Brakes don't work

[Clyde9]

From: MustangGT221  (Original Message)    
Sent: 5/24/2004 11:50 PM

Hi all,

Got my 72 Winnebago brave up and running now after sitting for 3 years. I was moving it around and realized that the brakes don't work. The e-brake was left on during those years, but I was able to move the vehicle fairly easily so I'm fairly sure it's not stuck. However, when I'm moving along at say 5mph, only the last inch of brake pedal stops the vehicle, there is not really any resistance either. I assume it might be low on fluid or needs to be bled....any thoughts?



Sent: 5/25/2004 7:56 PM

     I had the same problem last summer.  Check the following:  Wheel cylinders.  My rear wheel cylinders were leaking.  Also check the master cylinder.  I replaced mine because it had a small leak, and figured that a new one wouldn't hurt.  Also check for a leaking brake hose.  My repairs cost me a total of $350.00, not too hard on the old wallet, but a very needed repair.



From: denison    
Sent: 5/25/2004 8:17 PM

Lots of thoughts. Its not too surprising that your pedal goes to the floor, after the rig was sitting for 3 years. For sure you would need to bleed the brakes, first filling the master cylinder reservoir with fluid, then bleeding the boosters, then the wheel cylinders. While doing this you keep an eye out for fluid leaking from the wheel cylinders, or anywhere in the system. And of course keep refilling the master cylinder. That should improve the pedal action a lot. But it is likely you will be facing more brake work -- unless the wheel cylinders and master cylinder were nearly new 3 years ago. They don’t last as long when sitting for long periods as they would if they were in occasional use. The outcome of non-use would be the absorption of water into the fluid within the wheel cylinders and the master cylinder, and rust having formed in the bores of those cylinders. Some of this is normal and inevitable. A lot of it means enough corrosion of the smoothness of the bores, of the wheel cylinders and the master cylinder, as to need replacement or rebuilding. The boosters aren't as susceptible, since they are in the middle of the brake system, and don’t have as much opportunity to absorb water into the brake fluid. There are other reasons the pedal might go to the floor beside air in the brake system. If the wheel cylinders stick with the shoes extended, you will be wearing out the brake linings quickly, faster than the self adjusters can keep up with. Its also possible that the self adjusters are a little rusty and havent been adjusting the shoes up toward the drum as they should do.
Your would either have the parking brake (I call it a parking brake because I consider it too small to be useful for stopping the moving motorhome) on the end of the transmission, or on the rear axle. In either case the handbrake cable is likely to be stiff from old age. And you might be able to pull it on okay, but when you release it, I would expect that it doesn’t fully release the brakes shoes. Unless that cable is new enough to be shiny all along its length, I would check it for being seized up. on condition, and
I advise people to remove their brake drums and inspect the brake assemblies, free up the self adjusters, and generally take stock in there. Without good brakes, your motorhome is just a spare room for the in-laws.



From: MustangGT221    
Sent: 6/1/2004 3:20 PM

Well I checked the fluid level, the rear cylinder was empty and the front was almost empty. I filled it up and adjusted the front brake drums w/ the star wheel. It improved the pedal on the bottom end of the stroke, so they work right now and it stops the vehicle, but I'm going to adjust the rears too and see what happens..then go from there. I have a feeling it'll need a new master cylinder and maybe a booster.

Also, when you put the brake pedal to the floor as far as it'll go, the brake light on the dash comes on, whats that mean?



From: Im-still-Lefty    
Sent: 6/3/2004 12:40 AM

It means that there is a failure in the brake system. A light means you have
a brake circuit that is not producing pressure. It works by having a sliding
contact that will stay in the center when both sides have pressure, but will
be be pushed to one side if there is a lack of pressure in one side of the
system. Check it immediately. Lefty



From: LookNforTruth2    
Sent: 6/3/2004 5:15 PM

Hi there,
     We're having the same problem of the light coming on. How exactly would one go about checking the pressure of the braking system to make sure it is in proper working order? Any feedback would be greatly appreciated.

