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Mustang GT brakes on my Avanti?? Hummmm


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Edit per new picture location : 12/1/08

Well ... I guess I will share what I have been doing on my Avanti

lately. As many of you might remember I bought a set of rims for

it - 2003 Mustang Cobra rims.

Avanti03Rims4.jpg

Well, one problem I found that I had was the rim would contact the

upper A-arm pivot in the front on a turn, this is bad for the rim!

I contacted a guy back east who sells a 12 inch rotor disc brake

setup that bolts on. The problem - its $650 plus shipping. I also

want to upgrade my rear brakes, he sells a rear disc kit, but there

is another problem - its $450 plus shipping.[V] I wouldnt be that

concerned, but after sending out the $4250 check to the RIAA, I dont

have much left over for the mortgage, let alone brakes for a car I

rarely drive. The Avanti brakes need to be completely refurbished,

so even if I decided to keep the stock brakes, I am looking at over

1500 dollars in vintage discontinued brake parts ...

But .. along came my Mustang friend. See, Ford uses the SAME 5 on 4.5

inch wheel pattern (obviously since I could bolt the rims on) so the

rotors will fit my hubs also. My Mustang friend GAVE me his whole

1998 GT disc setup when he upgraded to Cobra brakes. 11 inch vented

front rotors, calipers, rear solid rotors, calipers (with parking

brake), and axle brackets. Since I am a CAD operator, I took the

dimensions of the bracket, and drew them up in CAD, I also got the

dimensions from the Dana 44 axle. It looks like the rear setup will

require some milling to thin the bracket a bit to move the mounting

surface out, and then a bolt pattern change, and open up one side so

it can slip over the axle tube and mount on the backside of the axle

flange. It will use three bolts to attach, which is common with a

disc brake caliper retrofit. The rotor will fit over the hub, and it

looks like the tapered backside of the stud holes, will nicely center

the rotor on the studs. Hopefully I can have the brackets modified

this next week at my work.

The front is a different story. I didnt get brackets, as the caliper

mounts to the spindle. I did some research and found a guy who makes

brackets to mount 03 Cobra brakes on a first Gen Mustang. I pulled

the image off his website and then imported it into CAD, then traced

it to get the basic angle and spacing from hub center for the caliper.

This is important to keep, as bleeding would become difficult! So,

armed with this new info, I felt good about using the GT front brakes

as well, you have more drive to adapt something when you get it for

free!! But, I ran into a problem. The Stude wheel hub is a larger

diameter then the inside diameter of the Ford rotor! Damn! This is

not the end of the world, as I can have the wheel hub machined to the

right size, removing metal is easier then putting it back. The rotors

on the Avanti are junk anyway. So I wasnt able to take the next step

of dimensions, so that I could continue with my brackets. I did some

research tonight on the web, looking to see if there was a hub that is

the right size for the rotor, that would fit my spindle - no dice. I

would rather use the Stude hub if I can, and the bearings are still

available. Interesting though, the 1994-04 Mustang hubs are NOT able

to be repaired! You can NOT put in new bearings! No joke! Now I

could get the hubs from my buddy (he mentioned that a bearing is now

making some noise, and then have my buddy at work machine the inside

to fit the Stude bearings, but .. thats a pain (though a possibility).

Back to the spacing problem, it looks as though moving the wheel out

1/4 inch will solve the clearance problem. The Stude rotor is mounted

on the backside of the hub, so it doesnt effect wheel position, but the

Mustang rotor is on the outside, between the rim and hub, and the

rotor thickness is .275, just a tad more then 1/4 inch. So if I can get

this to work, then it will work beautifullly with these rims. Though it

would not work well with stock steel rims, as the caliper position will

cause contact with the steel rims. Right now, because of the design

of the Cobra rims, the stock Stude brakes look pretty silly sitting WAY

back, and looking quite small. The NICE part about this swap, is the

Cobra uses the same hub, and caliper mount position as the GT, so

I can EASILY upgrade to 13 inch rotors and 2 piston calipers in the

future ... nice huh??

Tom

Edited by SBCA96
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Sounds great! Won't you have to change master cylinders also.

Technically, I shouldnt, at worst I should only have to install an adjustable valve

to set the proportion between front and rear. I already upgraded the car with a

dual master cylinder (something I suggest ALL Avanti owners do!!!).

