Jump to content
banzai510(hainz)

521 brakes , Stumped

Recommended Posts

I usually don't need help but Im stumped right now on this one

I changed my brake shoes on my 521 and now the driver side rear is getting HOT!!!!  doesn't feel like its dragging really. I drive into town it seems fine and not hot but when I drive to work 20 miles by the time I get there is hot and can smell it.  So I replaced the drums in the rear also and still does the same.  I thought maybe it was the parking brake spreader that was jamming up. I released that and now its hot again at work. Im stumped for now.. Drum out of round?(made in China) But it happen with the orginal drum and now this one.  I don't get it right now

Edited by banzai510(hainz)
  • Like 1

Share this post


Link to post

Did you change the wheel cylinder? Could be sticking. 

  • Like 1

Share this post


Link to post

 

 

Has to be rubbing to generate heat. Does tire spin freely? After pumping the brakes?

 

Maybe leading and trailing shoes were reversed on both sides before. Now the left rears were put on correctly by accident and this wheel is doing more work than the other side? Leading shoes are different from trailing shoes and brake harder by servo action from wheel rotation.

 

 

Maybe the other side has stopped working (for example wet shoes) and the left rear is doing all the work???

 

 

 

 

 

  • Like 2

Share this post


Link to post

all the brakes are warm when driving for awhile esp going down hill.

Just that the driver side rear is getting Untouchable hot.

as for leading and trailing shoe the parking brake has a hole for the Parking brake pivot so its really hard to mess this up. But what I remember its usually fits both sides. Most likely a CLONE of the other.

 

 

as for the cylinder being sticky it wasn't happening till I swapped the brake shoes.

 

 

Im just missing something simple but not catching it.

 

Mike as you mentioned about the leading and trailing. I thought of this also . a old guy at work told me they used to conform the shoes to the drum. But in 2oyears of owning this I never had rear proplems with the brakes on a 521 before. Its getting HOT and worried of going to fuck up the seal.

 

I had this happen on my Jeep where the drum is out of round and needed to be TURNED on the machine to get TRU round. But the drum releases fine when I have my girlfriend hit the brakes.  Maybe I will swap drums and see if it moves to the right side.

Edited by banzai510(hainz)
  • Like 1

Share this post


Link to post

If it is releasing on the jackstand the cylinder is likely ok. 


Is the drag different between the 2 wheels? 

Swapping drums sounds like a good idea, if nothing else it eliminates the drum as the issue.

  • Like 1

Share this post


Link to post

Yes it always spun around and releasing

As with most drums they all drag just a little bit. as one adjust them.

 

Im just pissed that all was fine then I had to change them thinking well its summer do this now before winter as the drums were getting on the thin side.

  • Like 2

Share this post


Link to post

Check to make sure the the adjuster slider (carrier) moves aft and forward with approximately the same force.  Factory specification, the  adjuster sliding resistance is 11 to 26 pounds of force to move it.

  • Like 1

Share this post


Link to post

Daniel the sliding adjuster seems to be a little loose but it moves.

 

 

I just showed the guys at work and it seems to work and they say the cylinder is good.

 

so Im going home early to swap the shoes maybe that works but notice Daniel that the slider as you call it does moves more easily that the passenger side

 

Edited by banzai510(hainz)
  • Like 1

Share this post


Link to post

I swapped drums and tighten the lower slider and got hot again. turned the brakes fwd to rear and than loosen and drove about 6 miles didn't get hot but will wait and try out this weekend.

Was hoping for people chime in on this

  • Like 1

Share this post


Link to post

vIlVHvJ.jpg

 

Shoe lining placement is important. Above you can see that the shoes are the same other than where the lining is bonded onto them. Note the lining is closer to the brake cylinder/adjuster at the top on the left shoe. This is correct positioning if the wheel is moving towards the left making the left shoe the leading and the shoe on the right the trailing. The shoe is even marked FORE so it is installed to the front.

