ntsqd
Heretic Car Camper
Have to set aside all of the wheel and spacer geometry and look at where is the center of the tire's contact patch. That is the crucial element, the most important dimension. If it has moved from stock, regardless of how you got there, then all of the components involved and affected will see larger loadings. How much larger depends on the variables involved and their values.
I believe Kurt has had a couple flanged LC axles fail under him. The transition from flange to axle shaft is a huge stress riser (radical change in cross section). Stress is like water, it isn't happy when it has to flow around sharp corners or when the 'plumbing' suddenly changes shape and/or size.
I cross posted a spacer failure posting of Grim Reaper's. I've never met him, but we've had various interactions across two forums over the last several years and he strikes me as the sort of man who does the periodic things that need to happen, like checking the inner lug nut torque.
The problem with the basic design of every offset stud wheel spacer that I've seen is that they are not consistently 1.5"-2" thick. They have holes to recess the lug nuts and they have holes to recess the head of the stud so that a normal stud is long enough. Necessarily these holes are on opposing sides of the spacer. The sharp corners in the bottoms of all of those holes are stress risers. The very holes themselves are stress risers.
There is no difference in the forces applied by a 1.5"-2" less deeply backspaced wheel than with a stock wheel running on a 1.5"-2" spacer. Those resultant forces would be the same. This is also true if the wheel is 3"-4" wider than stock, but has the same backspacing as stock. It is the real shame of my own FJ60, I really like those wheels, but they are 8" wide which borders on too wide for my tire size choice. I have not decided what to do about this. In Mogas' situation I am led to think that the combo of spacers and wheels results in the contact patch center being pretty close to the stock location. This is the best case use of spacers. The real problem is when a wider than stock, shallowly backspaced wheel is used with a spacer. This is a fairly common thing among rock crawlers in the U.S.
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There are a couple mechanism's that I see that would result in loose lug nuts, but if they were torqued to start with I do not think that they are backing off. The tapered seat or ball seat of the lug nuts & wheels is intended to act as a locking agent (and to help center the wheel on the hub).
The first is, assuming an aluminum spacer or wheel, that the aluminum distorts under load and cold flows (cold forges) out from under the lug nuts. There is a large precedence for this. I've experienced it on one race truck. Those that were supposed to re-check the lug nut torque at the first pit stop did not do it. We didn't make it to the second pit stop.
I am not aware of a direct cure for this except for time. From experience this eventually settles down and then the nut torque will stay pretty consistent. Some of the more expensive wheels have steel lug nut seats installed in the wheel. This keeps the lug nut from Brinnelling into the wheel and avoids the whole issue.
The second is that the wheel studs stretch. If there are large loads occurring then the studs will stretch and eventually they will break. Over-tightening them will only make matters worse. I know of two cures for this; larger studs or a higher strength alloy. The downside to the former may be packaging their larger size. The downside to the latter is that with higher strength typically comes less ductility. They won't stretch as much before breaking.
I believe Kurt has had a couple flanged LC axles fail under him. The transition from flange to axle shaft is a huge stress riser (radical change in cross section). Stress is like water, it isn't happy when it has to flow around sharp corners or when the 'plumbing' suddenly changes shape and/or size.
I cross posted a spacer failure posting of Grim Reaper's. I've never met him, but we've had various interactions across two forums over the last several years and he strikes me as the sort of man who does the periodic things that need to happen, like checking the inner lug nut torque.
The problem with the basic design of every offset stud wheel spacer that I've seen is that they are not consistently 1.5"-2" thick. They have holes to recess the lug nuts and they have holes to recess the head of the stud so that a normal stud is long enough. Necessarily these holes are on opposing sides of the spacer. The sharp corners in the bottoms of all of those holes are stress risers. The very holes themselves are stress risers.
There is no difference in the forces applied by a 1.5"-2" less deeply backspaced wheel than with a stock wheel running on a 1.5"-2" spacer. Those resultant forces would be the same. This is also true if the wheel is 3"-4" wider than stock, but has the same backspacing as stock. It is the real shame of my own FJ60, I really like those wheels, but they are 8" wide which borders on too wide for my tire size choice. I have not decided what to do about this. In Mogas' situation I am led to think that the combo of spacers and wheels results in the contact patch center being pretty close to the stock location. This is the best case use of spacers. The real problem is when a wider than stock, shallowly backspaced wheel is used with a spacer. This is a fairly common thing among rock crawlers in the U.S.
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There are a couple mechanism's that I see that would result in loose lug nuts, but if they were torqued to start with I do not think that they are backing off. The tapered seat or ball seat of the lug nuts & wheels is intended to act as a locking agent (and to help center the wheel on the hub).
The first is, assuming an aluminum spacer or wheel, that the aluminum distorts under load and cold flows (cold forges) out from under the lug nuts. There is a large precedence for this. I've experienced it on one race truck. Those that were supposed to re-check the lug nut torque at the first pit stop did not do it. We didn't make it to the second pit stop.
I am not aware of a direct cure for this except for time. From experience this eventually settles down and then the nut torque will stay pretty consistent. Some of the more expensive wheels have steel lug nut seats installed in the wheel. This keeps the lug nut from Brinnelling into the wheel and avoids the whole issue.
The second is that the wheel studs stretch. If there are large loads occurring then the studs will stretch and eventually they will break. Over-tightening them will only make matters worse. I know of two cures for this; larger studs or a higher strength alloy. The downside to the former may be packaging their larger size. The downside to the latter is that with higher strength typically comes less ductility. They won't stretch as much before breaking.