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my 8.8 swap issue any ideas?

mileshigh

NAXJA Forum User
Location
charlotte, nc
Ok so i swapped a 98 8.8 in my 1990 Xj jeep and put new rotors,pads,calipers on it,new hard and rubber lines. Along with putting all new brakes on the front dana 30. I bleed them and only had about 1" of brake pedal! So i replaced the master cylinder and brake booster with one from a 1994 Xj since i had the parts. Still the same problem...then i took the rubber o-ring out of the stock proportioning valve to see if that would fix it and still nothing. I can push the brake pedal to the floor and hold it and then push the gas and the jeep will power brake and stay still while the rear wheels spin. So i know the brakes are working and that the rear brakes provide all the pedal feel..so the last thing i can think to do is get a grand cherokee proportioning valve but i wanted to see what others had to say before i spent the money. So any ideas as to what my problem is?
 
What happens if you go and try to lock up the brakes?

the fronts do most of the braking work, what you're describing to me as power braking sounds normal.
The rear brakes on most everything can be broken loose if you hold the brakes and mash the gas. That's what happens on our stock 90 anyway.
 
did that same swap. 1990 xj w/d35 rear to a disc brake 8.8 and did all new rear parts and it was Fine when I was done.

I will say that the 2003 wj booster and master swap made a Huge difference in brake power though!
 
IMPRZV1 said:
Are the calipers on the correct side? Which way are the bleeders facing up or down...? I bet that is your problem.

I would say check this first also.

Kim
 
I had the same problem once and it was the brake calipers. They were backwards. Make sure the bleed screw is higher where the hose bolts up.

When I did the 8.8 swap, I did not have this problem. But I replaced the proportioning valve anyway with one from a Rubi and I could suddenly lock the 33's up on dry asphalt.
 
When I did mine (also did a front axle) I had the tire shop check my brake bleeding when they aligned the front end. Got rid of any weirdness I felt.
 
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