73 Challenger Brake Upgrade

Some of you that halped me out during my issue, Brake Help thread, this is what I did. Figured I would put it all in one place for easy viewing.

I upgraded my front discs to 03 Cobra disks, basically the 13" setup sold by Doctor Diff, who by the way is awesome! He tried to help me sort my world, even though I didn't buy from him. Honestly because I'm cheap, and I wanted the challenge.

After the above issues, which I'm almost positive were caused by crap vaccuum, I decided to upgrade everything. Enter oddball rear brakes and 03 Cobra hydroboost.

If you have questions, just fire away, the project is done now and I'm posting so others laugh and nit pick.

So, heres the basic numbers. I was going to provide coords from my DRO, but it started skipping, and I wasn't going to stop to clean it. You can duplicate the way i did, layout dye, punch a spindle center, and create arcs useing calipers. Find what looks good with known bolt hole spacing and center punch, drill on center punch marks.

I used the old bearings when i set it up on my lathe, worked, but i was planning to replace them anyway. Your going to need carbide tooling to cut on the hub, that thing is HARD. Also, at the bottom is a comparison of the SN95 hub vs the cut down E body. I was concerned about strength, until I saw how thick the e body hub really was.

Next layout the brackets, and cut. I used some thin aluminum to layout everything based on spindle center, then once i had a good grasp I used it for a template to center punch what would become my brackets.

So here's to test fitting. My measurements were spot on, and everything lined up nicly. For the record, I bought loaded spindles, $200 for the pair, and things had been painted red... not on an orange car we don't.

Lastly, to complete the front required lines, and extra bolts. Lines were sourced through Dr Diff, stainless braid for about when I would have paid at the parts store. Also, bolts from Fastenall, as prescribed in the first drawing picture.

Rears are next, didn't have much to start with, so lots of part #'s. Here's what I used:

Rotors - 03 Cobra Mustang, Duralast 54036 x2 $80, bolt holes are too small, so you'll have to open them up for it to sit flat.

Calipers - 01 Jag S-Type, similar to mustang, but more available. Pick and pull $20.

Hoses - 01 Camero outer's, Duralast 78537 x2 $24 (Metric Bubble flare ends)

Brake line -M10-1, 4 ft $7. To replace from center hose to disk hoses, no luck making bubble flares here, easier and cheaper to buy the dang line and redo center hose flares.

This step almost requires a lathe, and as always, start with a scrap piece to check fit.

Like I said, my DRO was acting fickle, so test piece first, but these are the coords i drilled on.

Center bore of axle ID should be what will fit OVER your axle housing, from the BACK, mine varied as axle housing OD isn't precision machined.
X: 0.00
Y: 0.00

Axle flange bolt holes (3/8 bolts, i cut mine under to form a tight press fit) I cut away the bottom bolt hole to allow it to fit over the axle tube, but will provide all 5 for the spacers.
1: X -.684 Y -1.660
2: X -1.843 Y -.382
3: X -.484 Y 1.816
4: X .699 Y .811
5: X 1.182 Y 1.355 Center Bottom hole

Caliper Bolt holes
1: X -4.395 Y -1.856
2: X -4.719 Y 1.961

I used a grinder to get the u shape in the bolt heads, when you see it in person you'll get it. Also, ground some snug fitting washers, 5/16 fender washers, as you don't want all that pressure compressing right on the aluminum.

I'm not giving specific deminsions, as with the single adjuster any movement effects both sides. I wound up useing my .100 spacers, but no gaskets, only gear oil rtv. Worked perfect on drivers side, perfect disk spacing on bracket, but not the pass side. If you look at the bracket above, it has a taper milled into it as the drivers side seemed crooked and disk spacing wasn't great on the back side. I think this might be some tow in the axle housing, as everything seats nicely, and with a litle taper milled in has great disk/bracket spacing.

Some extra pics to see the assembly. Of note, the hose fittings are metric, bubble flares... So, plan for this, it blind sided me, I thought everything was double flares.

Also, note the barrel fitting for the ebrake. This is how I used factory cables. They are about 2.5 inches long, and have a c clip holding them to the bracket.

Rear brakes done, for around $125.

Got a car meet to go to, hopefully I'll get the hydroboost conversion posted tonight.

Now for Hydroboost.

01-03 Cobra Mustang, got the booster, master and prop valve off ebay: $114 shipped

Brake Lines: Don't have the reciept, but less than $20
Dorman 071340BP (3/16 double flare to m10x1 bubble flare adaptor, for front line)
Dorman 785-434 (7/16 female double flare to 3/16 male double flare, rear line to wilwwod prop valve)
Dorman 785-462 (1/4 tube nut, front line into above adapter)
3/16 double flare line and fittings, dependant on how your brakes are currently setup.

Hydraulic Lines: From Summit $154.73
RUS-620421 $15.97 X4 (90 hose end)
RUS-648080 $11.97 (-6 to M18x1.5 o-ring adapter)
RUS-670530 $4.97 (-6 to M16mmx1.5 adapter, also requires Dorman 82540 nylon sealing ring $5)
RUS-632620 $50.97 (PowrFlex Hose)
AER-FBM2964 $8.97 (flare adapter for PS pump)
RUS-648010 $13.97 (o-ring 1/2-20 adapter for steering box)
I tried some cheap junk yard alternatives, a main hose from a 97 sunfire would get close, just needing some bending and a double flare for PS pump. But, the hydro to steering box hung me up, it's 3/8 down to 5/16 with an o-ring seal. It would have been cheaper just to go with the above summit order, way less headache.

Mounting:
4x5x1.5 material of your choosing, I used a sandwich of aluminum, one inch thick, plus another .5 plate.
4 x 5/16x2.5 inch bolts.

General Idea:
The Ford booster from mount face to eyelet is 1.5 inch longer than the factory booster. Also, if mounted right side up, that would expose the lines, and generally ugly it up, so I flipped the master and mounted it upside down.

I don't remember specifics for diminsions, but the Ford eyelet is larger and skinnier. This is a great time to make it from bearing bronze, and also replace the other pedal bushings with bronze while your at it. Pedal is oh so smooth now.

mounting holes are sketchy, I measured off the booster, but still not perfect. Center hole for booster is just centered on bolt patters, then recessed to leave .300 face thickness. This allows you to tighten the nut via chiesel, and then reinstall the snap ring. On the inside is an alignment pin, i drilled it twice once i decided to flip the booster, simply cut down some .25 steel stock as a dowel.

Also, the .500 plate was recessed where the two plates meet, this allowed me to trim the rubber boot and have the two plates clamp it.

next is to bolt it all in, first pic is lines up, ugly, second is lines down with booster flipped.

Next is lines. Order is: PS pump to Hydroboost in, hydroboost out to PS box, return from both tied together and then back to pump. I threw in a cooler on the low pressure side, junk yard piece off an excursion, $10.

and cooler

That, sir, is how you get 13 inch front brakes, 11.75 rear disks with parking brakes, and hydroboost all for under $700. I know, Ford parts on a Mopar, I'm the anti-Christ...let the spears fly. I tested it on the way home, from 65 it out stopped my wife in our 04 BMW 330CI. Not bad for a cheap redneck, and thats with crap junkyard pads.

john, great work on the brake upgrade.

John -- nice coverage!