Disc brakes, the pinnacle of stopping power, half the maintenance issues of drums, they clean better too! Clearly the choice for what we do. For the last 3 years I have been trying to figure out a way to convert the rear Dana 70 in the Stomper to disc brakes. There are only a few companies out there that make disc brake conversions for the 1 ton rear ends and most of the time they are pretty pricey. Here's what I found out.
TSM out of Castle Rock, Colorado is about the cheapest around for the conversion kits. Skip is the owner and he really knows his shit. TSM can be reached at 303-660-6882.
Here is a list of the parts that you will need for the conversion:
- Calipers, you can choose between those equipped with an e-brake and those without. The e-brake option will cost you Around 150$ more.
- brake rotors
- Conversion brackets that replace the drum backing plates and support the new calipers.
The above parts come with the standard kit for around $500. Prices depend on the application.
Additionally you'll need:
- Flexible brake lines since the calipers float as they wear, unlike the drum brakes. TSM carries these in braded steel or rubber lines with a handy weld on mount kit included.
- You may need new E-brake cables I was able to re-use mine.
- You'll need 2 new pieces of steel brake line as you'll have to shorten the existing ones to meet up with the new flex lines. Any parts store has these for less than 10$.
- Brake fluid-you gotta bleed em.
- Access to a mig welder is handy for installing the flex line brackets and to fab up the E-brake cable mounts.
I had some other issues due to the uniqueness of the Dana 70 conversion. Skip advised me that they made around 35 different variants of the Dana 70 rear end over the years and many of them have different spindle sizes and bolt patterns. Due to this no one makes a conversion kit for the 70. He agreed to help me figure it out and sell me a kit with a blank set of caliper brackets. The critical measurements needed are the distance between the bolts that mount the backing plate to the axle and the distance from the axle flange to the back of the hub flange where the drum mounts to the hub.
I have a Dana 70U model out of an 85 ford f350 dually on the Stomper. When I got everything measured up I hit the first impasse: the axle had only 3.5" of clearance between the 2 flanges approximately 4.25" would be needed. I was tired of the drum brake shit and ordered the kit anyway anticipating some machine work.
When the kit showed up the first step was to pound the drums off the hubs by pressing out the wheel studs using the BFH and brass punch. When I tried to install the new rotor on the hub I found that the center hole in the rotor was smaller than the hole in the drum. This left the option of machining the brake rotor or the hub. The best option is to have the machinist turn down the flange on the hubs so that rotor replacement would be easy in the future.
After the rotors were fitted to the hubs I installed the hub and rotor assy and placed the loaded caliper on the rotor. This way the measurements for offset needed for the caliper bracket could be made. After re-measuring about 7 times I found that I needed to cut the bracket in half and re-weld it 5/16" back. I had the machinist do this just to make sure it was perfect. I had it tacked and then fitted it up again before completing the welds. Upon reinstallation I found that my measurement was off by 1/8". We cut the tacks and re-welded again…this time it was dead on.
Now that we had all of the parts built to spec I clamped the brackets to the axle flanges and found that the rear part of the axle flange would have to be squared off to make room for the offset flange. The blue wrench made short work of the flange; the axle flange was then ground square.
With the brackets clamped securely to the axle the next step was to drill the brackets to bolt to the axle. Precision was required here and I got lucky and was only 1/16" off on one hole on each side.
Next I degreased the hubs and repacked the wheel bearings and hub with disc brake hi-temp axle grease. This is also a good time to replace the wheel seals on the hubs.
With the brake system bolted up it was time to move on to plumbing in the brake lines. The first step is to figure out where you want the flexible brake line brackets to mount and then weld them to the axle housing. With the brackets in place the flex lines are bolted to the calipers using the supplied hardware. Using a flaring tool I cut and custom bent the new steel lines to meet the flex lines. When all fittings were secured and tightened it's time to bleed the brake system.
The final step is to make the e-brake cables work. For this the original cables were used with the springs on the ends removed as the new calipers are already return loaded. Using some 1/8" steel and 3/4" pipe I zinged up the new cable brackets and bolted them in using one of the flange bolts. Last, the e-brake levers are set per the supplied instructions for proper tension.
Tools needed are as follows:
- various wrenches
- flaring tool
- 2 people or a 1 man brake bleeder kit
- proper hub nut socket to pull the hubs
- rtv sealer for the hubs
- big fuckin hammer and a brass drift or press for removing the wheel studs
- tube bender is nice for the new brake lines
- arc or mig welder
- torch
The job would be much easier if you have a more common axle like a ford 9 inch or Dana 60 or 44.
Total cost was as follows:
- conversion brackets, disc rotors
279.95
- rear e-brake calipers, w pads
300.00
- flex hose kit
50.00
- seals, grease, rtv, rags, fluid
50.00
- steel lines
10.00
- freight
25.00
- machine work
160.00
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- Total
874.95
