How close is too close? - Caliper to Wheel Clearance

[Whiskey11]

So the 2015 has arrived finally and I was testing the wheels I have laying around. 18x10 SVE Drifts most certainly DO NOT fit as the brake caliper hits the barrel of the wheel on the 15" 6 pot brakes. 18x9 ET45 Enkei PF01 DOES fit with a 5mm spacer (wheel lugs still have 5.5 turns till fully tight). The wheel spins freely around the caliper but the distance is really small and I'm wondering about how close is too close to the caliper to safely drive on them. I don't have an actual measurement as I was testing the wheels before work but there is maybe 3mm of clearance between the outside edge of the caliper and the barrel of the wheel.

FWIW, my plan is NOT to run these for autocross or track days or with any seriously grippy tire. If anything I'm looking at these wheels to run as winter wheels (talk about insulting to Enkei, but 18" snow tires are cheaper than 19" snow tires! ) with winter tires.

So what says the wisdom of S197 Forums?

 

[BMR Tech]

Two business cards thickness.

 

[Whiskey11]

Two business cards thickness.

Seriously? Is that all your HRE's are on your 2015?

 

[BMR Tech]

Seriously.

No. The HRE on the 15 and the 11 have a bunch.

My personal car, with the Billet Specialties, is 2 business cards.

 

[BMR Tech]

(I am not throwing that out of my ass - I worked with Billet Specialties on the S550 stuff, and that is straight from the horses mouth)

 

[Whiskey11]

(I am not throwing that out of my ass - I worked with Billet Specialties on the S550 stuff, and that is straight from the horses mouth)

Got it, will check again after this weekend. It was close but the wheel spun freely without any contact with the caliper so long as the spacer was there.

 

[CobraRed]

Two business cards thickness.

This.

You wouldn't believe how close some aftermarket wheels can get with brembo brakes and be fine. If my Rota's were 1mm of backspacing different I might not have been able to run them.

 

[jraskell]

So the 2015 has arrived finally

Pics or it didn't happen.

 

[Norm Peterson]

3 mm of clearance is a ton of space, especially inside the barrel diameter.

My Forgestars have less than 1.5 mm clearance to the struts way out there at the inner wheel flanges and the same at the tire sidewall. At about 0.9 mm, there was a tiny bit of tire rub on one side (fully corrected by fabbing up an 0.025" thick spacer from sheet aluminum). On another car, I had just under 0.030" clearance between the wheel flange and the outer tie rod end, no rubbing ever.

For a 20 threads/inch fastener I would never trust 5.5 threads to be sufficient. Ever, short of some absolute emergency need. Get longer ones, even if you have to cut them down so they fit your lugs and/or wheel locks.


Norm

 

[Whiskey11]

Pics or it didn't happen.

There will be more coming soon in a new build thread but here is a quick one for ya:

3 mm of clearance is a ton of space, especially inside the barrel diameter.

My Forgestars have less than 1.5 mm clearance to the struts way out there at the inner wheel flanges and the same at the tire sidewall. At about 0.9 mm, there was a tiny bit of tire rub on one side (fully corrected by fabbing up an 0.025" thick spacer from sheet aluminum). On another car, I had just under 0.030" clearance between the wheel flange and the outer tie rod end, no rubbing ever.

For a 20 threads/inch fastener I would never trust 5.5 threads to be sufficient. Ever, short of some absolute emergency need. Get longer ones, even if you have to cut them down so they fit your lugs and/or wheel locks.


Norm

Awesome, thanks. As for correct number of turns, I'm assuming you are using the "as much thread engagement as stud diameter" for the correct value? That'd be 10 turns on these studs. I'm not even sure the stock ones have that many turns. I'd have to double check what they are OEM. The front studs on the 2015's are insanely short compared to the S197's studs.

 

[Sky Render]

Can you fit a credit card in there? Yeah? Then forgetaboudit.

I had to remove the outside wheel weights to get clearance, and I've autocrossed them like that for years with no issue.

Sent from my Samsung Galaxy Note 4 using Tapatalk

 

[Norm Peterson]

Awesome, thanks. As for correct number of turns, I'm assuming you are using the "as much thread engagement as stud diameter" for the correct value?

Yes.

That'd be 10 turns on these studs. I'm not even sure the stock ones have that many turns. I'd have to double check what they are OEM.

With the OE lug nuts it's very close, I think I get just under 10 turns with the wrench after a very minimal 'starting' by hand (probably under 1 full turn). Chances are that you lose a fraction of a turn due to the end threads being somewhat less than "full form".


Norm

 

[mitch]

x5, credit card, couple business cards, and your good to go.

 

[Vorshlag-Fair]

The factory 19x9" 10-spoke wheels only cleared the factory Brembo caliper (laterally) by .050".

 

[Whiskey11]

The factory 19x9" 10-spoke wheels only cleared the factory Brembo caliper (laterally) by .050".

Lateral clearance isn't the issue here though. You know the spokes on the Enkei PF01, LOTS of clearance that way due to the spoke design. It's the barrel clearance that I'm more concerned with as the lateral clearance can be adjusted with spacers (within reason and stud length). Still good data to know for those looking at other wheels with close spoke to caliper clearance issues.

 

[ArizonaGT]

Been pondering this myself lately as well. Thinking to go to the Brembo 380mm Pro Kit for next season and really wondering how tight the caliper will be to the barrel of the 18x10.5 Enkei PF01. Doing some math on the Brembo drawings plus some very imprecise measurement of the wheel barrel says very close. What kind of business cards are we talking about here? Serious shit like in American Psycho or ?

 

[Norm Peterson]

I would think that anything over 1/32" radial clearance would be enough . . . but all bets are off if you bend a wheel on a curb or pothole.


Norm

 

[Sky Render]

If a wheel barrel is flexing more than a credit card's thickness, you've got bigger issues than caliper clearance.

 

[Pentalab]

I thought the 2015 used 15mm studs instead of the 1/2-20 studs on the 05-14 cars ?

 

[claudermilk]

There's a few of us running the AMR 18x10's, which barely fit over the 4-pot Brembos. Same a Vince: I cannot run wheel weights out there--just on the inside of the barrel; it took the tire place 3 tries before the guy got out of the assembly-line minivan-tire-replacement mentality and follow my explicit instructions. I've run them for 3 track days and a few autocrosses with no real problem. All I've seen is at some point a pebble got sucked in between & scratched the barrel paint.