What causes brake distribution to change when braking in reverse with 4 wheel disc

[AuroraGirl]

My car periodically will feel like its not braking very well, and ive found if I reverse and slam the brakes 1 or more times in reverse, it will make braking much more responsive and properly balanced, as if the front brakes are doing the fair share more so than before.

99 park avenue, 4 wheel disc brakes factory. not upgraded, all stock.

 

[foamypirate]

A lot of brake assemblies are designed to self adjust when applied in reverse. Very common design.

 

[AuroraGirl]

A lot of brake assemblies are designed to self adjust when applied in reverse. Very common design.

Mine say they do that automaticallyt and when forward. The rear also has no drums which is usually the adjustment. But its more than just adjustment

 

[Grit dog]

Disks have no “adjustment” like drums.
Not sure what phenomena happens to make them work better when you do the reverse adjust thing like for drum brakes, but a likely cause is a sticky caliper somewhere.

 

[1987 GMC Jimmy]

I’m no physics major, but the first thing that came to mind was also a pair of sticky calipers or a pair of brake hoses that’re collapsing on the inside. If it was just one hose or one caliper, it would pull to the side opposite the problem. Is it a big dual piston on the front and a baby, single piston on the back? I’d go through the fronts first because 70% of your braking action occurs there.

 

[AuroraGirl]

Hmmm, I think Ive had one behave stuck onece that corrected from a large stomp. I actually have new calipers to go on the car that I will be doing once I recieve dust shields. Rear were replaced. Brake hoses are also new. If it sounds like caliper not operating correctly, id bet you its probably the situation. When reversing it probably puts the calipers back to equal pressures, amounts, and stopping forward works properly for a hot minute. thanks

 

[AuroraGirl]

Would a banjo bolt being incorrectly installed/hose the incorrect direction cause what I describe?
My caliper hose had 4 crush washers and the hose was backwards on passenger side. ON driver side, the hose was correct but had 3 washers.

I hate this shop.

 

[foamypirate]

Disks have no “adjustment” like drums.
Not sure what phenomena happens to make them work better when you do the reverse adjust thing like for drum brakes, but a likely cause is a sticky caliper somewhere.

Oh, yep, you are correct. I missed the 4 wheel disc part.

 

[Grit dog]

^ Well it is impressive that the brakes don’t leak with stacked washers, so there’s that. Guessing the shop stacked washers to get the hole in the banjo to line up with the slot in the hose fitting and/or not bottom out in the caliper.

Why that stuff doesn’t fit? Wrong bolt or wrong hose.
But brakes don’t generally only work sometimes and not others. So this issue is perplexing. It’s not like an electrical short that is random.
Now, the ABS or some system could be randomly malfunctioning causing intermittent issues for sure.

 

[bucket]

^ Well it is impressive that the brakes don’t leak with stacked washers, so there’s that. Guessing the shop stacked washers to get the hole in the banjo to line up with the slot in the hose fitting and/or not bottom out in the caliper.

Why that stuff doesn’t fit? Wrong bolt or wrong hose.
But brakes don’t generally only work sometimes and not others. So this issue is perplexing. It’s not like an electrical short that is random.
Now, the ABS or some system could be randomly malfunctioning causing intermittent issues for sure.

Hmm, ABS. Does the ABS not operate in reverse? I'm pretty sure is does on other GM cars, but maybe not this one. Maybe there's an ABS problem and it's not letting fluid travel where it needs to, but mashing the brakes while in reverse let's it happen.