Well that’s not what I expected. 20” min for the front brakes. Here’s the rims the Popo use for those.
I wonder if the four pot brembo will fit under the rear 18”?
4piston front brake kit fits under 18" wheels.
6piston front brake kit needs 20" wheels.
not sure if you were asking me?
I have no idea what rear wheel diameter you need for the Corvette rear brake upgrade.
So I finally did someting with this subject...
And in my final educational session I came across this thread in my search results lol...
Upon re-reading it I realized there was some good info in here that I had not absorbed...
Thank you to all who contributed...
My main unsolved mystery was:
Will the 4 pistons fit inside 17" wheels?
...and the answer is Yes (but only if your math, math's out right)
Recently came across a pair of 4 piston caliper + pads + rotors + dust shields off a 2026 Escalade for $225. Was told they were driven during test drives and from dealership to afermarket shop, which was pretty obvi in photos. I double checked for fitment? Consensus was they fit with an approx 0.125" hardened spacer between caliper and bracket (moving caliper 0.125" outward).
They were a couple hours away but in a town where a longtime friend lives, and he comes here to work 1-3x every week. Called him up and he was coming next day. Had them in my hands in less than 24hrs lol.
Didn't attempt to install them until this morning...
I'll post pics immediately after posting this... Theyre on my phone and I dont have cord to move them over here w/me...
As you'll see in pics: They fit! Barely! ...and I mean BARELY!
0.105" clearance from back spokes lol... I'm running a 17 x 9 +18 with a very mild curve or dish shape in the spokes. ZERO chance they fit w/o that subtle curvature to the spokes. 0.105" is 1/4th of 1mm
Already ordered some hubcentric 3/8" spacers as that is too close for comfort imho...
**EDIT: Canceled spacer order....for now lol...
Im gone try to explain this as concisely as possible (sometimes hard for me)...
>>(Technical) Functional Fitment for the newer GM 4 piston brake upgrade onto a GMT900 is a combination of three distances and one wheel design feature....and it's not very easy to explain.....and even harder to comprehend if you dont have some decent knowledge/experience with these systems...
Those are: wheel offset, caliper spacer size, wheel width, and spoke shape. Rotor hat height is another distance that plays a role, but its role is only in the measurng of your current setup, just to see if your wheels are compatible.....but this post is long enough already so:
In short: the most common point of contact is casued by the 4" x 0.5" raised rectangular bump out on the outside face of the calipers. It makes contact with the backside of the wheel spokes.
If you're considering this brake upgrade? Before you do anything, put a tape measure through your spokes onto the face of the rotor and see if you have 2.5" or more available from the face of your rotor to the back of your spokes? Make sure to take note if you have a different measurement closer to center than out towards the tire? because that plays a role too...
That's a START...
Hope this helps someone some day...
