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
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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)

Attachment 50006

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).

Attachment 50007

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.

Attachment 50008

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.

Attachment 50009

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.

Attachment 50010

When you are done; it will look like this

Attachment 50011

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)

Attachment 50012

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

Attachment 50013

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.

Attachment 50014

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!)

Attachment 50015

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.

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.

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.

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.

NICE FIND!

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 :sorry:

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!!!

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.

Thanks
mike

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.

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.:humm:

Only one catch- parking brake.

The only alternative I see for the parking brake is a second caliper with an internal parking brake lever, then finding SEVERELY worn pads in an attempt to make it wide enough to clear the massive front rotor.

Using similar mounts, Cadillac Eldorado rear calipers (with parking brake) work just fine.

Attachment 49966

Did ya build this mount or buy it pre-made someplace. Also curious as to what rotor you used for this. I'll take all the details you can give.

the cadillac calipers are almost the exact same as like a 77 chevy k20 front caliper, only real difference is the e brake setup. and they bolt directly on to the same flange they use for the chevy so if you buy a premade piece made for the chevy mounting bracket, theyll bolt right on.

only down side about the caddy calipers is the core on them is outrageous. and make sure they come with the parking brake lever on them, because if they dont theyre very hard to come by

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oh ya and as for the rotor, they used the standard chevy 73-87 k20 rotor

Any more details?

what details you looking for? his is the same setup as mine is on my 14 bolt. ive done quite a few of these i can probably answer of of your questions with them.

its a pretty standard isntall, unbolt the drums, install the new caliper bracket into the old holes that the drums were bolted to (using spacers if necesary). then you pound the new rotor on the old hub like above, slide it back on the spindle, tighten all the spindle nuts, throw on the caliper and pads, and then rig up an e brake (if applicable). all you need is a pull style metal line that connects to that tab on the top of the caliper

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the brackets bolt on normally through the same bolt holes that the drum housing was on before. i guess you could weld it if you wanted to. i had to weld mine but its a new style 14 bolt but the 70 should bolt up.

as for why k20 rotors, the size is good, theyre CHEAP and VERY easily to come by. any and every auto parts store normally has them in stock theyre not hard to come by at all.

and as for vibrations, no, because even though it removes weight, it removes a balanced system and reinstalls a balanced system (I.E. the caliper is true just as a drum would be)

What is the axle tube width on that 70?

I'm just trying to verify they are the same as a small tube D80, and see if the victim I deal with (1999 NV4500 SRW) has the small tubes. If it does, this could get interesting!

Quoted from another site-

This could also help you out if you break that 10.5 inch rear end in the future.

how would it make it interesting with how big the tube is? it has nothing to do with a disc brake swap at all

Were tryin to figure out what all trucks this conversion could be done on.

Don't qoute me on it, but logic says the large tube D80 has a different flange then the D70 that the bracketry mount to, but the small tube 80 should have the same flange size since they have the same axle tube size. The small D80 still benefits from the 11 inch ring gear as compared to the 10.5 inch ring gear in the D70.

Maybe I should also ask what the distance is from hole to hole on the flange ya'll are running and then compare it to the 80?

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One last question for the day-
How is the brake pedal travel with the disc brake swap? OEM puts a larger master cylinder on the 2001+ trucks then the older ones, and I assume that is because of the disc brake rear axle. Discs GENERALLY use more volume then drums (One large piston on each corner vs two small ones).

I need to move some images to my host. Give me some time and I'll give more details. ;)

when you convert the discs in the rear, sometimes they will want to lock up because of too much brake in the rear, thats when a proportioning valve comes into play.

as for axle tube diameter coming into play, they make the mounts for any axle a ton of different places make them. i got mine from DIY4X: Catering to those who enjoy doing it themselves. i think i paid 65 bucks for them they were worth the money compared to making them myself for that much.

and as ford how many axles you can do it on, any full floating rear axle is pretty close to the same conversion, since they all work the same. whether its a dana 60, 70, 80, sterling, 14 bolt or any other rear end, as long as its a full floater its practically the same

I was just going to do this disk brake setup and use a line lock for an e-brake, it seems like a much easier and better way to do it to me.