Marvin



From: Im-still-Lefty    
Sent: 6/3/2004 11:17 PM

Ok, picture this, you have a plastic drinking straw with a bb pellet in it,
If you blow through either end the bb will move to the open end because there
is less pressure at that end. Now, suppose you take the same set-up, except
this time you have a friend at the other end blowing just as hard as you,
The bb will stay in the center because the pressure is equal at each end.
The brake light switch works just like this, you have both circuits from the
master cyl. (front, and rear) coming in, applying pressure to the sliding
switch inside the tube. If there is a lack of pressure in either part of the
system, front, or rear, the light will activate. A loss of pressure can be
for a wide array of reasons, bad master cyl., air in lines, holes in lines,
leaking calipers or wheel cyl. leaking hoses, lack of fluid, etc... you get
the idea. The professional way would be to hook up a special gauge to the
brake lines and read the the pressure produced at each wheel, then compare
that with the specifications to determine if there is a problem. Another
approach, much less accurate, is to pump up the brake pedal and hold it.
Then loosen a bleeder to verify that fluid comes out under pressure or not.
Starting at the wheels, and then working your way to the master cyl. one
joint at a time until you get fluid coming out, will find a blockage. If you
make it all the way back to the master cyl. without hitting fluid will tell
you the master cyl. is bad, or clogged, or needs bleeding. The down-side is
that you may get fluid out, but without a gauge you won't know if it is of
the correct pressure or not ,to safely apply the brakes ,evenly at each
wheel. Hope this helps a little, Lefty



From: denison    
Sent: 6/4/2004 11:42 AM

Besides air in the line (which is most likely) or an internal blockage (more rare but can happen with an old brake hose having inner deterioration) another cause of the brake fluid displacement -imbalance- making the red light come on can be that one (or more) of the brake self-adjusters are stuck. If all of the adjusters are working, they keep the brake shoes positioned almost touching the surface of the drum. Thus a wheel cylinder doesnt have to move far to be applying the brakes and only needs a small volume of brake fluid to do it, and your foot doesnt move the pedal very far.
With a stuck self-adjuster the lining still wears away with use, but the shoe returns to the fully retracted position afterward, instead of being held properly close to the drum surface. After enough braking action it then has to travel further to the drum, which takes more fluid coming into the affected wheel cylinder, and causes enough unbalance to make the red light come on. And your foot moves the pedal further.
I recall that your winny had the 413 engine? If so, it probably has the dual hydrovac booster brake system. There would be two large vacuum chambers mounted inside the frame rails halfway to the back of the chassis instead of a single vacuum chamber mounted in front of the master cylinder like cars have. They each have a hydraulic brake actuator attached, like a long remote master cylinder but without the bulky fluid reservoir. Both of these will have bleeders on top and need to be bled also. I bleed them before proceeding to the wheel cylinders. If yours are as stiff as mine were, spray the bleeders with penetrating oil for a few days before you try to loosen them, and be sure to use a wrench that is 6-point, not a 12 point! I think the size is 7/16th, or it could be 3/8th. You should only use 6 point wrenches on any brake bleeder nipples, and 6 point flare-nut wrenches on the brake line fittings. People often overtighten them too. Take good care of the hydrovac boosters, they are expensive to get rebuilt.
If bleeding the Entire system doesn't solve the red light coming on, and the master cylinder isnt leaking fluid into the pleated rubber dust cover, my next step would be to dismantle the brakes at each wheel, and do a visual check of the internals. Its not nearly as much work as rebuilding an engine, but is in fact more important! Most of the labor is jacking up the frame and getting the wheels off. I did this in 91 when I bought mine, and did it again this spring. Each time I freed up the self adjusters, put dry graphite lube on the threads, and opened up the wheel cylinders to clean out the murky mess inside. It took me one Saturday to do each side of the rear axle, though not all day. I was able to do each side of the front axle brakes in about 2 hours. This summer I also ordered new brakes hoses, just because mine are original. There are 2 hoses on the front axle, and on mine there are two on the rear axle. If your winny has 4 wheel cylinders on the rear axle then you have the same brake system I do.



From: spudboy    
Sent: 6/4/2004 1:15 PM

My light came on only when I really stomped the pedal to the floor while reversing...turned out to be my master cylinder.  My brakes were horrible and 'spongy', now they are great.  Alretta had the part.

-Spudboy



From: Kodiak-Silver    
Sent: 6/6/2004 1:29 AM

Hello all:
On the subject of brakes, I redid my front ones lines and all last year, but
after a trip two months ago I noticed, like your reader the red light coming on and
soft brake pressure.
I removed the reservoir to find the small rear one almost dry and the front one an inch
low.
I refilled them and ran it up and back quite a few times and finally it came back to normal.

