pre ’75 3/4 Ton Dodge Disk Brake Swap
By Bill Cooke
If you are running a pre-1975 Dodge W200 Dana 44 front axle then you know how much drum brakes suck! Forget panic stops, even with a power booster on the truck. They just CAN’T stop a truck like disk brakes can. Trouble is how do you convert to disks? It’s easy, fairly cheap and well worth the effort. Here’s all you need to know.
The first thing you have to do is find a Chevy 3/4 ton front axle. It can be a Dana 44 or the later and more easily had GM 10 bolt front axle. All you will be using from this donor is the spindles, backing plates, calipers, rotor/hubs and outer axle shafts. Rotors are dirt cheap to replace so don’t worry if they are shot. The best part about Chevy parts is they are cheap and readily available!
Here’s why you need the out axle stub shafts. The dodge shafts are shorter. How much depends on what year your truck it. They truck was using mid 50’s Dodge spindles and hubs. That makes the shafts a LOT shorter. The late 60 thru 74 axles have a shaft that is just about .2″ shorter than the Chevy shafts. They are all 19 spline shafts and you CAN make it work but you are better off getting the shafts from your donor axle and replacing them. Make sure you get new u-joints too. This is not where you wan to be skimping on parts!
Strip your Dodge axle down to the knuckle like this. Set the brake backing plate up on the leaf spring with the brake lines still attached. You’ll be transferring the line to the new calipers in a minute but why make a mess now. Some gear oil might come out of the axle tube. TO avoid this work on one side at a time and raise this end higher than the other. That will keep all the fluid inside and off the ground.
Only real difference between the Dodge and Chevy knuckles is the bolt pattern rotation for the spindles. The Dodge knuckle is on top. The Chevy is on bottom. You can see that the Chevy has it’s top stud at the 12 o’clock position while the Dodge is more like 12:45. This will provide one problem later on. Keep reading.
It’s now time to put it all back together. Stick the axle shafts back in, put the Chevy spindles on, the backing plates and torque the nuts down in cross pattern. Then grease up your new bearings (you did get new bearings, right?) and install them in your Chevy hubs. Slide the hub/rotor on the spindles and adjust the spindle nuts back torqueing it to 50 ft. lbs. and then back off 1/4 turn. Then torque to 35 ft. lbs and back of between 1/4 and 3/8 of a turn, or until the rotor spins very easily with no wiggle top to bottom. Put the lock ring in and torque the outer nut to 100 ft. lbs. This will JAM THE HELL out of the inner nut and will tighten up the bearings. Now install the locking hubs and bolt the calipers on with your new brake pads (c, mon! get new pads at least!)
Transfer your flexible lines from the old drum brakes to the new calipers with the banjo fitting pointing up from the hose as shown. The clearance will be tight but it will clear the axle ears at full lock steering. You’ll also have to rotate the fitting on the axle tube slightly to make it work. Disk Brake hoses are just a bit longer and work better so if you are buying new hoses get the ’75 and up 1/2 ton or 3/4 ton lines.
The bottom pic is the comparison between the Dodge lines and stock Chevy lines. The Chevy lines are just WAY too long to work.
Dodge
Here is the only draw back to this swap. The Dodge knuckles clock the caliper higher up. This moves the bleeder screw past the highest point and makes bleeding a bit more troublesome. One solution, park on a steep hill before bleeding the brakes. Don’t forget to block the tires. The other is to remove the top caliper mounting bolt and rotate the caliper away from the rotor on the bottom bolt until the bleeder is straight up. This means no “pump and dump” bleeding. You will need a power or vacuum bleeder for this job
Chevy
That’s it. It’s pretty easy and well worth the time and money. There is just no excuse for NOT having disk brakes. If not for yourself, for the poor guy in front of you!
