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Brakes went out... repair or convert to disc?


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So I got a '72 521, and was really stoked about it for a quick second... I've been really busy the last month, so I didn't have a chance to drive her that much, but drove her 5 or 6 times in the last two weeks.  Everything seemed fine, outside of a quirk or two.  Specifically, the brakes stopped the truck when I pressed on the pedal.  Seemed a bit squishy, but I wrote that off as me not being used to drums.  Today, I noticed that one of the tires was a bit low, so I pulled her out of the driveway (to flat ground, the driveway has a bit of an incline to it) and got the tire pressure squared away.  Afterwards, I went to pull back into the driveway, and nothing happened when I stepped on the brake.  As I rolled into the garage, which I had thankfully left open, I pumped the brakes, (nothing), and finally threw her into gear and dropped the clutch.  Not in time, unfortunately, I left a nice scrape on the bumper of the car parked there.  I know nothing about brakes, and less than nothing about drum brakes.  If I pump the brakes a bunch, a little bit of pressure returns to the pedal, but not enough that I'd trust it to stop the truck.  It quickly loses what little resistance it gains anyway.  Took some pics--











The reservoir on the right has plenty of fluid, the reservoir on the left is really low.  The brakes worked fine last week, what could have happened in the last few days to change that so drastically? 


I have various extra brake parts, new shoes etc... is it worth it for me to get the brakes fixed, or should I convert to disc brakes?  Keep in mind that I don't have the skills to do the conversion/fix myself safely, so I'd either be paying a shop to do the work, or begging for a fellow ratsuner to help me out.  Another thread said it'd be about $400 for Beebani's conversion, but I'm assuming that's just parts.


Thoughts/advice/offers of help?



Thanks y'all!

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In your picture, the right master cylinder, that has fluid is for the clutch.


The left master cylinder needs fluid.  That is for the brakes.  It need fluid, and then to be bled.


The brakes on a 521 are not self adjusting, like on a modern car.  You need to do that also.


I would suggest you take the time to learn how stuff works on your truck.  It is really self satisfying.  I would leave the stock system in place, until you understand it.


I doubt you could find a auto shop to do the disk brake modification for you for a reasonable price.  Not only is custom fabrication expensive, there would be insurance liabilities that a shop may not want to deal with.

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Thanks for the replies, guys!


Eagle_Adam-- I got some brake fluid, I'm gonna fill & check like you suggested... stupid question #1, do I need to drive it first, pump the pedal, or just wait and check?


DanielC-- preaching to the choir, I'd love to learn how stuff works on my truck.  I know how satisfying it can be.  It's not a matter of taking the time... it's a matter of finding someone to teach me, or at least supervise me.  I have no problem diving in and, say, changing a starter or an alternator.  Or even brake pads on a disc brake system, I've done simple stuff like that before.  But I'd be worried from a safety standpoint about blundering around with the brake system.  Or other stuff that could cause catastrophic failure/damage if not done correctly.


I'd love to learn about everything about the 521, if I could find someone local to teach/supervise me, I'd even be willing to pay 'em.  I would be one happy camper.  I'd be even happier if they were willing to be paid in beer or artwork... :lol:

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no need to drive it, nor would i till you bleed them.


fill it, have someone pump the brakes and check each wheel for leaks around the cylinder and hoses. If no leaks then bleed the system and go for a drive closed to home in-case you have to push it 

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hey brother.

no one is born with a knowledge of brakes. we all gotta learn sometime. and it seems now is your time to learn.


im the same as you where id much rather have someone either show me how to do it or correct me if im wrong. i didnt

have that growing up. just about everything ive learned was on forums or the internet.


brakes are really simple. just from reading your explanation, i dont think you will have to replace much or anything.

theres definitely a leak. find the leak and fix the leak. if its just a flare nut that needs tightening, tighten it, using a

flare nut wrench. invest in a good flare nut wrench, the ones i had from HF stripped during my brake job. they dont

even require that much tightening torque, but its a bitch to LOOSEN them on our old trucks. my flare nuts stripped and

i had to replace them. luckily oreilly autoparts (and similar) stock lengths of inexpensive brake line that is already flared

and already has the correct flare nuts attached.



discs are better, and nice to look at. i love mine. i had planned to do a disc brake swap, and then i HAD to when one of the springs on my front drum brakes broke, perfect timing.

