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Disc Brake Conversion Pros and Cons

Discussion in 'Early CJ5 and CJ6 Tech' started by veloamerican, Jul 4, 2014.

  1. Jul 4, 2014
    veloamerican

    veloamerican New Member

    Jacksonville, FL
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    I just bought a 66 CJ5 from a seller who described the brakes as "great." When I got the jeep this week I discovered that the brakes will need a complete rebuild. I would like to keep the jeep as true to its original character as possible, but I'm wondering whether the performance and safety associated with a disc brake conversion would undermine my goal. I'd be interested in hearing folks' thoughts on that topic.
     
  2. Jul 4, 2014
    jpflat2a

    jpflat2a what's that noise?

    Hermosa, SD
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    Install 11" brakes on all four corners.
    BIG improvement.
    Disc not worth it in my opinion.
     
  3. Jul 4, 2014
    colojeepguy

    colojeepguy Colorado Springs

    At the foot of...
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    I agree...UNLESS you plan on 4 wheeling where there's a lot of water crossings.
    Wet drum brakes are pretty much worthless...
     
  4. Jul 4, 2014
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    This topic has been covered many times in the past - https://www.google.com/search?q=site:earlycj5.com+drum+brakes+vs+disk+brakes - plenty of differing opinions.

    Depends on what your goals are. The 11" drums are a big upgrade. Installation is easy. The parts are cheap - literally millions of cars and trucks used these 11"x2" Bendix brakes, including many years for Ford F-100 pickup, one of the biggest selling vehicles ever produced. You can buy reasonably priced kits, or scrounge the parts, as you wish. Drum brake service can be frustrating for an amateur, but once you learn it's not hard.
     
    Last edited: Jul 4, 2014
  5. Jul 4, 2014
    Daryl

    Daryl Sponsor

    Bonney Lake, WA
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    11" brakes are a straight across bolt-on no fabrication option. They can also be easily reversed on a restoration. Well worth the effort and very effective if they are dry.
     
  6. Jul 4, 2014
    veloamerican

    veloamerican New Member

    Jacksonville, FL
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    Thanks everyone. If there is no nostalgia for the 10" drums from folks on this site, then I guess there isn't much point in keeping them.
     
  7. Jul 4, 2014
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    The 10" brakes are by Wagner(?), and parts are hard to source and comparatively expensive. No reason to keep them unless you are building an exact restoration, especially if you need new drums. Same with the earlier 9" brakes. The 11" brake parts are so much more cheap and plentiful, conversion often makes sense on pure economic grounds.

    Someone here might want bits of your leftover hardware if they are in ok shape.
     
  8. Jul 4, 2014
    Long&Low

    Long&Low Active Member

    Geauga County, OH
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    Most restoration folks are not really going to notice 9", 10" or 11" drums. But they will notice disc brake conversions. Its nearly as hard to find hen's teeth as it is someone that owned an original one of these vehicles. These vehicles are so basic that it is almost harder to reproduce a factory restoration as is it for other vehicles. One thing I've noticed from the restoration folks is that they pay way to much attention to body gap and paint finish. Willys and Kaiser produced these vehicles as tools or implements, they were not meant for the Sunday morning going to church crowd, nor the Saturday night cruise ins. Not only that but owners of these vehicles tended to customize them more for their own personal use, and being that the CJ5 remained in production for nearly 30 years people were used to swapping stuff from an '70's Jeep onto a 50's Jeep. Heck I've nearly gotten into arguments with folks are car shows telling me what is or was original on my vehicles. The dog dish hubcaps on my old J10 for examples, some guy swore up and down that those were off a GM product, sure they looked close, but they were not, they were original to the truck, and I bought the truck from the original owner.


    All in all, do what you want to your Jeep, I tend to favor safety over originality on some items, and brakes are one of those, along with installing a two bowl master cylinder. If it was me, I'd go with the 11" drums that Tim spoke of above, retains an original look, yet, gives you piece of mind on better braking, and lower replacement costs.
     
  9. Jul 5, 2014
    veloamerican

    veloamerican New Member

    Jacksonville, FL
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    Thanks for that perspective Long&Low. I do want the jeep to perform well off-road since that is what it was made to do and why I bought it. I suspect it would work fine with the 10" drums since that's how it was designed, but based on everyone's input here I think the 11" conversion would achieve the balance form and function I'm looking for.
     
