Weird Brake problem

[Bullitt-]

But If I understand brakes correctly...The caliper's piston and flex hose and line are all full of fluid...when you press the brake pedal more fluid tries to enter the same area causing pressure....it's not like there's a large open cavity that fluid has to fill...so I'm not certain where the volume of fluid comes into play....
However...I don't know what I'm talking about, and that's why I have a mechanic 

The way I'm looking at this is based on observation of most every front brake pad set I've replaced down through the years..The left side virtually always has more wear than the right... WHY?  I've been told that the line to the left side is shorter & offers less resistance than the right..makes sense to me even if the difference is imperceptible to the driver it's obviously there .. OK so you exaggerate the difference what's gonna happen? 
As far as explaining why pressure doesn't go down with some restriction I'd use the straw in the milkshake as an example.. bigger straw you can suck more shake through than a small straw given that you suck with the same effort... of course I could be wrong...LOL 

[dodj]

Pressure won't go down with restriction, but will make it take longer to reach pressure. So you will see the same pressure but reaction time will change. With hydraulics, flow is speed and pressure is strength.
I believe Bullitt is on the right track. With a blockage, flow is reduced, the pass side will catch up but you already released the brakes because of the left locking up. 

[anlauto]

I just called him and changing the rotors made no difference.

I just read him dodj's reply and the next thing he's going to try, is making a makeshift brake line going from the "T" block to the passenger's side flex hose.... then bleed that

He did mention that they did have "nice" flow on both sides while bleeding the brakes...

[CUDA JAS]

Are you sure he is using a Disc / Drum MC and not a Drum / Drum MC.

Not sure it would cause the problem, but you never know.

Jason

[Chryco Psycho]

there really is very little fluid movement , less than 1 oz so even restricted I cannot see it making that difference just for a split second at most .
 take a caliper to the pistons & make sure they are the same diameter , that will change the clamping pressure . They should be the same diameter but what if they  are not ?
 the front splitter block could be a problem but why have the same flow & pressure if it is restritive there ?

[brads70]

there really is very little fluid movement , less than 1 oz so even restricted I cannot see it making that difference just for a split second at most .
 take a caliper to the pistons & make sure they are the same diameter , that will change the clamping pressure . They should be the same diameter but what if they  are not ?
 the front splitter block could be a problem but why have the same flow & pressure if it is restritive there ?

Just a thought...? what if the piston oring was on backwards in one caliper? It wouldn't retract the same? I guess it would leak though? 
He did say he tried different calipers though? 

[734406pk]

I just called him and changing the rotors made no difference.

I just read him dodj's reply and the next thing he's going to try, is making a makeshift brake line going from the "T" block to the passenger's side flex hose.... then bleed that

He did mention that they did have "nice" flow on both sides while bleeding the brakes...

Nice equal flow while bleeding the brakes should indicate that the brake lines are ok. A restriction in a brake line usually will make one caliper slow to apply and also slow to release, (stuck caliper symptom). If this were the case, a separate pressure gauge, one on each caliper, should show a lag in pressure drop after the brake pedal is released when compared to the opposite side IMO.  How are the front tires? Tire pressure equal? Check to see if the tread pattern is directional and one tire is on backwards. Maybe try swapping left/right front tires?  Its a long shot.

[1 Wild R/T]

Might be time to invest in a new tool....

http://www.autoserviceprofessional.com/article/94527/tool-review-disc-brake-analyzer

It's measure brake pressure, but not the fluid pressure the actual mechanical force applied by the pads...

[73440]

The problem I had with a hose was not on a brake line per se, but what happened was  the internal lining of the hose had torn inside and acted like a flap blocking pressure in one direction.
Are the flex lines new?

[dakota]

A different angle: a while back, I changed the brake booster on my brother's car.  I didn't get the length of the threaded shaft on the booster quite right (too long), which kept the piston in the master cylinder from completely retracting when the brake pedal was released. The holes in the piston that are supposed to line up to release the brake line pressure were covered.   Once the caliper started to drag, it heated up the fluid stuck in the line which caused even more drag, particularly in the shorter brake line (driver's side) to the point where the driver side front caliper locked.   After pulling the master cylinder off the booster and turning the threaded post on the booster in a couple of turns, the problem went away.

[734406pk]

The problem I had with a hose was not on a brake line per se, but what happened was  the internal lining of the hose had torn inside and acted like a flap blocking pressure in one direction.
Are the flex lines new?

Yes, the hose flap acts like a check valve.

[AARuFAST]

Maybe not brake issue.  Check all of the front suspension..A bushings, tie rod, shock. bearings. 

[Chryco Psycho]

You could install a piston backwards it would hold a lot more fluid but would act the same .
 I have seen the torn inner lining problem before also but this seems to be releasing OK just appling differently .
 If they are ordering the same part #s the piston size could be different though

[spamtank]

 

[73_Cuda_4_Me]

What make / model Mopar?

Wheel bearing adjustment will affect braking, as will worn inner bushings on caliper mounting pins (lets caliper assembly tilt adding mechanical leverage to pad force)...