Disk Brake Conversion for a 1954 CJ3B

My jeep has been sitting for 15-20 years, therefore I will diffidently need to be rebuilding the brake system. I have been considering while rebuilding the brakes maybe I could upgrade to disk brakes. I have done some preliminary research but I don't see much of information on a conversion. KW has the conversion kits but those don't look cost effective. I know some members have upgraded their brakes but I cannot find 3B specific information. I would appreciate any input on the subject or lessons learned. One of my dilemmas is: is it worth it or should I just keep the jeep original? This may become more clear after I tear down the brakes and inspect the condition of all the brake parts. Second, question is has any one upgraded to a dual reservoir master cylinder? An additional question if these are original steel lines should I replace them. Any brake system thought or suggestions?! BRAKES ARE KINDA IMPORTANT!:D

Hey AJ-MJ, yes, upgrade to the dual reservoir for fluid push capacity and safety. At least I did on a 64 pickup, which is larger. The single reservoir goes bad, gets plugged, and where does that leave you, was my thinking. This upgrade was a rabbit hole inside of a beaver dam... Keep us posted!

AJ, Az has a nice setup in his truck. There are a few places offering up conversions for your Jeep and, it is usually not cheap. You really only need the discs on the front in a CJ. They will pop your eyes out with just front disc brakes and original rear drums. Whether or not to keep it stock is really up to you. I can tell you that if you are going to drive it around a lot, definitely put some disc's up front. They just don't stop real well in a panic with the factory brakes. Definitely a dual reservoir master.

I would be prepared to replace all the lines. Pre-bent lines are out there and they are real good. You can even get stainless lines pre-bent. I think I have posted sources on the lines somewhere. If you search the forum we have a few threads on brake lines.

THANKS: I may have found your post bmorgil. Is the vender https://www.inlinetube.com/products/jpb5401, InLineTube? People were saying they wished they had painted their lines. What is up with that? Lastly, while reaching their site they also have disc brake conversion kits for a little cheaper price.

Yes that's it. Great place. Brake line steel is usually fairly soft and easy to bend. It is usually a mild steel. Consequently they will and do rust. In areas where they salt the roads, in a few decades they will rot away completely. If you have a nice looking show rig and it bugs you to watch the brake lines slowly turn brown, you can paint them. The paint has to be protected wherever it touches something or when it scrapes off, that is where it will rust. So now if that really bothers you, you shell out the cash for stainless lines. Just keep in mind stainless lines are a bit more ridged and expensive.

Thanks again... I think the OE steel lines will suit me just fine... I am sure they will last longer than I will. :rolleyes: I have a spread sheet of stuff I need and the total is already causing me to swallow hard. JEEP = Just Empty Every Pocket...One more ice storm is passing through our area tonight, then I hope we have a few days of decent weather.

This some related information for dis brake conversion:https://cj3b.info/Tech/DiskBrakes.html

I wish I had painted my brake and fuel lines, the new spring sets as well.

It all depends on what you plan to do with your Jeep. I like the amount of sanity depravation that the old drum/manual brakes has to offer. I keep them around for certain times when I need a good butt kicking to keep myself humble. They are not that
bad, but they do have a nasty habit of being obstinate. With that being said, in my opinion, convert to at least front wheel disks. KW offers a dual pot master cylinder that looks pretty good, and is on my list of upgrades for our little Heep. One thing to keep in mind though, if you are running stock steel wheels and you do decide to upgrade to disk brakes, you'll run into interference with the caliper hitting the inside of the wheel and will need to go with a more modern wheel. Mid '80s Dodge 1/2 ton 4X4 pickups wheels will clear, and are a direct replacement, along with International Scout II wheels.


https://www.youtube.com/watch?v=ankK2MH1cI8

The photo is of the process of adjusting the original drum brakes after the top adjusters decided to loosened up.

THANKS gmwillys! During my research I found several YouTube videos. I think the best one is the install of the KW conversion kit because it has a couple of good suggestions. https://www.youtube.com/watch?v=1MsmJetnN2M. I went back and read the product information on the KW conversion kit and it states to replace rims. However, I also have a concern about the different pressures needed for disc vs drum.

