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Unread 01-12-2013, 05:09 PM   #1
mambosoul
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1987 YJ Wrangler 
 
Join Date: Feb 2012
Location: San Juan, PR
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YJ Rear Disk Conversion

Hello everyone........I have a problem and I hope I get an answer. Since I had to rebuild the rear of my 87 YJ.......I decided to convert my rear to Disk and I purchased the Crown D35Disk-2 conversion and I installed it. I is not a direct bolt on conversion I had to drill new holes to the backing plate in order for them to fit. I installed the calipers and pads and when I went to install brake hoses the was no copper washers, I looked around the shop and found 4 and installed them. I bled the system and could not get the rear disk to work it seems that there was no pressure getting to the rear. In the instruction it states that on some vehicles you might have to install an after market adjustable proportioning valve and I did and there was no change. Thought that the original master cylinder was not adequate since I was for rear drum system so I purchased a Rough Trail HD Dual Diaphragm brake booster and high pressure master cylinder and installed it (I bench bled the master cylinder).......no luck I get no pressure to the rear calipers. I need help, any ideas? Thanks in advance.

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Unread 01-12-2013, 05:29 PM   #2
Mark05059
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1989 YJ Wrangler 
 
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is the original proportioning valve still in place?
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Unread 01-12-2013, 05:32 PM   #3
mambosoul
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No I installed a summit adjustable proportioning valve....
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Unread 01-12-2013, 06:00 PM   #4
Mark05059
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check for fluid before the valve (would be just like your bleeding the brakes) then check for fluid after the valve at the valve. Then if you have fluid after the valve adjust so it throws all the fluid to the rear wheels until you get fluid to the calipers. The bleeder screws on all 4 wheels should be above the brake lines.
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/l , [____],
|---L--[]lllllll[]-
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Unread 01-12-2013, 06:41 PM   #5
Mywrangler94
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Ok, that kit is a DIRECT BOLT ON. So lets take this step by step. Don't get mad if my questions seem condescending because they aren't. I am just trying to help you. I did this conversion to mine. I have rear discs on my 94. The particular kit you say you have is for a 91-06. What the difference is between an 87-90 D35 and a 91-06 D35 I have no idea. But lets assume they fit. 1. Are you sure you have them on the proper side? The calipers should be toward the rear of the jeep. 2. Are you sure you have the calipers on the right side? When they are the bleeders should be UP. 3. Make sure you get fluid to the calipers. Check this by loosening the banjo bolts, don't remove them, and have someone hit the pedal. Fluid should come pouring out. Do NOT release the pedal till you have closed the bleeders otherwise you'll pull air into the system. Now lets assume that you have no fluid there....What to do next. First, loosen the main line on the distribution block on the axle. Again, hit the pedal. Make sure you have fluid there. If not, move further up the line. Check your fluid level make sure the master is full. Ok, now lets loosen the REAR brake line at the proportioning valve. Again, hit the pedal. If nothing, move to the other side. Loosen the line going into the valve. Hit the pedal. If the fluid coming out of the master spits, and is not a steady stream, you are air bound in the master. Bleed it till its steady, and work your way back to the calipers. I know its frustrating, time consuming, and seems repetitive, and it is, but it will make sure your brakes work. Just to let you know, I have rear disc's on mine. I didn't have to change anything else. Let us know what happens.
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Unread 01-12-2013, 07:44 PM   #6
mambosoul
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Mywrangler94.....none taken. I believe the difference in the bolt holes however that doesn’t make a difference, the calipers are facing to the rear of the Jeep however the bleeders are facing down. I will correct that and as for the rest…….I am taking those steps already. I will keep you posted, Thanks!
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Unread 01-13-2013, 07:48 AM   #7
Pawjob
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For cheaper you could get the disc off a grand cherrokee. Did the upgrade on my buddys MJ cost was about 80$ all together.
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Unread 01-13-2013, 10:32 AM   #8
Mywrangler94
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Fantastic bro....glad you figured it out..........hope all is well.....
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Unread 01-14-2013, 02:24 AM   #9
mambosoul
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Mywrangler94........my kit did not bring the copper washers that are supposed to come with the brake hose and as I look at the parts list that's in the instructions I noticed that it is not included. Can that be the reason fluid is not getting to the rear calipers? I am getting pressure at the T where the rear brake lines attach to on top of the differential...
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Unread 01-14-2013, 07:02 AM   #10
kjg26
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I would expect, without copper washers you'd have a huge leaking mess at the rear brakes.
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Unread 01-14-2013, 10:10 AM   #11
SeanB95YJ
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I'm curious (I'm sure I'm not the only one) why you chose to "upgrade" the D35 to discs, yet you're still left with a D35... I'd imagine what you spent on the conversion kit and whatever parts necessary, you could've came close to getting an Explorer 8.8 (or other axle with discs) that would also have upgraded the strength.

Speaking from experience.... about 15 yrs ago, I had an '87 XJ with a factory D44 rear that I upgraded to discs... at the time once I was done I was into it for around $400-500 (but at least that was a 44 - a huge step above the 35)
had I known at the time about the 8.8 compatibility, I would've gone with the 8.8 instead.
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[FONT="Comic Sans MS"][COLOR="Blue"]Sean B. - Schenectady, NY - 95 YJ, 350/700r4/NP241, JB Shorty SYE, 8.8 rear, 2" BDS, 1" homebrew shackles, Daystar 1" BL, TJ flares, 35x12.50 General Grabber AT2 on 15x10 Bart D-Truckers, Polyshield polycarbonate windshield, HD over/under crossover steering
[/COLOR] [COLOR="Red"]swap/build thread: [url]http://www.jeepforum.com/forum/f22/after-almost-4-years-finally-my-own-build-swap-thread-1542284/[/url][/COLOR][/FONT]
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Unread 01-14-2013, 10:22 AM   #12
Mywrangler94
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like was said....you would have fluid pouring out all over.......
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Unread 01-14-2013, 10:39 AM   #13
YJames90
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Quote:
Originally Posted by SeanB95YJ View Post
I'm curious (I'm sure I'm not the only one) why you chose to "upgrade" the D35 to discs, yet you're still left with a D35... I'd imagine what you spent on the conversion kit and whatever parts necessary, you could've came close to getting an Explorer 8.8 (or other axle with discs) that would also have upgraded the strength.

.
It was only a matter of time for this response
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Unread 01-14-2013, 10:49 AM   #14
WakeDoctor
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Quote:
Originally Posted by SeanB95YJ View Post
I'm curious (I'm sure I'm not the only one) why you chose to "upgrade" the D35 to discs, yet you're still left with a D35... I'd imagine what you spent on the conversion kit and whatever parts necessary, you could've came close to getting an Explorer 8.8 (or other axle with discs) that would also have upgraded the strength.

Speaking from experience.... about 15 yrs ago, I had an '87 XJ with a factory D44 rear that I upgraded to discs... at the time once I was done I was into it for around $400-500 (but at least that was a 44 - a huge step above the 35)
had I known at the time about the 8.8 compatibility, I would've gone with the 8.8 instead.
A 44 or 9" would probably be an ok option. The pumpkin and the 31"s would have him dragging on everything.
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Unread 01-14-2013, 03:04 PM   #15
mambosoul
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Thanks for all the responses.......the problem is fixed. The calipers were backwards meaning with the bleeder screw down. It seems that the piston was retaining air in that position or it was not filling with fluid properly. As for chanhing the differential.....it is very hard to get parts down here and I am not rock crawling with my jeep so the D35 should be good for now. My next project is replacing the 4.2 for a chevy 6.0 from a silverado 2500 Hd with a Ax-15 trany........
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