Brake issues

[Andy Illes]

There have been a lot of posts about brake issues (and I got several PMs about it about a year ago).  Just now, Rodney with soft brakes.  So... since it's nice to be able to slow/stop 3+ tons of Clipper barelling down the road..... here's what I've learned from watching my farrier shoe my horses... which work sortta like brakes.... except ya gotta go "whoa", instead of stomping a pedal.

In essence, here's how brakes work.  There are 2 types of hydraulic brakes... disc and drum.  Drum brakes (rear) are like a cake pan that rotates with the wheel.  Inside are 2 "shoes" with a friction material on the faces to contact the drum, and are fixed to the axle.  Little double-ended hydraulic cylinders push the shoes out against the drums to brake.  Disc brakes (front) have a beefy disk that turns with the wheel, and a fixed "caliper".  The caliper is a U-shaped jobbie that fits across the disk, with hydraulic pistons on both sides that clamp friction pads against the disk.  Brake lines connect the cylinders and calipers to the master cylinder on the firewall.  The master cylinder is basically a pump that forces brake fluid to the cylinders/calipers when the brake pedal is depressed.  Between the pedal and master cylinder is a large "drum", which is the vacuum booster.  When the pedal is pushed, it's linkage works the master cylinder, and also actuates a valve in the booster (through which the mechanical linkage passes) which applies vacuum to a large diaphragm attached to the mechanical linkage, adding a considerable boost to the manual pedal pressure.  If you wanna see just how much, go to a safe place, disconnect the vac line to the booster.... and try stopping.  You better have thighs like Ahnold!!!

On braking, what happens is that, through linkages, you push a piston in the master cylinder.  The piston draws brake fluid from the reservoirs on top and forces it into the brake lines, and on out to the wheels.  Since fluids don't compress (like air), equal pressure goes to all 4 corners, expanding the rear cylinders/shoes against the drum, and clamp the calipers on the front rotors to effect braking. If there are air bubbles present in one or more lines, the air will compress and "absorb" braking pressure, giving a "soft" or "spongy" feel to the pedal... and also, any so a brake with air in its line will also apply later than the others that don't have air... or not at all, depending on how much air, and brake pressure.  If you brake hard enough, that wheel will also begin braking if/when the air is compressed to the same pressure as the hydraulic pressure, though with a spongy pedal.  With less brake pressure, the vehicle will pull to one side or the other, since one side is braking more than the other.  If a line with air in it is heated, the air bubble will expand and can apply braking force to that wheel, causing the brake to drag and the vehicle to pull to that side.

Since most of you are W. Coasters with mountains, brake heating is also worthwhile to understand. Although brake fluid is formulated for a high boiling point, hard continuous braking can nevertheless heat it enough to boil... with a result identical to air in the lines, enough that you can run out of pedal-travel and get you slapping your head for not having a parachute along.  Also, as the friction material on the shoes and pads heats, it progressively loses friction ability, and braking fades as a result.  

Metallic linings/pads (and now, ceramic) and silicone fluid (DOT 5) tolerate MUCH higher temps, which is why you won't find a single NASCAR/Indy?Formula/Baja/motorcycle, etc., racing team that doesn't use them. Silicone fluid also doesn't absorb moisture. The only thing to switching is that you MUST THOROUGLY PRESSURE FLUSH all of the old, regular fluid out with denatured alcohol... these fluids are NOT compatible!!!  Switching to silicone fluid, and premium high-temp (i.e., metallic) linings/pads is - in my opinion - a VERY worthwhile, relatively inexpensive, investment.
   NOTE: Disc calipers require special attention to flush, because they contain a small reservoir of fluid that will ordinarily not drain, since the drain nipple is at the top.  The pads/pucks must be fully depressed to expel as much old fluid as possible before flushing... or even better, the caliper should be disassembled for flushing.

First thing in any brake diagnosis is to make sure the reservoir is full.  Look for a rectangular cast iron jobbie, most likely on the firewall under the hood, with a cap on it held by a spring clip.  That's your master cylinder.  Just flip the clip off with a screwdriver.  There are 2 chambers and both should be full.  

