brake upgrade for CJ7 - JeepForum.com
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post #1 of 11 Old 04-09-2019, 08:43 PM Thread Starter
82SuperstarCJ
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brake upgrade for CJ7

Hello, everyone -
I have read through the few posts discussing parts and process around changing out the original disc brakes for GM truck brakes.
I have an 82 CJ7 with a d30 front axle. Just a couple questions for anyone who has successfully performed the upgrade:
1. brake rotors - I cannot seem to find 1-1/8 thick rotors for a 78 CJ7 at any of the big auto parts stores. Summit Racing has them on line. Any thoughts?
2. I saw a couple threads mention the need for a spacer that must be installed to ensure the rotor is running in the middle of the caliper. And I have read some threads where the spacer is not mentioned. What's the story here?
3. My stock brake hoses are about 13 inches long. The mid-80's Chevy pickup truck brake hoses are about 20 inches long. I have 31" tires on stock wagon wheels, and no suspension lift. Which hoses should I purchase?
4. Finally, I saw multiple threads that discuss the need for some grinding on the caliper mount to allow the caliper to move naturally. I guess it will be clear to me when I install the parts to determine if/where to grind?

thanks so much for the help. This forum has been soup helpful over the winter as I have tackled a laundry list of tasks on this Jeep to get it ready for some serious fun with my girls.

Dan

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post #2 of 11 Old 04-09-2019, 10:08 PM
StoneTower
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The International Scout II uses the same rotor.

https://www.rockauto.com/en/catalog/...hub,rotor,1896

TheJeepGuy sells the caliper brackets. I got my calipers and pads locally at O'reilly auto parts. You want the later metric Calipers. I was told to get the cheapest organic pads O'reilly auto parts sells. They work great at low speed and do not have to get warmed up like some semi metallic pads. I think the calipers are around $20 each and the pads are around $13 for the set.

I got my braded brake lines from TheJeepGuy. I got my rotors from Summit.

You have to grind part of the bolt holes off that used to hold the Jeep caliper bracket for the new Chevy caliper bracket to fit flat.
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post #3 of 11 Old 04-09-2019, 10:18 PM
Cutlass327
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What setup do you have now, and what are your plans? Just larger front, all 4 disk, convert from front drum to disk?

Rick

1978 CJ5 5.0HO/T177/D300, '86 D30/D44 WT axles, 'glass body, 31x10.5 BFG A/T, TDK galv'd frame - DD and weekend toy


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post #4 of 11 Old 04-10-2019, 07:01 AM Thread Starter
82SuperstarCJ
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It has the original power rear drum and front disc. My plan is to keep the Jeep as original as possible. No rust, original paint. It will be a fun driver to use with the kids or a relaxing ride in the cornfields of Iowa!
In the process of all the work I have been doing over the winter, I took a look at the design of the original disc brake setup and was pretty surprised at how it was engineered. Plastic sleeves for the caliper slide holes? It just seemed like a very poor design and I was so happy to read about the GM upgrade.
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post #5 of 11 Old 10-12-2019, 10:45 AM
woodtree60
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Hi All. I have an original owner 1986 CJ7. My rear drums have licked up from no use. I want to get her back on the road. So I figure I may as well work on front disc as well as rear rotors. Talking to Ryan the Jeep Guy. His brackets for the front along with upgraded diss,pads etc I can buy locally makes sense. I was thinking about trashing the rear drums and parts and buying new, then putting back together. I figure, that they would in turn work as well as they could. Really tired of downshifting and braking my cj to stop completely. Please let me know your thought and any advice is greatly appreciated. Joe
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post #6 of 11 Old 10-12-2019, 09:52 PM
StoneTower
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Your first step is to get the rear drums off. They have pullers you can rent for free at the auto parts stores if they are stuck. Unless it has been sitting rim deep in mud in a field somewhere the drums will not go bad unless they are grooved from use.

You will probably need new wheel cylinders which are cheap. You will need to flush out your lines too.
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post #7 of 11 Old 10-13-2019, 12:15 AM
BagusJeep
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you need to let off the brake adjusters first, then tap lightly with a rubber or hide mallet on the drums (Ok, I use a piece of wood and BFH). If they are truly stick, try a puller and give it another tap. As said above, they are usually salvageable and the service parts, springs, shoes etc are dirt cheap. As the rears give about 20% braking effort, they do not need upgrading unless you have big tyres and/or more power.
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post #8 of 11 Old 10-13-2019, 04:43 PM
GISharp
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Good Day,


My answer might be overly simplistic, but I have an 85 CJ 7 and I all I did was upgrade my brake reservoir. I can lock up all 4 tires on pavement with my 31's. The upgrade was cheep and had a real impact on my system. It might be worth starting there, before taking any more intrusive actions.


Just my 2 Cents...
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post #9 of 11 Old 10-14-2019, 09:43 AM
schardein
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I've done this conversion on a D27 (closed knuckle) and a swapped in Dana 44 from a J10. So not exactly the same as converting the factory D30.

I'm not sure what caliper mount brackets you are looking at, but the originals from the 70s to early 80s were nearly 3/16" thick and are the full circumference of the disc (see last pic). The later ones, the thick steel was only around the mount, and the rest was a welded on thin tin shield that rusts or gets bent easily. The older ones will support the entire weight of the vehicle if the wheel/tire/hub was ever to come off the vehicle while off road. Square body 1/2 ton 4wd Chevy trucks, Blazers, and Suburbans (73-80) all used these mounts. Possibly later years as well, I don't know when they went to the different mount with the tin shields.

I don't remember the part numbers, but I used Chevy truck lines and they are plenty long for my roughly 2.5"-3.5" of lift.

I had a small amount of the rear hub face (where the disc mounts) machined down to bring the disc more closely into the center of the caliper.

My setup uses a Ford hub because it's a D44. Ford spindle, the disc is the thicker Jeep disc. Standard 1/2 ton Chevy calipers.

The Chevy brake setup is a good design. I did this conversion in 2007, and I think I've replaced the pads once. Still running the same calipers and rotors.

If you need a real stopping power upgrade, consider converting from a vacuum booster to hydroboost. I swapped mine a while back, and the difference was night and day. Easily lock up 35s but is very controllable (which is what you want, locking up the tires isn't the best stopping technique).

I plan to do the Chevy conversion on a 80 CJ5 I am currently putting together. It will use the stock D30 axle, so I am also interested in what others who have done it have to say.
Attached Thumbnails
front 44007.jpg   front 44008.jpg   front 44013.jpg  

1983 CJ7, 5.3, NV3550, D300 4:1, Fr D44 Detroit, Rr D44 OX, 4.56, 35" SSTs on beadlocks
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post #10 of 11 Old 10-15-2019, 06:53 AM
jeepdaddy2000
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earlycj5.net has a LOT of disk conversion threads, both for the 30 and the 27.
https://www.bing.com/search?q=site%3...ZI&form=MOZTSB

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post #11 of 11 Old 10-16-2019, 12:44 PM
NormWild
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Quote:
Originally Posted by GISharp View Post
Good Day,


My answer might be overly simplistic, but I have an 85 CJ 7 and I all I did was upgrade my brake reservoir. I can lock up all 4 tires on pavement with my 31's. The upgrade was cheep and had a real impact on my system. It might be worth starting there, before taking any more intrusive actions.


Just my 2 Cents...
I agree, I have manual brakes with 33s and this thing stops great. I would make sure your rear brakes are adjusted properly so they are engaging and fully contributing. Next step would be to change the pad compound on the front to something with more bite.

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