First Scooby-Doo "Rhuh-Rhoh" Moment - Brakes Question

[mach'er]

It helps if you read that with a Scooby voice. "Rhuh-rhoh Shaggy."

So, I already have 15-17MY Mustang GT rear brakes for the newer IRS system in hand (well, really, in a box). They are the 13" rotors in the M-2300-MR kit from Ford Performance.

I ordered 17" Halibrand replica wheels.

I now see that the two might not quite be compatible. Somehow I missed that.

If that's correct, there is the 'put in a wheel spacer, longer lugs, maybe modify the caliper a bit' course of action. BUT, there's also the 'change the order to 18" Halibrand replica wheels, and upgrade the front brakes to something bigger too' course of action. Obvious question... Why do I need to go bigger front brakes to take care of a fitment issue with the rear brakes? Well, I don't really. But, but, but, really... If I'm opening up the wallet again for 18" wheels, why not? And, if I do change to 18" wheels, the complete kit's 11" front rotors are going to look tiny in there (that's right, right - the kit includes 11" rotors?).

It seems weird to have 11" in the front, and 13" out back. So, I kind of like the idea of upgrading the front brakes.

For front brakes, I see a 12.88" Wilwood kit through various places. There's a 14" kit from Levy Racing (94-04 Mustang, so that works, right?). I'm sure there are other 87-04 Mustang front brake kits out there as well.

Perhaps I'm just trying to talk myself into this, but my question to all you experienced people is:
What's the best option for front brakes in a Roadster with manual brakes? I'm sure there are many, many opinions, and concerns about balance and whatnot. Please, let me know your opinions and experience.

Thank you,
--Curt

[Gordon Levy]

If you are using 18" wheels you can use pretty much any of 13" or 14" kits. Also my 4 piston rear kits are going to be a far better option than the single piston factory based stuff. I do have rear kits in 12.2 and 13"

[scottiec]

Also remember it is a 2300 lb car. You don't want to outbrake your tires too quickly on the street.

[edwardb]

I can't offer many specific recommendations. But some general comments. Because of the near 50/50 front/rear weight distribution these cars need plenty of rear brakes. More so than the typical DD. So it's a good thing to have big brakes in the rear. But I wouldn't pair the 13-inch GT rear brakes with 11-inch fronts. BTW, agreed 11-inch sounds small compared to some of the bigger brakes now becoming pretty standard, but keep in mind this is a pretty light car as already mentioned. Plus with the smaller wheels that were typical in the past, wasn't possible to put real big brakes in these. Set up properly, they still stop just fine. I have the optional Wilwood 6-piston 12.88 fronts / 4-piston 12.88 rears in my new build. Note these are different and significantly better than the single piston Wilwood rears FF has sold for some time and still has available. Not many miles, but they seem to work very well. They will fit either 17 or 18-inch wheels as I understand. But since you already have the GT rear brakes, not sure I'd mix the OE style brakes and the Wilwoods. I can't say what would be "best" for your front brakes. The answer is subjective at best, and depends on your planned use, etc. If you want to keep the GT rear brakes you have now, why not matching GT front brakes? I don't know specifics because I have no experience, but just a thought. If you do need to bump up to 18-inch rims, not the worst than can happen. I have them on my new build. I wasn't sure at first, but I've grown to like the look. They don't look that different than the 17's, and unless you had them side by side, maybe wouldn't even notice. I was a little worried about the ride with the even lower profile tires, but it's no issue at all. The new IRS rides great.

[CDXXVII]

I am pretty sure this is similar to the setup that came with my 15 year anniversary. PBR calipers with 13" rotors. This is similar to the 2004 Mustang Cobra front brakes and they work fine. i have the 17" Factory Five wheels with 13" rotors front and rear with no issues.

https://lmr.com/item/SVE-2300KC/must...BaKBoC4t_w_wcB


You can see that the rotors really fill up the wheels.

[mach'er]

Thanks for the feedback, guys.