Please let me do some thinking out loud and some body that knows more than I do straighten me out. Let me profess: I am not an automobile mechanic and have very limited automotive skills and knowledge. However, about 20 years ago, I bought a Comanche (MJ) that needed a lot of work. (Hence my user ID). Anyway, I installed a 5 inch lift kit and “big” tires therefore, I really needed better brakes. So I upgraded the brakes. As I remember it, I put a modified booster from a newer model Cherokee (XJ) and larger rotors on the front. I think I changed the original proportion value to an adjustable proportioning valve in the brake line going to the rear brakes. I can remember adjusting it. It was kinda like adjusting your brakes by feel and skid marks. I needed to properly balance the brakes because the fronts do more of the braking and you do not want the rears locking before the fronts. My thinking here is that the required pressure for disc brakes in the front and drums in the back you would have to be different pressures both while braking and when your foot is off the brake. So should you put disc brakes only the front or front and back. Anyone familiar with the proportion value requirements? The more I think out loud the more I am talking myself into sticking with the original brake system… DANG, I hate it when I do that! As long as I drive like “I’m Driving Miss Daisy” and the brakes don’t pull to the side, I think I will be fine. Can anyone comment on this?

Your thinking is correct AJ. The proportioning valve is the key to balancing front to rear brake force. Locking up the rears before the fronts will cause spinning, especially in a short wheel base. Front discs and rear drums were quite common in the 70's and 80's. The front brakes do much more of the work than most realize. The harder a vehicle is able to stop with the front tire brake combination, the "G's" it can pull from the front, the more the weight will shift to the front. Eventually if you can get the traction and the brake clamp, lifting most of the weight off of the rear tires altogether. I have seen a few tire brake combinations pull some serious G forces on a skid pad. In some cases you could adjust the rears almost completely out.

To compensate for the pressure differential requirements of Drum / Disc, a combination valve is used to compensate internally. https://www.ebay.com/i/264968429497?...kaAhBKEALw_wcB It does a few things to make the drums work smoothly with the Discs. I would recommend using the dual master cylinder recommended by the people you are buying the kit from. They had better know if their kit needs a proportioning / combination valve or not. In any event you described how to adjust a proportioning valve perfectly. You go out and lock them up. Fronts must lock first. For street cars we always tried to lock the fronts and barley drag the rears. When you are track adjusting a lot of factors come into play. That is the benefit of adjustable over non adjustable proportioning valves. Its not a big deal. I can tell you know what your doing. Don't let it scare you off if you want some nice brakes. Order up your favorite kit, put in a Dual Master cylinder and a combination valve and you will love it I am sure. You don't need anything fancy or adjustable unless you want that. A simple off the shelf 1970's era gm combination valve will do the trick.

Thanks again for keeping me on the straight and narrow bmorgil: I think I have forgot more than I know about fixing cars. But I do want good brakes! In the early eighties I was in the army and stationed in Germany. I bought a decent Mercedes 230 SL roadster. What I later discovered was that it did not pass the German inspection because of rust. Therefore, I hired out all the repairs and brought it back to the US. So that is when I discovered the need for good brakes on a CJ5 with over sized tires. While towing my Mercedes behind my CJ5 I had to do an emergency stop. I ended up in the meridian of a 4 lane highway and rolled/totaled both vehicles. I was lucky to walk away with only a scratch on my leg. The state troop said I was lucky that not many people walk away from roll overs. Ever since then brakes and brake maintenance has a pretty high priority to me. I will mostly likely call KW when I get to the point of rebuilding the brake system. I am pretty sure they should be able to provide some guidance since they sell the kits. I have one more related question. Is the DOT 3 brake fluid satisfactory or should I use the DOT 5? I understand the benefits of the DOT 5, I am just wonder the use the the old jeeps.

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Originally Posted by AJ-MJ

Is the DOT 3 brake fluid satisfactory or should I use the DOT 5? I understand the benefits of the DOT 5, I am just wonder the use the the old jeeps.