Tom

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B) which master cylinder did you use? their seems to be several mention. john

Technically, I shouldnt, at worst I should only have to install an adjustable valve

to set the proportion between front and rear.  I already upgraded the car with a

dual master cylinder (something I suggest ALL Avanti owners do!!!).

Tom

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Technically, I shouldnt, at worst I should only have to install an adjustable valve

to set the proportion between front and rear.  I already upgraded the car with a

dual master cylinder (something I suggest ALL Avanti owners do!!!).

Tom

I dont remember, I know it was for a Chrysler, early 70's. I have the box in the

garage somewhere, I can look it up when I find it. I found a site that even had

the number a couple days ago, thought I saved it, but now I can not find it.

https://www.studebakerparts.com/studebakerp...es/dskdual.html

http://www.aoai.org/forums/index.php?showtopic=224

Tom

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Sorry about the focus on some of these pictures ....

The Studebaker hubs are now modified to accept the Ford rotors with the rotor lug

holes drilled out to the next SAE size - 5/8. The original Ford rotor holes being

metric these days. Here is the stock hub after separation - before mod :

fronthubmod01.JPG

fronthubmod02.JPG

The Ford rotor is 5.6 inchs in diameter where the hub needs to fit, the outside of

the hub was turned down to 5.5 inches, if you were to want to go with the Cobra

13 inch rotor from the start, I am assuming that the Cobra has more room in the

back, but this is not verified yet. I know that the rear rotor will fit the stock Stude

hub without being turned down:

fronthubmod03.JPG

fronthubmod04.JPG

I used Chrysler wheel studs, which are for a 1/2 and 3/4 ton truck from the 70's

all the way to 2003 - nice huh? Wide array of availability. Napa part number is

BK6412184, they come in boxes of 5. The only problem in using them is they are

for a larger hole. The Stude knurl is .645, but the knurl on these studs is .668. I

used a 21/32 drill to give me ~.012 of interference fit, then added Loctite. It is

pretty easy to do, with a hand drill and a vice. The studs are 1 3/4 inch long, with

a shoulder that would extend out to center the rotor.

fronthubmod05.JPG

fronthubmod06.JPG

fronthubmod07.JPG

I found that the old Stude rotor makes a perfect holder for the hub when pressing

the studs in, nice and stable. I might mention that one of the hubs on my Avanti

was a drum brake hub, with a disc pressed on the back, so I know that this will

work for either hubs. I found that the disc brake hub, accepted the stud straighter

then the drum brake hub. This is because the drum brake hub is not machined on

the back. This was easy enough to "fix", by putting the rotor on the hub, and then

tightening the wheel on to draw the rotor onto the hub. This straightened the studs

to the correct position (since the tapered hole in the rim will force the stud to

perpendicular to the hub face). I didnt have to do this with the disc brake hub.

fronthubmod09.JPG

fronthubmod10.JPG

fronthubmod11.JPG

Tom

Edited by SBCA96
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Here is the finished hub - ready for a Ford rotor!

fronthubmod12.JPG

fronthubmod13.JPG

Here is the difference between the stud rotor and the Ford, the Stud is non-vented

and only about 3/8 thick, each half of the Ford rotor is 3/8 thick. The Stude one

worked great in its day, and still is good for a few stops, but I wouldnt trust it on

a twisty auto cross course! ;)

fronthubmod14.JPG

Here is the dinky little bracket that holds the stock Stude caliper in place, it only

uses three of the available 6 holes, and mounts on the back side.

fronthubmod15.JPG

Compared to a Craftsmen 9/16 wrench .... so cute!

fronthubmod17.JPG

Here is the hub and the spindle flange just waiting for the new brackets to come

out of my head:

fronthubmod16.JPG

fronthubmod18.JPG

Sorry, I didnt get a shot of the rotor on because the battery in the cam died, but it

does fit and spins true. The thickness of the rotor made the passenger side clear

perfectly and the drivers side almost clear the upper A-arm. It is driveable now (if

the brakes worked), I think that I will use an 1/8 spacer in between the rotor and

the wheel, the wheel studs are long enough to handle this. They are larger studs

then Ford used anyway. I took all the dimensions that I needed to draw up the

brackets in CAD, they look fairly simple to do.

Tom

Edited by SBCA96
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  • 1 month later...

Well ... here is the next step in the Mustang GT brake project : test bracket. Its

always best when prototyping, to test your dimensions before going to metal. I

used some masonite to fab a rough bracket and test the design.

