Road Runner Nest

Hi, i have a '71 Roadrunner with manual drum brakes. I want to switch the front drums to disc. What parts need to be changed? What are my options as far as what will work? I'm planning on using original equipment rotors and calipers for easy future repair and replacement.
Thanks,
Jim

First you need to replace the spindles. You have two choices here. 1st you can go with the 71/2 b body spindles. These have the small bearing and the expensive to replace disks. The second option is using spindles from a 73/4 e-body or 73-76 A body. These are the large bearing units and the disks are fairly cheap and plentiful. Along with the spindles you will need to get the caliper mounts. You can use the ones from the applications I stated above for use with the 10 3/4" disks or you can get ones from a C body car and use the 11 3/4" c body disks. You MUST have 15" wheels to use the C body disks!!
The calipers are the same for both ( as far as I know) and so are the pads.

The master cylinder will need to be changed and either a combination valve ( containing a residual valve, brake warning switch and splitter) OR just get a adjustable pressure valve and plumb it in the line out to the rear brakes.

Thats pretty much it except for the flexible brakelines to the calipers.

Thanks for the suggestions! Is there a difference in the different spindles you mention that would give one an advantage over another? I do have 15" wheels, but I don't know where to turn for the parts you mentioned above.
Jim

the difference in the units is the size/diameter of the spindles. The larger units are much easier and a WHOLE LOT CHEAPER to get disks for. Last time I checked the disks were $125-140 per disk for the stock ( small spindle) 71/2 units. The 73/4 e-body 73-76 A body disks cost about $45 each. Moving to the big "c" body disks will give you better braking performance as the the disk is bigger.


The place to find them is at the boneyard. Usually you can pick up everything off of one car for maybe $75-100 buck or less. You aren't going to find these in a catalog anywhere.

Are the C-Body ones the taller ones? Will they be OK?
Jim

The C body caliper mounts are 1/2" taller than the B/E/A body units because they get used with a 11.75" rotor vs a 10.75" rotor for the other bodies.
If you use the C body caliper mount then you have to use the C body rotor ( which btw is why you have to have 15" or better wheel diameter when using them)- the spindles still need to be gotten from an E or A body in the years stated previously as the C body spindles are a different in a couple of way that aren't fixed easily.

Let me know if you have any more ?'s

You can also use the spindles,rotors, calipers,and parts from any cordoba,dodge magnum (70s),aspen,volare plus a bunch of other mopars.

now someone will come here and say not to use these spindles but i bet they have never tried the conversion.

Read this:
http://www.bigblockdart.com/techpages/spindles.shtml

BRIAN

Road Chicken, what options do you have if you want to stay with the 14" wheels? What cars?

mopar71 wrote:Road Chicken, what options do you have if you want to stay with the 14" wheels? What cars?

The only thing you can't do with 14" wheels is to use the 11.75" C-body disk, and the caliper mount that goes with it. Everything else is the same.

Posted: Thu Nov 30, 2006 6:55 pm Post subject: FILTH REVIEW

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You will need to get from a donor car:
(parts from filth ave or aspen volare)

spindles (dust shields)

calipers

rotors


Things you may need to purchase:

The lower ball joint is the same on all b-bodies 73 and up drum or disk..
so get them new OR JUST USE YOUR OLD ONES.

you can exchange your rotors, calipers, get new wheel bearing,and break
pads OR JUST USE YOUR the ONES. chances are these will be just fine
and if they are not they are easy and CHEAP to replace.

Ask for the flex brake hose to fit a 73 roadrunner...these are longer

things to keep up with:

the sliding caliper will have metal tabs and banjo bolts that are easy to loose..


A-BODY A What!!!
(this info is for A-Body only)

If you are converting an a-body you will need the UPPER A-ARM from:
any 73 and up "a-body" disk or drum (or an aspen or volare) these will
have the larger ball joint like our B-Bodies have. And lower ball joint from
73 and up A B or E car for your A-Body(the lowe ball joint will require
9/16 grade 8 bolts and lock nuts...the A have smaller bolts)

DONE


The cool thing is this set-up will work all the way back to the mid 60's
cars. ( A fella in the club just put a set on a '57 chrysler 300 convert....ised lower ball joint from fifth ave) And parts are way cheaper ....Like $35 dollar rotors...WOW that
beats the crap outta $150 each....

Your new caliper placement will be in the rear and not in the front....your
disk size will be 10 7/8...almost 11".....for the purist it is not exact....but
the set-up is way better than the pin type.....I mean I wouldn't put it on
my hemi car(like I have one) but my 72 rr bigblock airgrabber car sure
stops nice......Take care and contact me for any info....scott

Good info Thanks!

How about master cylinder? Can you just use the existing one or will that have to be replaced? I am guessing you would HAVE TO put in an adjustable proportioning valve? I am looking at doing the conversion on both of my Satellites. My boys are picking up the spindles today.

here is somethng i just came up with...a jeep 90's grand cherokee has
an identicle valve to a 71-72 cars....it even has the spot for the l bracket our cars use...(it slides over the brass sticky-out-thingy and then you hammer the brass flat)

they are the same size and shape...the only difference I could find was the numbers on the newer part are laser etched???

just look at the pic



take care all