Probably zero. Braking is really limited by the tires, not the brakes. The stock brakes can stop the car up to the capability of the tires, or darn close . . . once or twice in a row.

Like joey said, all big brake upgrades are really for track use where they have to stand up to the heat of repeated braking from high speed. That and looks . . . plus they do feel more powerful (sensitive) under your foot but don't really stop the car much quicker.

 

This is especially true with stickier tires. Sticky tires means later braking which means hotter brakes which means fade. Larger rotors have more mass to dissipate that heat.

 

I can't find the thread now, but the first time I'd heard about this mod, the OP of that thread was struggling with the rear brakes overheating at the track unless he turned off TC and SC, which he was not comfortable doing. Adding the larger rotor allowed him to leave the nannies on at the track.

 

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I think I am the original OP you are referring to. The stock 11.8" GT rear brakes are fine for street use. But at the track (road course), these will overheat like crazy, after only a few laps. Moving to the 13.8" upgrade solves this problem perfectly. Heat dissipation, fixed.
(my original TMS thread = https://themustangsource.com/forums/...pgrade-537228/)

 

Thanks for the reminder. I couldn't remember the specifics about using TC and SC. Reviewing your thread, it was when 5.M0NSTER said he had no issues but drive with the nannies off. IMO if one is planning on driving with the nannies off this mod may be diminishing returns.

 

On road track, IMHO, you really want both Traction Control and Advance Track full off so they do not interfere. When you are getting close to the limit you don't want the system all of a sudden doing something that changes the way the car is behaving, that will cause trouble. I have had an issue where Advance Track comes back on, and I swear it spun me twice. (could have been driver error too, of course)

Even with the Advance Track off, the stock rear brakes still get real hot. Mine were running about 100 degrees hotter than the front (after a cool down lap, probably more during the session).

The larger rotors brought the rears down to about the same temp as the front, or a little cooler, which is how it should be.

 

I also get less rotor cracking with the larger ones in the rear since they run cooler. But agree with Bert, now my rears are about the same temp as the fronts and all brake pads and fluid are happier. The brake bias is adjusted with pad selection, and I'm very happy with the 13.8" rear rotors. Just cracked my first one at my last event and the previous rotors had close to 2000 miles on them

 

Are you using the adapters or did you go the oem route?

 

Adapters. I've put on about 2000 track miles on them and 5k street miles. I just inspected them about 2 weeks ago and they look perfect. No signs of wear, cracking, etc.

 

That makes me feel a LOT better . . . if YOU aren't breaking them on the track, NOBODY will!

But actually I would be more concerned about the original brackets between the add-on bracket and the axle; that is where the added stresses would show up. Assume you checked those too.

 

No issue with the OEM hardware either. I'm glad to offer some thorough testing on parts

 

Here are the best Prices I have found so far... They are online at Sunrise Ford in LA...

Priced so that I have an all new setup. Not sure if I really need the nuts and bolts replaced since I just crossed 13K miles. Usually a good idea to start out with new ones though.

So I can pick this up for somewhere between $280 TO $318 shipped. Prices include shipping at this location.

Now to see if I can get my dealer to beat these parts prices. If not will they be willing to just do the install or is it going to become a winter project...

 

I purchased mine though Tasca.

 

Just a reminder in case it wasn't already clear above:

the easier and cheaper way to do it, is to buy the adapters from the guy on E-Bay or SVT forum, and just get the larger rotors from Tasca or Rock Auto or whoever (pretty sure all the details and links are earlier in this thread)

 

Could you post a link to the eBay bracket?

 

http://m.ebay.com/itm/05-14-Mustang-14-Rear-Brake-Rotor-Adapter-Brackets-GT-Boss-302-GT500-V6-13-8-/152249146338?hash=item2372c19be2%3Ag%3AjgQAAOSwF1dUTPnF&_trkparms=pageci%253A3d345db2-8b5d-11e6-bbee-74dbd1e066af%257Cparentrq%253A976d9c771570a2a3d5b0a8e3ffff803e%257Ciid%253A2

 

Those are the exact ones I have

 

Thanks!

 

thanks D, Yep, those are the same ones I was talking about.

Link was also posted earlier in this thread, look back because there is a link to the same guy selling them on another forum but cheaper without the e-bay commission

 

Thanks!

I checked with them and AutoNation White Bear Lake (was Toulsey Ford). Prices were better at both, but by the time I added in shipping it was not as good as the ones posted. Sunrise Ford is a tad higher on the parts, but without any additional shipping costs it is the winner so far.


I know no one has seen any issues with adapters. I just have my concerns. When it comes to something as important as stopping, I just am not willing to take the risk. It usually does not end well for me when I take the easy way out. So I plan to swap to the GT500 adapters.

I would like to get my Tranny and Rearend serviced soon anyway. So I plan to do the differential and mod at the same time. It will depend on the what I find out from the dealer for prices of parts or if they will install when buying else where. They have for other mods before.