I have read many posts about converting early A-bodies front drum brakes to disk brakes using components from 73 and up disk brake equipped vehicles, but what would the process be to convert a 73 Duster from front drum to disk brakes? Sorry about the clueless-ness in advance. I'm just very new to all this stuff. Any help is appreciated.
73 Duster front drum to disk conversion
- Thread starter Jdelaga09
- Start date
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You'll need pretty much all of the same components as the earlier cars, with the exception of the upper control arms. You should already have large ball joint UCA's on your car. But you'll still need the 73+ A body or F/M/J disk spindles, rotors, calipers, master cylinder, and proportioning valve, along with new wheel bearings and brake hoses.
Mopar92
Well-Known Member
I'm digging this thread up! Just bought a 73 Duster and had the same question. I did this conversion 15 years ago on my 70 Dart. How do I know if I have the large ball joint upper on my 73? Sounds like this is simpler this way. All I need are the spindles and of course what you said above. But as far as suspension goes, I'm pretty much set? Thanks.
On a 73 you should already have the large ball joint upper control arms.
Are the front drums finned or ribbed? I believe those only came on the 73 up large upper ball joint cars.
Spindles, caliper mounting brackets, calipers, dust shields, master, distribution/proportioning valve/block, hardware, etc. from any 73-76 A, 76 up F,M,J or 73 up B.
Remember these replacement brakes are large bolt pattern so you may want to consider changing the rear to LBP as well.
Are the front drums finned or ribbed? I believe those only came on the 73 up large upper ball joint cars.
Spindles, caliper mounting brackets, calipers, dust shields, master, distribution/proportioning valve/block, hardware, etc. from any 73-76 A, 76 up F,M,J or 73 up B.
Remember these replacement brakes are large bolt pattern so you may want to consider changing the rear to LBP as well.
Mopar92
Well-Known Member
Yeah I've got an 8 3/4 setup to roll under it with the driveshaft as well. Thanks!
This article pretty much sums up disc brake conversions using factory parts.
http://www.moparaction.com/Tech/archive/disc-main.html
http://www.moparaction.com/Tech/archive/disc-main.html
No, it doesnt.
Grab a 7/8" wrench, check the upper ball joint nut if it's that size. If it is, you have big ball joint uppers. If it's in the 11/16" range, SBJ.
Sure, except for the minor detail that it's 100% wrong about the FMJ spindles. Ehrenberg didn't check the geometry, he didn't install a set of FMJ spindles and put his car on a rack, he just assumed, incorrectly, that because the FMJ spindles were different they were bad.
They aren't. Mopar Muscle actually did the comparison of all the stock geometry compared to the geometry when using FMJ spindles. The result? The geometry is different, but the difference is small enough that the average driver would never notice. Not only that, but the FMJ spindles actually provide BETTER geometry for lowered cars with wider tires. It's all in there. The geometry and camber curves are also handy for showing how good the geometry of the torsion bar suspension actually is too.
http://www.hotrod.com/how-to/chassis-suspension/mopp-0503-swapping-a-and-b-disc-brake-spindles/
Mopar92
Well-Known Member
The geometry seems bad on these cars stock. Ever follow a Mopar while cornering... I can't even begin to describe how F'd up it looks. Huge camber gain on the inside wheel etc. it's painful looking. Much like following a Ford twin I beam! ��
Do yourself a favor and read the article I posted, and actually look at the numbers for camber gain. The geometry is actually quite good for radial tires, especially on a car that has been lowered slightly.
Which is why it has been demonstrated that these cars, with the torsion bar set up, can pull close to 1g on a skidpan when set up properly. In fact, there's a video of TireRack's professional test driver in which he drives the Hotchkis Taxi in a tire comparison and compares his times to the stock 3 series BMW's that he usually drives to test for TireRack. The Hotchkis Taxi, a 4 door '70 Satellite, was over a second a lap faster. Maybe you think it looks funny, but that geometry can push a '70 more door around the track faster than a 2012 3 series Beemer. Go figure.
***Update***
Here's the video. A little long. You can pretty much just start at the 3minute mark. At 4:30 you can watch the Hotchkis Taxi kicking butt. And at 6:00 min TireRack's professional driver goes into how the Hotckis Taxi is a full second a lap faster than the BMW 3 series, even though Woody (tirerack's driver) had never driven a "protouring set up car" before the test and has probably turned thousands of laps with that 3 series.
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