Does anyone know if I can use a 1978 Plymouth Volare as the donor car for a disc brake conversion on my 1974 Dart Sport?

different discussion held long time back formed this post:
http://www.slantsix.com/UBB/Forum16/HTML/001370.html
scroll down to some parts #'s I posted for GTS225, you can get the disks and the calipers, "hardware" but you need the knuckles from a 1973-1976 A-body or 1973-1974 E-body, and A-body UCA's/LCA's (been a long while...)...

The F-body guys are lucky that they can use the knuckles out of the late B-Bodies (Cordoba's are a lot more common in my area than Valiants...)

someone else may have more info to update your parts hunt.

-D.Idiot

This has been discussed to death on various mopar orientated boards, with magazine pundits weighing in on both side of the discussion.

The bottom line is that the spindles, rotors and calibers from a '78 Volare will bolt onto your Dart. If you use the UCA from a '73-'75 A-body, '70-'74 E-body or a '66-'70 B-body. Wither this is smart thing to do is open to debate. The F-body spindle is 1/8" longer then the A-body spindle. This may cause problems with the front suspension geometry. This is were the debate is centered.

For your edification, I used a complete setup from a '75 Dart for my conversion on my '65 Dart. I also had access to F-body parts, my choice was the tried and true.

Here's the thing. The selection of new wheels to fit the 5x4" small bolt pattern on my son's '74 Dart Sport is extremely limited. Personally, I would also feel more confident in disc brakes. Is this a misconception?
Don't discs have quicker and straighter braking ability?

I am determined to convert the 9" drums over to disc for both those reasons. As I understand it, the only way to get the larger bolt pattern on the rear is by replacing the 7.25" rear end with a 8.25" or 8.75"?

Returning home Sunday from a swap meet in Houston, we ran across a '71 Dart and a '78 Volare, each sitting by the road for sale. Both of them had a slant six. Unfortunately, the Dart had drum brakes and really not any other parts to use on our Sport. The Volare had disc brakes and, of course, the larger bolt pattern wheels. That's why I asked the original question of robbing the disc brakes.

Would the rear end be something to also consider robbing for the larger bolt pattern? We have a Dodge 360 engine stored away to maybe someday swap out, and I know there will be a lot of components to change out, one being the small rear end. I thought we would be at least one step ahead if we do that now, killing two birds with one stone.

Jerry

Depending on junkyard resources in your area some A-bodies from the 1974 to 1976 years could be had with disk brake fronts and 7 1 /4" rears with 10" drums and large bolt pattern (mostly standard for the 1976 model year after 12-1-75....), anyhow.... if thinking about the later powerplant upgrade definate-ly getting an 8 1/4" would be wise (1973-1976 heavy duty braking, 340/360, some disk cars and certain other packages had them...), otherwise the 8 3/4" with LBP axles would be the trick...

I have gone through two 7 1/4" LBP rears already (just cheaper to swap than fix 'em...), and my last 3 A-bodies have been manual disk brake cars...


good luck on your hunt, usually the best approach is finding the item that 'works', but is still cheap an plentiful at the local wrecking yard...

-D.Idiot

Ok, on a '74, you should have no difficulty physically bolting on the spindles and brakes from the Volare. You'll use the Dart's control arms. I am running a different disc combination (shorter spindles, taller discs) and the Dart can really stop pretty hard with the discs.

I was originally skeptical about the taller F-body spindles. However, had I known when I converted my Dart to discs what I know now, I would have used them. One visitor from BigBlockDart.com posted a considerable amount of information on the effects of the taller spindles - he had used suspension modeling software to work out the effects on the geometry, and talked with people who had raced A-bodies with both spindle types. The conclusion he drew - which I'm inclined to agree with - is that the taller F-body spindles have a marginal performance advantage and no drawbacks, but the difference very small.

