first give away or how did you notice? Noise or heat or....
 

Nomad2day

Longhair Redneck Geek
Sorry to see the failure Al and that does suck for sure.
On my 07 Bulldog they did not leave the area where the hub seats on mine and the powder coating is chipping off on the other side of the hub where it meets the wheel face. I have had one hub bolt come out as well and most of them loosen up as the powder coating crushes down or breaks. I am not sure what to do myself about this.
Neil
 

lee

Well-Known Member
shit Al! Sorry for you there buddy. Mine were masked when I had it done but my powder coater also builds bikes, which probably helped. I also don't think I have the inner spacer in between the bearings on my wheels from what they said.

Hope you get that sorted out before too long. Can you not get some maching done and cut new spacers to align the wheel?
 

RCAdd1ct

JAFO
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Not a Big Dog but mine were masked off, too.

My issues have been the bolts snapping on the pulley side on the back tire.

Last time I had three broken bolts and two were real loose.

That was a fun ride. :bang:
 

Tim

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Sorry to hear about your bearing/hub Al, but thank you for sharing so that we all can learn from it.

Making this a sticky thread and moving to customizing, where others may ask about powder coating.
 

Tim

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Just thinking out loud here... what would be the downfall of boring out the bad area of the wheel and having a steel sleeve pressed in?

The sleeve would have to be the same ID as the wheel/hub was originally, but it could save the wheel/hub if something ever happened again.
 
Just thinking out loud here... what would be the downfall of boring out the bad area of the wheel and having a steel sleeve pressed in?

The sleeve would have to be the same ID as the wheel/hub was originally, but it could save the wheel/hub if something ever happened again.
Tim yes you could do this as well, but since the area thats messed up is non functional and was advised that sleeving it would still require welding. If you bore it out then that wall thickness becomes thinner and the torque may twist the outer material which is what supports wheel.
 

T Mack

SUCKER FREE
Damn,,,,,,

Damn al glad ur okay.... looks like you put a few miles on those bad bearings.... could have been real ugly if it locked up doing 70.... Like GM asked what gave it away or made you take apart to look??? Im sure there was allot of noise...
curious???
 
Damn al glad ur okay.... looks like you put a few miles on those bad bearings.... could have been real ugly if it locked up doing 70.... Like GM asked what gave it away or made you take apart to look??? Im sure there was allot of noise...
curious???
Just heard a popping noise when I was about 5 miles from home from the rear end. I stopped and looked around and then noticed some aluminum shavings around the brake caliper. So I decided to head straight home and within another mile all the rest of the balls came out and rear end started bouncing around. I had to shut it down and call for a flatbed to get me home.
 

Gas Man

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WOW... you need to start truckin ur bike abt 10 miles from your house before you ride. All your crazy weird failures seem to happen within that distance. :loony: :lol:
 

gearsmithy

Active Member
even if you did shim out your center spacer for correct wheel bearing endplay, you'd still have problems down the road since the powdercoat will break down over time, gradually loosening your hub anyway.

Consider this.... those fasteners that hold your wheel hub in place don't do so with shear strength - i.e. it's not the bolt that's holding them together, it's the friction between your two mating surfaces that keeps your hub on. If you have powdercoat on one surface you're effectively changing the material properties said surface and altering the way the fasteners themselves function. Not to mention that over time that powdercoat will break down, causing a loose hub which is even worse IMO.

I think you should consider bead blasting them and having that jackass re-coat them properly.

My .02

Edit: Also, if you use sealed wheel bearings the problem will be magnified since they are more sensitive to side loads than timken bearings.
 
Last edited:

Gas Man

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even if you did shim out your center spacer for correct wheel bearing endplay, you'd still have problems down the road since the powdercoat will break down over time, gradually loosening your hub anyway.

Consider this.... those fasteners that hold your wheel hub in place don't do so with shear strength - i.e. it's not the bolt that's holding them together, it's the friction between your two mating surfaces that keeps your hub on. If you have powdercoat on one surface you're effectively changing the material properties said surface and altering the way the fasteners themselves function. Not to mention that over time that powdercoat will break down, causing a loose hub which is even worse IMO.

I think you should consider bead blasting them and having that jackass re-coat them properly.

My .02

Edit: Also, if you use sealed wheel bearings the problem will be magnified since they are more sensitive to side loads than timken bearings.
He may be onto something with the blast and re-coat
 
even if you did shim out your center spacer for correct wheel bearing endplay, you'd still have problems down the road since the powdercoat will break down over time, gradually loosening your hub anyway.

Consider this.... those fasteners that hold your wheel hub in place don't do so with shear strength - i.e. it's not the bolt that's holding them together, it's the friction between your two mating surfaces that keeps your hub on. If you have powdercoat on one surface you're effectively changing the material properties said surface and altering the way the fasteners themselves function. Not to mention that over time that powdercoat will break down, causing a loose hub which is even worse IMO.

I think you should consider bead blasting them and having that jackass re-coat them properly.

My .02

Edit: Also, if you use sealed wheel bearings the problem will be magnified since they are more sensitive to side loads than timken bearings.
I understand and I am quite familiar with residual torque vs. dynamic torque and asked several engineers beforehand and don't feel this will be an issue. Here is a nice read.

The need to measure torque doesn't necessarily stop when the assembly is finished. Manufacturers often audit finished assemblies to measure residual torque. This is a measure of the tension that remains in the joint after it has been fastened.
Torque auditing detects loose fasteners and "yielded" fasteners--fasteners that have stretched so much that they no longer provide clamp load. Auditing also detects joint relaxation. In many cases, torque auditing is the final judge of the harmony between the fastening tools, product design and materials, and the assembly process.

Residual torque can be measured using a power tool hooked up to a rotary transducer and torque analyzer. However, residual torque is most often measured using a transducerized electric wrench, a dial wrench or a preset hand tool, such as a click wrench or slip wrench. A click wrench has a calibrated mechanical cam that resists movement until a set torque is reached. A dial wrench has a spring that translates torque into motion on a calibrated dial.

Fastening experts warn that residual torque and dynamic torque are not identical. Residual torque is often lower than dynamic torque. In many cases, the joint relaxes after being fastened. Joint relaxation occurs to some extent in all fastened joints. One part embeds into another. A layer of paint, a spring washer or a soft part, such as an O-ring, compresses under the clamp force.

This relaxation, or creep, is most obvious and dramatic right after force has been applied. In most joints, creep appears within the first 10 to 50 milliseconds. However, some joints can take a long time to settle. Residual torque measured 1 hour after assembly can differ significantly from residual torque measured a day later.

"The farther away in time you get from fastening, the less likely it is that the residual and dynamic torque measurements will correspond" .

Residual torque can also be higher than dynamic torque. To test a joint after it's been fastened, the operator must overcome friction to start the fastener rotating again in the tightening direction. An accurate reading depends on the operator's ability to stop the moment he sees movement. "It's harder to get something rolling than it is to keep it rolling".

Another factor that can influence residual torque is "cross talk." This occurs when torque applied to one fastener affects another fastener in the same assembly. Changing the fastener installation sequence often solves the problem.

Because of these problems, fastening experts advise assemblers to avoid putting much stock in differences between dynamic and residual torque measurements. "Measuring residual torque won't tell you what caused the problem, only that there might be one". "It also can't tell you how good the fastening tool is."
 

gearsmithy

Active Member
That is a good read, and you and I could probably nerd out about fasteners and physics all day but the real question at hand is knowing what you know now would you feel comfortable riding that wheel as is even if the end-play was properly set? If it was my problem, I would take it back to the powdercoater and have him redo it, because finding out isn't worth my life you know?
 
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