A line lock was my first thought until I asked more about it. Seems they don't work well for long term use as in overnight parking and such and for the guy's still usin the stock brake lines, line expansion over time would be a serious issue.

If you have any leaks, even the smallest one, you could wake up to your truck being at the bottom of the hill, if it doesn't try to run something over before hand :argh:

just gonna throw this out there, we have a pettiebone at work an the only thing that keeps it at the top of our hill every night is some sort of line lock thing, flip the leaver stand on the brakes and thats it. thing stays put. so i would allmost be willing to try it.

As it was said above though, one small leak, even the smallest of leaks and overnight you could lose pressure and find your truck in somebody else's driveway by mornin. Try explaining that to your neighbor that comes home in the mornin from workin his night shift and your truck is in his driveway while his wife was home alone. Lot a safety factors there when your talkin about around the public usage.

Ok but the smallest "leak" in a brake line can also make you loose your brakes when driving and rear end someone, anything can fail at anytime. That's like saying your emergency brake cable could break at anytime and do the same thing. Since I have an auto the only time I ever use my e-brake is when I am loading a trailer or are on a serious hill. My Mustang I always leave in gear with the E-Brake on because its a stick. Occasionally I have left it in gear and not used my E-brake and never had her roll away.

As long as the good and bad sides of the discussion are shown, that's all that matters. From there each reader can decide for themselves is all I wanted. Like I said, the line lock was my first idea also when i started readin this but with the alternative given to have a parking brake with these other calipers then to me it's a simple decision.

World would be a boring place if we all did it the same way.:tu:

A small leak can go unnoticed in day to day driving. Take a look under the wheel cylinder dust seal in 75% of the cars on the road over 2 years old and tell me what you see. My money is on them leaking. All 4 pistons leak some 1995 Buick, and have leaked for years. It brakes fine. EVERY Jeep I've worked on with drums have had a minor leak in at least one of the 4 pistons. Calipers are the same way, but they are typically more of a pain to check, so everyone just waits until they are leaking out of the dust seal before replacing them.

If you have been into the internals of your automatic, you would use your PARKING brake much more often. The parking pawl's are very small, and should not be put to the task of holding your vehicle in place on a hill.

That being said, please do it and let us know how it works out! I'd be interested in putting the Jamar brake lock on my Miata once its done depending on what calipers I use in the rear (possibly the stock front calipers)

nice to see everyones opinion!! still think the line lock would work tho. and i do park on a hill every night and my e-brake cables froze since it's winter and she never ends up in the street with her just being in gear.......

Someone needs to step up and try it. I'd gladly tell everyone it works, and my worries are just from hanging out with Murphy constantly :)

hey DIY4X sells a kit FOR $140 and says that you have to use there roters, and great lake off road wants $79 for brackets that sounds kinda expensive for brackets

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and from auto zone for the eldorado rear calipers its &116 with the core included

the nicer kits i have seen comes from Twizted Engineering Home Page i have ordered a bunch of stuff from them and diyx and i would have to say twizted engineering rear disc swap is much easier and more complete.

An electric line lock will get hot with current going through them. The b&m one I bought for my S10 said 1 min of on time max. Just my .02. :c:

Only one catch- You have to source your own E-brake brackets.... already checked that route :dang:

Looking at the DIY4X site they show mounting plates different for the Dually 70....

I'm going to contact them directly today and see what ,other than the mounting bracket is different....?

Great thread.....And I will be using e-brake style calipers....Guess I gots to start looking for Caddies in the local yard.....

What years' do these need to come off...Any one know...?

Thanks, John.

Late '70s IIRC.

i wanna say 76-78 eldorados

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twizted enginering doesn't have anything for a dana 70 that i could finde:dang::dang: i really would like to do this swap, but i can't hardly finde the stuff for the caddy's rear calipers:argh::argh: and working e-brakes would be really nice siince my inspection mechanic(my uncle) said he wouldn't pass it unless the cables were hooked up

This is where I got my rear disc conversion stuff ~ EGR Performance Brakes, brakes for Dodge, Ford, Chevy, GMC, Tahoe, Yukon, Excursion, Dakota, Durango or whatever you drive.