RAD Ideas : Mustang GT and Cobra brake adapter bracket update

[karterfred88]

Scott,

Ford designed the front setup to use the same caliper mounting hole
for both GT and Cobra. The calipers actually make up for the difference in rotor size. If I was to
go with a different smaller rotor (to replace the 11 inch GT I assume is your question), it would
require a different caliper and possibly different mounting hole locations. That would require the
use of different caliper mounting brackets for the front again - which I am trying to avoid. With
a simple machining to the outside edge of the stock Studebaker hub, the GT rotor slides on just
fine. This is a one time modification just like the stud change, from that point on you just get a
Ford part, open the holes a tad (as shown in my threads) and they slide onto the shoulder studs.

The GT version of this setup allows the use of 15" wheels. Only the Cobra setup needs 17+.

For the record, GT rear rotor is $29 and the front is $32 dollars at your local auto parts store.

Tom

What year Mustang uses an 11" front rotor? All I can find are references to a 10.5 (or 10.8 on some replacement part sites). The 10.5 appears to be the same part number as the Explorer 2WD. Even though the rears on the Explorer are 11.22 so I think I could use your new front set up to mix/match to the standard Explorer rear end with disc brakes and 32 spline axles. The reason I want to be sure they'll be compatible is I need to get rid of the stock Dana 44. It needs a rebuild, has the 4.09 up diff ( not very daily driver friendly) and needs new rear drums. Changing the diff and gears, axles to flanged and new drums makes it not worth the effort. Since the Explorer rear end is so close to a bolt in, except moving the spring pads in 3/4" per side and locating new traction bar mounts, a used assembly, even rebuilding it completely is way less than working on the Dana.

[Springstreet]

[sbca96]

Mike,
Since you're using Mustang brakes now on your Avanti, are you still using the Bendix booster? Have you considered or tried switching to a Hydraboost system not dependent on engine vacuum?

The idea is to make available modern options at the wheels. Someone could certainly adapt the
hydroboost if they wanted. I personally never saw a problem with the old school vacuum booster
arrangement. Also, as far as I can tell, Ford has abandoned the hydroboost setup anyway. One
has to wonder why. FYI, my name isnt "Mike".

What year Mustang uses an 11" front rotor? .. snip ... It needs a rebuild, has the 4.09 up diff ( not very daily driver friendly) and needs new rear drums. Changing the diff and gears, axles to flanged and new drums makes it not worth the effort. Since the Explorer rear end is so close to a bolt in, except moving the spring pads in 3/4" per side and locating new traction bar mounts, a used assembly, even rebuilding it completely is way less than working on the Dana.

The 1994-2004 Mustang GT used an "11" inch rotor in the front, it might actually measure slightly
less but its always referred too as "11 inch" in passing. "13 inch" for Cobra.

I am not familiar with the Explorer axle. Is it an 8.8 assembly? I have read they are solid-well
built axles and I was considering one for my Avanti as well, but I figure its best to stick with the
Dana 44 as most people with Studebakers wont have the know how or facilities to convert an
8.8 to fit their Studebaker. My Avanti has the 3.31 Dana TT from my Hawk that was wrecked
years ago. The TT works fine, but the axle is tapered and lacks the Radius Rod stands. I figure
once I do the flanged upgrade, I will have the stands welded on and add the Gib-trac setup. As
of now, I just stay off the gas, it tends to wheel hop in 2nd gear with the Hawk heads installed
and the TKO gearing.

Doug,

Thanks .. its a slow process and costs money to get the parts to measure. I wonder how I can
find the info of that 6 bolt pattern, did they add two more bolts and keep the other four the
same? Being out of work limits the funds to spend on this and my wifes '99 Camaro SS LS1
sprung an oil leak that is proving difficult to resolve. At the moment it leaks the same amount
of oil as my 50 year old Avanti (which has the original seals!).

Tom

[karterfred88]

Sorry Tom,
My mind was elsewhere when I referred to you as Mike, my bad. The explorer 96 up to I think 2002 is an 8.8 32 spline. The sites I visited didn't refer to the GT brakes as 11" but 10.5". Anyway the Explorer front rotors match the part number for the GT fronts, but the calipers are different. So your new brackets will work for me!! As to your Camaro oil leak, can't help you there. The LS v8 is too different from my 4.3 V6 to compare, but If it has an engine oil cooler check the block where the hoses mount. Another famous Chev spot is the rear valley cover/manifold seal to the block. Springstreet-- why not make a template off the housing end on stiff paper and send it Tom

[sbca96]

I see where the confusion is. The GT Mustang uses a 10.86" diameter front rotor (referred as 11")
and 10.5" diameter rear rotor. I thought you were referring to the front rotor rather then the back.
I didn't want to mix models with the setup, since I figure many people would just grab the parts off
of a car in the salvage yard, and take everything at once.

