Discussion
kambites said:
I'd never noticed that some cars only have three before. Never seen a six either, I don't think.
The number of bolts tends to increase with vehicle mass, so tiny light comedy cars have 3 (2CVs can be added to the others listed), normal cars have 4, heavy cars have 5, 4x4s have 6 and HGVs have loads (and not the puny M12s cars tend to use).You can get the same clamp load by increasing the size of the bolts while reducing the number, which is how single nut wheels work in racing and on a few road cars.
Captain Muppet said:
kambites said:
I'd never noticed that some cars only have three before. Never seen a six either, I don't think.
The number of bolts tends to increase with vehicle mass, so tiny light comedy cars have 3 (2CVs can be added to the others listed), normal cars have 4, heavy cars have 5, 4x4s have 6 and HGVs have loads (and not the puny M12s cars tend to use).You can get the same clamp load by increasing the size of the bolts while reducing the number, which is how single nut wheels work in racing and on a few road cars.
Captain Muppet said:
The whole "spigot takes load" thing is bunk. Spiggot rings are often plastic, and on some vehicles don't exist. They are a location aid for assembly. If there were meant to take load they wouldn't be relying on 3mm of engagement in to a soft aluminium casting.
...and the spigot would be a taper so that there's no slack, like on a knock-off wheel.
Captain Muppet said:
kambites said:
Krikkit said:
Don't forget the bolts aren't holding the weight of the car, just stopping them coming off the spigot.
No, but they are taking the drive and braking forces. Unless I'm missing something, the only thing stopping the wheel from rotating around the spigot as far as the potential play in the bolt will allow, is the friction between the back of the bolt-head and the washer section? If that interface does start to move, I can't see the bolt retaining its tightness for long. The whole "spigot takes load" thing is bunk. Spiggot rings are often plastic, and on some vehicles don't exist. They are a location aid for assembly. If there were meant to take load they wouldn't be relying on 3mm of engagement in to a soft aluminium casting.
Krikkit said:
Captain Muppet said:
kambites said:
Krikkit said:
Don't forget the bolts aren't holding the weight of the car, just stopping them coming off the spigot.
No, but they are taking the drive and braking forces. Unless I'm missing something, the only thing stopping the wheel from rotating around the spigot as far as the potential play in the bolt will allow, is the friction between the back of the bolt-head and the washer section? If that interface does start to move, I can't see the bolt retaining its tightness for long. The whole "spigot takes load" thing is bunk. Spiggot rings are often plastic, and on some vehicles don't exist. They are a location aid for assembly. If there were meant to take load they wouldn't be relying on 3mm of engagement in to a soft aluminium casting.
If I hadn't written bolt clamp load software for an offshore engineering consultancy years ago, and then got in to a hobby that involved having 40 spare wheels and doing maybe 14 tyre changes in a day, I wouldn't have thought about it much either.
v8will said:
Plenty of wheel manufacturers hold TUV certificates for wheels fitted with PCD variation bolts (the correct name) and even wheel spacers.
I see no issue with them.
porsche provide a 5mm spacer option for the Cayman ont heir configurator.I see no issue with them.
Sometimes I think there is a desire to slag soemthing off, not because it is a slightly less elegant engineering solution, more as a dig at the group of owners that are perceived to be using them.
J4CKO said:
v8will said:
Plenty of wheel manufacturers hold TUV certificates for wheels fitted with PCD variation bolts (the correct name) and even wheel spacers.
I see no issue with them.
porsche provide a 5mm spacer option for the Cayman ont heir configurator.I see no issue with them.
Sometimes I think there is a desire to slag soemthing off, not because it is a slightly less elegant engineering solution, more as a dig at the group of owners that are perceived to be using them.
k they are talking about.It wasn't a direct quotation, my point was that this thread is mainly people moaning about a simple solution to a problem faced by a lot of car owners. You yourself appear to be part of this group, saying they are a "terrible solution" and used by "chavs". There was also someone questioning how could they even be legal.
Comments like that can only lead the reader to one of two conclusions:
a) these people do not know what they are talking about as they are perfectly safe and legal and a very practical solution to a common problem
b) these people are ignorant snobs that feel the need to seek some kind of moral highground
Comments like that can only lead the reader to one of two conclusions:
a) these people do not know what they are talking about as they are perfectly safe and legal and a very practical solution to a common problem
b) these people are ignorant snobs that feel the need to seek some kind of moral highground
Captain Muppet said:
The friction is generated by the bolt preload. Until that friction is overcome the bolts (and the spigot if there is one) will see no shear load. It's the reason that greasing the hub face makes me shudder.
Just so I understand this correctly, you are suggesting that the wheel bolts themselves don't actually turn the wheel, but rather the clamping force, or friction, between wheel & hub faces? Obviously there are cavaets to this, such as fitters not retorquing the wheel bolts correctly, etc?I must admit, I've greased hub faces on the rear wheels of FWD cars because they never get hot and rust onto the hubs solid. Never had any issues doing this in over 20 years.
Obviously the driven wheels are a different matter, but even then I don't see it as a massive issue personally. If it were, shirley the hub faces and corresponding wheel faces would be slotted, or something?
And expanding on this a little further, what about the 6 little M8 bolts that connect the driveshafts to the inner CV joints on VW Golfs, including the VR6? I can't believe these tightened to ~ 40lb-ft can generate enough friction to cope with ~180lbft engine torque, which is then multiplied considerably in the lower gears? I would say the shear load is very much on the bolts themselves in this case.
Edited by SuperchargedVR6 on Thursday 29th November 15:44
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