FFR 11.65 rear brake caliper/pad question/problems

[willie knuckles]

Background: I have a FFR kit with the IRS and standard FFR 11.65 rear brakes (from what I understand these are from an 87-88 Thunderbird Turbo). I have struggled with the installation of the StopTech pads on the rear - they were a VERY tight fit (even with the suggested retainer clip modifications noted in the manual). I simply could not get the pads to fit which was maddening (too wide/tight with the clips). I read thru several posts on the forum, emailed FFR, measured the dimensions of the pads (as listed at the manufacturer website) to ensure that they were correct, etc...I ultimately purchased some Powerstop Z26 (found on the forum) pads to try something different.

I now have the Powerstop pads installed but am concerned that the fit is still too snug (it was still a struggle to get the pads/shims installed). Question: with the pads/clips installed, should the rear caliper move fairly freely when I compress it by hand? My front caliper was an easy build and wasn't a struggle.

Thanks for your help!

[rich grsc]

Well the new IRS brakes are not off a T-bird. Did you confirm the pistons where fully retracted? The need to be rotated to retract

[willie knuckles]

I will double check the pistons again. Dan from FFR told me that the brakes were from a 87-88 Tbird.

[rich grsc]

The T-bird brake where not 11.65"
Something doesn't make sense, why would they use a 35 year old brake system, when the modern brakes that are on the new IRS fit right on, with no issue?

[BEAR-AvHistory]

Is this a new chassis or an old one?

[willie knuckles]

Is this a new chassis or an old one?

I'm guessing a "new" one? - my kit was delivered June 2023.

[BEAR-AvHistory]

I'm guessing a "new" one? - my kit was delivered June 2023.

OK your car uses modern brakes. The T-bird brakes were from much older kits. They have nothing to do with current versions.

[willie knuckles]

I have done some research/digging - the pad application is 87-88 Tbird. My pads should be correct. I have double checked the pistons - they are fully rotated/retracted. Without the pads/clips in place, the calipers move freely. Once installed (a VERY tight fit for the pads/clips - described above), the calipers will move a little with a lot of effort.

Any thoughts / suggestions are appreciated - thanks again for your help!

[DW66]

I heard that FFR did the Thunderbird brakes in the beginning because there weren't enough brake cores with the new IRS option when it came out. Sorry I can't help with your tight pads but I would strongly suggest using 2015 and up Mustang rear brakes unless you are running 15" rims. The original brakes that came on the 2015 and newer Mustangs are obviously better than the old Thunderbird. Everything bolts together as it should and there are tons of brake pad options for the newer brakes. If you were to run the newer brakes with 17" rims the only thing that has to be done is grind a little material of the outside of the caliper to clear the rim. I bought a used drop out from a 2015 Mustang and used everything. No added brackets and adapters. Everything just works as it did from the factory.

Dave

[Jeff Kleiner]

Well the new IRS brakes are not off a T-bird. Did you confirm the pistons where fully retracted? The need to be rotated to retract

OK your car uses modern brakes. The T-bird brakes were from much older kits. They have nothing to do with current versions.

Guys, the T-Bird 11.65" rear brakes are an option for the 2015 Mustang based IRS (option #16765). This allows the use of 15" rims which won't fit with the late Mustang 13" rear brakes.

One thing that I haven't seen mentioned is caliper alignment on the rotor. Even with the piston fully retracted if the caliper is not properly centered on the rotor it may be that when it's tightened to the bracket the front or rear pad is making hard contact with the rotor surface. If this is the case, depending on whether it needs to move in or out it will require shims or taking some material from the caliper mount.

Jeff

[rich grsc]

Guys, the T-Bird 11.65" rear brakes are an option for the 2015 Mustang based IRS (option #16765). This allows the use of 15" rims which won't fit with the late Mustang 13" rear brakes.

One thing that I haven't seen mentioned is caliper alignment on the rotor. Even with the piston fully retracted if the caliper is not properly centered on the rotor it may be that when it's tightened to the bracket the front or rear pad is making hard contact with the rotor surface. If this is the case, depending on whether it needs to move in or out it will require shims or taking some material from the caliper mount.

Jeff

Thanks. I did not know that was an option or that it would work.
Now, if I can just remember it.

[nashuanuke]

Willie, any luck? I'm struggling with the same thing; I just manhandled a rear caliper for an hour until my forearms were shot trying to get the pads in with the clips.

[AA-ron]

I finished my kit this summer and am running IRS with the 11.65 standard brakes from FFR. At the point of installation I could barely get them to spin by hand-- pads very tight against the rotor. I was told this was fairly normal. Even with the wheels were mounted they were very difficult to rotate. After the first few miles, everything loosened up and now they spin freely.

[phils88gt]

I still don't understand this. The 87-88 thunderbird doesn't use 11.65 rotors. I have one of these cars and have raced it as a road race car. The turbocoupe only has 10.125" 4 lug rotors. The v8 thunderbirds have drum brakes of that year. 11.65 is the diameter of 94-03 mustang cobras which is what I have on my FFR.

Phil

[michael everson]

Phil. They are only using the T-bird caliper. The rotor is from a Saturn Vue. That is if you are using the small brakes to clear the 15 inch wheels. If you use the standard 13 inch rotors, FFR is still using the T-bird caliper. They make brackets to adapt it to the newer Mustang stuff. As Dave said, if you not using 15 inch wheels, grab some actual 2015 and newer calipers and throw the T-bird stuff in the trash.
Mike

[phils88gt]

Tbird caliper from the turbocoupe on the 2015 irs spindle with a custom bracket? Can you even get a quality turbocoupe caliper anymore?

