Disc Conversion For Your Dana 70 Rear Axle - Diesel Bombers

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Old 01-01-2010, 01:18 PM
RSWORDS's Avatar

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Join Date: Mar 2007
Location: Gloucester, VA
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Default Disc Conversion For Your Dana 70 Rear Axle

Really Good Read Here!

Publish date: Mar 1, 2005
By: David Dennehey
Source: Toyota at Off-Road.com
Dana 70 Disc Brake Swap - Trucks 4x4 @ Off-Road.com

First lets ask the question, why a Dana 70? What about the more commonly available and cheaper 14 Bolt rear end? Well, in my case, the price was right, it was rebuilt, had the right gears and was the right width. On first glance, many would not be able to tell the difference between a 14 Bolt and a Dana 70. Same size ring gear, generally around the same width, come under heavy duty trucks, and so on. But there is more than meets the eye.

Some Specifications and Facts on the 14 Bolt:
  • Max gearing is 5.13:1
  • Very limited locker selection
  • 1.5 30 Spline Shafts
  • Max Torque Rating: 6242 Lb-Ft of Torque
  • Cast Iron Housing
Some Specifications on the Dana 70:
  • Max gearing is a massive 7.17:1
  • Excellent Locker Selection
  • 1.5” 35 Spline Shafts
  • Max Torque Rating: 8,000 lb-ft or 8,800 lb-ft for the HD
  • Nodular Iron Housing
The two most significant of those are the gearing and torque ratings. You can gear a Dana 70 45% higher, and it is about 30% stronger than a 14 Bolt. Also to be noted is the different housings, nodular iron is much stronger (Ford fans know of the famed N marking on a 9” housing). It is also easier to weld to if you are doing an upper 4 link mount on the housing.

As for cost; a 14 Bolt is generally dirt cheap due to its availability. I picked up my Dana 70, rebuilt, in great shape, no rust, grease marks still on the gears, and shipped from Texas to CA for 300$. Not bad.

The drums on a Dana 70 are massive. I asked the seller to remove them so shipping costs would be cheaper (FYI; Final shipping weight was 298 pounds). With the drums gone I decided to do a disk brake swap.

First you’ll have to remove the axle shaft. Simply take off the bolts that go into the hub and slide out the shaft. These are torqued VERY tightly, if it’s not on a vehicle, you will have to rig up a way to hold the pinion down, or get a heavy friend to help. (Some of my studs were already removed a while back when I was planning this)

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Next you’ll have to pull offthe hub from the axle. Do this by using your fancy hub tool to take off the nut. Or, just use a chisel (When tightening it back down, I recommend getting the tool to set proper preload).

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I picked up some disk brake brackets from Great Lake Off road for about 55$ shipped.Upon getting them and all the other parts I learned I needed some spacers to position the caliper correctly.

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Next came the expensive part. All Rotors and calipers came off a 1977 K20 front axle. They are commonly available at any auto parts store. I highly suggest just getting a set of loaded calipers. I got mine for $44, and you’ll have to eat the 20$ core charge. They come with the caliper pins (which run about 8$ a pop!) pads and the caliper itself. This is much cheaper than piecing it together. Brake Rotors ran me $45 each (No core charge). Total was somewhere around $220. Now came the fun!

First was the job of painstakingly pounding out all the studs.

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Next, put the rotor on the back of the hub, and pound the studs back through. This is not as easy as removing them since the holes on the rotor are not splined like the studs and hub.

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When you are done; it will look like this

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Now reinstall the hub and rotor back onto the axle; Using your 35$ socket. Or not (I chose not since this will not be run for a long while)

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Here is the caliper, out of the box and ready to go with all required parts

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Now remove the pins from the caliper, slide it over the rotor, line up with the holes on your bracket, and bolt it up. Hopefully you’ve gotten any necessary spacers, and everything lines up well, like this.

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Now repeat for the other side, and you have a disk brake equipped Dana 70 axle. Disk brakes are lighter, more compact, easier to maintain and actually work when wet. This is no doubt an excellent upgrade.

Before I called it a day, I had to make sure my wheels of choice fit on it (Of course I was pretty sure, but nothing beats seeing it on there!)

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What you see is a stock Hummer rim, 16.5” wheel with 7” of Backspacing, with plenty of clearance. A 16” wheel would also probably be fine. 15” wheels have been run, but you would likely have to grind down the outside of the caliper, which seems like a poor idea to me.

In hindsight I would recommend painting the caliper. I thought it just had a gunmetal finish, but it was bare metal and now needs some wire wheel action.

So there you have it, under 300$ for some high quality disk brakes! It will surely have no problem stopping any size tire the Dana 70 can hold onto.

Last edited by RSWORDS; 01-01-2010 at 01:31 PM.
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Old 01-01-2010, 03:05 PM
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very easy swap and very cheap IMO. ive done it to some 70's and also 14 bolts and its very highly reccomended! huge difference.

only down side is on the dodges you gotta run an adjustable proportioning valve.
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Old 01-02-2010, 12:33 AM
Diesel Fan
Join Date: Jan 2010
Location: Eugene<,Oregon.
Posts: 64
Default Noobie Question..?

I have a Dana 70 Duelly Axle out of a 79 Ford 1 ton....I am using it under my 64 Crew 4x4 Project...Will this swap work on it you think...? The Studs in the pics look to be pretty long already....Wondering if it was a Dually too...?

Great find either way....I have 2 buds with 70's under their trucks already....

I wonder how hard it would be to integrate on a 93 Dodge with ABS...?

Thanks, John.
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Old 01-02-2010, 01:36 AM
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Join Date: Aug 2009
Location: Lincoln, CA
Posts: 2,124

the abs on the old dodge i would assume would just be MIA as with any axle you do a swap on.

those studs also look long i noticed too, i had to replace mine with some longer ones.

but as for if itll work, a disc brake swap is about the same level of difficulty on any full floating axle, they all work pretty much the same, so they will all be pretty straightforward. but if it is a semi flaot axle, your in for a little bit of a chore.
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Old 01-02-2010, 01:40 AM
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Old 01-02-2010, 02:02 PM
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cha ching... NEXT PROJECT... right after i actually put my air dog on then the exhaust manifold and turbo are the next purchases hahaha its going to be awhile
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Old 01-03-2010, 10:42 PM
Diesel Fan
Join Date: Jan 2010
Location: Michigan
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I've done about 3 do it yourself conversions on the dana 70 and it is well worth it.. Nothing gives me more pleasure than ripping off those big honkin drum brakes on our precious first gens!!!
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Old 01-04-2010, 10:15 AM
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Join Date: Apr 2009
Posts: 474

I have some questions.

are those weld on brackets?
why the k20 rotor, why not the use the front rotor?
any vibrations (thinking that taking weight off the axel could cause vibrations)

my rear has to be rebuilt this weekend and I,m really thinking hard on doing this.

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Old 01-04-2010, 01:23 PM
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Location: Illinois?
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So the biggest issue here, what are ya doin for a parking brake. Not so much a problem for the Auto's but mandatory for a hand shaker.

Last edited by Uncle Bubba; 01-04-2010 at 01:43 PM.
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Old 01-04-2010, 01:33 PM
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not sure, i was going to worry about that when I got there.

I have a 5 speed, shouldn't be that complicated to install something to work a parking brake????

open for any suggestions.
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