So you are saying that the rotor the 1994-2004 Mustang uses in the front is the same rotor that
an Explorer uses in the rear? That explains why they use a different caliper, the front rotor is an
inch thick as compared to the solid rear rotors just over a half inch thick. Even the vented Cobra
rear rotor is just shy of 3/4 inch thick. Neither the GT or the Cobra rear caliper will accommodate
a one inch thick rotor.

Tom

[bezhawk]

Diesels still use the Hydroboost, and for a supercharged car, it makes sense to use hydraulic pressure instead of non existent, or very little vacuum. I think Ford probably dropped it on the Mustang because of cost. Their diesel pickups still use it. But then again diesels make up to 50 or so lbs of turbo boost !!!

[karterfred88]

Also Mustangs went to Electric power steering, thus they could leave off the power steering pump, to gain a few net HP. The Autozone site listed both the explorer RWD front rotor and the GT front rotors with the same part number, but it varies from one source to the next on actual diameters of each. Could be they are close enough to use in both. For me it is a way to put decent brakes on the front and use the already present disc brakes on the Explorer rear without mixing Chevy, Ford and Cadillac parts to get a complete modern braking system ( and be cheap at the same time!).
Tom
By the way, do you still have some of the GT brackets or are they all gone. My rear end has so much lash, and the pinion flange has so much play that I'm considering doing the rear end swap sooner rather than later, instead of getting into spending a fortune rebuilding the old Dana.

[Mangusta1969]

Tom,

Just wanted to let you know that I am still very interested in your Mustang disk brake setup for the front and rear of my 63 Avanti. I like the fact that there are all kinds of "performance brake" options available due to your choice of 1994-2004 Mustang brakes as your basic foundation. There are also so many Mustangs out there, in my lifetime, I will never have to chase down some lower production number parts.

I am planning to use 13 inch drilled and slotted Cobra rotors and calipers in the front and "11 inch" drilled and slotted Cobra rotors and calipers on the back. The rotors and ceramic pads are available quite inexpensively through amazon.com, powerstop.com, summitracing.com and rockauto.com, as well as others; I think the powerstop guys even have red powder coated calipers available for the rear of the 04 Cobras (not sure about availability of red powder-coated front calipers from these guys).

My Avanti needs rear axle brake work right now and I would like to do this disk brake conversion sooner rather than later.

Hopefully you have enough interest from others on this forum to go forward with this project. Let us know your development plans for your "Gen II" brackets when you can.

BTW, I just installed some Powerstop zinc-plated, drilled and slotted rotors on my 2004 Jeep Grand Cherokee. They look great and stop great, solving the typical warped rotor issues that a number of these Jeeps have. I even ordered a set of these Powerstop vented rotors for another car that has some minor brake issues. I guess these Northern NV hills/mountains are sort of tough on brakes.

[jlmccuan]

Not knocking Tom's brake setup, it works great. I made my own rear brackets as they weren't available several years back when I got mine. Just a caution about the drilled and slotted rotors. Most folks are finding that the benefits of the drilling in particular are not worth the constant replacement due to cracking. For track only cars where the rotors are considered throw away items after each event maybe. But daily drivers will find slotted only last longer and neither drilled or slotted to last best.

[Mangusta1969]

Not knocking Tom's brake setup, it works great. I made my own rear brackets as they weren't available several years back when I got mine. Just a caution about the drilled and slotted rotors. Most folks are finding that the benefits of the drilling in particular are not worth the constant replacement due to cracking. For track only cars where the rotors are considered throw away items after each event maybe. But daily drivers will find slotted only last longer and neither drilled or slotted to last best.

Jim,

I hear you about the possible rotor cracking issue due to cross-drilling. However, the Powerstop Z26 Street Warrior drilled and slotted rotors have a beveled shoulder at the outside edge of each cross-through hole that "should" reduce the cracking problem. Powerstop also has a two year warranty against cracking, so I was willing to take a chance. For certain, high rotor heat under mountain braking conditions caused my Jeep's OEM rotors to warp. The non-vented rear rotors were the worst warp victims, too, although you would think the front rotors suffered the most during mountain braking.

Thanks for your feedback on Tom's Gen I disk brake setup.

[karterfred88]

Tom,
PM sent--do you have any of your original adapters for the 11" mustang GT?

[sbca96]

By the way, do you still have some of the GT brackets or are they all gone.

Unfortunately, I do not have any stock left on the original brackets. In the past I have only
made about 10 sets at a time. I have also decided to make the leap into finally offering a rear
bracket. This is a slightly tricky area, as Ford used two separate brackets for the rear. Plan is
to use just one bracket for either options.

Tom,

Just wanted to let you know that I am still very interested in your Mustang disk brake setup for the front and rear of my 63 Avanti. I like the fact that there are all kinds of "performance brake" options available due to your choice of 1994-2004 Mustang brakes as your basic foundation. There are also so many Mustangs out there, in my lifetime, I will never have to chase down some lower production number parts.

