Front brakes

Grit dog wrote:
What I found was during acceleration, if wheel spin was detected, the car would apply braking force to the rear brakes to control minor wheel spin prior to defaulting to traction and stability control engaging.

Excellent point and trucks do that too when the box is unloaded, ie RWD with no weight over the drive wheels. Similar to my point that proportioning valves that use ride height sensors are overusing rear brakes when they sense that the truck is unloaded.

RoyJ wrote:

Grit dog wrote:
There's a reason that front brakes are never smaller or less capable and generally always larger with more stopping force than rear brakes on ALL vehicles.

On LIGHT vehicles / trucks.

Starting in Class 4 / 5, rear brakes starts to match or slightly exceed the fronts. Ram 5500s have 15.5" rear disks IIRC.

Class 7 and above, single / tandem axle dumps, city buses, hwy coaches, tractors, all have significantly more rear braking power than the front. There's a point where weight transfer can't overcome the much heavier rear axle, especially with long wheelbases.

Yup, 10-4, roger that, I agree. This thread was about a 3/4 ton truck though.
My mistake for using the term “all” without context …

Grit dog wrote:
There's a reason that front brakes are never smaller or less capable and generally always larger with more stopping force than rear brakes on ALL vehicles.

On LIGHT vehicles / trucks.

Starting in Class 4 / 5, rear brakes starts to match or slightly exceed the fronts. Ram 5500s have 15.5" rear disks IIRC.

Class 7 and above, single / tandem axle dumps, city buses, hwy coaches, tractors, all have significantly more rear braking power than the front. There's a point where weight transfer can't overcome the much heavier rear axle, especially with long wheelbases.

mkirsch wrote:

Grit dog wrote:

RoyJ wrote:
The front brakes more under HEAVY braking. The proportioning valve assumes enough weight transfer has occurred and send more hydraulic pressure forward. Under light braking, most modern trucks/cars use the rears more.

Now if the fronts are actually cold / lukewarm, there might be a problem.

Have you tried hard (threshold of ABS) braking and then carefully feel the front for increased heat?

scroll up 2 posts. OP said his brakes work fine.

Then why in hell did he ask the question in the first place?

Exactly!
But what I gathered from his cryptic first post was that he slapped now pads on all 4 corners and 1 or 2 new rotors in back. And then drove it around the block once, stuck his finger on each brake and found that the one(s) with the most friction with new rotors were warmer.

Grit dog wrote:

mkirsch wrote:
BenK that's all well and good but all that does not stop the adjuster from rusting up and throwing the whole thing on its ear. Who wants to be tearing apart their rear brakes every 6 months to free up/replace the adjusters? That's why they end up the way they end up.

While BenK is reminiscing about his nose bleed brakes, he does have a very good point.
ANTI-SEIZE! Being in the upper rust belt, you should be like the Frank's Red Hots grandma and "Put that on everything!"

Did that. Pulled the adjuster completely apart and gobbed it on like butter on an ear of sweet corn. Still seized up in 6 months. Pull the drum off and there is no evidence of it ever having been applied.

Grit dog wrote:

RoyJ wrote:
The front brakes more under HEAVY braking. The proportioning valve assumes enough weight transfer has occurred and send more hydraulic pressure forward. Under light braking, most modern trucks/cars use the rears more.

Now if the fronts are actually cold / lukewarm, there might be a problem.

Have you tried hard (threshold of ABS) braking and then carefully feel the front for increased heat?

scroll up 2 posts. OP said his brakes work fine.

Then why in hell did he ask the question in the first place?

mkirsch wrote:
BenK that's all well and good but all that does not stop the adjuster from rusting up and throwing the whole thing on its ear. Who wants to be tearing apart their rear brakes every 6 months to free up/replace the adjusters? That's why they end up the way they end up.

While BenK is reminiscing about his nose bleed brakes, he does have a very good point.
ANTI-SEIZE! Being in the upper rust belt, you should be like the Frank's Red Hots grandma and "Put that on everything!"

My 2003 2500HD had the rear brakes done at about 200,000 km & the fronts were worn out about 30,000 km later. Most of the driving was done unloaded.

BenK that's all well and good but all that does not stop the adjuster from rusting up and throwing the whole thing on its ear. Who wants to be tearing apart their rear brakes every 6 months to free up/replace the adjusters? That's why they end up the way they end up.

mkirsch, agree...but drum/shoe setup can be super tuned to be pretty good...still not as good as disc

Supper tune has to start when they are brand new. Once the slider wears a groove in the backing plate, they will never be able to be super tuned.

Part of that super tune is to liberally coat the adjustment assembly with anti-seize grease. Inside the dead-end hole, the rod that pokes into that hole, star wheel side, etc....but...not so much as to have it migrate to the friction material

Then the backing plate where the shoe edge rides on. I rub in (burnish) anti-seize and not so much to have the grease get onto the friction material.

There is a reason all shoes edges have that V or Z bent, and it is to increase the surface area & to NOT wear a groove into the backing plate because the 'swept' area is larger

Also grease the self-adjuster cable routing

Back when was a partner in a SUV/Suburban forum, many complained about poor rear braking performance. Even went out and helped a few and all of them had almost brand new rear shoes when they took it apart (just supervised their hands on, as won't hands on personally). One guy had over 100K miles and his shoes were brand new)

Too many variables to have one size fits all regarding front vs rear braking.

Back on the OP's question/situation...since they didn't notice until the rear went metal to metal, doubt if they will now know the difference with brand-new friction materials on all four. Guessing a repeat to find metal to metal down the road...unless their mechanic found and fixed whatever was the 'real' problem