Brake Squeal

[camperguynj]

Sent: 6/4/2007 7:47 AM

Help! 1968 D22 - P300 Chassis Total brake overhaul done - lines, shoes, boosters, master cylinder replaced and yet I still have the deep squeal that is getting louder that I had when I purchased Winnie in 2005.

The noise? - a deep metallic squeal from the front - can be heard for miles - scares the be jabbers out of the car in front of me and causes peoples heads to turn to see what's coming when I apply the brakes. I now feel the squeal vibration in the pedal which varies from being hard to mushy. I have been told it's the new pads and will go away once they are "seated" .... they have been blown for dust and recently ran through some rain ... but the noise is still there. Any thoughts? Your input has and is valued.
- Jim

[Slantsixness]

 Sent: 6/4/2007 8:52 AM

Jim,

A couple of ideas.

I won't bore you with the long drawn out "are they the right parts" blog that we usually start out with, but with that in mind, the wrong master cylinder can cause the front brakes to lock up or apply when not wanted....

Also, you said "pads" but it's pretty rare to have disc brakes on a P300, so I'm assuming you have drum fron brakes.

But here are some things to check:

Bearing seals installed upside down, and not correctly seated. (will cause a constant or sometimes intermitent squeal)

Front brake adjuster cables, adjusters etc. installed backwards on one side or both  but if your's is by chance wrong, it could cause your symptom.

Bad bearings, or bearings adjusted too tight (and they would be bad then)

Bearing seats (cups) not installed all the way. (this will be obvious when you take the drums off, the drum edge will have ground off a line in the brake shoe, and there will be metal dust in the grease.)

Drums not properly seated in the Hub assembly. If the hubs are not flush with the bolt face of the drum, it will wobble.

Have a friend drive beside you in front and back on both sides and see if it's just one brake squealing, or both fronts. And it could be the rear brakes. From driving, you may not be able to tell; rear end noises propogate into the cab from the doghouse cover, and it sounds like a front noise, when it's actually not. Typically, you'll barely hear anything from the rear from the side window, since the brakes are so far underneath the coach.

Last but not least.....

You have a driveshaft mounted parking brake and possibly a Center bearing. Don't be too surprised if it turns out to be the source of the noise. If either of these is the problem, the pulsating problem with the brakes might be due to warped drums or even just flat spots in the tires being misinterpretted as a brake problem.

If you have to fix the parking brake, you'll need to find a junkyard for replacement parts. Alternatively, just take it out and remove the shoes inside. It won't work then, but it could be the source of the noise!

Good luck Jim, it has to be something fairly simple. I hope this points you in the right direction!

Tom

[Jupp318]

Sent: 6/4/2007 10:25 AM

Jim,

The simple method I have always been tols to cure squeal is to file a small chamfer around the pads or shoes.  I have been told the cause is a burr on the shoe or pad.  It has certainly worked for me in the past, so much so that I do this as a matter of course when fitting new pads.

Cheers Ian...

[Lefty]

Sent: 6/4/2007 3:14 PM

A squeal can also come from two other things. vibration in the pads due to a loose fit, and improperly cut rotors.

Pads must fit snug, use pad shims on the back of them. Also, a little bit of Brake Quiet applied to the back might help.

About rotors, when they are being turned, the depth of each cut determines the final finish. A shallow cut results in a fine finish, and a deep cut gives a rough finish.

I always cut mine at 0.050" per pass until it was true and had no grooves, then a final cut at 0.005" to give a good finish. Also, they should finish with a few seconds of the uni-directional sander (an attachment that gives a non-directional finish.).

Lastly, could be the pads themselves. Some brands are just bad about noise. As are some types of materials. Metallic pads are the noisiest, while ceramic pads are the quietest.

[Slantsixness]

Sent: 6/4/2007 6:37 PM

I'm pretty sure Jim's got Drum front brakes, so the normal "noise" problems wouldn't apply, unless Jim has disc brakes??? in a 69 M-300?... not likely.

Jim? hey... which do you have there? I seem to remember somewhere I read it was front drums.....might have even been the ebay ad 2 years ago.

Drum truck brakes may "howl" like an 18 wheeler, but not normally squeal like a metal to metal friction sound. if they "howl" The drums need to be re-surfaced, or the shoes "burnished" to correct the issue (both cures are probably your best if it's the source of the noise).  Take a look at Dan's photo guide. If they aren't together correctly you could have chatter of the shoes (forgotten retainer clip) or a dragging or broken return spring (which would probably be pretty chewed up by now, and that would cause a pulsation in the pedal too....) hmm....