Phil

[willie knuckles]

Guys - thanks for all the replies/help! My original plan was to use 15 inch wheels, but now plan on using 17 inch wheels. It looks like I need to ditch the T-bird calipers for 11.65 brakes (and the FFR mounting bracket/adapter plate, smaller rotors). Do you have any specific recommendations for brakes/13" rotors that I can order off the internet? Other rec's in terms of the parking brake cable, etc.? - Thanks for your help/input!

I plan on sticking with the stock brakes on the front --- If I switch to the 17 inch wheels, do I need to do anything differently on the front in terms of brakes/fitment?

[BUDFIVE]

Willie, lots of options with wide price range. Powerstop KC681226 is a kit with 13” slotted and cross drilled rotors, painted calipers and z26 pads for 2015+ Mustangs. I’m putting a set on my roadster IRS in the next week and have 17” wheels. I’ll post when I have them on and have checked the wheel clearance. By the way, they make a matching set for the front. I’ll watch and see what you go with.

[CraigS]

Actually I would go to a salvage yard for calipers and rotors. I might even buy just one side to check fit. When I did the IRS retrofit on my MkII I got a take-out complete rear w/ the brakes. AT the time I had 3 sets of Bullit 17" wheels. One set, (OE Wheels) from many years ago would not quite clear. The more recent sets from American Muscle fit just fine.

[DW66]

If using 2015 and newer factory brake calipers and hardware you will have to grind down the top side of the calipers to clear FFR 17" rims. I'm using all 2015 OEM brake stuff and it works great but again you will have to do some grinding to clear the rims and be careful of where the wheel weights get stuck on. I have power brakes with FFR supplied brakes in the front and 2015 in the rear and my car stops on a dime. I went this route do to easy parts replacement in the future. Everything is over the counter and easy to get.

Dave

[BRRT]

PowerStop rear brake kit, specified for a 2019 Mustang GT. 13" rotors.


This is the FFR 18" wheel. Quite a bit of clearance.


I purchased parking brake cables from RockAuto, OEM Motorcraft. The 2 cables were about $45 total before shipping.
Motorcraft BRCA373 (Right)
Motorcraft BRCA286 (left)
Checkout Fixit's build page for a good plan on the PB cables
https://thefactoryfiveforum.com/show...amp-9365/page4

[willie knuckles]

I appreciate all the help/feedback. With my change to 17 inch wheels - will I need to change the front brakes/rotors?.....

[BRRT]

I appreciate all the help/feedback. With my change to 17 inch wheels - will I need to change the front brakes/rotors?.....

Nothing says you have to. I elected not to use the FFR supplied front brakes. I used the Mustang Cobra calipers and 13" rotors. Once again, mine were sourced from PowerStop.


This is with the FFR 18" wheel. The bigger rotor fills the wheel nicely.

[BUDFIVE]

I installed the front and rear Powerstop 13” brakes as discussed in my earlier post and they fit the 17x9” front just fine. The 17x10.5” rears required some washers (0.210” total)to clear the caliper. In my build thread I am contemplating which spacer to use (1/4”?) to avoid grinding on caliper. Anyway I told you I would update on the rear 13” brakes with 17” wheels.

This pic is 17x10.5” with 0.210” spacer.
IMG_4625.jpeg

2nd is front 17x9”

[Mat1asBEV&ICE]

Dang, I was just about to install my 13" rear rotor/calipers for my IRS (18" wheels) with the bracket until reading this post. Now I'm thinking I should change it. Wasted time painting the calipers. Oh well.

Sorry for piggy backing. Since I have the 13" rotors from FFR, are new calipers and pads the only things I need?

Thank you.

[michael everson]

Yes Matt
Mike

[MavTeam]

I installed the front and rear Powerstop 13” brakes as discussed in my earlier post and they fit the 17x9” front just fine. The 17x10.5” rears required some washers (0.210” total)to clear the caliper. In my build thread I am contemplating which spacer to use (1/4”?) to avoid grinding on caliper. Anyway I told you I would update on the rear 13” brakes with 17” wheels.

This pic is 17x10.5” with 0.210” spacer.
IMG_4625.jpeg

2nd is front 17x9”

Do you remember the model numbers of the kits you used. Looking at using power stop brakes also.

Did you use spacers or as some said did you grind caliper?

[nashuanuke]

I had the same issue, I found multiple videos and advice saying its ok to file or grind the edges of the pads slightly to get them to fit into the calipers. That's what I ended up doing.

[Doc76]

I had the same issue, I found multiple videos and advice saying its ok to file or grind the edges of the pads slightly to get them to fit into the calipers. That's what I ended up doing.

This was the only thing that I could do after installing an FFR 11.65” rear disc kit today. I struggled with the pads for an hour before it dawned on me to mic it. When I checked the opened where the stop tech pads sit and added x2 material thickness for the clips, the pads where size for size. So I got them in but could not get them straight and absolutely couldn’t move them.
They should slide freely in there.
I too ended up filing the ends to free them up.
Worked fine, just sucks having to start modify a “bolt on” kit.