Jackrabbit41 Posted April 13, 2015 Share Posted April 13, 2015 My stopping power sucks. Would it help to get disc brakes on the back? Or bigger on the front? I don't know much about brakes. Would I be able to do this? Thanks. I got a 87 long bed 5x4 Link to comment Share on other sites More sharing options...
Dillithium Posted April 13, 2015 Share Posted April 13, 2015 Identify your rear axle first, then we can talk about discs. Use this handy chart: http://b.cdnbrm.com/images/prm/homepage/TouchClarity/images/articles/infographic/differential-identification-chart.jpg It will be either a DANA 35 or DANA 44, AMC 20 was only in 86 I believe. Secondly, drums vs discs is a tiresome debate but it will not yield you much more braking power. One of the best upgrades is a brake booster from a WJ or 96 XJ. Google is your friend in this case. But before you do that, how are your pads/discs on the front? All lines are bled correctly with recent brake fluid? Link to comment Share on other sites More sharing options...
Jackrabbit41 Posted April 13, 2015 Author Share Posted April 13, 2015 Ya it's a Dana 35 Pads are brand new up front and it all jsut got serviced a month ago Link to comment Share on other sites More sharing options...
Blue XJ Posted April 13, 2015 Share Posted April 13, 2015 If you want to swap to disks, find a Grand (ZJ) with rear disks in the junkyard and grab all of the brake hardware. They had Dana 35's with disk brakes. You'll want the proportioning valve from under the hood as well. Link to comment Share on other sites More sharing options...
Lee21490 Posted April 13, 2015 Share Posted April 13, 2015 My stopping power sucks. Would it help to get disc brakes on the back? Or bigger on the front? I don't know much about brakes. Would I be able to do this? Thanks. I got a 87 long bed 5x4 Could also upgrade to a bigger vacuum booster. Btw we live in the same town! I'm right off Alabama St. Link to comment Share on other sites More sharing options...
Jackrabbit41 Posted April 13, 2015 Author Share Posted April 13, 2015 My stopping power sucks. Would it help to get disc brakes on the back? Or bigger on the front? I don't know much about brakes. Would I be able to do this? Thanks. I got a 87 long bed 5x4 Could also upgrade to a bigger vacuum booster. Btw we live in the same town! I'm right off Alabama St. We should go wheeling some time. I live in south hill, 17th street. Where do you usually go around here Link to comment Share on other sites More sharing options...
Jackrabbit41 Posted April 13, 2015 Author Share Posted April 13, 2015 Also, do you guys know how to post pics in here? I want to put some of my truck photos on Link to comment Share on other sites More sharing options...
Lee21490 Posted April 13, 2015 Share Posted April 13, 2015 My stopping power sucks. Would it help to get disc brakes on the back? Or bigger on the front? I don't know much about brakes. Would I be able to do this? Thanks. I got a 87 long bed 5x4Could also upgrade to a bigger vacuum booster. Btw we live in the same town! I'm right off Alabama St. We should go wheeling some time. I live in south hill, 17th street. Where do you usually go around here Actually i'm most likely going to Sumas Mt. with a few people this coming saturday. You're more than welcome to join! And to post pics, Upload the pic to a site like Imgur.com & Copy the image link, Click the image icon on the bottom row about half way & paste the image link. Link to comment Share on other sites More sharing options...
Jackrabbit41 Posted April 13, 2015 Author Share Posted April 13, 2015 My stopping power sucks. Would it help to get disc brakes on the back? Or bigger on the front? I don't know much about brakes. Would I be able to do this? Thanks. I got a 87 long bed 5x4Could also upgrade to a bigger vacuum booster. Btw we live in the same town! I'm right off Alabama St. We should go wheeling some time. I live in south hill, 17th street. Where do you usually go around here Actually i'm most likely going to Sumas Mt. with a few people this coming saturday. You're more than welcome to join! And to post pics, Upload the pic to a site like Imgur.com & Copy the image link, Click the image icon on the bottom row about half way & paste the image link. I take my quad up there, but is there any jeep trails? Link to comment Share on other sites More sharing options...
Jackrabbit41 Posted April 13, 2015 Author Share Posted April 13, 2015 And is there any jeep clubs around here? Link to comment Share on other sites More sharing options...
Lee21490 Posted April 13, 2015 Share Posted April 13, 2015 My stopping power sucks. Would it help to get disc brakes on the back? Or bigger on the front? I don't know much about brakes. Would I be able to do this? Thanks. I got a 87 long bed 5x4Could also upgrade to a bigger vacuum booster. Btw we live in the same town! I'm right off Alabama St. We should go wheeling some time. I live in south hill, 17th street. Where do you usually go around here Actually i'm most likely going to Sumas Mt. with a few people this coming saturday. You're more than welcome to join! And to post pics, Upload the pic to a site like Imgur.com & Copy the image link, Click the image icon on the bottom row about half way & paste the image link. I take my quad up there, but is there any jeep trails? Yea, There's actually quite a bit of trails up there. Nothing crazy... But its still fun to go up hit a few trails & Shoot some guns. Not sure about any jeep clubs around here. I know there's one that meets towards seattle fairly often though. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted April 14, 2015 Share Posted April 14, 2015 Rear brakes could be helped as well by unhooking the rear load sensing prop valve and tying it up to the 1 o'clock position. Or by eliminating that rear valve altogether. This fix will give full braking power to the rear brakes. Link to comment Share on other sites More sharing options...