As for large bolt pattern axles. The 8 1/4" and 7 1/4" axles both came in large bolt pattern versions. I used to think all large bolt pattern A-body axles were 8 1/4" units, which bit me when I dragged home a large bolt pattern rear axle from the junkyard only to realize I had a large bolt pattern 7 1/4". I think on a '74 you can just swap the shafts and brakes with those off a large bolt pattern 7 1/4" unit. The 8 3/4" axle used in A-bodies only came as a small bolt pattern unit from the factory, but there are some that have been converted to large bolt pattern. Some Ford 9" and 8" rear axles also bolt in and give you the large bolt pattern; look for Granadas, Monarcys, Mavericks, and early Mustangs as donor cars if you're considering this route.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Thanks guys! I hadn't done a disc conversion since 1991 when I used 73 Dart pieces on my 72 Dart. I recently started scrounging again for my '64 Barracuda and searched quite awhile before finding a disc brake A body. This information along with the spindle swap thread on this topic really opens up doors for this conversion! Every F body you see has discs! What about the proportioning valve? Can I use the one from the F body, or will I have to get an adjustable one?
Thanks,
Rob

If this swap is done on 72 drum brake car, I would also need the larger lower ball joint and a upper control arm from a 73-76 disc brake car?? Is this correct?
Thanks,
Rick

Correct.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

Just to clarify, to swap from older drums to discs I thought you just needed the upper control arms and spindles. I believe I used the original lower control arms when I did mine years ago. Also, don't later A bodies with 10" drums have the larger upper ball joint? Where do you measure for comparison? If I still need both control arms I'm pretty much still in the same boat of having to find a disc brake A body. Also, what about the proportioning valve? Can it be from any front disc/rear drum car? Thanks again,
Rob

The LCAs can be used from any car, drum or disc - they are the same. The prop valve is probably OK from any disc/drum car, although I have drum/drum valves in both my cars with an adjustable valve in the rear line as well. Tuning for every car is always the best way to go.

Lou

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Home of Slant6-powered fun machines since 1988

I used one from a '73 A-body. This was on a suggestion from the person I bought my parts from. He had tried several different years and even one from a 1/2 ton PU and the '73 worked the best. I know my car brakes very evenly with no lockup.

Please forgive my ignorance. I really am trying to stay up with you guys on this brake conversion subject, but it's all new to me. I know you will get me through it.

I have finally found what may be my salvation. I now have a line on a '73-'74??? Dart Swinger. The fender tag indicates '73; the door label says '74, which do you trust? Anyway, the car has front disc brakes, rear drums, and 4-1/2" bolt pattern. Just what I was looking for.

I started this thread with the whole emphasis being that I want front disc brakes for safety and stopping power, larger bolt pattern for wider selection of wheels, and as a bonus maybe a larger rear end for future 360 swap. The only unknown is the rear end. It's really muddy and overgrown with weeds where the car is located and I wasn't in the mood to crawl around underneath looking just yet. The scrapyard owner will lift it up for me with a forklift if I want the parts.

Have I completely solved my problems and can end the search? It appears that a bracket is on the firewall where the master cylinder is located on our '74 Dart Sport. I assume it's for a power brake booster. That and the master cylinder are missing on the Swinger. I don't recall if the proportioning valve was still there. Do I have to have the booster and master cylinder, or will my MC work? I guess, if the prop. valve is gone, I will have to find one of those. Hey, how about the '78 Volare I am eyeing for its Super Six setup? Can all those items come from it? Do I also need to rob the brake pedal?

You guys have been great, keep the ideas coming.

Jerry

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There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

It's most likely an 8 1/4. That's what I would think, anyways, cause I had a '75 Scamp with a 318, and that had the 8 1/4.

i just bought a '73 dart custom 4 dr parts car for 100 bucks. it was a 318 car with a 7 1/4 rear. just what i wanted since i have a 7 1/4 sure grip.
73 was the first year for the large bolt pattern for the a body, and, in true mopar fashion, only on the disc brake cars. all of this stuff (including m/c and lines) will be transplanted on my '63 valiant soon. the lower ball joint is the same part number for the 10" drums and the disc cars. the strut rods are larger in diameter on the 73/up disc cars than the earlier versions and should be swapped on as well for improved handling. i think this affects lca choice as the holes may be bigger in the arms.
as an aside, it is amazing the amount of structural stuff that looks like it will swap onto the '63. i needed framerails for the '63 and it appears that the the trunk/rear floorpan will fit into the valiant as well (according to my tapemeasure anyway.)
will post more soon.

-james

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