B"H
There are lots of caveats you need to know before attempting to convert the front drums to discs. If time is a premium it's probably NOT worth all the aggravation I went through to get the discs to work.
First, some background. The Wilwood brake disc kit is the ONLY one available for Slant Six A-body Mopars. For V8 cars with the 10" drums, several other manufacturers provide kits, but only Wilwood makes the kit for the 9" drums. I bought the kit from Magumforce Racing at www.magnumforce.com. Wilwood makes kits of different types; for street cars make sure you order the HEAVY-DUTY kit. The light-duty and medium-duty kits are for RACING ONLY!! All the labels and boxes say "For Racing Only" but both Ron and Wilwood assure me that the heavy-duty brakes can be used for daily drivers not used for racing (MY Dart, racing? NEVER!!!!!!!!!!!)
After the kit arrived, first I verified the parts in the box. Fortunately everything was in place. I not only ordered the kit itself, but had to include the following extras:
Before I began the installation, I noticed that the original factory rims don't fit the disc hubs. That's because the hole pattern in the original drum rims is smaller (4" diameter). If you can find MoPar rims from a later car, like an Aspen/Volare, or a later Dart ('73 or newer) with disc brakes, the rims will match the holes but BEWARE that most of these rims do NOT clear the calipers!!!! I made a trip to the junkyard near my wife's summer camp in upstate New York and got two MoPar rims; neither cleared the caliper. When I returned to Brooklyn I continued my search for rims that fit. The trick here is the shape of the inside curve of the rim. These rims are two-piece and where the inner piece is welded to the outer one, the curve should start, NOT beyond it. I found a wide Ford rim which seemed to be better, but still froze tight when I bolted it onto to the disc hub.
The solution was to get a set of wheel spacers; they come in 3 mm, 5mm, 5/16th inch, etc. The big Ford rim took a 3 mm spacer and cleared nicely, giving me enough room on the stud for the lug nut to tighten securely. One MoPar rim didn't clear at all and the other one clears with a 5 mm space. I'm going to look for another rim (probably from a Ford Aerostar) which can take the 3 mm spacer since the 5mm unit doesn't have many threads left over for the lug nuts.
Of course, now I have two different sets of wheels so I need a second spare (ecch!). I haven't been able to find a rim to fit; I bought a donut spare but again it doesn't clear the calipers even with the spacers! Back to the drawing board.
Next, the end piece for the master cylinder that bolts to the brake pedal, is too small for the factory bolt to fit through. The hole in the m/c piece can't be enlarged since it has an inner, rotating fitting that can't be drilled out. Only solution was to use a skinnier bolt. But the nut doesn't lock in place and I'm nervous that the nut might come off eventually, causing the bolt to fall out -- thus NO BRAKES!!!! I'm planning on drilling a small hole in the end of the bolt, installing the nut and then put a cotter pin through the hole with a washer between the cotter pin and the nut. Hopefully, that will hold.
After that, the question comes as to how the hydraulic system is set up. You should use a proportioning valve which means cutting a section out of the rear brake line and installing this valve. However, it looks like on my Dart, both front and rear lines come into some sort of "junction box" under the front subframe rail and I don't know if the front and rear hydraulic lines are interconnected or separate. In order to use the proportioning valve the lines MUST be completely separate. I don't have the time to check so I skipped the valve.
After I installed the kit and the m/c I bled the system, but couldn't bleed the left rear brake because the bleeder valve is frozen and I didn't have a wrench to fit properly. I found I had a high, hard pedal but the brakes are hard to apply. I don't know if this is because I need to proportioning valve to force the front brakes to do more of the stopping or not but I don't have anyone to help me with this so I'm leaving it as is for now.
Again, I would advise anyone planning to convert their Dart to disc front brakes to very carefully decide if they want to go through all this mishugas. I think a much better solution would be to add a vacuum booster to the drums and let it go at that. However, I've been unable to find a booster for the car so I gave up on that idea.
I'm hoping eventually to straighten it all out, but it's gonna take TIME and MONEY!!!!
I then turned the proportioning valve to the almost closed position (reduce pressure to the rear brakes) and, voila, they worked! I now can stop the feeling of discs in front! Today it was raining on the trip home from work and the brakes worked really well; with the drums you didn't stop when it was wet outside; you had to dry them out by keeping your foot on the pedal. Not so with the discs; they stop short and true!
I still need to find a spare, I'd like to use a doughnut if possible so I have more trunk room.
I drilled a hole in the end of the brake pedal bolt and slipped a bent nail though it, to prevent the nut from coming off.
I would strongly recommend anyone doing this conversion review the FAQ on the Wilwood website which has some useful technical information. Also, Ron Jenkins at Magnumforce is a treasure store of information on how to convert Darts/Valiants to front discs; he has done a number of these conversions himself. Readers can feel free to contact Ron or me with any questions on the conversions.