Weld spacer to a rim - Solved.

[Mooro]

Yeh I understand that (I'm an engineer by the way)...thats exactly what I'm saying...the high stress point is where the spoke meets the hub and the moment due to the lateral forces acting at the contact patch is reacted...no question that is a point of high stress....but the last time I remember looking at the back of a rim, the spoke attached more to the front of the hub rather than the back which is where I'm talking about welding...if you look at that last FEA plot you will see that these stresses die off pretty quickly and it is possible that the 5-10mm corner at the back of the hub doesn't actually see much of these stresses.

I have no doubt that there will be some stresses here and in perfect world you would not go messing around with these things but all I'm suggesting is that it is not necessarily a point of HIGH stress...I guess we might be disagreeing over what you would classify as a point of high stress.

I'm not disagreeing that there will be stresses there but in my opinion the area of high stress will be more localised around the spoke to hub junction rather than at the back of the hub.

At the end of the day I don't think you can say for certain one way or the other without looking at something like an FEA because a wheel and it's loadings is a much more complicate geometry than a ruler on a desk.

Mooro,
Think of it this way. Grab a plastic ruler and hang it off your desk, about half on the desk and half off. Hold the ruler firmly to the desk with one hand near the edge of the desk, and with the other hand, push down on the ruler from the very end of it. Where is the greatest amount of stress applied?? Well if you keep pushing the ruler, it will break where it meets the desk. Any 10 year old who has gone too far with the musical ruler game can tell you this.

So, translate that, your hand was the studs, I hope your hand wasnt at the very edge of the desk, but rather a bit in, like a stud would be. The desk is the hub, solid cast steel, not going to break from road stresses, and made of much stronger material than your rims. The ruler is the rim, alloy is flexible, and so the plastic ruler does an ok job of representing it. You apply pressure at the end, like where the tyre contacts the road... the ruler bends more the closer to the desk it goes, and less at the end where you are applying the pressure. This is due to torque being a multiple of force applied, by the leverage distance.

Can you see what I am getting at?? From engineering basics (without having to go into FEA), its pretty easy to see that the high stress point of the rim is where it meets the hub. This is why rims are thicker there. They are then recessed for weight saving and a number of other reasons, but ribs are left in place for rigidity.

Clear as mud??

[wilbo666]

But it isnt a spacer, its a disk rotor. A spacer has no other purpose than to move the rim outwards... the disk rotor has the purpose of... well being a disk rotor, so it is not a spacer. So yeah, using my interpretation, the letter of the law allows hat type rotors to be used.

So if one decides to use a two piece disk (disk with alloy hat) for example...one could get the 'hat' section made with a 30mm cross section, it wouldn't be a 'spacer' tho...it would be a 'brake disk hat', and you've already decided that the what could be called 'spacing' action that comes with a hat over hub disk is OK?

Grey area?

Cheers
Wilbo

[CrUZida]

Has anyone checked the wording the NCOP's have?

Here it is for you



To me that says ANY spacer or ANY adaptor between the rim and the rim mounting face is illegal.

Now, changing to disc over hat moves the rim mounting face to the front of the disc, which is what it was designed to do in its factory fitment, therefore legal.
One could also argue this point quite successfully if required.
I doubt you'd be able to argue the use of a spacer in the same manner.

A spacer between the hub face and a disc over hat is not illegal according to that section, providing you comply with the other requires of stud length and hubcentricness.

Furthermore, welding a spacer to the hub is illegal according to the last sentence.

[wilbo666]

Has anyone checked the wording the NCOP's have?

Yep

I have...

To me that says ANY spacer or ANY adaptor between the rim and the rim mounting face is illegal.

One could also read:
"Fitting of wheel spacers (or adaptors for dual wheel conversions) between the wheel mounting face and the road wheel is not allowed....blah blah.."


As meaning that adaptors (bolt ons) are OK as long as it isn't for dual wheel conversions...


Don't get me wrong, I'm all for correct wheel offset or putting spacers under the disks, but I like playing the devil

Cheers
Wilbo

[Mooro]

I have no doubt spacers are illegal and if spotted they won't be accepted but I think that goes for a lot of the modification people have on their cars these days with the new NCOP rules.

[o_man_ra23]

So spacers are illegal, and replacement wheels must be designed correctly for the particular hub/axle.

So, unless you do an FEA and full design and have it approved by an authorised engineer as being a valid rim design, then the welding of spacers to the rim is illegal... and poor engineering practice. I wouldnt ride in a car or want to be on the same road as it if there were spacers welded to the rims, no matter what was done to them after the welding... just too risky. Race cars throw away rims if they get dented, as the fatigue incurred when straightening the rims is enough to kill it during full race conditions... even from minor dents.

EDIT: any mod that was engineered before the NCOP is perfectly legal. It is not necessarily legal to transfer that mod to another vehicle, as it will need to be re-assessed even if your transferring from one body to another (ie you find a body with no rust and wish to use that for your previously engineered project... prior to the change in rules, you would go back to the same engineer, and he would have a check to make sure the same design was used, perform a few routine tests to confirm and sign off)

[Mooro]

Yeh I wasn't ever discussing the legalities of it...it's always been illegal in my view, but so is running a PowerFC with the new NCOP regulations.

There is probably lots of things I will be doing to my road car that a race team with racing budget wouldn't do to their race car...I'd hazard a guess that goes for a lot of the things done to road cars.