I am currently on a pad that shows no signs of leaking and haven't been able to detect
anything "abnormal" any where so far.

Could the rear pads soak up this much with some kind of malfunction ?
I hope not, but would appreciate any input.

Thanks.



From: Kodiak-Silver    
Sent: 6/6/2004 1:34 AM

Oh, by the by (it's late) My Geritol mobile is an 80 brave with 454, and shes mine
all mine.

S.



From: denison    
Sent: 6/6/2004 8:14 AM

I imagine your 1980 has drum brakes on the rear, but I don’t know if it has the hydroboost power brakes, or the vacuum type booster. Its all too common for an old master cylinder to begin leaking from its piston seal. With some vacuum boosters the leaking fluid can ooze into the vacuum chamber, and subsequently with brake operation be sucked into the intake manifold via the hose that runs between the intake manifold and the booster. You look inside the end of this hose to see if it is wet with fluid. Otherwise you would never see outside evidence of such leakage. If you have the hyrdroboost brake system, where power steering fluid operates a small booster chamber, brake fluid can still leak from an old master cylinder, but I don’t know what provision is made for its escape. You could still have had a brake fluid leak, but if it was not a real fast leak YET, the gummy evidence might have been washed away by rain, or while driving on rainy streets.
If one of your master cylinder reservoirs was empty, then I would assume there is, or was, a leak somewhere, or that the pads on the disc brakes have worn an extreme amount. In either case I would assume further work is needed.
The rear wheel cylinders can leak fluid into the inside of the drum, but I would think you would notice a grabbing or squeaking from the effects of the fluid on the brake linings. How long has it been since the rear drums were off and you had a close look at the situation inside there?



From: Liv42dayOK    
Sent: 6/6/2004 8:31 AM

I say we christen Dave Denison with the title: "Dr. Dave"!  Do I hear any seconds to the motion? - Sob

Dr. Dave, Phd, CWH  "The Doctor is in and will see you now."



From: brakeparts
Sent: 6/7/2004 11:28 AM

Ahem, the Doctor has missed one small detail... the owner describes a 454, which means that this is a P30 MHC chassis, a Chevy, and will quite possibly have 4 wheel disc brakes, which means that in addition to being a hydroboost, whether drum rear or disc, then there is also the possibility of substantial caliper sloppiness against the support knuckle, for which oversize keys are made to take up the gap, up to .220 inches...and this will cause substantial displacement in the master cylinder as well as other issues.

Of course, there could be an old fashioned leak somewhere in the system...so the best advice is to take the thing apart and review all the components of the related hydraulic system looking keenly for a leak. The master cylinder would be a good candidate for replacement at this age, but if it were internally bypassing, I would not expect to see the rapid loss of fluid from the reservoirs. Good Luck, and Kodiak-Silver, you could call me directly if you want to get into this further,

Yours,

Geoff

Alretta Truck Parts Inc.
www.alretta.com
brake parts specialists



From: DOUG THE DOG    
Sent: 6/10/2004 11:56 PM

hey,  Let's all remember the first fundamentals of a low brake pedal,

# 1 CAUSE;
   as your brake lining wears thinner from use, you need to use more pedal action than you did before to compensate for the missing/worn brake lining.
CURE.....  Replace brake pad's and or shoes,

# 2 cause;   a breach (hole/leak) in the hydraulic brake lines happens due to rust eating those metal brake lines or the rubber portion of your hydraulic brake lines failed.      Replace brake lines now!

This is just the most common stuff ,   Good Luck and  PLEASE DON'T FOLLOW ME!    DOUG THE DOG



From: MustangGT221    
Sent: 6/29/2004 12:47 AM

Well, my RV has the 318 motor, and it's a 72 Brave. I jacked up the rear tires, and the passenger wheel turns freely but the left wheel is dragging (I can't turn it by hand). I tried to adjust it w/ the star wheel but some of the teeth on it are worn and I couldn't turn it more than a 3/4 turn. The pedal has no pressure at all, the last inch of pedal will stop the vehicle, but barely. I was in reverse going about 5-7 mph and hit the brakes to the floor and i chirped the right front wheel, so that wheel is stopping ok, but the rest are not. I have a feeling its the master cylinder, but the owner is a mechanic so we're going to have a closer inspection on Thursday. If there was pressure, but just air or a blockage in the lines, I would think I'd feel atleast some pressure in the pedal, I have none.