Caliper to wheel clearance for 15" wheels on Gen 1 coupe

[defilade]

Car details: 2009 Gen 1 coupe, complete kit with IRS, 8.8" rear, and 15" halibrand-style bolt-on wheels supplied with the kit. My understanding is the rear brakes are from an '03-04 Mustang Cobra 4.6.

I'm troubleshooting a scraping sound in the rear and found that the caliper is touching the inner edge of the wheel on the left, and there are just a few mm of clearance on the right.

The builder documented his build in a photo album and it was this way from day one. He even commented "boy this is close to the rim" (this is the right rear): https://www.flickr.com/photos/51103049@N00/8448374537/in/album-72157621399986948/

This can't be the intent of the design, right? Because that small a clearance does not seem appropriate.

I'm attaching a pic of the left side where it's actually scraping a little. In the short term we're going try putting in new pads and hopefully that will push the calipers apart a little.

Longer-terms solutions would seem to be 1) 15" wheels with less offset, 2) 17 or 18" wheels. But is there another solution for this set of wheels and brakes that works?

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[65 Cobra Dude]

Can you just put a 1/4” wheel spacer in there?

Henry

[defilade]

Can you just put a 1/4” wheel spacer in there?

Henry

Yes spacers are one option, although the studs are already short so I'd probably need to use a thicker, bolt-on spacer.

[65 Cobra Dude]

Gen. 3’s need a 1” spacer to move the wheels out and they are bolt in and come with the kit. I don’t think you’ll need bolt in ones for a 1/4” spacer and if you do, maybe put on longer studs?

Henry

[defilade]

Gen. 3’s need a 1” spacer to move the wheels out and they are bolt in and come with the kit. I don’t think you’ll need bolt in ones for a 1/4” spacer and if you do, maybe put on longer studs?

Henry

Thanks. We ended up adding 1" bolt-on spacers and that did the trick. Of course that means I couldn't run the 275/60s I already had, as they were hitting the wheel arches. Fortunately I had a set of 265/50s and those fit just fine.

Longer term I think I will have to move to 17" wheels with a custom offset to put the wheels in the right spot where I can run the right size tires. If I wanted to stick with 15" wheels, I could change the studs and go with a smaller spacer. But given the lack of tire options, I'm reluctant to invest more in the 15" platform.