Brakes- Drum to Disc

[N2TRUX]

To help reduce the frequency that we have to answer similar questions on the same topic, I want to do a FAQ directory for suspension. This will serve to enhance the makeover that the FAQ forum is currently undergoing. I have been monitoring the frequently asked questions that are posted in the Suspension Forum and the one that seems to warrant the highest priority is brakes.

I plan to have a resource list for several levels of upgrades. I know some guys want to run drums and upgrade them, but I don't see many requests there so we will skip to the next level for now.

It seems the common place to start for basic improvement is converting front drum to disc. With that in mind please post your resource for drum to disc conversions. I will update my master list as input is received.

Later we will be adding categories for rear disc, big brakes, etc. For now lets stick with the basics. If anyone has previously posted a "How To" or would like to contribute one now, please let me know.

Drum to disc-
6 lug-
5 lug-
73-87 conversion-

Source-
Performance Online-Forum Vendor
Early Classic Enterprises
Master Power Brakes
Brake Tech Solutions

[cparman]

are you looking for where we buy the parts or how did we do it? I have used Master power Brakes, and Brake Tech Solutions as sources for complete kits. If you have questions or want tech tips I might have a few of those also?

[jlaird]

do you want us to reply here or PM so you can put everything together?

[N2TRUX]

I am looking for sources, methods, how to's, etc. Anything that would benefit those researching the subject.

Please post it here as a get a ton of PM's daily.

[72BlckButy]

Ken, not that you need another one... but I sent you a pm.

After you have a little time, check it out and let me know what you think.

[cparman]

Is this what you were looking for?

DRUM TO DISC INPUT

Where do I start?
Decide if you are going to buy an aftermarket kit, of do a transplant from a newer truck.
If using a transplant, make sure that you get it ALL! On some, not all booster/master cyl/ proportioning valves will be the same, there will be two ports to send brake fluid to the front brakes, and one to send fluid to the rear brakes. You do not need to use both fronts. Just plug off one of the fronts, and “T” into the other one sending fluid to the front brakes.
With aftermarket kits the above will be described in the instructions. They will also recommend to run a new ¼” line to the rear brakes instead of the existing 3/16” line. I have done it both ways with positive results.
I always paint the master cylinder. I use a POR 15 product called Factory Manifold Gray. It will make the master cylinder look like new for a long time, instead of rusting and looking bad. I will wipe the master cylinder with thinner, or brake clean, and let dry. Stir the paint, do not shake, and use a foam brush. I will do two coats about 12 hrs apart, and then let dry for at least 12 hrs. Once I have this done, I move to the work at the wheels.

SAFETY IS FOREMOST!!
Jack up your vehicle, and put jack stands under the lower control arms as close as possible to the lower ball joints as possible. Slowly let the vehicle down, until the jack is free.
Remove the wheels
If using a drop spindle, remove the cotter pins from the outer tie rod ends, upper and lower ball joints.
Remove the nut from the tie rod end, and with a hammer, and a FIRM blow strike the spindle where the tie rod end attaches. A couple of blows and it should fall out. The same with both upper and lower ball joints. Discard the OE spindle.
Install the new drop spindle. Tighten all three nuts, and install new cotter pins.
Pack grease into the new wheel bearings. Put a bit of extra grease in the new brake rotor, and install the inner wheel bearing, and seal.

Set rotor on new spindle and install outer wheel bearing. Install new washer, and tighten new nut and seat the wheel bearing. Once the washer and nut are installed, tighten the nut, while turning the rotor, until it becomes tight and a bit hard to turn. Back off the nut until the rotor is free, and install the cotter pin, and the new grease cap. REPEAT ON THE OTHER SIDE.
Install the new brake calipers and brake hoses. I like the stainless braided brake hoses for an improved brake pedal feel. I have done several with rubber hoses, and stainless hoses. THEY BOTH WORK JUST FINE!
INSTALL THE BRAKE BOOSTER
Depending on the kit, you might need to drill a couple of holes, but I doubt it. You will need to drill a new hole in the brake pedal about 1" below the existing hole to accept the new lower location of the rod coming from the booster. Once you get the booster in place, concentrate on the brake pedal height. In most aftermarket kits there will be a threaded adjustable rod UNDER THE DASH, the will adjust the height of the pedal off of the floorboard. The adjustment under the dash just raises and lowers where the pedal rests when the brakes are not applied! You will need to find an engine vacuum source to feed engine vacuum to the booster. You need a minimum of 17” of vacuum for the booster to operate properly.