Pete M Posted April 14, 2015 Share Posted April 14, 2015 assuming nothing is actually malfunctioning in your truck, a swap to the late model booster will give you the best improvement. :thumbsup: Link to comment Share on other sites More sharing options...
Incommando Posted April 14, 2015 Share Posted April 14, 2015 assuming nothing is actually malfunctioning in your truck, a swap to the late model booster will give you the best improvement. :thumbsup: Amen. This is the best safety swap I have ever done. It is a night and day difference with my 96 XJ dual diaphragm booster even with factory brakes. Not a hard swap at all, either. Link to comment Share on other sites More sharing options...
gogmorgo Posted April 14, 2015 Share Posted April 14, 2015 This. The best way to improve braking performance is really to increase braking pressure, by way of booster or master cylinder. Larger discs will help with managing heat and wear, but only a slight performance advantage from the longer lever arm. Link to comment Share on other sites More sharing options...
xjrev10 Posted April 14, 2015 Share Posted April 14, 2015 I didn't swap the prop valve when I went to rear discs and WJ master/booster set up. You do have to cut a line and plug a line in the back for the load sensor tho. Link to comment Share on other sites More sharing options...
Megadan Posted April 29, 2015 Share Posted April 29, 2015 This. The best way to improve braking performance is really to increase braking pressure, by way of booster or master cylinder. Larger discs will help with managing heat and wear, but only a slight performance advantage from the longer lever arm. Somewhat true...but it's not quite that cut and dry. If you do the basic brake force math using the factory disc brakes front and rear with a 1" master cylinder bore and 60lbs of input pressure you end up with a bit over 4900lbs of front braking force and a bit over 2800lbs of rear braking force (with ZJ rear disc setup). which gives a 61.5% braking force bias. and a total braking force of 7700lbs. Just increasing the rotors in diameter by 1" front and rear (12.02 front and 12.21 rear) with the same braking force input you end up with just shy of 5500lbs of braking force front and a hair over 3100lbs of braking force rear - a total of 8600lbs of braking force . All of that from only a 1/2" increase in that lever arm radius at each end, and without any change in the brake line pressure, and as a result, brake pedal feel or travel. On top of that better thermal management you brought up - which is never a downside. going to a larger bore master cylinder actually reduces brake line pressure, and as a result brake force, at the same input force. Smaller, the exact opposite. This will also greatly change the feel of the brakes and the brake pedal travel. It's not something I would do lightly to improve braking power personally, but is an option. Generally, the change in master cylinder size should coincide with a change to caliper piston diameters, which also greatly effect brake force in relation to said master bore size. etc etc yadda yadda. I learned a lot about brake math and setups after swapping C5 corvette brakes on to my Isuzu. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 30, 2015 Share Posted April 30, 2015 assuming nothing is actually malfunctioning in your truck, a swap to the late model booster will give you the best improvement. :thumbsup: Absolutely. 99 to 2004 Grand Cherokee booster/master combos are plentiful in the junkyards. Be sure to get the brake lines coming out of the master cylinder with it. Link to comment Share on other sites More sharing options...
cruiser54 Posted April 30, 2015 Share Posted April 30, 2015 This. The best way to improve braking performance is really to increase braking pressure, by way of booster or master cylinder. Larger discs will help with managing heat and wear, but only a slight performance advantage from the longer lever arm. Somewhat true...but it's not quite that cut and dry. If you do the basic brake force math using the factory disc brakes front and rear with a 1" master cylinder bore and 60lbs of input pressure you end up with a bit over 4900lbs of front braking force and a bit over 2800lbs of rear braking force (with ZJ rear disc setup). which gives a 61.5% braking force bias. and a total braking force of 7700lbs. Just increasing the rotors in diameter by 1" front and rear (12.02 front and 12.21 rear) with the same braking force input you end up with just shy of 5500lbs of braking force front and a hair over 3100lbs of braking force rear - a total of 8600lbs of braking force . All of that from only a 1/2" increase in that lever arm radius at each end, and without any change in the brake line pressure, and as a result, brake pedal feel or travel. On top of that better thermal management you brought up - which is never a downside. going to a larger bore master cylinder actually reduces brake line pressure, and as a result brake force, at the same input force. Smaller, the exact opposite. This will also greatly change the feel of the brakes and the brake pedal travel. It's not something I would do lightly to improve braking power personally, but is an option. Generally, the change in master cylinder size should coincide with a change to caliper piston diameters, which also greatly effect brake force in relation to said master bore size. etc etc yadda yadda. I learned a lot about brake math and setups after swapping C5 corvette brakes on to my Isuzu. I went this route, in this order. Somewhat scientific and logical. 88 XJ rear discs off a Grand. Nice. 90 MJ 95 to 96 booster and master keeping rear drum brakes. Holy mackereel!! WJ booster/master on the XJ that already the rear disc conversion. Very nice!!! Link to comment Share on other sites More sharing options...