   TIPS: 1)  Wet pads/linings significantly diminish braking until dry.  After a puddle, brake hard for a few seconds to dry them... and if running in rain, do it periodically... so you have good braking when you need it.  2)  When checking fluid level, if it looks dark & grungy, flush the system... it's worse down in the lines and wheel cylinders/calipers.  3)  Bad tire pressures can mimic brake problems. 4)  If your Clip's been sitting a while, apply light brake pressure the first 20 yards so to polish rust off the discs/drums.... it'll keep your wife from launching into the glove compartment at the first stop.  4)  Periodically, check each wheel for leaks... a wet streak down the INSIDE of wheels/tires (on rears, could also be axle seal leak... feel/smell it).  4) When getting a "brake job", make SURE the thickness of rotors and drums is measured, the minimum is stamped on 'em.... do NOT machine to less.  5)  Do NOT economize on linings/pads... get premium metallic.  5)  Even minor brake dragging can cause rapid tire wear and axle seal and bearing failure (from heat).  6)  At the FIRST sign of brake trouble... diagnose and fix it.  It will NOT go away or get better!!

TROUBLESHOOTING:

Stops ok but VERY hard pedal - Power brake problem.  The vacuum booster's that big round gizzmo under the hood, attached to the master cylinder, that the brake pedal linkage goes to.  There is a large (usually metal) vacuum line to it from the carb base.  Remove it at the booster with the engine running... you should feel strong suction.  If there's good suction, new booster time.  If not, look for a leaky line.

- Pedal goes to the floor easily with hardly any, or no, brakes (can often be "pumped" back up) - Bad master cylinder.  Very low or no reservoir fluid, and/or a TON of air in the lines.

- Stopped with brakes on, pedal slowly sinks (can often be "pumped" back up) - Bad master cylinder.

- Soft pedal, but with some and/or uneven braking - Air in the brake line(s).

- Pulls to one side or the other (no noise) on light to moderate braking - Air in the line(s) on the side away from the direction it pulls (with soft pedal).  Oil/grease on brake linings/pads (good pedal).

- Grinding/grating/squealing noise, with or without good brakes or pulling - worn linings/pads.
   NOTE:  Sometimes, good disc pads chatter and/or squeal.  Check that any retaining clips are in place, and all parts stores carry goop for noise.

- Solid pedal, good brakes, but pedal goes down too far - misadjusted/worn rear brakes (disc brakes are inherently "self adjusting").

- Pedal feels ok, no pulling, but braking seems only 1/2 usual - Half the master cylinder's piston is shot (it's a dual system working diagonal wheels).

- Pedal "pulses" - Warped rotors and/or "hard spots" on rotors and/or drums.

- Brakes drag/don't release - Air in lines.  Loose/cocked disc pads.  Cocked pistons in front calipers.  Broken return springs on rear shoes.

- Pulls, regardless of braking - Low tire pressure or dragging brake on side it pulls to.
   NOTE:  A draggy brake can be from air in that line, or a sticking wheel cylinder/caliper. Bleed first, see if that fixes it.

   Comment:  As seen, a lot of brake issues trace to just air in the lines.  Brake lines snake up and down and every which way.  It's VERY difficult to get air bubbles which have risen to the top of a bend (particularly where lines loop over the rear axle) with the pump-the-pedal/bleed/pump-the-pedal method (for one thing, it's really a 3-person job... one pumping the pedal, another underneath bleeding a brake, and another keeping the reservoir full).  A pressure bleeder can be rented, is a one-man job, and moves a LOT of fluid a LOT faster, and in a steady stream, to move bubbles right along and out, no matter where.  Most hold a quart, so all you have to do it replace your reservoir cap with the pressure bleeder's, fill the bleeder with fluid, pump it up... get underneath and start opening bleeders.   It's also a great way to flush the system with denatured alcohol and switch to silicone fluid...