Personally if it was done correctly, correct pre-heat was used with the welding and the spacer was hubcentric to the wheel and hub I think it is an option worth considering...assuming it was done professionally and with consideration of the design and construction of the wheels in question. Without question it is best just to buy the correct wheels in the first place but I personally prefer the option of welding spacers to the wheels rather than bolting the spacer to the wheels.

Having said that I'm by no means a professional in the area of wheel design and metallurgy, but I just think it is not necessarily a bad option but certainly not the best option

[o_man_ra23]

Just thinking about this a bit more cos I'm possibly gonna have to go down this path. My thinking is that the HAZ (heat affected zone) is only going to be 5-10mm deep at the most and with correct pre-heat you can minimise residual stress so the majority of the wheel will be unaffected.

Thoughts?

My thoughts are:
-Its illegal
-You know its illegal
-Your an engineer (so am I)
Its probably going to cost about the same as buying a set of correct fitting rims
-You dont know large amounts about rim design or metallurgy, therefore you would need to pay somebody who does a lot of money to tell you whether its going to work or not... and I dont think you will find anyone who will be willing to sign off on it at all... no matter how much you paid them.
-You are playing with the balance of the rim as well, which will need to be machined correctly, further increasing cost

In my book, I dont know why you are still even arguing that its possible, as it is in no way practically possible, therefore it should not be done. The best solution in every way is to buy the correct rims.

So theres my answer to your initial question.

["Z" UTE]

Well put, o man ra23, I will now unsubscribe from this thread.

cheers Chuck.

[Ben Wilson]

There is always the argument that if you bolt a spacer to the rim, then it's part of the rim. As such, it's no longer a 'spacer', it's a modified rim.

I really can't see any safety reason to ban spacers, as long as it's located well, the track doesn't change dramatically and the studs are long enough..

[Mooro]

Haha, just so I can have the last say

I'm not really interested in the legalities of it and from a strength point of view I'm still not convinced it is a bad idea but your point regarding the balance of the wheel and the overall cost is well made and on the basis of this I will lay it to rest in my mind

[Mooro]

There is always the argument that if you bolt a spacer to the rim, then it's part of the rim. As such, it's no longer a 'spacer', it's a modified rim.

I really can't see any safety reason to ban spacers, as long as it's located well, the track doesn't change dramatically and the studs are long enough..

Yeh I agree with this but I can see the reason for banning them though. In my opinion a well designed set of spacers doesn't pose an unnacceptable risk but a poorly design set of spacers is a disaster waiting to happen. It is not feasible for the guys down at the pits to separate the shit from the good so they have a to make a blanket rule banning them.

[CrUZida]

There is always the argument that if you bolt a spacer to the rim, then it's part of the rim. As such, it's no longer a 'spacer', it's a modified rim.

And then the rim needs to be engineered and/or approved, which puts you back at square one.


As for PowerFC, its perfectly legal if you get an emissions test done (and it passes).
It doesn't need to locked under NCOP rules.

AND, the NCOP's state that you an emissions test is required ONLY if the system is visibly different than a stock setup.

LT3
4.0 MARKING & TAMPER-PROOFING
4.1 Are there any visible indications that the vehicle's emission equipment as supplied by the manufactuere have been removed or tampered with?

Note: If the answer to the above is NO, the testing cannot be approved under Code LT3

To me that says 'if they can't find it, it doesn't need testing'
Although that last line is VERY open to interpretation.

[DoctorDubb]

Has anyone checked the wording the NCOP's have?

To me that says ANY spacer or ANY adaptor between the rim and the rim mounting face is illegal.

I can definately see where you coming from. But could you please give me your definition of 'rim mounting face'. I would define it as "the face to which the rim is mounted to". Therefore if i have bolt on adaptors (read bolt on spacers) to the hubs. This then gives me a new 'rim mounting face' for the rim as this is what i now bolt/mount the rim to and i have no spacer of any sort between the 'rim mounting face' and the rim. This means i am complying with that statement. The question would then be is this modifying the hubs? I would assume not as i didnt touch the hub just bolted something to it.

And as long as im within 25mm track change in total i should be able to get it engineered and A-OK with NCOP rulings if i understand correctly. I have no idea wether or not an engineer will see it this way.

Just a note: Im planning on running bolt on HUBCENTRIC spacers on the front to match up with the increased length of the diff in the rear. Not for the fully hectic JDM goodness with flares as i know how dangerous spacers can be in the wrong hands. Otherwise i need to find a pair of offset rims in +25 and the same pair in +45 which aint going to happen anytime soon as they dont usual make an rim in two offsets unless u go custom.

[CrUZida]

You are correct in your thoughts.

However,

Now, changing to disc over hat moves the rim mounting face to the front of the disc, which is what it was designed to do in its factory fitment, therefore legal.
One could also argue this point quite successfully if required.
I doubt you'd be able to argue the use of a spacer in the same manner.

Personally I treat spacers and bolt on adaptors as the same.
Change the bolded word 'spacer' in the above to 'bolt on adaptor' and you'll have my thoughts/opinions on the matter.

With everything else you modify on your car, get an engineer to approve it, AND get the Trans Dept to approve the report and you are fine.

Getting an engineer to approve something is somewhat easy.
Getting the people who helped write the rules to bend slightly just to suit you is much harder.

Last time I enquired about such things 'because the rims only come in that offset' or 'because its too hard to find rims that legally fit with mods' were not good enough reasons for them to bend the rules.