Megadan Posted April 30, 2015 Share Posted April 30, 2015 This. The best way to improve braking performance is really to increase braking pressure, by way of booster or master cylinder. Larger discs will help with managing heat and wear, but only a slight performance advantage from the longer lever arm. Somewhat true...but it's not quite that cut and dry. If you do the basic brake force math using the factory disc brakes front and rear with a 1" master cylinder bore and 60lbs of input pressure you end up with a bit over 4900lbs of front braking force and a bit over 2800lbs of rear braking force (with ZJ rear disc setup). which gives a 61.5% braking force bias. and a total braking force of 7700lbs. Just increasing the rotors in diameter by 1" front and rear (12.02 front and 12.21 rear) with the same braking force input you end up with just shy of 5500lbs of braking force front and a hair over 3100lbs of braking force rear - a total of 8600lbs of braking force . All of that from only a 1/2" increase in that lever arm radius at each end, and without any change in the brake line pressure, and as a result, brake pedal feel or travel. On top of that better thermal management you brought up - which is never a downside. going to a larger bore master cylinder actually reduces brake line pressure, and as a result brake force, at the same input force. Smaller, the exact opposite. This will also greatly change the feel of the brakes and the brake pedal travel. It's not something I would do lightly to improve braking power personally, but is an option. Generally, the change in master cylinder size should coincide with a change to caliper piston diameters, which also greatly effect brake force in relation to said master bore size. etc etc yadda yadda. I learned a lot about brake math and setups after swapping C5 corvette brakes on to my Isuzu. I went this route, in this order. Somewhat scientific and logical. 88 XJ rear discs off a Grand. Nice. 90 MJ 95 to 96 booster and master keeping rear drum brakes. Holy mackereel!! WJ booster/master on the XJ that already the rear disc conversion. Very nice!!! rear discs and WJ booster are next on my list. There are 5 ZJ's with rear discs and 2 WJ's at the nearby pick and pull. If everything goes right, I plan on grabbing most of the parts I need to do the conversions and re-doing my front brakes and bleeding the whole system. My brakes right now work well enough, but they don't inspire confidence. I plan on getting the main brackets for the rear disc and using rebuild calipers and new rotors. Anything from the booster side I should grab? ZJ or WJ prop valve? Link to comment Share on other sites More sharing options...
cruiser54 Posted April 30, 2015 Share Posted April 30, 2015 This. The best way to improve braking performance is really to increase braking pressure, by way of booster or master cylinder. Larger discs will help with managing heat and wear, but only a slight performance advantage from the longer lever arm. Somewhat true...but it's not quite that cut and dry. If you do the basic brake force math using the factory disc brakes front and rear with a 1" master cylinder bore and 60lbs of input pressure you end up with a bit over 4900lbs of front braking force and a bit over 2800lbs of rear braking force (with ZJ rear disc setup). which gives a 61.5% braking force bias. and a total braking force of 7700lbs. Just increasing the rotors in diameter by 1" front and rear (12.02 front and 12.21 rear) with the same braking force input you end up with just shy of 5500lbs of braking force front and a hair over 3100lbs of braking force rear - a total of 8600lbs of braking force . All of that from only a 1/2" increase in that lever arm radius at each end, and without any change in the brake line pressure, and as a result, brake pedal feel or travel. On top of that better thermal management you brought up - which is never a downside. going to a larger bore master cylinder actually reduces brake line pressure, and as a result brake force, at the same input force. Smaller, the exact opposite. This will also greatly change the feel of the brakes and the brake pedal travel. It's not something I would do lightly to improve braking power personally, but is an option. Generally, the change in master cylinder size should coincide with a change to caliper piston diameters, which also greatly effect brake force in relation to said master bore size. etc etc yadda yadda. I learned a lot about brake math and setups after swapping C5 corvette brakes on to my Isuzu. I went this route, in this order. Somewhat scientific and logical. 88 XJ rear discs off a Grand. Nice. 90 MJ 95 to 96 booster and master keeping rear drum brakes. Holy mackereel!! WJ booster/master on the XJ that already the rear disc conversion. Very nice!!! rear discs and WJ booster are next on my list. There are 5 ZJ's with rear discs and 2 WJ's at the nearby pick and pull. If everything goes right, I plan on grabbing most of the parts I need to do the conversions and re-doing my front brakes and bleeding the whole system. My brakes right now work well enough, but they don't inspire confidence. I plan on getting the main brackets for the rear disc and using rebuild calipers and new rotors. Anything from the booster side I should grab? ZJ or WJ prop valve? ZJ prop valve guts. Link to comment Share on other sites More sharing options...
xjrev10 Posted May 1, 2015 Share Posted May 1, 2015 My brakes work just fine with the MJ prop valve, and the load sensor removed and the port plugged in the prop valve and line plugged in the back. WJ Master/booster ZJ discs Be aware not all WJs have the flex lines. Link to comment Share on other sites More sharing options...
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