Cobra Brake Swap Issues

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98BLKLSC

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I recently bought a Mark VIII that already had the Cobra 13" brake swap on the front.

When I first got the car, it would pull hard left during any moderate braking. I attributed it to a stretched soft line on the passenger side. I replaced the soft lines on both sides and that problem went away.

A problem that it continues to have is no braking power. If you ease into the brakes it stops better than if you nail the brake pedal. It's almost as if the brakes fade instantly.

Any ideas? I don't think the calipers or lines are bad. I am thinking it's the brake booster, but I am not sure.

Help is appreciated! Let me know if you need more info for diagnosis.

97 Mark VIII LSC Cobra PBR calipers 13" front brakes, stock rear.

EDIT: Reference THIS thread as this is the previous owner of the car.

EDIT 2: Reference another GMAN thread. THIS
 
Air in the brake lines since you replaced the soft line.

Also of note, how are your lower ball joints doing?
 
I just replaced the upper control arms / ball joints and lower ball joints yesterday, so those are new Moog pieces.

The car did this before the soft lines were replaced and it bled fine. I don't think braided lines would change anything because new rubber lines wouldn't balloon.

Any other ideas?

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Pads are bedded in. I am going to have the rotors turned / pads replaced because I don't know if they're crappy pads.

Crappy pads doesn't explain what is going on though.
 
THIS thread is the same issue and it's the previous owner of the car.

I guess the master cylinder and brake booster have been replaced, so what does that leave? The front calipers are new-ish and the front rubber lines are new.

So that leaves the rear lines and calipers and/or air in the system. When I bleed it next, how do I get the ABS pump to turn on?
 
I was asking about diag trouble codes wondering if ABS is the problem
 
After you did fronts did you bleed all 4? Also when you bleed do you bleed with hose into a sealed container with 1/2 inch of fluid already in it? If not ,you should.
 
Find a gravel parking lot and panic stop a few times. Or drive it in a grass field and slam on the brakes a few times. It will pass the air thru the pump, then you can bleed it out. That's pretty much how I did mine.
 
The answer to your issue is in here....

ebc_supreme_brake_chart.jpg
 
What does it matter if it goes into a container at all ? I've bled out thousands of brake systems and never used a sealed container with fluid already in it..
however for Painted calipers, using a hose attached to the valve will help prevent drips from getting on the paint


20120822_120326.jpg
 
I have bleed millions of brakes with out container also. If you want to make sure 100% your not getting air in system while bleeding this helps. Just did this on ice bleed brakes 2 times, pedal felt soft. Did the container bleed and nice firm pedal. Plus when you use clear tubing you can see if fluid is coming out solid or still air bubbles in fluid.Also another thing that can be done if bleeding with hose is grease around bleeder to make sure not sucking air past bleeder threads. I am not TELLING people what to do just throwing things out there. Take it or LEAVE it.
 
Sapperfire, I assume you have tightened that upper control arm bolt since the photo? Looks a little dangerous as pictured....
 
DieselDan said:
Find a gravel parking lot and panic stop a few times. Or drive it in a grass field and slam on the brakes a few times. It will pass the air thru the pump, then you can bleed it out. That's pretty much how I did mine.
Click to expand...

I will have to give this a try. On pavement, they don't engage hard enough to come close to engaging ABS. I don't have any DTC or CEL for anything. I have a friend with access to IDS, so maybe I can see if he'll come over and run the ABS pump for me.

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Right on the Mark said:
I have bleed millions of brakes with out container also. If you want to make sure 100% your not getting air in system while bleeding this helps. Just did this on ice bleed brakes 2 times, pedal felt soft. Did the container bleed and nice firm pedal. Plus when you use clear tubing you can see if fluid is coming out solid or still air bubbles in fluid.Also another thing that can be done if bleeding with hose is grease around bleeder to make sure not sucking air past bleeder threads. I am not TELLING people what to do just throwing things out there. Take it or LEAVE it.
Click to expand...

Thanks for the advice. We did not bleed them into a bottle with fluid already in it. I'll make sure I do that next. Grease around the bleeder sounds good too.

I wish one of you was close to NW Ohio so you could help me. I appreciate the help so far.

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I bled mine by myself recently with a vac/pressure tester (Mighty-Vac) type gun; it took awhile b/c I went around 2x, just like you said: rear pass, rear drv, front pass, front drv....all new clear fluid, some guys use blue fluid to see better....speed bleeders help but they're about $12 each
 
Post 3 from JA. on the link you posted.
Will it hold it if you power brake the car?
Click to expand...

Did you see if the brake can hold the car?
Its not clear if g-man did this.
 
Yeah man, I just hung everything up to snap a pic, then everything came back apart for more painting.. then all back together and torqued
 
dnsherrill said:
I bled mine by myself recently with a vac/pressure tester (Mighty-Vac) type gun; it took awhile b/c I went around 2x, just like you said: rear pass, rear drv, front pass, front drv....all new clear fluid, some guys use blue fluid to see better....speed bleeders help but they're about $12 each
Click to expand...

I will have a friend help and see if I can get a vaccuum bleeder. I'll probably just stick with cheap fluid until I figure out the issue and know it's solved.

ford nut said:
Post 3 from JA. on the link you posted.


Did you see if the brake can hold the car?
Its not clear if g-man did this.
Click to expand...

The brakes can NOT hold the car. I have tried this a few times (burnouts of course!) and no luck past maybe 1500 RPM. That seems like a really, really low stall, so I'm thinking the brakes are just weak.

For any other clarification, I did not bleed all 4 when I cracked open the front.
 
That's fine that you only bled the fronts, as long as you never let the reservoir run dry. I still thi I you have air in the system. Are your bleeders pointing up?
 
DieselDan said:
That's fine that you only bled the fronts, as long as you never let the reservoir run dry. I still thi I you have air in the system. Are your bleeders pointing up?
Click to expand...

The reservoir never went dry when I was bleeding them. The front bleeders are pointing up, yes.

Rear, I haven't looked yet.

If only the front brakes were working, wouldn't the car still be able to be held with the brakes? The car pushes before the tires spin. I know all 4 brakes are engaging at least a little since the rotors stay "clean".

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