Brake Conversion - JeepForum.com

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post #1 of 17 Old 11-13-2016, 04:24 PM Thread Starter
86renegade
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Brake Conversion

About the Jeep:
1986 CJ-7 Base
4.2L Straight 6

If possible, i want to convert the drum brakes to disk brakes.

I was doing some research on servicing drum brakes and it seemed pretty difficult to do along with the fact that drum brakes don't work nearly as well as disk brakes.

Has anyone on here done this conversion before? If you have: What was the approximate cost of doing this?

Second: My parking brake will not engage(im guessing it has something to do with drum brakes severely needing servicing).

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post #2 of 17 Old 11-13-2016, 05:28 PM
NoticeablyFAT
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I can't say anything about converting to disc brakes, but I just replaced the pads & springs in my drums and it wasn't nearly as difficult as people make it out to be. If you have just a little bit of mechanical ability and can follow directions, you've got it.
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post #3 of 17 Old 11-13-2016, 05:50 PM
OrangeCJ-5
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Drum brakes work just fine and are easy to work on with the correct tools. There are multiple threads documenting disk brake conversions using different parts with mixed results. You would also have to change the proportioning valve because of the different pressure required for disk vs drum brakes. Do one side at a time so you can use the other side as a reference. The parking brake might not work because the cables are seized in the sheath which has noting to do with the drum brake components.

Drum brakes use shoes and not pads. Pads are on disk brakes.
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post #4 of 17 Old 11-13-2016, 06:12 PM
Chrisinchwk
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I hve done the disc brake conversion. Not because I wanted better brakes but the ease of maint paired With drums filling with mud and i was curious how hard it would be.

Not super hard but if your al all intimidated by doing your drums it my be a bit more difficult thn that.

At the end of the dy the proportioning valve had little to no difference. Even by passed it for the rears out of curiosity.

At the end of the day its tough to say if they are any better than well adjusted drums. I did change from 31s to 35s so its a tough comparison. They work well and feel good but still takes a crap load of pedal to lock up the fronts but they do work. Have never been able to lock up the rears at all. YesI know they should never lock but I have an adjustable proportioning valve I can dial them back with. Might tinker somemore as its of the road for the winter.

Probably cost me 600 bucks Canadian but 300 of that would have been spent on new parts regardless if I converted or not.

2.5 million in my labor, but it's a labor or love.

Forgot my Ebrake actually works and I never have to mess with it. Always in adjustment more or less

Chris
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post #5 of 17 Old 11-14-2016, 01:24 PM Thread Starter
86renegade
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Quote:
Originally Posted by NoticeablyFAT View Post
I can't say anything about converting to disc brakes, but I just replaced the pads & springs in my drums and it wasn't nearly as difficult as people make it out to be. If you have just a little bit of mechanical ability and can follow directions, you've got it.
Do you have any links to good walkthroughs for servicing drum brakes? I've done disk brakes plenty of times but drum brakes are a whole new thing for me.
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post #6 of 17 Old 11-14-2016, 01:35 PM
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Originally Posted by 86renegade View Post
Do you have any links to good walkthroughs for servicing drum brakes? I've done disk brakes plenty of times but drum brakes are a whole new thing for me.
The Factory Service Manual would be a good place to start.

Matt


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post #7 of 17 Old 11-14-2016, 01:47 PM Thread Starter
86renegade
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The Factory Service Manual would be a good place to start.

Matt
Ive never been able to find a good FSM for my jeep
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post #8 of 17 Old 11-14-2016, 01:53 PM
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Ive never been able to find a good FSM for my jeep
Post #17

http://www.jeepforum.com/forum/f8/84...27/index2.html

Just save each PDF file to your hard drive, so you will always have it. Best part is it's FREE!

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post #9 of 17 Old 11-14-2016, 02:52 PM Thread Starter
86renegade
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Quote:
Originally Posted by Matt1981CJ7 View Post
Post #17

http://www.jeepforum.com/forum/f8/84...27/index2.html

Just save each PDF file to your hard drive, so you will always have it. Best part is it's FREE!

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Awesome, thank you!
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post #10 of 17 Old 11-14-2016, 09:44 PM
NoticeablyFAT
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Originally Posted by 86renegade View Post
Do you have any links to good walkthroughs for servicing drum brakes? I've done disk brakes plenty of times but drum brakes are a whole new thing for me.
I just went to YouTube and started searching. The Bleepin' Jeep one is not bad. Take some pictures before you start, and as you pull things off set them off to the side in as close to the assembled configuration as possible, including hooking springs back into the proper connection points. I've heard the drum brake tool makes things easier, but I managed fine with vice grips and a big flathead. I didn't pull the hub, it would have been easier but it didn't want to come off in the five minutes I was willing to spend on it. I also didn't need to replace any of the parts, but the hardware kit was eight bucks and did both wheels, so I went ahead and replaced all the small bits.
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post #11 of 17 Old 11-15-2016, 02:24 PM Thread Starter
86renegade
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Originally Posted by NoticeablyFAT View Post
I just went to YouTube and started searching. The Bleepin' Jeep one is not bad. Take some pictures before you start, and as you pull things off set them off to the side in as close to the assembled configuration as possible, including hooking springs back into the proper connection points. I've heard the drum brake tool makes things easier, but I managed fine with vice grips and a big flathead. I didn't pull the hub, it would have been easier but it didn't want to come off in the five minutes I was willing to spend on it. I also didn't need to replace any of the parts, but the hardware kit was eight bucks and did both wheels, so I went ahead and replaced all the small bits.
Me and a friend using a combination of google and youtube serviced both brake drums and their components last night. took several hours(like 4 or 5) but we got it done eventually.
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post #12 of 17 Old 11-15-2016, 09:56 PM
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Drum brakes are less effective than disc brakes, that is true.

