Disk brake conversion

[HotRodPC]

That's alot cheaper than Mico systems and if it works, it works.

 

[chevyzz8]

does these pic cover your questions

Which Rotors and Calipers did you use?

 

[TexasOutlaw87Cummins]

Did Duallys have Dana 70s ?

 

[kleedus]

i used square body 3/4 ton front rotors and calipers i bought new ones from orieliy auto parts for a 86chevy 3/4 ton

and as far as the dana 70 yes dually trucks did come with the dana 70 but not all duallies did

cab and chassis used a narrow 14 bolt

if it was a pick up with a normal bed from the factory it had a dana 70 witch was wider than any other rear axle

this is just what i have run into not sure its 100 percent true

 

[TexasOutlaw87Cummins]

Any hope for us having rear disc brakes then ? I was looming the other day said 70 next to the pinion so just figured it was a 70

 

[chevyzz8]

i used square body 3/4 ton front rotors and calipers i bought new ones from orieliy auto parts for a 86chevy 3/4 ton

and as far as the dana 70 yes dually trucks did come with the dana 70 but not all duallies did

cab and chassis used a narrow 14 bolt

if it was a pick up with a normal bed from the factory it had a dana 70 witch was wider than any other rear axle

this is just what i have run into not sure its 100 percent true

Will this clear cab and chaasis rear? duals and leafs so close on mine maybe enough space for a finger

 

[kleedus]

diy4x has a kit for a dana 70 rear disc brake set up
http://diy4x.com/cart/index.php?route=product/product&path=37&product_id=50


and i am not sure if it will clear a cab and chassis or not i have a couple cab and chassis trucks i could try to messure it and see

 

[da_raabi]

I know this thread is a bit old, but I'd like to update with the fact that diy4x has a Dana 70 dually disc conversion kit:

http://diy4x.com/cart/index.php?route=product/product&path=37&product_id=149

It says all you need is a set of 3/4 ton rotors/calipers (no e-brake though), and then a disc/disc prop valve or master. My only question to those who have done rear discs, did you use an aftermarket prop valve or a later-model master? Did you have hydroboost if you used a different master?

 

[nvrenuf]

I have vac brakes and used a master cylinder off of a '99 C3500 (factory 1 ton, vac assist 4whl disc application).

 

[77 K20]

I have vac brakes and used a master cylinder off of a '99 C3500 (factory 1 ton, vac assist 4whl disc application).

Sorry for the dumb questions- but don't know a whole lot about the brake system. So if you put disc brakes on the rear and you install a master cylinder off of a newer truck then you do not need the special proportional valve?

And what is the vac assist for?

 

[da_raabi]

Pretty sure it eliminates the prop valve.

Heres another question: will a vacuum master work on a hydroboost truck? I have hydroboost and I was looking at using a vacuum master on it...

Also, which 3/4 ton brakes do I need? Rockauto has both 13" and 11" rotors, which should I get?

EDIT: I was wrong on the rotors, they are ALL 12.5" rotors, but for some reason there are options for 11" rotor calipers, not sure whats up with that but oh well. Also, from what I can see a master cylinder off of a vacuum boost truck should work with hydroboost, but the bore on the '99 master mentioned above is only 1 1/4" while the one listed for the C30 is a 1 5/16". Will this be a problem, or is 1/16" not a big deal in the master cylinder bore?

 

[John-e Bravada]

Did you ever figure out what to run for a hydro rear disc setup? Mine has a rock hard and not very powerful pedal. I'm thinking of running a smaller master for more pedal throw and power. I developed a leak and have to bleed it so there's no time like the present to swap master.

 

[77 K20]

Did you ever figure out what to run for a hydro rear disc setup? Mine has a rock hard and not very powerful pedal. I'm thinking of running a smaller master for more pedal throw and power. I developed a leak and have to bleed it so there's no time like the present to swap master.

Do you know what size bore your master has now? Running a smaller bore does indeed make more pressure and will give you a softer pedal feel, but will require the pedal to move to the floor more. If you go too small it can make the pedal sink all the way to the floor and you won't stop either.

 

[John-e Bravada]

I'm not sure, stock 86' C30 454 hydroboost size I didn't measure it when I swapped hydroboost units. I should have...

 

[77 K20]

I'm not sure, stock 86' C30 454 hydroboost size I didn't measure it when I swapped hydroboost units. I should have...

So far by looking around online it looks like 1.312" is the stock size bore for a '86 C30.