That's some nice fab work mytbtruck. What is the lug spacing on those hubs? I have a Lincoln MKVIII IRS that I am putting in my 1950 Merc coupe and was surprised to find that the hub lug spacing was 4-1/4 (108 MM) vice the 4-1/2 that is standard for Ford.

 

Holehagg. Suggestion. Measure the front arm you cut off and go with that thickness OR use the cut off center section of the front arm, Split that piece to widen and fill in the center with extra leftover pieces. The arm all ready has the rounded edges. I haven't done it but it looks doable.

Charlie. In previous threads someone said later Mustang rotors were 4 1/2 and something about them being inter-changable. chuck

 

There are conflicting specs on various web sites regarding wheel lug spacing but this chart came from one of the more comprehensive sites:

T-BIRD 85-88 15 X 7 4X108 1/2-RH - M
T-BIRD 89-97 15 X 6 5X108 12mmX1.5 63.9 H
T-BIRD SC 89-97 16 X 7 5X108 12mmX1.5 63.9 H
T-BIRD 02-on 16 X 7 5X108 12mmX1.5 63.9 H

If you believe this data then every T-bird from 1989-on has 5 X 4.25 inch (108 mm) lug spacing.
I have more than a passing interest in this topic. To get to the 4.5 inch hub I had to buy Cobra Mustang hubs and rotors and move the calipers to accomodate the 11.62 inch rotors. The process was painful...I raise the point for those who are considering one of these IRS systems for their truck. Don't get me wrong, I love this IRS and for those who don't mind buying 5 X 4.25 inch lug spaced rims then life is good. My interest is to keep the lug spacing on the rear the same as the front which for me is 4.5 inches.

 

What was so bad? I was under the assumption the only difference between the Mustang & MN12 was the hubs. I was under the impression the rotors were the same D just with the larger bolt circle.

 

That's the same assumption that I was under...the MKVIII rotors are 10.125, the rotors to match the 5 X 4.5 hubs are 11.62. That's a 1.5 inch difference in diameter and to make things even more interesting the larger rotors also have a deeper offset (0.5 inch). There are so many variables when looking at these Ford brakes that it's hard to know what yr/model wil fit other applications. I have yet to find a chart like the one above that is for brake rotor dimensions. Right now I am machining caliper bracket to adapt the MKVIII calipers out and back so that I can use the Cobra rotors. I guess that an 11-5/8 rotor isn't all bad...

 

the birds , cougars and mark8's are all 5x4 1/4 bolt pattern . the front hubs from the previous sn 95 stang are the same , but 5 x 4 1/2 . the only rear hubs for the irs in 5x4 1/2 are the ford motorsports "kit car hubs" which are actually the replacement for the next mentioned , the sn95 based cobra that came with the irs in it . the front rotors are a direct swap i think , but the only rear rotors that will fit the irs are the cobra ones which are a lot bigger than the 10 incher's on the bird . so you gotta find a cobra in a bone yard , find fords part number , or make a taller caliper bracket . i could swear there was a 'stang rotor at one time i found in all my digging for the bird i drive , but i can't find the notes . or you could do what larry did and redrill the hub and rotors for the correct pattern . the wheel selection is real limited for the 5x4 1/4 pattern .fords kit hubs are / were 150 each last time i looked . the mark 8's all had aluminum center sections , rear arms , and some other lightwieght goodies compared to our lowly birds cast iron parts . the 6 cylinder cars had a 7.5 inch based center section i believe . if so the parts from a v8 8.8 center section and it may not interchange . i got ton's of notes on these things , as if i don't kill it or sell it the 95 of mine is third project inline after the 53 and 52 . just gotta dig fella's the info is readily available .

 

Here are the parts numbers for the hubs and bearings from Ford Racing...these are the "Kit Car" hubs which are nice because they don't have the ABS rings on them. The bearings are the good Timken items which are pretty much the same for all the IRSs...

