Rim separates from flange

[boomer1025]

Try putting rubber gasket material between the hub and rim where they bolt together. Also make sure the nuts are not bottoming on the bolts when you torque them.
For some reason your not getting enough clamping force or the surface between hub and rim is too slippy/smooth.
Another thing you might want to try is putting heavy flat washers under the bolt heads and nuts if possible.
Re-torque the bolts after several hours of use a couple of times

 

[CalG]

This can only be a hardware issue. Not sufficient clamping force to keep the clamped surfaces from moving.

Any movement is too much. The bolted connection will only continue to loosen. Suspect incorrect hardware. As mentioned, the nut may be bottoming on the threads before full clamping force is achieved. Rubber in the interface is a BAD IDEA. It only allows relative movement.

Welding would be an option to discovery.

My bet is a set of hardened washers and a close examination of just what is pinching up when you apply that five foot cheater will answer the question that even the dealer and mfg. warantee missed.

You didn't give the size of the wheel fasteners that are failing. If the bolt holes are torn, welding in some reinforcing tabs with new holes may be an expedient.

Post pics if you can. There may be evidence that has been missed. ;-)

As a stop gap, CHECK those wheel fasteners prior to every use. Any movement will show as "debris" at the faying surfaces. NO MOVEMENT IS ACCEPTABLE!

 

[geoffleach]

Here's the problem

The cap screw is M14x1.5x50mm, grade 8.8. That's 'as delivered' from the factory.

The first time this happened the rim-to-flange connections were ripped apart. This time I was alert to the problem and found it when the cap screws had worked a bit loose. The holes in the rim-to-flange connections appear to be unaffected.

I'm going ahead with new hardware and careful torquing, checking every use.

You suggest an 'hardened washer' What hardness spec would satisfy that?

Thanks for the help.

 

[geoffleach]

You have an expensive sophisticated machine and the manufacturer needs to be held responsible.

An excellent point, and one that I'll take to heart.

 

[CalG]

Commercially, "Hardened washers" are not often available in different grades as bolts may be.

Washers are either of high quality and "hardened", or they are not. and likely soft as butter!. Hardened washers are MARKED! So identification is easy.

Make sure there is sufficient clamping pressure with the bolted connection, and I feel your problems will be behind you. Check them often, they have shown a weakness.

Those fasteners are "hammered! No muy bueno!

The "problem" is obvious. The fasteners were not always tight.
Observe the damaged threaded region of the bolt. Positive indication that the clamping force had slackened, and the two surfaces worked against the the bolt . That should never happen in a wheel flange.