i have at present a 1966 dodge dart gt, 225 slant, 904, and 9" drum brakes that i am putting through a full mechanical restoration (threw a rod) and adding some upgrades along the way. my questions are as follows: what is the final rule on doing the disc brake swap outlined by Mopar Action on an early A-body? will the upper control arms off a 73-76 donor car bolt up correctly on my 66? further, does it matter whether the donor car had drum or disc setup? finally, i am trying to upgrade to the big bolt pattern at the same time . . . were there different setups that had big bolt patterns and what about a-body 8 3/4 rearends, did they all have a big bolt pattern? until i figure this out i can't make other decisions about rearend stuff, wheel and tire options, master cylinders, etc. . . . please help!!

thanks

rushford

dartgt66@hotmail.com

You should probably search the threads for this, because it's been beaten to death by people smarter than me. But here goes: yes, any A-body control arm(upper or lower) 'bolts' into your '66. But, I believe starting with the '73,'74 (BBP) disk setup they went to a larger upper ball joint. One way I KNOW works, is to find a '73 or later A-body disk donor car and use the whole upper/lower cntrl arm, spindle, lower ball joint, caliper and bracket, assembly and just bolt the whole unit in. You'll have to come up with a custom sway bar(if you want one), but I don't think that would be much of a problem. I've seen other forums talk about swapping spindles side for side so you can run the oem bar for your '66. But I don't see how that can work properly(geometrywise), and I don't think you're gaining that much anyway because the oem '66 bar is pretty wimpy, if you could even find one.

All A-body 8 3/4" rear axles are SBP. If you want BBP, there are machine shops out there that can redrill the SBP axle flange and the drum to BBP.

Or, you can have some custom BBP axles made up.

Another possibility, the route I went many years ago on my '67 'Cuda, was get some BBP 8 3/4" backing plates(incl all brakes and hdwe), drums and axle shafts from some HD application, and have the shafts shortened (to A-body length) and resplined.

Another possibility, one that I used on my '66 Cuda, is just locate a '73 or later A-body 8 1/4" BBP rear axle and swap the entire assy in.

You'll have to have the driveshaft shortened if you swap in anything bigger than the 7 1/4".
Keep your original e-brake cables, because you'll probably have to swap them in to whatever axle you swap in.

Oh yeah, whatever you do, get rid of the single reservoir m. cylinder. It's an accident waiting to happen. They are actually becoming kinda hard to get(read expensive), which to my way of thinking is a good thing.

fglmopar@aol.com

I've done this exact same swap before, with great results. While my Dart doesn't nose-dive much when you stomp on the brakes, that's probably due to the suspension geometry and 0.870" torsion bars I'm running. It stops pretty hard, and doesn't throw any strange "surprises" at me like the 9" drums could. However, the pedal feel is downright weird (manual brakes with a master cylinder meant for power assist), with light effort and a very long pedal throw. Perhaps braided brake lines (such as MP P/N P5249274) may reduce the length of the throw, but it works well once you get used to it.
:
: will the upper control arms off a 73-76 donor
: car bolt up correctly on my 66?

Yes, they bolt up like they were meant to go there.
:
: further, does it matter whether the
: donor car had drum or disc setup?

Only for the spindles. The upper control arms are the same for all '73-'76 models.
:
: finally, i am trying to upgrade to the big bolt
: pattern at the same time . . . were there
: different setups that had big bolt patterns...

The Mopar Action conversion will give you the large (4.5" x 5) bolt pattern.
:
: ...and what about a-body 8 3/4 rearends, did
: they all have a big bolt pattern?

Unfortunately, all stock A-body 8 3/4" rear axles are small bolt pattern. All A-body 8 1/4" rear axles are large bolt pattern, but not all large bolt pattern A-body rear axles are 8 1/4" axles. I was under the impression that all of the large bolt pattern rear axles were 8 1/4", and pulled a large bolt pattern 7 1/4" unit by mistake once. That one's now in my Dart, since with its larger drums and beefier shafts (the large bolt pattern ones have a bit more material in them), I figured I might as well just put it in so I didn't have a silly mismatched set of wheels on the Dart. I may go with something tougher when that breaks, though.

Some options that don't use A-body parts for getting a large bolt pattern include putting in a '70 or earlier B-body 8 3/4" axle in there (bolts to the springs, but you may need to tinker with the fenders a little or run wheels meant for a FWD car out back, as the wheels are moved out nearly 2" per side), modifying an "unsuitable" 8 3/4" axle (either by narrowing a too-wide one or redrilling a SBP one), or putting in a 8" or 9" F*** rear axle out of an early Mustang, Granada, or some of their other Dart-sized, leaf sprung cars.
:
: until i figure this
: out i can't make other decisions about
: rearend stuff, wheel and tire options,
: master cylinders, etc. . . . please help!!
:
: thanks
:
: rushford

You have several master cylinder options. The cheap bolt-in one is a '73-'76 cast iron cylinder, which bolts right up to where your original was. You could also use the aluminum M-body cylinder, but that requires about $150 or so worth of adapter kits.

Matt

Hello Rushford,

I am with Matt and Bud on almost all counts. I put the 11.75" front discs on my '64 Dart about 2 years ago and they are amazing, and I have recently switched my 8.75" to big bolt axles.

You definitely need the '73-76 A-body UCAs to go with the disc spindles since they use a different upper ball joint.

I would recommend getting a $40 adapter plate from <A HREF="http://www.arengineering.com">www.arengineering.com</A>, and running the '85 Chrysler 5th Ave aluminum master cylinder, or for more pedal effort and less throw (what I like), get an aluminum MC from an early '80s 2WD Dodge truck (I asked for an '84 and it cost me $35 since I didn't have a core). This is almost as cheap as the early master cyl, and you get a better unit that weighs less and looks good for a long time (no rust). You don't need a special MC pushrod for this - the stock one works just fine.

I also recommend putting an adjustable prop valve ($40 from Summit) in the rear brake line so you can tune brake bias. I consider this essential for a car with a modified brake system, and even helps cars with stock systems.

Also, Moser Engineering sells NEW 8.75" big bolt axles for about $210 shipped to your door. I just bought these and I think it's the easiest way to go, and almost the cheapest. It would be a little cheaper to get junkyard C or E-body axles and shorten them, but a helluva lot more work and almost as expensive by the time you get done with shipping costs. You also need the 10X2.5" drums from a B, C, or E body 8.75" to complement those axles.

Another good option would be to find an 8.25" axle. Those are getting scarce and are harder to work on, but have cheaper SureGrip units than the 8.75", and already have the big bolt pattern ('73-76 A-bods).

Yet another option would be to get a B-body 8.75" as Matt suggested, which are a little wider, BUT then you can run late-model Mustang wheels, which have a large backspacing and just about offset that axle width change. This would take some measurements and thought, which I could help with if you decide to do this. FYI, I just put rear discs and 16X8 aftermarket Mustang rims w/ 245/45-16s all around on my '64 Dart and they fit well and perform and look awesome!

Have fun!

Lou