BENCH BLEED THE MASTER CYLINDER:
Some not all aftermarket kits will come with a couple of plastic nuts, and a plastic line the will attach to them. If you do not get this make your own, or go to the parts store ask for a brake master cylinder bleeder kit. Just a few bucks. Using a screwdriver, slowly push the piston in the rear of the master cylinder in and then let it release, until you do not see any bubbles in the master cylinder while pushing the piston in.
You will probably need to configure your brake lines at this time.
Find the brake line going to the rear brakes, and compare the nut on the line to where that line will connect to the proportioning valve. You should have a new fitting in you kit to use. You will need to cut off the old fitting and install the new fitting, and DOUBLE FLARE the line. Do not be afraid to do this!! I just takes practice. Buy a small piece of line at the parts store and practice a few times. Use the flare that came on the line to compare your work too. Be honest to yourself! There may be two separate lines to the front brakes. If so, you have two options. Use both, or buy a brass T, and join them together. I have done it both ways. Either works. Test fit the master cylinder to the booster to see how your lines will fit up to the proportioning valve. Do this without removing the bleeder lines so you do not make a mess with leaking brake fluid. If all looks good, install the master cylinder and tighten it up. Quickly remove the bleeder lines and install your brake lines. Tighten all lines, rinse with water, and wipe dry.


Go get a drink of water. Open both bleeder screws at the rear wheels, and keep the master cylinder full of fluid while you gravity bleed the brakes. Try and run a pint of fluid thru the system, before closing the bleeders. Do the same for the front wheels, and then call your buddy to help bleed the brakes. I will ask the pumper to pump the brake pedal 3-4 times and hold it down while I open the bleeder screw. Continued pumping will sometimes cause the brake fluid to foam and cause a bunch of other problems. Once you think there is no more air in the system. Pump the pedal a few times to push the caliper pistons out, and then see how the pedal feels, and how far off the floor of the truck it is.

What should I do when the brakes work, but the brake pedal is almost on the floor?

In most aftermarket kits there will be a threaded adjustable rod UNDER THE DASH, the will adjust the height of the pedal off of the floorboard. The adjustment under the dash just raises and lowers where the pedal rests when the brakes are not applied! SO, if you want to taylor your new brake system to your shoe size do it here.

What if the brake pedal is where I want it to be INSIDE the truck, but have to push it a long way before the brakes are applied?

Make SURE the rear brakes are adjusted properly, and then check gap between the booster rod, and the master cylinder is too much. Unbolt the master cylinder from the booster WITHOUT removing the brake lines. Roll up a small ball of clay ( steal it from your kids, or grandchildren) and put it on the pin coming out of the brake booster. Reinstall the master cylinder to the booster. Make sure to tighten the two nuts all the way. Remove the master cylinder again, and see if the clay was compressed. If not the rod is too short, and needs to be made longer. Some not all rods are threaded, and will adjust by turning them. The non adjustable ones will need to be have a puddle of weld applied to them, and then ground shorter as needed. Once you have it were you think you need it to be test drive and MAKE SURE the brakes are no applied when coasting at idle with your foot off the brakes. 1/8th inch is a lot of gap!!!!!

Upon the initial road test, drive lowly around down the street, and apply the brakes a bunch. Then take a short (one mile) drive and recheck everything. Look for leaks in the lines, see if the brakes are staying on and not releasing etc. DO NOT ASSUME ANYTHING! Be safe, and take a few short drives and gain confidence in your hard work. Check to make sure you have brake lights.

[N2TRUX]

Nice work cparman! That's the kind of stuff I am after.

[cparman]

Thanks!

As i am sure you well know every job is a bit different, but for the most part this works. The self inflicted wounds cannot be spelled out in something like this. I /we have done a bunch of this kind of stuff, and the times my blood pressure went up was when I was going behind someone, OR someone had install " really good, I SWEAR " used stuff. I try and ask my customers just what they or their family are really worth. Some undervalue themselves. If you need more PM me and, like my friend Jim ( a mopar guy) says, talk/type slowly I am a Chevy guy.

Chip

[LostMy65]

Oops! I meant to post in this thread...

I honestly have been searching.

I don't like to just start a new thread when there is already a similar one.

I know for the 60 chevys we switch out the whole crossmember to get discs on the front.
What does one need from a 73-87 that has front drums to switch to front discs?

[lolife99]

Originally Posted by LostMy65

Oops! I meant to post in this thread...

I know for the 60 chevys we switch out the whole crossmember to get discs on the front.
What does one need from a 73-87 that has front drums to switch to front discs?

Disc brakes were standard starting in 1971.
All the 73-87 trucks will have front disc brakes.
Did I mis-read your question?

[LostMy65]

Originally Posted by lolife99

Disc brakes were standard starting in 1971.
All the 73-87 trucks will have front disc brakes.
Did I mis-read your question?

Actually,
I'm finding many 3/4 tons from 1973 to 1978 have front drums.
Yes, it's very random, but the surely have drums.
My father-in-law's 73 GMC 3/4 ton came new with drums in the front.

So I'm curious how easy it would be to switch it to discs in the front.

Thanks

[1985-GMC]

Huh, that's strange. Ive never seen or heard of that, maybe it was on very base model trucks? Do you have a picture?

If it indeed has drums on the front, you could probably just rob everything spindles out from a donor.

[LostMy65]

Sorry, no pics - My father-in-law recently sold his truck.

Whenever I see a listing on craigslist, I email or call if it has front discs or drums.
About 1 outta 4 says drum. These are for 3/4 ton trucks. The newest so far was a 1975 3/4 ton gmc. The guy said they are surely drums all around because he just did the brakes.