CMC 17" Wheel Weight & Welded Spacers

[BryanL]

Z06 wheels weigh more than 18 I believe and think over 19 (I'll weigh one this weekend) so shoudln't be because of that. Sounds like it was for the Mustang and the Enkie wheel? I'm not aware of ever seeing an F body with a welded wheel. A director probably got a good deal on some lightweight 17" CCW's or something and wanted them legal at the time for the weight. Raise the weight to 19 lbs without a welded spacer.
The logic in a budget series to allow buying a $2k set of wheels and then welding on a spacer just so it's legal doesn't make sense to me.

[RichardP]

The Z06 wheels weighed 19.0 lbs on my bathroom scale that has .5 pound resolution. Depending on the scale, you could easily get a bit above or below 19 lbs. As a strong, cheap, and readily available factory wheel that closely meets the specifications, it seems likely that it was the wheel in mind when the current CMC rule was made. The fact that it is no longer cheap or all that available isn't really relevant. The rule wasn't created around the Enkei wheel as that wheel wasn't even legal until the rule was changed to allow including the spacer weight in the calculation.

I don't think changing the allowed wheel weight (up or down) is a good idea. Up will make some people's wheels illegal. Down will send a bunch of people scrambling to buy new wheels. Allowing wheel spacers to be included in the weight is the easiest/cheapest way to get everyone to an equal spot. There are a lot of cheap wheels available for the Mustang but they are usually in the 22 lb range. There are wheels that cost a bit more but they come in below weight. The Enkei wheel costs about the same as the going rate for the a good Z06 wheel. There is really nothing in the marketplace for the Mustang that hits the sweet spot like the Z06 wheel without including the spacer in the weight.

I do think not requiring the wheel spacer to be welded to the wheel is a good idea. Welding a billet spacer to a cast wheel of an unknown alloy isn't a good plan and could even be dangerous in some cases. I also don't get the point? A light weight wheel is only legal with a spacer and checking for a spacer at impound is trivial. It also takes wheels that would be AI legal/desirable and makes them CMC only so they are harder to sell.


Richard P.

[mach1]

I pushed to remove the welding requirements due to safety. It’s also easy as hell to audit.
If I end up building a fourth GEN I’m going to get a Ford bolt pattern hub and axle so I can easily use and purchase the enkeis

[marshall_mosty]

The real genesis of the rule change was due to an Enkei RPF1 with a steel spacer that was attached to the wheel with screws (drilled the wheel and counterbore in the spacer) then plug welded so the attachment screws can’t back out or the wheel separated from the spacer, making a pseudo custom wheel).

That led to folks saying the heavier spacer “mass” was in the middle of the wheel, hence lowering the rotational inertia which created an advantage. That prompted the rule to be written around an aluminum wheel and aluminum spacer.

I’d still lobby for a permanently attached (screws plus plug weld which is easier with standard billet 6061 spacers).

Since the original steel spacer and alumunimum wheel combo was my idea and Jeremy was clever enough to try it (and McSpadden copied the idea with my CAD file for the spacer and took it to Nationals), blame all this on me... LOL

[Sook]

The real genesis of the rule change was due to an Enkei RPF1 with a steel spacer that was attached to the wheel with screws (drilled the wheel and counterbore in the spacer) then plug welded so the attachment screws can’t back out or the wheel separated from the spacer, making a pseudo custom wheel).

Adding holes to the center bore of the wheel scares me... and then plug welding them will locally destroy the wheel's temper.

That led to folks saying the heavier spacer “mass” was in the middle of the wheel, hence lowering the rotational inertia which created an advantage. That prompted the rule to be written around an aluminum wheel and aluminum spacer.

How does going to aluminum solve remove the inertial advantage? I'd rather go with a steel non-attached spacer. I can make your wheels (thanks for the deal btw) work with steel spacers.

So here's the question, if I show up to COTA with aluminum spacers not welded to my wheels will I be DQ'd? I wouldn't take the risk of showing up with a car that directly goes against the rule book, if we can get clarification ahead of time against welding wheels it'd be awesome.

- Josh

[Suck fumes]

yah sook make sure you get clarification on anything wheel related. I saved all Marshals approval messages on my phone when i took my setup to Utah at miller mot park just to cover my butt cause it created a firestorm online once people realized what i did to the wheels (marshals idea) to make weight. BUT it’s the budget way around spending thousands in fikse or ccw wheels.

[marshall_mosty]

Just to clarify the plug weld would ONLY be on the spacer, not the wheel. The only permanent modification are the tapped holes that the screws which hold the spacer on screw into.

Regarding steel vs aluminum spacers, for a given weight and thickness, the outer diameter of the spacer would be smaller on the steel spacer (advantage)...

[BryanL]

yah sook make sure you get clarification on anything wheel related. I saved all Marshals approval messages on my phone when i took my setup to Utah at miller mot park just to cover my butt cause it created a firestorm online once people realized what i did to the wheels (marshals idea) to make weight. BUT it’s the budget way around spending thousands in fikse or ccw wheels.

Marshall-will you approve my aluminum rear diff cover? I'm not aware Marshall was ever a CMC director to my knowledge to give "approval"? I'm pointing this out more because I get uneasy about anything that needs an "approval" since it's likely pushing the intent of the rules or possibly worse.

I agree with Tyler and any others that modding a wheel is a potential safety issue.

Wheel weight rule just has a better benefit for the Mustangs with the Enkei wheel option unless there is a wheel under 18 lbs for the F-body that ins't over $2k for a set (though I sure like the looks of the CCW). There are all kinds of advantages/disadvantages for each platform.
Sook-send it in for rule change request in our now non-existant silly season to get it approved to lower the wheel weight since it improves safety, lowers cost, and doesn't impact performance since people were already running the Enkei. Heck maybe you could get the rule changed before hand instead of a nod/wink approval.

I also agree with DAlgozine that it seems to be a goofy loophole that shouldn't really be in CMC. But then I'm checking to see when my custom Ford 9" with aluminum center section is going to be delivered so I can get it installed before nationals because my aluminum diff cover with a drain plug is illegal. Just doesn't make sense to replace it with a stock cover when for $3,800 I can get a stronger diff, better posi, and nearly unlimited gear options. Only downside is I have to order a new pair of CCW's for the different bolt pattern.