Here is the test bracket mounted on the spindle :

testbracket01.JPG

The large radius is to clear the massive wheel cylinder on the front caliper.

Here is the modified Studebaker hub mounted on the spindle:

testbracket02.JPG

Then we slip the Mustang rotor over the studs (with the metric holes drilled to the

next size SAE : 5/8):

testbracket03.JPG

And finally test fit the caliper onto the bracket to see how we did:

testbracket04.JPG

Turned out that I got pretty close on my first try. The only drawback was the lower

caliper bolt is right in line with the steering arm on the spindle. Not really a HUGE

problem, there are some tools that will allow the torquing of the bottom bolt, its

just nice when everything clears perfectly. Other then that, all looked great, now

to mill some 6061-T6!

Tom

Edited by SBCA96
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Masonite just doesnt compare to the look of machined aluminum. My work has a

lot of odd sized 6061-T6 scrap laying around, and even though my first choice was

to go with 7075-T6, you can not beat the price of free. Doing a comparison in the

strength of each, and steel .. the yeild and the expansion, it seemed that 7075 was

overkill anyway. But, I used 3/4 thick 6061-T6 - just in case.

Here is the drivers side bracket mounted on the spindle :

6061-T6brackets01.JPG

6061-T6brackets02.JPG

Using 3/4 inch thick aluminum gave me the opportunity to create a grease cavity

in the back side of the bracket. This is something that Studebaker used at all four

corners of the car, it is there so that if a grease seal was to fail .. the grease will

ooze harmlessly out the back .. and not end up on the drum or disc.

6061-T6brackets03.JPG

Here is a view from further back, sorry about all the grime and crud, I wasnt in the

mood to clean any more then I have too to check fitment. Once I swap out the GT

rotor and caliper for the big Cobra stuff, I will scrape and paint everything.

6061-T6brackets04.JPG

Here is the hub back on, and as you can see, designed in the bracket inner dia lets

the hub sit inside of it ... so if the grease seal fails ...

6061-T6brackets05.JPG

Now on to the passenger side, a mirrored bracket :

6061-T6brackets06.JPG

The rotor and caliper mounted :

6061-T6brackets07.JPG

6061-T6brackets08.JPG

There they be! Ofcourse the next step is to attach the Mustang brake lines to the

Studebaker frame, and for that the factory Mustang brackets didnt work, and the

factory Studebaker ones didnt either. So ... time to cut and bend and weld!

Tom

Edited by SBCA96
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After jacking the car up so that the wheels dangled, I figured that THIS would be

the "Worst Case" senario for the rubber brake hoses. I would end up trying quite

a few different locations and angles of the hose end before decideing on the best

position. The hose needed to be able to flex without rubbing anything throughout

the travel of the suspension and the turning of the wheel. What a pain! I found

that the stock Mustang brackets needed to be 90 degrees from what they were.

So I cut off the "business end" and then bought some steel stock. I wanted to use

the existing holes in the frame to bolt it down and locate it so that it wouldnt turn.

Here they are!! :

brakehosebracket01.JPG

I dont know how to weld, but the supervisor of the machine shop will weld simple

parts for fast food fries. These cost me a large fry from Mc Donalds. This next pic

shows WHERE these go, I bet now it makes sense.

brakehosebracket02.JPG

A close up ... pretty aint she?

brakehosebracket03.JPG

And of course one for the other side as well :

brakehosebracket04.JPG

The hoses dont contact anything when the wheels turn back and forth and the only

modification to the hose was an adapter fitting on the DRIVERS side to turn the

larger flare to the size Studebaker uses. Strange, but the PASS side was the same

size as Studebaker and didnt need to be changed. The wrench needed to tighten

the hose was a metric, but the flare was SAE - go figure.

My dad and I drove around and the brakes worked AMAZINGLY well. I had hoped

for an improvement, but there is NO comparison. Granted the old brakes were in

pretty bad condition, but the addition of a vented rotor will help cooling. I plan on

switching to the 13 inch Cobra brakes as soon as I get my tax refund. My dad

wants the GT parts for his Avanti.

Is anyone interested in something like this being marketed? I feel that by using

the original hubs, it really reduces waste, and doesnt require buying hard to find

rotors or using sleeves. Not to put down the great work that others have done to

keep Studes on the road, but I think there is always room for another viewpoint.