  • Like 2

Share this post


Link to post

thanks

Mine said FF on both so I just swapped it and will see what happens.

 

Mine was like you said above it slightly different bt no more than a 1/4 inch if that. Those drums its a lot MORE difference

  • Like 1

Share this post


Link to post

When your changing out your brake shoes you have to release the e-brake completely from the center pull or at the very least loosen the adjustment as it is set/adjusted for the old brake shoes, when you put new brake shoes on that e-brake shoe can rub and get hot.

Also you can get the drum on because the adjuster is not adjusted yet, once adjusted did you find it hard to remove the drum when you pulled it apart to see why it was getting hot and then have trouble getting it back on without loosening the adjuster?

  • Like 1

Share this post


Link to post

Is it possible you have two of the fore shoes on one side and two of the aft shoes on the other side?

  • Like 1

Share this post


Link to post

Indeed! If you don't notice the lining placement. You could replace by noting the original placement but this assumes the last guy did it right. 

 

If you reverse the leading and trailing shoes on both sides the vehicle, it will gave more grab backing up.

 

I don't think all shoes are leading and trailing. I think I've seen sets where the lining is centrally located and all four are the same.

  • Like 1

Share this post


Link to post

Matt.  I don't know they were sealed plastic wrap in pairs and assume they are correct but maybe placed together wrong?.   I will recheak this weekend. Just had jack truck up 15times and tired of doing it. Never had this happen before in 20yrs of ownership

 

Wayno the ebrake cable broke years ago so there is no tension on there.

the drums come right off as I antiseize the shit out of them now. so there is no dragging going on and off once I get them centered on. I also bleed it to release all tension from the cylinder.

Edited by banzai510(hainz)
  • Like 1

Share this post


Link to post

well they seem to work now.

More or less I just swapped the shoes from front to back and put a old drum on. Since it works (this morning Im going to just leave it.

I only need to get 4  or 5 more years out of this 521 then dump it

Edited by banzai510(hainz)
  • Like 2

Share this post


Link to post

You can dump that thing at my place when your done with it. :)

  • Like 1

Share this post


Link to post

I said that back in the '70s. Took 8 years and it was still running.  521s are like zombies.... they run on an inexhaustible supply of evil.

  • Like 1

Share this post


Link to post

well my brakes heated up last night again. the passenger one was hot and the right side was getting warm

 

I adjusted the slop out of the front brakes and I think this might do it. Like Mike said maybe the rears were doing to much of the work.

 

we will see. I should have adjusted it from the beginning

  • Like 1

Share this post


Link to post

Well you could take out on a gravel road at 10MPH and jam the brakes on, get out and look at the marks. Might take several tries to get it right but they should all skid roughly equal. The 521 was a single master so weren't the wheel cylinder cylinder diameters engineered to provide the correct rear bias rather than a proportioning valve? The fronts should do the majority of the braking and the rears just compliment the fronts. The last thing you should have is the rears lock before the fronts. Once locked they can fish tail around. 

 

Never thought about adjusting the fronts, I assumed you were on top of that Haha

  • Like 1

Share this post


Link to post

Did you clean and lube the backing plates?

 

Did you check the axle bearing for play?

 

Pictures or it did not happen!  LOL

Share this post


Link to post

well it was hot again last night.

 

Where you lube the backing plates?

 

Can a somewhat loose lower adjuster move around and cause this.?????????????????

 

 

seems like going to work its not as hot but coming home it real HOT.

going to work I have longer strectches where I don't use the brake. Coming home the last few mile I use the brake a lot and the rim is really warm.

 

Guy at O rileys say its the wheel cylinder. I said it never happen until I put new brake shoes.

 

I tool the drum in to get turn just by chance the drum is out of spec

Share this post


Link to post

The insides of the shoes rub against raised bumps in the backing plate. I think lithium grease will do or brake grease at least. Lithium won't melt and run down. Put a dab anywhere metal parts chafe and rub like the adjuster slide..

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.