Mustang 8.8 rear disc

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joes68340s

joes68340s

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Has anybody worked with the 8.8 rear disc calipers. I have been having trouble bleeding them. When opening the valve under pressure very little fluid comes out. The discs don’t seem to be working as I see no wear on the rotors. It seems like there must be some blockage not sure. I didn’t install this rear ended just stuck with it for now.
 
Bleeder could be clogged. Unscrew the bleeder all the way and see if it flows then. If not it may be a residual valve (distribution block)or whatever they were called. That is bias to the front brakes for more pressure if you had disk front and drums back previously.
 
Hello,
Can you try to bleed (just a test) by loosing the line that goes from the body into the rubber hose that goes to the rear diff.
This way if you get no pressure (little fluid) you know its forward of the rear. Then try at the out put of proportioning valve feeding the rear and see the results. You can also check at the output of the master (to the rear) and see.
Check that you have complete travel of the rod going into the master and the piston in the master is not sticking.
You should also remove the bleeders at the calipers to see if there clogged.
Keep us up to date on your findings.
Happy Mopar :) (and ford's i guess LOL)
Arron
 
I have replaced the distribution block the rear calipers flow the same. I have a 15/16 aluminum master. I think either blockage in line or possible master issue.
 
Have you checked/replaced the soft line that goes from the hard line down to the rear axle? Those rubber lines are a pretty common fail point, and they tend to swell shut from the inside so they often look ok from the outside.
 
Yes all the rubber lines are braided lines. I wonder if the smaller braided line in rear could be restricting fluid.
 
joes68340s said:
Yes all the rubber lines are braided lines. I wonder if the smaller braided line in rear could be restricting fluid.
Click to expand...

I’d still check it. Braided lines still have an inner sheath. I would hope that they don’t fail as frequently as the rubber lines, but there lower quality braided lines too.
 
What type of proportioning valve do you have. If it is for front disc and rear drum you need to add an adjustable prop valve for the rear lines
 
When you installed them, did you rotate the piston to compress inward or just press them in with a clamp? If you pressed them in you may have damaged them.
 
dano said:
When you installed them, did you rotate the piston to compress inward or just press them in with a clamp? If you pressed them in you may have damaged them.
Click to expand...

Can you elaborate so that folks like me, who will do this swap in the future and don't know why that's bad to simply press the piston in, might be interested.

Thanks!
 
I believe some of the Mustang rear calipers (94-04) have an integrated parking brake that require the piston to be rotated to move the piston back in the bore. There is a Helix inside that when the parking brake lever is pulled pushes the caliper out to set the parking brake. This needs threaded back in to compress the piston. There is a tool for doing it, some use needle nose pliers. There is a pair of spanner wrench type notches in the piston that you can engage. Ford/Mustang is not the only MFG to use this method. I've seen it on Lincoln, Audi, and Mazda and probably more. My dad pressed the pistons in with a c-clamp on the rear of his 94 MK VIII and trashed both calipers.
 
Last edited:
dano said:
I believe some of the Mustang rear calipers (94-04) have an integrated parking brake that require the piston to be rotated to move the piston back in the bore. There is a Helix inside that when the parking brake lever is pulled pushes the caliper out to set the parking brake. This needs threaded back in to compress the piston. There is a tool for doing it, some use needle nose plyers. There is a pair of spanner wrench type notches in the piston that you can enguage Ford/Mustang is not the only MFG to use this method. I've seen it on Lincoln, Audi, and Mazda and probably more. My dad pressed in the pistons in with a c-clamp on the rear of his 94 MK VIII and trashed both calipers.
Click to expand...

Ahh, that makes sense. Thanks for taking the time to reply with the info.

-=C
 
I am wondering if the calipers will still work properly without the e brake cables hooked up.
 
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