M-1109-A
M-1215-A

I found some reference to a bracket that was being sold by a guy named "Fast Eddie"...the bracket was fairly crude, kinda matched his trade name I guess. If there is any interest I could post a tech post that documents the process.

 

Ok not so sure but what about using Mustang rotors and not the Cobra ones? I show 10.5" rotors used on a 2000 Mustang with a 3.8 V6.

 

there's a guy i think by that monicker on a thunderbird forum that is chock full of info , i believe and he has a good rep . but he also tells you what to do too make your own , at least i think i got an message from him somewhere that he did . it's called TCCOA . look it up i got kinda p144y with a couple of guys on there over there remarks to something i posted , and some of 'em need lessons in being kool to all . if you can overlook it and just dig for info you can find a lot of stuff there . i haven't been there for a bit as i just don't want too have a " techtard rambo " argue with me over something , too old or the aggravation ............

 

Closer but still too big and you can't be sure about the backspace. If the backspace was the same then it would be possible to machine down the outer edge of the rotor to get it to the proper diameter. The Cobra was the only IRS-equipped model with the 4.5 inch lug pattern that's what took me down this path to begin with.

 

http://www.fordmuscleforums.com / braking-articles / 480958-how-change-bolt-p...
Here is a simple way to drill new holes in a rotor. I would want the plate to be 1/2 inch or more thick so you drill a straight hole if not using a drill press. Also need to consider the center hole diameter. I googled Ford rotors and found this. chuck

 

I had a tough time getting that link to work so I finally went to the site and found the tech article. Here's another copy of the link, I think that the FTE site has added some extra characters to the link... How to Change a Bolt Pattern - Ford Muscle Forums : Ford Muscle Cars Tech Forum
Very ingenious the way he made the drilling jig, I agree that a thicker template would be better. Another thing that caught my eye that is very important is the fit of the rim to the hub centering ring...as you can see in his photo, there is a significant gap between the rim and the hub centering ring. A spacer will definitely be needed here.

 

A friend of mine owns a parts store and let me peruse through an AC Delco brake book. I came up with some possible rotors to use with the 4.5 circle. I do not have the center hole D information. The information runs in this manner. Part number, OD, height, nominal thickness, discard thickness, type.

The TBird rotor (4.25 circle): 18A567, 10.16, 1.79, .715, .657, Vented
18A353, 10.15, 1.775, .395, .354, Solid
18A867, 10.1, 1.93, .865, .79, Vented
18A892, 10.08, 1.78, .945, .882, Vented
18A1319, 10.303, 1.854, .827, .748, Vented
18A1677, 10.157, 1.783, .394, .315, Solid

I realize the solids appear much thinner but do not believe they are thin enough to cause the piston to blow when the pads are completely down to metal. One could also fab shims for the pads with the thinner solid rotors. The 1319 rotor is just under 1/8" thicker than the original. I would not expect a problem but even if so taking a little off the face of the pads would solve this problem. Height difference is roughly 1/16". My personal lean is towards the 1677 or 1319. All of these rotors are the 4.5 circle.

 

If anyone is intgerested the best place for info on the MN12 irs is the SCCOA, Super Coupe Club Of America. Board is full of helpfull guys and there are some very knowledgable guys on there when it comes to these units. I know Fast Ed personally and he's a great guy. He is not selling those relocation brackets any more but there is another guy there that is making them. They are used to move the caliper out to run the cobra rotors on the MN12 chassie. You can re-drill the rotor to the 4.25" bolt pattern or change the hubs to the 4.5" cobra hubs as well.
Here is a link to a thread with the guys contact infor in case you would like a set. I will be using them on my 50 Merc that I have installed the Mark viii IRS in.
New rear Cobra brake 11.65" brake rotor upgrade kit. - Super Coupe Club of America Forums

Drew

 

Kevin, I just caught this, I got rid of it...I tried to sell it after I went with my explorer axle, no bites on it, so it's got to be a Honda and soda cans by now..
Scrapped it last summer...sorry...there have been several t-bird's at my favorite salvage yard. Not sure what years have this unit though.