Cyclical drum brake squeak...and another brake problem

[cglax6]

Weeks ago, I decided to do a front disc brake conversion on my '76 CJ5 . I purchased a kit from Horsepower Sales, LLC...which by the way is the way to go, in my opinion. Awesome service and the kit that he sells is a true bolt-on solution that doesn't require any cutting or grinding.

Anyway, the reason I did the conversion...besides better braking...was to get rid of this god-awful squeak coming from my front left drum. The reason for the squeak was because the drum itself was off-center and rubbed against the shoe causing it to squeak with every full rotation of the tire. I tried taking it to the shop to get machined to match, but it didn't help.

So after the install, (including a new master cylinder and prop valve designed for disc/drum) brakes, I ran into a couple issues.

First and most annoying: cyclical squeak is back...traced it to the left rear brake. It didn't show up until after I did a panic stop about a week after I installed the front discs. Before you ask, I bench bled the new MC, and bled the brake lines. I installed all new brake lines since I was messing with a new MC and prop valve anyway. The rear brakes are only about 8 months old and contain all new components.

Here's the other problem: Sometimes, it feels like that left rea brake is not letting go. The squeak doesn't start unless I press on the brakes fairly hard. If I know a stoplight/sign/traffic is ahead, I can brake easily enough to stop me, but if something comes quick, I stop harder and the rear brakes engage more and the squeak shows up. Doesn't go away until I engage/disengage the parking brake...and it doesn't happen when I go in reverse.

I know it's not letting go because after it happens, that wheel is twice as hot at the right rear wheel, and when I'm starting from a stop, I slow way down while pressing in the clutch while shifting. There's also a hot brake smell when I'm stopped at a light. And when I coast, I seem to slow down a lot quicker even when the brakes aren't applied.

The squeaking also seems to be relative to how hard I press in the brakes. Say if I brake just enough to get the squeak going, it's a soft squeak. But if I jam on them pretty good, the squeak is louder.

So, that being said, I think this is all tied to one problem...the left rear brake not letting go all the way (with a side of drum being out of round). I still need to take the drum off and make sure the wheel cylinder is moving in and out as it should. If it isn't, I'm looking for what to do from there. I'm thinking the worst it could be is a failed wheel cylinder...or some sort of debris in the brake line. I have 3 little kids that like to play around with my stuff in the garage, so there's no telling if they tried to stick something in the line or not when I wasn't looking.

Also, when I was troubleshooting the front drum before the disc conversion, I purchased 3 new drums, and they were all out of round. Got my money back, but it was very frustrating.

I'm also beginning to think that the squeak was coming from that left rear brake the whole time. When it came back after installing the discs, I wanted to murder someone. I kept my old front drums and the front right never made a noise, so I may start with swapping that one out and see what happens. I'll adjust the pads and go from there.

Just looking for opinions on this one...I'm thinking that I have a bad cylinder or something in the brake line that is preventing the cylinder to fully retract. Best case, the shoes are just adjusted a little too tight...but that doesn't explain the intermittent squeak.

Sorry for the long-winded post...just trying to answer questions before you guys ask them.

Thanks!

 

[Lumpy Grits]

Stop driving it till you pull the drum for inspection.
Bet as soon as you pull the drum, you'll see the issue if it's broken parts etc
Might not be a bad idea to have both drums 'turned'.
LG

 

[mriplaybass]

First off, make sure that your parking brake is properly adjusted, and fully releasing when you pull the release handle. Don't just do this by pulling the release and trying to turn the wheel. Take the brake drum off and make sure that the brake shoes are fully seating back on the top centering post.


Check to see if there is a ridge of rust on the inside edge of the brake drum just past where the shoe would contact the drum. If there is, use a heavy wire brush on a grinder or a stripping disc to remove the rust ridge.


Try swapping the drums from one side to the other to see if the opposite side will now squeak.


If everything is properly aligned and operating freely, try filing a small bevel on the leading and trailing edges of both brake shoes. The 90° angle that is on the shoe leading and trailing edges from the factory is notorious for causing squeaks.


Years ago, when a brake drum was turned, the shoes were also "arced" to match the larger diameter of the drum. Not too many places do this anymore. Sometimes this will cause a squeak. Take some 80 to 120 grit sandpaper and give the shoes a good roughing up. One of these procedures will almost always take care of the squeaks.

 

[cglax6]

I should be able to take a look in a couple days.

The shoes already had a bevel on the leading and trailing edges, so that's not the concern...and doesn't explain why the shoes don't want to let go.

My concern is that it doesn't start happening until I depress the brake pedal beyond what you'd consider mild pressure. I think something is preventing the shoe from returning to where it needs to live when there's no pressure in the line.

If it happens and it feels like that wheel is slowing me down between shifts or while coasting, throwing it in reverse a few feet takes care of that part of the problem, but it still squeaks. Engaging the parking brake and the disengaging it almost always resolves both issues.

So here's what I'm thinking could be a list of problems (in order of repair difficulty):

1. Drum so out of round that it doesn't allow the shoes to function properly
2. Loads of brake dust not allowing the shoes to seat properly w/ no brake line pressure
3. Bad/broken return spring(s)
4. Bad wheel cylinder or misaligned pins
5. Something in the brake line preventing fluid to return to the MC

Not sure what else it could be. I'll probably be able to get into it tomorrow after work.

Appreciate the help.

 

[mtnwhlr]

Try swapping the drums from one side to the other to see if the opposite side will now squeak.

I think this is a good idea to start it will tell you if it is the drum or not.

 

[Torxhead]

When you get in there feel for any axle slop from a bad wheel bearing.

 

[cglax6]

When you get in there feel for any axle slop from a bad wheel bearing.

Was thinking the same thing on my drive home from work today...not in the Jeep, though! She's grounded until I figure this thing out. Last thing I need is catastrophic failure on the road.

 

[mriplaybass]

I don't know how you would check the residual valve, if you still have one, so if it still exists, you may want to replace it. Also, make sure that the small bumps that the brake shoes are meant to ride/rest on are not rusted, and apply a thin layer of brake grease to these bumps.