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The main advantage of DOT 5 fluid is its higher boiling point - something you might have concerns about in your German Mercedes or other really high performance car, but probably not in a CJ.

Here is a cut and aste from a pretty good explanation of the differences:

DOT 3 is always the cheapest option—DOT 4 is about 50% more expensive than DOT 3 and DOT 5 is about two times more expensive than DOT 4. Some owners mistakenly assume that the higher cost of DOT 5 equates to better performance, but this is not always the case. In fact, sometimes the exact opposite is true. To get a better handle this, we need to take a crash course in chemistry.

Common brake fluids such as DOT 3, 4, and 5.1 are mixtures of glycols and glycol ethers while DOT 5 is silicone based. DOT 3, 4, and 5.1 are hydroscopic, which is a fancy way of saying they absorb water. We know what you are thinking--brake line moisture is evil! It is true that we try to keep our brake systems "dry", but over time, even a buttoned up brake system with tight seals and new lines absorbs moisture. The key here is what happens to that moisture after it enters the system.

DOT 5 doesn’t absorb moisture. But even though DOT 5 doesn’t absorb water, it can’t/won’t prevent moisture from entering the brake system. And since the water isn’t absorbed by DOT 5, moisture puddles and causes localized corrosion within the brake system. As funny as it sounds, DOT 3, 4, and 5.1 absorb moisture, which in turn eliminates the puddling that can cause corrosion. More importantly, when brake fluid heats up, water trapped inside the brake lines (but not absorbed by the brake fluid) is converted from liquid to vapor. Steam compresses easier than liquid. With this in mind, imagine barreling down the road at high speed and hitting the brakes. When the hydraulics sends DOT 5 fluid through a pocket of steam in the line, that drop in pressure creates a soft pedal . (Probably not a Jeep concern..).

Most folks know they aren't supposed to top off DOT 3 or 4 brake fluids with DOT 5, but don't know why. The answer goes back to the chemistry. Combining even trace amounts of a glycol-based brake fluid with DOT 5 can cause the two incompatible fluids to gel, resulting in poor braking. Converting to DOT 5 also requires thorough flushing and removing ALL traces of the old fluid to avoid seal damage.

This is another case with an Old Jeep where newer is not necessarily better.

A previous owner installed disk brakes on the front on my CJ3A. It stops great on the single cavity reservoir but I had an interesting couple of seconds in the yard when it failed. The rear drum brakes are disconnected on mine. When I discovered it I was a little concerned but I wasn’t missing them so upgrading the rear is at the bottom on my list of things to do.

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Originally Posted by 51 CJ3

A previous owner installed disk brakes on the front on my CJ3A. It stops great on the single cavity reservoir but I had an interesting couple of seconds in the yard when it failed. The rear drum brakes are disconnected on mine. When I discovered it I was a little concerned but I wasn’t missing them so upgrading the rear is at the bottom on my list of things to do.

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Since most of the braking on a CJ-3 comes from the front brakes, it would not be unusual for someone to have disconnected the rear brakes, especially with the improved braking from front discs. If you get around to working on the rear brakes, just repairing and reconnecting the original brakes would probably be more than just "good enough".

And - just remember the line from the phone commercial; "If the brakes won't stop it something else will."

Generally speaking, the key works. I drove out of Reddington Pass and crossed Tucson, AZ after a brake hose blew while we were out riding the trails. The vehicle was a 66 CJ5. Kept it in second gear rolling down the hill. I left it in gear and used the key to start and stop at the stop lights. Had to do similar one day when my clutch linkage broke in downtown Tucson.

If I work on the rear brakes I am likely to go ahead and convert it. The drums aren’t in very good shape.

If you are going to "use it", I don't think you can go wrong with good front disc's and good rear brakes, with a dual master cylinder. For the show and parade original is nice. Using it on and off highway, I don't think you can over brake it.

51CJ3 your way was how I was told to do also. Must be a wildcats thing.