Disc Brake info!

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Andre68

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Well, I'm pretty new to working with brakes, but in removing my front suspension components to rebuild them, of course the brakes need attention as well. The car is a 68 dodge dart, it had the front end "upgraded" how ever long ago, and the person I bought the car from wasn't sure what the donor car was. Now I believe the brakes are Chrysler single piston calipers, with 11" brakes. other than that I dont know much about brakes. Seeing I'm rebuilding the front end here are my questions.

1)Does anyone know what time period these brakes are from? Year wise
2)What is the bolt pattern?
3) Also, should I rebuild the calipers? or just buy new ones?
4) I believe I read somewhere that the discs should get machined, is that something I should do?
 

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Those appear to be the 73-76 A-body Disk Brakes...I think you'll just need to buy parts for a 73 Duster to get the right stuff.

4.5" Bolt Pattern

Those parts don't look so bad. I'd probably get some reman calipers and new hoses (likely $15/side) and slap a new set of pads on it
 
Yea I will just buy some new calipers and pads. Also what do you mean by have rotors turned?

Well this is the kit I bought
http://www.p-s-t.com/s.nl/it.A/id.53/.f?sc=12

It was there kit for single piston calipers. I did put that my car was a 68 dart in the vehicle criteria, should this kit work? Or should I get one for a 73 duster?
 
It seems to be the same kit for a 73 dart. They don't seem to have a kit for a duster...
 
Cool yea I just realized that I forgot to switch the dodge to Plymouth! Haha but yes they are all that part number
 
Andre68 said:
Also what do you mean by have rotors turned?
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You take them to someone who "turns" them on a brake lathe to true them up. I actually own one of these, and in a "previous life" have turned thousands of drums and rotors

[ame="http://www.youtube.com/watch?v=wUh5NPNb9VQ"]Brake Lathes - AMMCO 4000E Brake Lathe Rotor Reconditioning - YouTube[/ame]
 
Most major parts stores or any automotive machine shop
 
You just have to ask around. In the last few years, the Chinesian imports have actually driven the price of new rotors down, and many folks have gotten rid of their drum/ disk lathes.
 
Those rotors/discs look pretty good, doesn't look like they need turning. Most times rotors have grooves and ridges that require them to be smoothed by turning. On the disc there is stamping/casting letters around hub that gives minimum thickness. Parts store or machine shop can measure to see if the discs can be safely turned.
 
The rotors could still need turned for flatness, in that the brakes will pulsate and you'll feel it in the pedal when you apply them. I thought mine looked good smooth enough when I put them on, but they were warped and pulsated so have to come off for turning.

Min thickness says .94 inches right on them so I'd measure them to see what they come out to. Or take to the parts store and have them check them. AutoZone type places don't turn rotors, you'll have to find a mom-and-pop type store for that. At least that's how it is around here. Being that the bearing hub is still part of this rotor design, I bet it'll be worth having them turned before buying new.

Agreed just get new pads and calipers, and be sure to take the old calipers in for the core charge.
 
I wouldn't put the rotors back on without a light check cut in a brake lathe.
These rotors were heavy duty in construction compared to what they make today.
Even so, they did warp when they got hot enough.
 
hey well my pst front end kit arrived but no inner tie rod ends... do I buy 73 duster tie rod ends? or 68 dart tie rod ends?
 
What is it cost wise in getting the rotors turned to buying replacement rotors?

I will say the cost of these brakes isn't too bad, it's about $30 for the pads, about a little over $20 for the calipers, and I saw new rotors for $35 each. Total comes out to around $150 for the new disc brake set up.

If its only $150, and I know these are base model disc brakes, why do people say disc brakes are expensive?
 
Andre68 said:
Do I need a different type of brake cylinder?
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To do the conversion complete and proper you would need a disc brake master cylinder and maybe a proportion valve too.
If you want to save that for a later date you can stop the car with the master cylinder you have. I do recommend completing the upgrade now though.
 
Andre68 said:
What is it cost wise in getting the rotors turned to buying replacement rotors?

I will say the cost of these brakes isn't too bad, it's about $30 for the pads, about a little over $20 for the calipers, and I saw new rotors for $35 each. Total comes out to around $150 for the new disc brake set up.

If its only $150, and I know these are base model disc brakes, why do people say disc brakes are expensive?
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Depending on where you go, getting rotors turned for $5-10 each is a typical price. It's still a pretty good savings, even with the cheap price you found for rotors. I've seen them more like $50-up here. However keep in mind quality. There are different levels of it and cheaper price usually means cheaper quality. If your used ones are pretty old, chances are they are a better rotor over the new $35 ones.
 
We'll I went to oreillys because the did turn rotors there and the minimum thickness is .94 and he said mine were at .96 and that by the time they got turned there would be a good chance that rotors would probably be pass the limit. He said they looked fine though, that he would just take some sandpaper to them and use them for a bit longer.

So I took some 150 grit garnet paper and began sanding! One rotor didn't really sand much dust but it got a shiney look to it. The other was sanding off a lot of like black dust and just looked dull afterwords, don't know why this is! Took a picture!
 

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Too bad you don't live here. I'd turn 'em for you. Frankly, there is a LOT of leeway on the old 60's -70's rotors, not the case with modern single thickness designs.
 
In addition to eliminating flat spots or warpage, resurfacing the rotors gives your pads a "different" friction coefficient to work with also. After many repeated heat cycles from stopping the metal actually hardens and can compromise quality braking. Taking a few thousandths off makes for a smoother/quieter pad-rotor engagement.

I wouldn't lose any sleep if min. thickness from turning rotors is below "discard" thresh hold by a tad.

The newer rotors (cheap/import) appear to warp more easily than the OEM ones from way back.
 
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