Thanks for your kind words, and yes the idea is to have ultra common parts available, whether a
person grabs "Take offs" from Craigslist, or buys new on one of the many online sites, or just
takes a trip to the local FLAPS. I think part of the confusion within the Studebaker world is
having OPTIONS, that's something you just don't have normally. I guess that's why some people
are still holding onto the idea my design doesn't allow the use of 15 inch wheels. The Cobra setup
is an option, the original brakes seen in my magazine article, and on the forums 8 years ago are
just plain old GT single piston with an 11 inch rotor. Easy peasy to fit in a 15 inch rim.

Options go beyond the Cobra's 13 inch rotor, there's a Baer setup that uses a 14 inch rotor and
a 6 piston caliper. The idea of using the drilled AND slotted rotors on my Avanti was for the
look, the zinc plating really keeps them nice looking. In order to really SHOW the options I
had to go to the extreme, drilled and slotted was the way to accomplish this.

Not knocking Tom's brake setup, it works great. I made my own rear brackets as they weren't available several years back when I got mine. Just a caution about the drilled and slotted rotors. Most folks are finding that the benefits of the drilling in particular are not worth the constant replacement due to cracking. For track only cars where the rotors are considered throw away items after each event maybe. But daily drivers will find slotted only last longer and neither drilled or slotted to last best.

Thanks, it has been on my car now for getting near a decade, I haven't had any negative feedback
on fitment or on in service use. I recall sending the modification drawings to you to modify
your Cobra rear brackets. I actually recently un-boxed the ones you started to modify, but sent
to me after you cut a set of your own. Did you put them onto the car ever? The center hole
isn't enlarged, and the counter-bore was never created? I used them to create the 3D model of a
Cobra bracket seen in the CAD files above.

I have had the drilled and slotted rotors on the Avanti for quite some time now, and do not see
any cracks forming. The Avanti does not get driven "Daily" but I do not know of many Studebaker
owners that drive theirs daily. The drilled holes are all countersunk, so this might help. As
I mentioned above, I used the drilled and slotted rotors to SHOW the options available. Think of
it as a model home with the French Door upgrade, perhaps not super practical, but darn pretty!

Jim,

I hear you about the possible rotor cracking issue due to cross-drilling. However, the Powerstop Z26 Street Warrior drilled and slotted rotors have a beveled shoulder at the outside edge of each cross-through hole that "should" reduce the cracking problem. Powerstop also has a two year warranty against cracking, so I was willing to take a chance. For certain, high rotor heat under mountain braking conditions caused my Jeep's OEM rotors to warp. The non-vented rear rotors were the worst warp victims, too, although you would think the front rotors suffered the most during mountain braking.

Thanks for your feedback on Tom's Gen I disk brake setup.

My wife warps her 1999 Camaro SS 12 inch rotors (w/2 piston caliper) every couple months.

Tom,
PM sent--do you have any of your original adapters for the 11" mustang GT?

Sorry .. I replied above and via PM.

Tom

[jlmccuan]

I had the Ford ones on my '66 but made the stainless steel ones I sent you the CAD drawings for on the laser I was setting up for a customer. I believe they were DXF's as I work in SolidWorks. The stainless looks a lot nicer than the cut up Ford pieces and the stone guards fit better. I wasn't thrilled about the way the Ford pieces had the countersinks. The plates I made allowed me to shim the calipers to get them dead center over the discs as the end play adjustment on the right axle causes the disc to space differently than the left. There is enough space when the caliper retracts to clear OK, but I just wanted it dead center.

[sbca96]

Jim,

I get what you are saying, its just odd the mounting holes are off (rotated) and the center hole is
too small to fit my tapered axle Dana 44 housing. It looks like it was mounted at some point, but it
must not have been on the inside of the axle housing flange? Yes, I noticed a difference right to
left, but I ended up making them the same and have not had any issues. The new design will have
shims and no counter bore, since its a clean slate, not Ford bracket.

I will PM you on some further questions.

Tom

[sbca96]

Still working on entering all the data for the rear brakes into the 3D software. I took apart the
Avanti rear brakes and re-measured EVERYTHING. My notes are from 2006 and I wanted to get
refreshed with how everything fit (or in some cases didnt fit). I have a couple emails to Dana
in an attempt to get some iges or step files of the center section. I do not really need it for this
effort, but it would make the model look better. I had some ideas for future suspension mods so
the info might be handy. I was disappointed to find that the e-brake support on the caliper will
interfere with a double duty rear bracket .. so back to two separate rear brackets : GT / Cobra.

The 3D model is coming along ... there are quite a few 3D models for Ford 9 inch, but not Dana.



I even decided to model the wheels I used, its not as easy as it sounds, had to create the profile
of the wheel, then cut the spokes out, but they draft outward, the software did not allow a draft
cut to a projected surface. I figured out a work around.



Tom