F53 brakes

[twinboat]

Originally Posted by gatorb8

if the brakelines are bleed correctly and the pads/rotors/ calipers are good, I suspect hydroboost

could the rubber brake lines be expanding?

If the lines expanded, the pedal would go lower, until it hit the floor.

I don't recall that being the issue.

[radnpad]

It’s also about weight and tire size also might want to see what the vacuum is for when you are braking, if it is low then your booster won’t function properly.

[CaptronNZ]

Sorry YC1 Pressure IS pressure and the only way this changes is if the applied area changes.

There is a micro time delay for pressure to equalise but PSI is PSI and the larger piston surface area is already almost full therefore there is very little flow. It's all down to the square mm of piston applying force to Sq mm of pad surface area and wheel/weight size and the friction coefficient of the pad.

I agree with another poster that the type of brake pad is also a factor with long life pads tending to give less mechanical advantage and poorer stopping power.

As the F53 chassis is highly leveraged given it only has 16" wheels, stopping becomes critical as mass increases. And a 36' RV fully loaded pushes that limit.

At the moment it feels like an old truck of mine did when I replaced brake pads with metallic pads; i takes longer to stop but lasts longer. I need to find a way to test the booster function.

[vincee]

Class C's on the Ford F450 chassis have 16" wheels, 18K lb. class A's on the F53 has 19.5" wheels, 22K, 24K, and 26K F53's have 22.5" wheels, same size as semis.

[Betr2Trvl]

One very simple, no cost suggestion.

I think you’ll find that pushing DOWN on the brake pedal is much better leverage, and hence more effective braking effort for the same leg pressure vs. the tendency to push forward like you have for most of your life in other vehicles and is a hard habit to break (pun intended) and isn’t something most folks would even think about...... take a look at the brake pedal pivot point, and it’s pretty clear why......

I don’t know if any brake pad that is purposely intended for safe extended high temp use will provide high “cold bite” like pads on most street cars / light trucks have. Better and safer to adjust how much leg pressure you need to apply to lower cold bite, than dealing with no bite unexpectedly when soft pads glaze under high heat conditions.

And yes, it’s actually pretty easy to get into the ABS if you just use your leg (and push down). I’d suggest that you try it sometime in a safe place to do so, at a reasonable speed, and of course everything secure in your RV and I’d suggest you do the same in your cars as well so you know what to expect when ABS engages.

[gatorb8]

Originally Posted by twinboat

If the lines expanded, the pedal would go lower, until it hit the floor.

I don't recall that being the issue.

got it
I still suspect hydroboost or something like glazed pads/rotors if pedal is stiff

[Waiter21]

could the rubber brake lines be expanding?

Yes, a tiny bit, but I doubt this is causing the problem. One quick pump of the brake pedal and you should be good.

Weak brakes tells me either the boost is problem (I kind of doubt, these tend to work or not) or the pads and disk are glazed and / or not bedded properly.

I install severe duty pads (rated for heavy trucks), use a die grinder with a sanding disk in it to clean the rotors. this removes any glazing and exposes metal. Don't grind them, just clean them.

Bed the brakes, This does a high temperature cure of the adhesives in the pads and deposits a film on the disk, this process greatly improves the friction.

[F4Gary]

Originally Posted by TeJay

I'm not an expert on brake lines but I'm almost 100% sure all flex brake lines are covered with steel webbing which would/should prevent them from expanding.

Factory brake hoses are almost always not covered with braided steel. You have to go aftermarket for those. Especially on a 2010 F53 truck chassis.

[CaptronNZ]

Greetings Vincee, and while your assessment of the F53 wheel sizes may be accurate, it still elaves out the older F53's with 16" wheels - like mine.

Thanks for everyones suggestions.