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Old 03-26-2014, 06:10 AM   #1
Big M73's Avatar
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94 yj brake upgrade w/8.8

Ok I have a 94 yj I put the 95 dual diagram booster and mc on it I also did the 8.8 axle swap with disc. I've bleed the brakes several times including vacuum bleeding but still can't get any peedle. Do I need to change my portioning valve and if so to what? Or is it something else?

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Old 03-26-2014, 01:03 PM   #2
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Are the 8.8 calipers on the correct side? The bleeder needs to be at the top. Just asking cause that is a common mistake that is made.

The only other thing it could be is the master cylinder, if you are not getting any pedal at all. Did the rod to the pedal come with the new MC? The dual diaphragm booster requires a longer rod, if I remember correctly.

I have an 8.8 disc on my 87, no new MC or booster. Doesn't even have a proportioning valve on it, and it stops fine with 35's.

'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...
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Old 03-26-2014, 02:18 PM   #3
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Yea there on the correct side. May be the angle they are at since I did the soa. But didn't know if my proportional valve would work with the new rear disc brakes.
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Old 03-26-2014, 06:00 PM   #4
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Post a pic of the brake calipers so we can see the angle. When I did my swap I bled them twice and they were ready to rock.... I take it you checked for leaks?
94 YJ 4.0L 5-Speed-Tube fenders, rear body armor, 4 1/2" SUA lift-35" MT Baja Clawsmounted on Aluminum TR BL's-D30/F8.8 4.10's.

Next project; Fozzy locked d30 with ten factory axles, powertrax no-slip for the 8.8. $$$ I need to either get a new job or ditch the girlfriend to support this thing....
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Old 03-26-2014, 09:11 PM   #5

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Did the brake master get bench bled first??? And confirm the calipers are on the right side on your 8.8 as mentioned above.

When you mounted the master did you adjust the throw on the vacuum booster to engage the master cylinder piston.

Just did this haven't bled yet but all the same with an 8.8 that was working before.

Let me know what you got and pictures may help.
89 2.5 TBI, 4" RC lift, 1" Booms, SYE, Adams Driveshafts front and rear, Ford 8.8 with 4:88s, BFG 33X12.50X15, and a ton of other stuff.

AF Jeep Club Tail Number 184
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Old 03-28-2014, 10:29 AM   #6
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I installed the 95 yj booster and a master cylinder for an e350 on my 89 YJ with 8.8 rear with discs. Results were not great, spongy brakes... deleted the e350 mc and put on the mc that came with the 95 booster, after bleeding, i can lock up all four wheels like nobodys business. Lots of adjusting that went on, but you do not need to replace the proportioning valve. Double check your vacuum and another thing you need to be sure of is that the rod inside the mc is pushing in far enough, if its not, then you need to extend it...

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