i am sizing up my SBG AP BBK and I need 6mm to clear 17x8 RPF1s. I have OEM studs and don't want to redo wheel bearings as I just did them not too long ago. I am basically stuck between going with a 6mm spacer which leaves 9.4mm of threads. If I went this route I would by fresh lug nuts which I need anyway. I check my lugs between sessions so if it seemed like this wasn't a great long term solution I could put in extended studs during the winter. With a 225 and +45 I may need to roll a touch.

Option 2 is the project kics 10mm which serves as an adapter. I am not super crazy about this setup as it doubles the mounting points that could possibly come looseand there is no way to check the ones under the wheel unless I remove the wheel itself. Plus it isn't a cheap solution. Also I would need a roll for sure.

The only difficulty with the 6mm is that I can't find one specific to the S2000 front bore and would need to get a generic one that has a larger bore.

Thoughts? Buying new wheels or selling the brakes is not an option

 

After giving it some thought I am thinking I will go the 6mm eBay spacer and new lugs, test fit and see how it feels, if it seems sketchy then put the OEM brakes back on until I can toss on extended studs.

Any advice on a good steel lug nut has a sharper taper and immediate thread engagement? My gorilla lugs have a more broad taper and the threads don't start until about 1mm into the lug itself. I want all I can get with this setup!

 

Option 1: buy my old wheels 17x9+35, lol
Option 2: get the longer studs, we have a press, make a visit

not a big fan of tracking on the bolt on eBay spacers

 

Yeah the bolt on spacers are not a good solution. With the 10mm spacer I only have 10mm of thread engagement, actually less because there has to be some thicknessto the spacer under the nut AND it is aluminum. With the 6mm option I have 9mm of threads and I will use steel lugs. IMO that is the route. If I could install the studs without pulling the hub I wouldn't mind that route. I would likely do this over the winter if I go with the 6mm spacers.

Now the issue I am running into is finding 6mm spacers that match the center bore. I can find ones that are larger, but the exact size I can't find. I can find a 3mm and maybe just stack 2?

 

Between the two I like the 6mm spacer with 9.5mm of thread coverage. Not great, but I think better than doubling the hardware risk with the bolt-on hubs.

I don't see why 2 3mm hubs would give you a problem. Good Luck

 

https://store.gaugemagazine.com/

This website will make custom spacers, $70 shipped

 

My vote is C) Replace studs with ARP

Safety shouldn't be compromised.

 

I will likely do that over winter, but I have talked with several people locally who said they would have no concern. People run light weight aluminum lug nuts, you could argue safety is comprised there. IMO the 6mm spacer on OEM studs is safer than the bolt on spacer.

 

Couple of things came to mind wile reading through the OP and responses here.

The seat of the wheel determines what kind of lug seat you need to mate to the wheel. Putting a slimmer taper to get more possible threads out of the lug nut means you are not getting a proper lug seat on the wheel, that's not good and your trading one safety aspect for another.

The other thing is yeah 6mm is pushing past the threshold to be safe which is typically 5mm MAX. You need a min of 6 full revolutions of the lug nut on the studs and for most wheels that seems to be 5mm, but that's not a hard rule either so you better measure.

Also a bolt on spacer is perfectly acceptable to run as it was designed, another failure point? I just mentioned 2 actual real failure points above that some are willing to compromise on and accept over a actual engineered piece that's been utilized on thousands of cars for how many years? There is no more trial and error here, its a proven solution that ive employed myself. Make sure the studs/spacers are brand quality with proper grade studs, nuts on the spacer are trq to proper spec and that they are hub centric on the drive wheels and you wont have a problem.

And finally the problem with a 10mm spacer with integrated studs is that the studs and nut protrudes well beyond the face of the spacer and that means it wont mate to the wheel. Typically 15mm is the slimmest design ive seen that will fit into the back recess of the wheel, but that's wheel dependent, usually 20mm is the min sure deal. In the OP case, longer pressed in studs seems to be the only safe and working solution here to get reasonable fitment without massive outer fender flaring. The RPF1 8.5 +40 has miles of room for BBK and puts you near same fitment as if you were to add a 10mm spacer, so you may want to consider a higher cost solution of a new pair of matching wheels that actually work for the sake of ease here.

 

^^^ I didn't mean to imply that I would use the incorrect lug nut, I was just going to buy fresh proper lug nuts that had a better taper. My gorilla lugs are worn and have a broad taper, others have just a touch sharper taper and slightly earlier thread engagement. Both will work with a wheel designed to take a tapered lug.

As for the bolt on spacer it is a bit concerning that you would have an opinion with so much certainty but don't really understand how they work.

They do make 10mm ones and you either cut the studs flush or if you have wheels like mine there is a space on the backside of the wheel that the studs recess into. Also 15mm would still not sit flush as there is 23mm of stud sticking out beyond the rotor face. I know because I measured to figure out that I will have 9.5mm of thread engagement with the 6mm spacer 1.5mm threads =6 threads.

This also made me realize that the bolt on spacer, which I would agree is a safe proven method can't possibly have more thread engagement beyond this (the nuts cant be anymore than 10mm). The only difference is that the spacer now directly holds on the wheel and they are made of aluminum. This lead me to where I am now, if that design has be proven 1 more mm of spacer for a couple of events until I get longer studs installed has to be fine.