Shoot me an email if interested : sbca96@aol.com

Now I am working on the rear disc setup ... the brackets are done, and on the axle

and I am modifiying the hubs with the Dodge wheel studs. The outer dia of the hub

doesnt need to be machined down, because the inner dia of the Mustang rotor is

larger then the front and the Stude hub is smaller - perfect fit. The rotors actually

fit fine, but its recommended to have at LEAST 8 threads of contact on wheel studs

and I was at 5 with the stock length studs. I ordered the stock Mustang rear hoses

for the setup, because I didnt get those from my friend. I was happy to find that

Autozone includes the banjo bolt in the hose kit. Before you laugh, they are nice

hoses made by Wagner. Now I have to figure out the plumbing, once I get all the

wheel studs in ... had a mishap with one of the 5 studs I COULD get (damn the

StupidBowl, most the autoparts stores closed early today!), it contacted the socket

that I was using when pressing the stud in, and ruined the threads on the stud.

GRRRRRRRR!

Oh well .. gotta buy 6 tomorrow now.

Tom

Edited by SBCA96
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I must also mention that "Bobby" the machinist thats been doing all the work for

me after hours, has been absolutely wonderful. If it wasnt for his patience with

the sometimes last minute and "on the fly" design changes this wouldnt have even

happened. Even the slight "correction" that we had to do on the rear brake caliper

brackets he didnt cringe (much) at. Thanks Bobby!! You dah Man!

Tom

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I thought that I would share what the Cobra brakes will look like, the calipers

come in both black and red (that I am aware of) and are actually 2 piston, not

4 piston like I had originally mentioned (thanks Ed and Eric for setting me

straight on that!). I got confused with the Baer 4 piston setup that my friend

had converted to (which got me the GT brakes!). If memory serves there is

an 8 piston caliper also available, but thats CRAZY talk!

These images were "borrowed" from http://www.edbert.net/brakes.htm .

After doing brake pads on my 1993 Camaro Z28 for the last 10 years, I had

thought that the Stude hubs could be modified to allow a "slip-on" rotor to be

used (like most newer cars). After finding out that Ford still used the same

bolt pattern as years ago, I knew that the Ford rotors would fit. After getting

Ed's brakes .. it all came together. When looking for the dimensions of the

angle of the caliper position, I came across "Mustang Steve" who makes a kit

that allows the installation of Cobra brakes on a first gen Mustang. It was his

website that I got the angle I needed. He was also very helpful by telling me

that Ford still used SAE flare thread (http://www.mustangsteve.com/).

10 inch rotor compared to the 13 inch Cobra:

brakes1.jpg

Other assorted views :

brakes2.jpg

brakes3.jpg

brakes4.jpg

brakes5.jpg

Tom

Edited by SBCA96
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I need to check the fitment of a stock Studebaker wheel on the new brake setup,

but I am pretty sure that it WILL NOT fit, due to the caliper being out farther to the

wheel. This brake setup would require upgrading to wheels that fit a 1994 to 2004

Mustang. This can be viewed as good OR bad depending on your perspective. I

see it as GOOD, since during my search for wheels for my Avanti (over 10 years)

I couldnt find anything that looked good. They just dont make nice wheels in the

stock offset, at least not that work well with the design of the Avanti. Two things

I need to check on .. one confirming that the stock wheel fits or doesnt fit, and then

two what steel wheels are available for a 1994-2004 Mustang. I am pretty sure

that the base Mustang used steel wheels, and they should be 15 inch. Technically

that would mean the stock Stude hub caps could be used. I will check with my

Mustang buddies and see.

Tom

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I need to check the fitment of a stock Studebaker wheel on the new brake setup,

but I am pretty sure that it WILL NOT fit, due to the caliper being out farther to the

wheel. This brake setup would require upgrading to wheels that fit a 1994 to 2004

Mustang. This can be viewed as good OR bad depending on your perspective. I

see it as GOOD, since during my search for wheels for my Avanti (over 10 years)

I couldnt find anything that looked good. They just dont make nice wheels in the

stock offset, at least not that work well with the design of the Avanti. Two things

I need to check on .. one confirming that the stock wheel fits or doesnt fit, and then

two what steel wheels are available for a 1994-2004 Mustang. I am pretty sure

that the base Mustang used steel wheels, and they should be 15 inch. Technically

that would mean the stock Stude hub caps could be used. I will check with my

Mustang buddies and see.

Tom

Tom,

I'm running 15" Steel Wheels from a Lincoln Towncar(early '90's) 6.5"rim width and the offset is ~0.5" farther out. Will you be at the Griffth Park meeting the 18th? Would like to see your efforts up close.