Let us know. We'll get you through it without too much headache, money or curse words... I already know about how many brain cells you blew out just getting the boosters re-done and the parts.. If I was in Jersey, I'd come fix it myself for you. (unfortunately, I won't be in Jersey until November, if we even get there this year.)

Tom

[Lefty]

Sent: 6/4/2007 8:53 PM

I didn't pay one bit of attention to the year model he gave (1968).
Your right, it would be drums all around. 

[camperguynj]

Sent: 6/5/2007 7:48 AM

When I post about mechanical issues and such, please remember those classic words uttered by Bugs Bunny ... "What a Ma-roon"
Yes, they are drums not disc.

Fortunately, since the entire system was done by a good mechanic ... who I am coming to trust more and more ... and has been of great help and freely willing to offer advice and teach me ... and the work is guaranteed ... AND with all your sound trouble shooting advice ... soon the only howling and squealing I will here is around a campfire on a Saturday night.

... and Tom ... November? You going to be in my neck of the woods?

 

PS ... I will keep you posted ...

... and those boosters I had reconditioned ... well now they are rusting ... 39 years and they were fine ... sigh

[Slantsixness]

Sent: 6/5/2007 8:12 AM

Jim,
Yes, we may go to Brick (grandparents) for Thanksgiving and the week before, but my wife's family is from all over Northwest and Mid Jersey (Trenton west to Philly and north to NY) (like from exit 6A up to the city, and out to the PA/NY borders in the North... I may want to come to see you just to get away from them!  I can never go to Jersey without driving 200 or 300 miles around to see all these misfits, so even a 100 mile detour would be worth it!

But right now it's just a "plan" not a commitment... yet (unless you ask my wife...)!
 
Go ahead and paint the boosters... It won't hurt them., niether will a little rust. I use Epoxy paint, lasts forever. Wipe down the metal brake lines with a little used engine oil too, keeps them from rusting too..

[camperguynj]

Sent: 6/6/2007 2:43 PM

Well, I've been told the squeal/howling was the result of "glazing". They roughed up the surface of the shoes (?) to alleviate it. Tom - You call it a detour, I call it hiding - if you ARE up in this neck of the woods - and you want or need to ... LOL ... you gotta swing by and stop.

Jim

[enigma960080]

Sent: 6/6/2007 3:27 PM

Many years ago, I had a 79 Chrysler Lebaron, Disc Front, Rear Drum  brakes.  The  rear brakes  would squeal  on every application of the brakes. What I remember was the brake shoes, even though they had significant thickness left, were cracked. The linings (all 4) had jagged cracks  from the top of the shoe to the bottom of the shoe.  I never  found the  cause, I replaced the  shoes  and  had the  drums turned  and  there were no more problems.

2 more cents  for you to ponder....

[camperguynj]

Sent: 6/11/2007 1:33 PM

OK ... back from the weekend and road testing after abraiding (sp?) the pads  Results? .... the howl/squeal has subsided but is still there ... man-o-man

Signed,
Frustrated

[denisondc]

Sent: 6/15/2007 10:22 AM

If I had a brake 'groan' I would look for any reason the brake shoe was being prevented from lying flat against the brake backing plate, or that one of its ends (the one that bears the force when going forward with the brakes on) was not solid, or the shoe was bent at that point. The brake backing plate could be bent I suppose, or not bolted tightly to the spindle. I think a wheel cylinder that isnt bolted snug to the brake backing plate might allow a groan/squeal. With a lot of our brake shoes, the lining on the front-facing shoe is not as long as the lining on the rear-facing shoe. (The rear shoe gets more pressure during braking when the vehicle is rolling forward.)
Years ago lots of brake drums on passenger cars used to have a long fat coiled spring strung around the outside of the drum, in an annular groove provided for the purpose. The reason was to eliminate groaning brakes!

[camperguynj]

Sent: 6/20/2007 12:56 PM

the howl is still there and I am becoming aware that it is less when cold but after several applications the noise returns. Yes, being very cautious about applying and riding brakes (never did before ... but overly cautious now)

Tomorrow it is back down to the shop and we are going to take a look at the drums since there are no cracks, the shoes were chamfered as Jupp mentioned keeping our fingers crossed that now that the pedal (and spring ) has been set correctly that just roughing up the shoes one more time should do the trick.

With that said ... LOL ... anyone have a good resource for drums?

- Jim.

