Brakes
Brake Related Articles
- Early CJ 11″ Drum Swap
- Early CJ Disk Brake Swap
- Drilling Drum Brakes for Better Braking
- Installing Herm’s Dual MC Kit
Brake FAQ
- How do I improve my brakes?
- Is there anything I should watch out for when mounting disc brakes?
- How do I adjust my brakes?
- Can I add power brakes to my old Jeep?
- What are Mico-brakes (often misidentified as “micro-brakes”)?
Converting your 9″ drums to 11″ drums will be a cheap and easy upgrade. Disk brakes are an option but more expensive and not as easy. See articles above for these options.
Is there anything I should watch out for when mounting disc brakes?
Answer 1: First off see this page: http://oldjeep.com/disc.htm.
Answer 2: More info: Be careful not mount the caliper backwards so that the bleeder isn’t as high as it can be. I mounted my calipers on the wrong side at first and fought with trying to bleed them and then discovered they were on the wrong sides and swapped them around and the brakes bled out right away then. I remember an old mechanic telling me how most calipers are mounted on the aft side. Supposedly they get less slush and mud on them that way. I vaguely remember Ford had a problem with their trucks in the mid-70’s due to the calipers being on the front. Ford’s fix was to change over to aft mounted calipers on later years. Also, the flexible brake hose would be in a more protected location behind the axle.
One word of warning on the conversion I used ‘77 1/2 ton backing plates and ‘86 calipers, the calipers fit except that you have to grind a notch on the left hand backing plate. The ‘77 plates are the same on both sides apparently they are different in later years and the left hand caliper has a projection which lines up with a notch in the backing plate. Takes about 5 minutes with a grinder to adapt it.
Don’t forget you need to plug the fill hole w/ a flush fitting plug that doesn’t stick too far into the knuckle. (Wouldn’t want it to hit anything in there would we?) Since you have the knuckle off, now’s a good time to take it with you and try to find that plug. I had to use an Allen head pipe plug that I put on a lathe and rethread to get it to fit to the right depth. Then I cut off the top to make it fit flush with the knuckle. (In case you’re wondering, I chucked a cutoff Allen wrench in the lathe and stuck the plug on it and held the plug on with the end stock) This was much easier having the knuckle there to test fit after each cut.
Before I get going on this I should mention that although this explanation will work on those models with both “heel” and “toe” adjustment, and “feeler” slots in the drums, there is a better method.
Let’s start from the presumption that the following work has been done on the brake system:
- All the brake lines have been replaced and/or, are not internally rusted and clear.
- All the slave cylinders and the master cylinder have honed and if they have pitting in them, they have been re-sleeved. (I do them in stainless steel).
- New cups have been inserted. (Rubber grease).
- All the brake shoes are in good order and if the radius measurement is oversize then they have been replaced with oversize shoes.
- The shoes have been “matched” to each drum and machined to fit.
- Each drum has been skimmed and made as round as possible in an old vehicle.
I guess mention should be made that all flaring on brakes should NEVER be single flares. And, it would be sensible to clean the system with method and fill with synthetic to avoid future water attraction and internal rusting.
So you’ve done the preparation and now you’d like a hard pedal and good brakes. You can do this job by yourself, or with someone in the drivers seat giving you a hand. If you’re by yourself you need to run the motor and drive the wheels so make sure that you have been safety conscience and the vehicle is very secure on the stands.
Place the vehicle on stands so that all wheels are off the ground. Starting from the wheel that has the shortest brake lines (from the master cylinder) you:
- Adjust the shoes outwards so that the wheel can just be turned (with a fair bit of oomph from you).
- Hop into the drivers seat. Put the vehicle into gear and rotate the wheels slowly. WHILST the wheels are turning, pump the brake pedal about 6-12 times. Stop the wheels.
- Go back to the same wheel and you’ll find that you’ll be able to adjust it out some more. Do that.
- Repeat 2
- If necessary repeat 3
Now do the next closest wheel to the master cylinder. Work your way around the vehicle.
The reason you need to “bed” the brake shoes are because these models don’t have a “heel” camber adjustment and each time you “pump” the pedal you are adjusting the “heel” of the shoe.
The shoes should have about 5 thou clearance between the shoe and the drum (internally).
If you use your own strength whilst adjusting outwards you’ll find that if you can move the wheel by hand (even though it may “sound” as if it’s scraping) – it won’t be too tight.
Your goal is to have a “solid” pedal with about 1-inch of movement.
Can I add power brakes to my old Jeep?
If what you are after is disc brakes you can have that with your stock running gear. I have a 47 CJ 2-a with disc brakes front and rear with the stock Dana 25 and Dana 44. How I did this was I got backing plates, spindles, calipers, and rotors off of a Chevy half ton pickup. It all bolts on and you can use ford half ton rotors or Jeep rotors and spindles to keep the 5 lug pattern. That is what it takes to put them on the front and maybe a little grinding for caliper clearance. on the rear they bolt on also but you have to get axles made because what you are doing is full floating the rear end. So is that you will have hubs on the rear or you can take the hubs off of a full time front end and not have hubs. I almost forgot you need stub axles from an early Chevy Dana closed knuckle front end the u joints on that stub axle and the one on the inner axle on the 25 are of the same size and you need the stub to match the finer spline on the internal hub. As for power brakes I would go to a wrecking yard and take some measurements and see what you can fit in your engine compartment and if you change to four wheel disc brakes I would find a master cylinder off of a car that has four wheel disc brakes.
For those of you whom may not know what a mico brake is it a supplementary hydraulic braking system that pressurizes you regular brakes, it is NOT a replacement for a parking brake but to be used in combination with one.
Lately I have been thinking about adding a mico to my jeep when I redo my brake system. When I thought about this the way the 66 CJ that I have is a single chamber master cylinder like most early jeeps. The problem when I try to sketch the plumbing out on paper is that the lines split directly out of the master cylinder. This would be a problem because you cannot pressurize the whole system at the same time, and then would not be effective as it was designed. How has anyone added these to their own Jeeps? Another problem is that I will also be adding a hydro-vac unit and would I be safe adding the mico in front of it or after? I will probably be using the basic lever lock model 02-640-125 or a similar older one that I have laying around with out the low pressure warning switch (I really hate hearing the horn).