Wheel spacer .. how much of it do you really need ?
 

So was looking at the back of my 949 6UL today .. and noticed that the back of the wheel wasn't completely flush to the hub.
There's a X shaped rise a few mm.

https://cimg6.ibsrv.net/gimg/www.mia...ddda33ed80.jpg


For my application, I'm using a 949 15x9 +12 wheel and I need 20mm spacers in the rear. The spacer is a nice aluminum hub centric unit and already drilled for 4x100 as well as 4x114 but still weights a hefty 21.6 oz. I'm thinking of trying to further reduce weight by removing the area of the spacer that the wheel doesn't mount flush to. Similar to how Keisler's timken hubs are modified / scalloped but more extreme.

https://cimg3.ibsrv.net/gimg/www.mia...90d1d3d056.jpg

But ... figure I would ask first if this was a horrible idea or not, before I break out the grinder. I'm thinking the worse I can do is throw off the balance of the spacer if I didn't remove the material evenly enough. However, if I pretty much mirror that X, I assume it should be good as I assume that X on the wheel is balanced.

So .. LMK what do you guys think ?

I can't think of a reason why not. But I'm only on my first cup of coffee.

The MiataCage spacers a lot of spec Miata guys use are already sort of doing some of that. They cut some away and drill quite a bit of the rest. I think most of them are just round because they are easier to make like that.

Miatacage.com. Wheels and Spacers

Wow, I'm loving those Miata Cage spacer design but .. so much $$$ and not thick enough. I'll start cutting my own today.

I think they also ditch the hubcentric part that sticks into your wheels too so you may like your "cut" ones better. I've used hubcentric and not on a much heavier R32 I have and as long as you snug the lugs down before you put weight on the wheels it always seemed to center fine.

As an engineering student i can say there isnt a problem. Spacers are usually cut on a lathe and left sphericle to reduce cost.

At the same time though i would suggest doing a cad pf your design and stress testing it to make sure it can handle the loads!

Good luck!

I'm likely in the minority here for the "all of it" mentality but how much weight would cutting or drilling really remove, is it worth the hassle and / or risk?

(not that I think there is likely much if any risk).

The thing is, any weight removed is unsprung. Makes a big difference, which is why you see wheel manufacturers making their products as light as possible.

I can't see a problem replicating the mating face of the wheel. Hardness would be my only doubt, though that may be independent of shape.

Sure but aren't we talking grams here?

Hey, it worked for Lotus.

Two things to keep in mind: spacer load-bearing surface area (pay attention to the spacer itself deforming) plus balance.

Sure did, it also frightened some and and killed one of their drivers.

hmmmmm this seems extreme to even want to fix this...... put a small 2-3mm aluminum spacer from a good known company and put your wheel on... done... no ?