Chuck S

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Tom,

I'm running 15" Steel Wheels from a Lincoln Towncar(early '90's) 6.5"rim width and the offset is ~0.5" farther out. Will you be at the Griffth Park meeting the 18th? Would like to see your efforts up close.

Chuck S

Cool .. so then this would return the wheel back to the correct "center" position. Good to know that

there are rims available to use the stock hubcaps. For the most part it can be turned back to stock.

The mod of the hub is "kinda" permanent, because of the larger stud. Granted you COULD still use

the drums drilled out to fit the larger shoulder of the stud. I dont see getting the car to that meet,

I currently have the rear brakes apart, and even if I got it back together in time, I wouldnt trust the

rest of the car to make it the 3 hour drive.

Tom

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You should consider marketing the conversion. I know at least one who would be interested.

Paul

And who would that be? .. lol! Well .. I am certainly considering that option, the setup will be featured in an

upcoming Avanti club magazine, so for those of you who are members like myself, you will get this set to

your door soon. I am looking for input, and would also like to hit up SDC for feedback. If I know that there

is enough interest, then perhaps brackets are in my future. We shall see. I still have yet to receive ONE

Email from any interested parties. Not even for Info! This forum in amazingly dead. I actually hear some

crickets chirping when I log in...............

Tom

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  • 4 weeks later...

I am trying to put together a first run of 8 sets to be sold. With

the cost of material, and unfortunately not being able to do the work

machining the adapters myself, my overhead is high. If I do offer

these, its NOT going to allow me to quit my job.[;)] The Cobra brake

setup requires 17 inch rims, that might be a problem for some people.

The GT brake setup can all be bought from Autozone, BUT they require

the machining of the hubs. Since the person buying the kit HAS the

hubs, thats an operation that "he" must have done, that creates a bit

of a problem (I have been doing a LOT of thinking on this). So the

Cobra kit would be an easier install, but would require larger wheels

and "rubber band tires". To me this is a GOOD thing. I have priced

the rest of the Cobra kit online, and its just shy of $500 for all

the parts (thats AFTER the adapter). This will get you :

Two Aluminum 2 piston "PBR" Calipers in black (Mach 1/Cobra) w/pads

Two 13 inch zinc coated cross drilled and slotted rotors

Two stainless steel high pressure braided brake hoses

These are all new parts, the price I mention includes shipping inside

California (outside would be more obviously) and tax.

If we go with the GT setup on the other end of the spectrum, Autozone

carries EVERYTHING, and it would be roughly 225.00 including tax for :

Two Reman Calipers (they have yellow or red for more)

Two new 11 inch vented rotors

One metallic brake pad set

Two rubber brake lines

My inital calculations are looking like 150 to 250 for the 4 required

brackets, thats the two billet 6061-T6 aircraft grade aluminum caliper

mounting brackets (which weigh under 2 pounds each), and the two steel

hose mounting brackets.

So if you look at the extreme end of the "factory" brakes, thats about

$750 MAX total for some awesome brakes, if I my costs for the bracket

hit the high end of my estimate. Thats 100 more then Steeltech, but

its also a LOT more brakes, easier to find replacement parts, simple

upgradability to even 14 inch and 8 piston calipers. On the cheap end

thats $475 total for the GT brakes with the high estimate for the

brackets, yet still gives you the ability to upgrade later to Cobra

brakes, since the brackets fit either caliper.

Either setup requires the Napa wheel studs at 2 bucks a piece.

I plan on taking this Avanti to a road course track eventually, so I

want brakes that will stop it, lots of early Mustang guys are using

the 13" Cobra brakes on their cars. They look great and stop great. I

see them as a MUST if you are going for this look.

Tom

Edited by SBCA96
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Yes, unfortunately, this site is fairly dead; the Yahoo Avanti site is a good one; I'm surprised more of the Avanti people don't post on this one.

Sounds like YOU need to do some recruiting! Bring Um over here Gman!! ;)

Tom

Edited by SBCA96
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Site is unlisted: http://autos.groups.yahoo.com/group/avanti/

I wish the guys there would indeed use this site....much better format than the Yahoo style, where the posts are run together in consecutive order rather than by subject.

I'm relatively new to that site (under a year), and don't understand why this site isn't utilized more.

The other few forums I am on all avoid the Yahoo format, but it's apparently the one of choice for the Avanti guys.

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