Hope this helps someone.
Andy

[Rodney]

Thanks Andy
good stuff to consider. I still don't think I have all of the air out of my system after using an vacuum bleeder at each wheel and pumpin a quart of fluid thought the system You would think that would do it but I am still at about half peddle after the play in the linkage is taken up which is about and 1 inch. good and solid about half way down. I replaced the read shoes when I did the rear axle work and have them adjusted right up. I am going to drive it a few miles while towing and see how she  does.
I haven't ever towed the boat which doesn't have any brakes on the trailer so I am asking a lot from the brakes on the Clip. When I towed the race car on the car trailer which has a good set of brakes on one axle the rig stopped very nice. I am considering brakes on the boat trailer as heavy as the Clippers are alone I just  may be asking to much stopping to much weight with to little brake.  Brakes Like Taquilla I don't think a Guy could have to much :lol:
Cheers
Rodney

[Andy Illes]

Hiyya Rodney.

Just read your other post about the brakes.... I'm glad the pressure bleeder did the trick.  It's really the only way to go.  Mine has a bunch of different cap-adaptors, with one of 'em having the line coming out the side, which fits the tight Clip space without removing the master.

Your post got me wondering why I'm wearing the (new) passenger-side rears like crazy.  I looked at the brakes and they were fine, but I hadn't thought to check the brake lines like you did.  Thanks for that heads-up.  Next project for me...

Anyway, glad you're stopping ok.

Andy

[Rodney]

Yes Andy they are much better now
We took the clipper down to the lake this weekend for some boating and to test out the brakes. I had the boat already down there so it was an easy test drive, we did need the extra room for the 3grandkids, wife coolers, Water toys ect. That was great to have all of that room to haul the stuff and a place to mix a margarita after the days fun on the lake. The brakes were a but smelly from the spillage of the fluid from doing the job. I Gunked and hosed the mess down but still had to burn off the mess. I knew right away that the rear brakes were working better than ever Cuz I could hear them squeek some when getting into them on the hill.
Something must be UP with your system if you are wearing uneven?
I am going to pressure test the lines and see what  each wheel is getting. I have the gauge made up for setting up my race car. On the right track now but going to take it a little further when I find the time.

See ya
Rodney

[Andy Illes]

Rodney... I just crawled back out from going over my lines with a fine-toothed comb (it's a daybreak job here, before the sun gets hot).  Sure enough... surprise, surprise... a nasty little kink on the driver's side, so I'd guess the passenger-side mustta been braking earlier, and those tires were taking the brunt of initial braking.  Not sure why it didn't show up before this last trip back from DC, maybe from the little rebar incident?  Though I didn't see anything that looked like the line got a hit.  Oh well.  Now, it's into town for new lines, then dig out my tubing bender, flanging tool and jug of silicone.

Thanks again for that tip, I wouldn't have thought to look for that otherwise.  Are these great forums, or what?!   :lol:

[Andy Illes]

Rodney... I just crawled back out from going over my lines with a fine-toothed comb (it's a daybreak job here, before the sun gets hot).  Sure enough... surprise, surprise... a nasty little kink on the driver's side, so I'd guess the passenger-side mustta been braking earlier, and those tires were taking the brunt of initial braking.  Not sure why it didn't show up before this last trip back from DC, maybe from the little rebar incident?  Though I didn't see anything that looked like the line got a hit.  Oh well.  Now, it's into town for new lines, then dig out my tubing bender, flanging tool and jug of silicone.

Thanks again for that tip, I wouldn't have thought to look for that otherwise.  Are these great forums, or what?!   :lol:

[Rodney]

Those small kinks are hard to see when the line is wrapped with the wire.
hope that it solves your brake issue. I am  much pleased now after getting mine back to where they were. I am pretty sure I kinked the brake line on my clipper... :oops: sometimes a person can be his own worst enemy :twisted: .
I took a pair of flat {duck bill} vise grips and carefully pintched of the rubber line going to the rear axle while I changed the line so's not to lose all of the fluid and have to struggle with the bleeding issue again.  
time for work so talk to ya later
Rodney