  10. Jul 9, 2014
    davet

    davet Member

    Andover, MN
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    I put discs on my '56 because of safety concerns. I have no doubt that bigger drums will be better than what you have. I initially plumbed in a hydr-vac unit to my 9" drums and it made a world of difference. It was easy and cheap. I mounted the hydr-vac unit in front of my grill. It was clean and painted nice.
    I use my CJ on the road and on the trails. When I had the drums and came back from a trailride (especially a wet, sloppy one) I not only would pull the drums and clean inside but I found that the sand and mud in the drum would wear my shoes during the trailride. This meant that I would have to re adjust the shoes after each ride. What I found was that when I pulled the boots off the wheel cylinders I had sand inside. The inner rubber cups would get sand under them and it would leak. I didn't always notice the leak because I was hosing everything off. What I had to do was take the wheel cylinders apart after every ride, clean them out, give a quick hone and put new cups in. One ride wasn't particularly wet or sloppy so I skipped pulling apart the cylinders and just hosed everything out. Afterwards I was cruising down a long grade at about 40 mph when the light ahead changed. I got on the brakes and my Jeep pulled hard to the left and almost rolled me over. I got home and found the right front wheel cylinder was leaking and had sand under the inner cup. This caused that wheel not to brake. I didin't drive it again until I figured out how to put discs all the way around. I spent around $250.00-$300.00 (been a long time) which included new calipers, rotors, rubber lines, pads and a little machine work on the rotors and hubs. I use the original MC. They've been on for well over 15 yrs and I've never had a braking problem no matter what the conditions. Removed the hydro-vac too. Just my experience.
     
  11. Jul 16, 2014
    veloamerican

    veloamerican New Member

    Jacksonville, FL
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    Thanks Davet. After checking with a lot of vendors comparing pricing and availability of 11-inch conversion kits I ended up purchasing a front disc conversion kit from R&P 4WD and a rear 10" rebuild kit from Kaiser Willys. To the extent others may find the results of my research helpful, I will post my results when I return home from my current trip in a couple of weeks. I actually put together a spreadsheet. The bottom line is that I found that (1) 11-inch conversion kits are hard to come by currently because according to Herm the Overdrive Guy the demand is outpacing the supply of back plates, and (2) the cost of a front disc conversion isn't much more expensive than an 11-inch conversion.
     
  12. Jul 16, 2014
    davet

    davet Member

    Andover, MN
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    Does the conversion kit include a new MC? If you use the stock MC you will probably have to go into it and remove a little round screen ahead of the plunger assembly. My calipers only released part way when I first installed on all 4 wheels. I removed the little screen and they have worked fine ever since.
     
  13. Jul 16, 2014
    veloamerican

    veloamerican New Member

    Jacksonville, FL
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    Thanks again Davet. It didn't come with a MC kit. While I plan on purchasing a kit, I'm going to see how the brakes work with the existing MC first. I'll definitely keep your experience in mind.
     
  14. Jul 17, 2014
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    The part you may need to remove is called the residual pressure valve. On drum brake systems it holds approximately 10 psi of hydraulic pressure on the system. If you end up removing it you may need to install a 2lb. Unit in te disc brake circuit to keep the brake fluid from draining out of the system back to the master cylinder. If you have a single reservoir master cylinder you would also need to add a 10 psi unit to the drum brake circuit (if so equipped). In line units are readily available from Speedway, Summit, Jeg's, and a host of places.
     
  15. Jul 17, 2014
    davet

    davet Member

    Andover, MN
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    I'm no expert but I can relay my experience at least. I was having an issue, off road only, where I would suddenly get a pedal that on first pump would go to the floor. A 2lb residual, inline valve from Summit as Nikmil mentioned seemed to correct this. Within a few weeks of installing the valve I got a rock hard pedal with nearly no travel. Turned out to be the rubber guts inside the valve had turned inside out and we're not allowing fluid through. Took the valve off and they were fine. I did, later, install another new valve because people said it was better with a valve. Soon after, that one failed again and I got the hard pedal. I,ve been running without one for many years. You may have better luck with one though.
     
  16. Jul 17, 2014
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
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    Had you removed the original residual pressure valve from the master cylinder?

    I could see where the original rpv would be worn and not hold full pressure but daisy-chaining another valve could create this problem. I ran my original master cylinder for years with no external rpv, only the original. However, the original in the master cylinder was worn just enough where another was not necessary. When I replaced that particular m/c it became necessary to have an external unit and not have the original internal in the m/c unit installed.
     
  17. Jul 18, 2014
    davet

    davet Member

    Andover, MN
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    Yes, I had already removed the original the valve in the original MC. I had to take that out because the calipers didn't release all the way with it in place. I'm not sure about why the external ones were failing but both failed the same way after about the same amount of use.
     
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