I did speak with Gordon last night on the phone, and I have a pretty good idea of what I want to do. I'd like to keep the 17" wheels, and get brakes that are going to "fill the hole" both front and back, and work well together (and with the car). Either front or back could be upgrades later, but I'd rather just incorporate it into the initial build. So now, it's just a matter of deciding what I'm actually going to do, now vs. later.

Gordon stated he has 13" Wilwood kits for both front and rear, and that both do fit the 17" wheels. After researching the Wilwood products, I'm assuming we were talking about 12.88" kits. I know he's probably sold a boatload of these kits, and certainly probably knows what he's talking about - but, once bitten, twice shy on my part.

Can anyone out there confirm that they used them, and that the Wilwood 12.88" fronts and/or rears did in fact fit in their 17" Halibrand replica wheels without resorting to wheel spacers, grinding calipers, or anything else of the sort? I'd really love to get independent confirmation before spending more, again, on parts that aren't quite compatible. Yes, I know those things aren't job stoppers and I'll probably be modding a lot as I go through the build; however, if I wanted to do those things in this case, I could just keep the S550 rear brakes I already have.

CDXXVII: Thanks for the link. Which 13" rear brakes are you using with the 17" wheels?

The idea of improving the brakes appeals to me. The idea of spending up to $3k and still having interference issues to deal with does not.

Thanks guys!

[edwardb]

These are the rear brakes I have on my build. They obviously clear the 18-inch wheels just fine. http://www.factoryfiveparts.com/2015...od-irs-brakes/. Factory Five themselves says they need a 1/8-inch spacer to clear 17-inch wheels. That's a minor and very easy thing to do. I sure wouldn't let that bother me. Just a thought. The brake kit is cheaper when ordered with the kit. You still have time to make changes. I made several after mine was first ordered. When I apologized for that, they told me it happens all the time.

The front 12.88 Wilwood setup, also a bit cheaper if ordered with the kit BTW, doesn't show needing any spacers for 17-inch wheels. But certainly worth asking.

[Avalanche325]

I have the FFR Wilwoods and the FFR 17" Halibrands. No spacers, lug changes required.

A friend of mine has Gordons Wilwood setup. 17", but not Halibrands, no issues.

If Gordon says they fit......they fit.

[edwardb]

I have the FFR Wilwoods and the FFR 17" Halibrands. No spacers, lug changes required.

A friend of mine has Gordons Wilwood setup. 17", but not Halibrands, no issues.

If Gordon says they fit......they fit.

There are two different FFR Wilwood rear brake options. Not sure which one you have. The one that's been around for awhile is a 12.19 diameter single piece rotor and a single piston caliper/e-brake assembly. I can confirm that fits FFR's 17-inch wheels with no issue. Had that setup on #7750. The newer Wilwood setup FFR offers was released along with the 2015 Mustang IRS. 12.88 diameter 2-piece rotor and four piston caliper and separate e-brake caliper. Have this setup in my new build and can confirm fits in 18-inch wheels without modification. No experience with this setup in 17-inch wheels. Can only take FFR word that they need 1/8-inch wheel spacers when used with 17's.

[CraigS]

I have the OEM 2015 IRS brakes on mine w/ 17 inch American Muscle Bullit wheels and they just bare cleared w/o spacer. I needed to be sure they didn't put any stick-on weights in the outermost inch or so of the back inside of the wheel. IE just behind the spokes. So I wonder if the FFR Halibrands will be OK. Where did you find that they won't fit? BTW the brakes work very well and so does the built-in parking brake.

[mach'er]

After looking at my options, and the reports of what fits, I couldn't pass up just adding the FF offerings to my kit order, and taking advantage of the summer sale discount (sorry, Gordon). A bit more than the PBR kit, but the summer sale made the hit less unpalatable. I'll add the stock brakes to my "sell eventually" pile.

I do not like wheel spacers. We had to deal with them on the Lincoln LS and they were a pain, with dissimilar metal problems out the wazoo. But, I'm gonna have them in the back, and probably will learn to love them (or at least ignore them). On the plus side, I get to learn a new skill with the safety wire.

CraigS: There is a thread in the Ask a FF Tech about this, which I didn't see while planning, only after buying parts.