[Slantsixness]

Sent: 6/20/2007 8:10 PM

Jim,

Some of this is re-iterating what Dave Denison said, in a bit more detail:

Take a straight egde (metal ruler, yardstick, piece of angle iron, whatever you have...)  and check the "flatness" of the backing plates (the round metal mounts that the brake shoes sit on). One or both could be bent or skewed enough for the shoes to ride in the drums funny or "seat" incorrectly. This would be most noticeable if the howl was more prominent when the brakes were lightly applied, and the firmer the pedal pressure, the noise would lessen.

Are the shoes correctly mounted? the leading and trailing shoe surface differs from front to back, and also is mirrored from side to side. (here's another conundrum... some shoes are the same face size front and back, but be sure to measure the length of the face between the left side wheel brakes and right side wheel brakes... it COULD be that you have the shorter shoes on one side of the winnie, and the longer on the other. And... this is a common mistake, that anyone could make... but it doesn't usually cause howling, but at least this is another thing to check out.)

Are your brakes adjusted too tight??? This might cause this symptom, but it would Glaze the shoes (Glazing would be darker, Shiny looking brake shoes), and you would have a familiar "burning brakes" smell (that awful smell you've witnessed coming down a mountain with some moron riding his brakes down a 15% grade... right before the smoke pours out from, or is already coming out of his front brakes...)

It's very unlikely that your drums need replacing, or that replacing them will solve your Howling/groaning/squealing....  "Whatever-you-call-it-today". There is an off chance that the hubs are not mated correctly with the drums. Have your guy check that out too (are all the wheel studs firmly seated, and correct for the hub and drum?)

A couple old tricks:
(These are tricks, not guaranteed cures, they're "what the heck, I'll try anything" solutions. I can verify that these tricks do work, but it's hard to say as to what degree of improvement... or if they will fix it.... it's your call... I'm only quoting the "black magic" here.)

1. Have the drums resurfaced, and leave them "unpolished"... meaning that they are just cut once (whithin specs) and no final corrective turning/ surfacing. The drum surface will be a bit rough, but this will work itself out in 100 miles or so.

2. Paint the drums with Epoxy paint (Black would be better than pink...!). A few good coats. Why? It will act as a sound insulation, and deaden any resonating of the drum. After all, the drum is a giant bell, as you might expect..(just drop one once... and not on your foot... you'll recognize the infamous "bell" sound, that is remarkably similar in tone and note of the howling)


All right.. now your armed with more things to "Check" and do... maybe it's as simple as something just not sitting flush, or even one of the old tricks...

Either way, you bought a Winnebago, not a bad Trombone player!

Tom

[camperguynj]

Sent: 6/22/2007 6:35 AM

update: Squeal/ Howl - had both rear drums off yesterday morning and the left rear is scored and too thin to have turned. Bummer.

Thanks for all the input and help ... while the results may not be the best (replacing drums) the education and advice I received was put to good use and ... well ... as the commercial sez ... priceless.
- Jim

[Slantsixness]

Sent: 6/22/2007 12:09 PM

Jim,

That sucks. (no other better way to say it...)

But, you can find a rear drum or two in a junkyard. They rarely ever go bad or beyond resurfacing. (the average life expectancy of these drums is 200,000 miles).

New ones? next to near impossible, but there probably is one or two somewhere, but are you willing to look that hard and pay that kind of money?

As far as where in Jersey or northeast PA you'll find a junkyard, I don't know...

[ClydesdaleKevin]

Sent: 6/24/2007 6:44 AM

Here's another thought:

The rear axle is held onto the chassis just by its giant U-bolts and the leaf springs.  If the junkyard pickings in Jim's neighborhood are THAT slim, then couldn't he just switch out the rear axle to whatever is available in a junkyard?  Assuming the axles are the same width and gear ratio, and the leaf spring reenforced area on the axle is in the same location, then theoretically he could switch out the rear axle and use the drums and wheels that CAME with that rear axle.

I know its a lot of extra work, and more expensive to do it that way, but if everything lined up, including the driveshaft length, then in theory it would work and work well...especially if he can find a good/cheap deal on the whole shebang at a junkyard.

Just a thought.

Kev

[camperguynj]

Sent: 6/29/2007 8:13 AM

just wanted to pop in and let you know that I have read all the messages on replacing the drums and am overwhelmingly appreciative on the info and you all jumping in to help and am processing it all ... and looking local, too ... I will keep you posted ... meantime got get the nose back to the grindstone ...

- Jim