However, the reason most manufacturers still use them on the rear is that under heavy braking there is weight transfer to the front and the rears are unloaded. Whilst the rear brakes are only contributing around 20% of the braking effort, it is fine to have less efficient drum brakes. The typical drum brake design incorporates the emergency or parking brake and is a cheap and reliable braking system. When you change to discs you theoretically have more braking ability but in practice it is marginal.

If you upsize the tyres to 35" or above, you will struggle to stop with CJ brakes. That is a different ball game.

Servicing drums is quite straightforward.

Getting mud inside them is only an issue for mud pluggers, most Jeepers will never have had a drum brake slip due to mud. However if you are building it for mud, it is a valid consideration.

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post #13 of 17 Old 11-17-2016, 03:38 PM Thread Starter
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Originally Posted by BagusJeep View Post
Drum brakes are less effective than disc brakes, that is true.

However, the reason most manufacturers still use them on the rear is that under heavy braking there is weight transfer to the front and the rears are unloaded. Whilst the rear brakes are only contributing around 20% of the braking effort, it is fine to have less efficient drum brakes. The typical drum brake design incorporates the emergency or parking brake and is a cheap and reliable braking system. When you change to discs you theoretically have more braking ability but in practice it is marginal.

If you upsize the tyres to 35" or above, you will struggle to stop with CJ brakes. That is a different ball game.

Servicing drums is quite straightforward.

Getting mud inside them is only an issue for mud pluggers, most Jeepers will never have had a drum brake slip due to mud. However if you are building it for mud, it is a valid consideration.
Mudding is definatley something i planned on doing, i wasn't aware that the drum brakes could get mud inside them and be affected by this. I had a friend help me service the drum brakes and it was difficult at first but we got it done in about 4-5 hours(having never serviced these types of brakes before it was a steep learning curve).
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post #14 of 17 Old 11-18-2016, 09:20 AM
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Originally Posted by Chrisinchwk View Post

At the end of the dy the proportioning valve had little to no difference. Even by passed it for the rears out of curiosity.
Not exactly. The difference in the proportioning valves are that disc brakes require a small amount of residual pressure so that the brake calipers do not "relax" too far. The residual pressure keeps the pads close to the discs.

Drum brakes on the other hand, do not require that residual pressure. The shoes back away from the drums by spring tension. Using a proportioning valve designed for disc/brake instead of drum/drum will cause nothing but problems. The residual pressure supplied by the disc/drum valve will cause the shoes to constantly drag against the drum and eventually cause them to lock up due to the heat of the friction. I learned this the hard way.

While you would not have the problem I described, if you keep the residual valve designed for drum/drum you will have a momentary lag in your brake performance. You may perceive it or you may not; but it will be there.

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post #15 of 17 Old 11-18-2016, 09:39 AM
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Originally Posted by WindKnot View Post
Not exactly. The difference in the proportioning valves are that disc brakes require a small amount of residual pressure so that the brake calipers do not "relax" too far. The residual pressure keeps the pads close to the discs.

Drum brakes on the other hand, do not require that residual pressure. The shoes back away from the drums by spring tension. Using a proportioning valve designed for disc/brake instead of drum/drum will cause nothing but problems. The residual pressure supplied by the disc/drum valve will cause the shoes to constantly drag against the drum and eventually cause them to lock up due to the heat of the friction. I learned this the hard way.

While you would not have the problem I described, if you keep the residual valve designed for drum/drum you will have a momentary lag in your brake performance. You may perceive it or you may not; but it will be there.
You are backwards on that. Drum brakes use a higher residual pressure. If you leave in the disc/drum proportioning valve when doing a disk/disk conversion you will hold the rear disk brake pads too tight against the rotor. Following is the quote from Willwood on their residual pressure valves.

Quote:
Wilwood two pound and ten pound residual pressure valves retain a minimum brake line pressure to help eliminate excessive pedal travel in both disc and drum brake systems. The two pound valve is used in disc brake applications where the master cylinder is mounted below the horizontal plane of the calipers and fluid drain back occurs from gravity and vibration, thereby causing excessive caliper piston retraction and a longer brake pedal stroke. The minimal two pound residual pressure prevents fluid from flowing back without causing the brakes to drag. With drum brakes, a ten pound valve is used to compensate for return spring tension and maintain wheel cylinder sealing in the drums. Residual Pressure Valves are made from billet aluminum and color coded for easy identification.

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