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Dawa-- thanks for the encouragement, brother! ...and thanks for the tip on the flare nut wrench, I'll probably be picking up a set so as not to strip out my brake system's nuts.


Yeah, I didn't have anyone teaching me car stuff growing up either.  What little I do know was mostly learned from the internet, and Chilton guides.  Trying to see details in those dang tiny black & white pictures in the Chilton guides, haha... I learn more all the time, though, and when I have kids I'll definitely be teaching them.  The ignorance stops here! Or at least gets reduced a little... :lol:


I definitely want to do the disc conversion eventually, but if I can fix the drums (and learn in the process), I'll do that first.  On a budget, etc.  Was just curious as to how expensive/complicated the conversion was.  If fixing the drums is as simple as finding a leak and tightening a nut or replacing a section of brake line, I'll definitely be doing that.


Thanks again, y'all!

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Where in Washington are you?

Maybe a member can come help you out.


I'd say get brakes adjusted tight, top and bleed fluid, then see where you stand from there.



Brake shoes need to have as little play as possible.

Reason being is the fluid needs to push those against the drum.

Less play means less pedal stroke to actuate the shoes.

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What ever you do do NOT drive it until it is fixed.  The 521 has a single master cylinder for all the brakes, so a leak anywhere in the system causes a total failure of that system. Modern cars have dual masters which basically divides the brakes into two systems. If one fails the other will work to get you stopped, though at a reduced level.


As stated, fill the reservoir and pump the brakes. You may see or hear the fluid being pushed out of a broken line or dripping from a brake drum.



You could also remove all the wheels and drums and look for wetness.

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Man, if a member felt like coming over and helping with this brake issue I'd be eternally grateful...


I stay around the Tacoma area, but the truck was (temporarily) parked just north of Seattle.  It's gonna stay there until I either fix the brakes or get her towed to a shop, though, not trying to drive with shady brakes obviously...


It's raining pretty hard here right now, but it's supposed to be dry from tomorrow on.  I got a bottle of brake fluid, and my bro's gonna let me borrow his floor jack, so I'll be doing the fill fluid- pump brakes- try to find and fix leak- bleed, tomorrow or the next day.  Got a Chilton guide and an internet connection... Gonna see if I can adjust 'em while I'm at it, thanks for the adjustment advice!

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The most likely leak is a wheel cylinder that converts hydraulic fluid motion into mechanical brake shoe motion. On an old 521 I would replace all four corners. This is not complicated but becomes expensive if paying a mechanic to do it.

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Thanks Datzenmike, I definitely won't be driving her until I get this fixed! 


Yeah, I thought that both reservoirs in the pic were for the brakes, until DanielC clued me in. :confused:   That it's a single-cylinder system explains the total failure this morning!


I'm going to try to jack her up and look from underneath first, but if I can't find the leak that way (I'm thinking I will, but who knows) I'll try the removing the wheels thing.

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Repairing leaky drum brakes was the first thing I did when I got my 521. It was a great first experience of getting to know my car :)  My reasoning is if your going to keep the drums, make sure they are in tip top shape. I had two leaky wheel cylinders so I went ahead and replaced all 4. While it was apart I got the drums resurfaced, replaced all rubber brake hose, and new shoes too. This is also a great time to repack your front wheel bearings if your up for it. 

    The whole process took way longer than expected but I am so glad I did it myself. I never knew how much satisfaction stepping on brakes could bring!

IMG_1163_zps0bbe0484.jpg mmmm braakes


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that orange spring is the spring that broke on one of my front brakes making it mandatory 

for me to have to utilize my accumulated disc brake swap parts :)

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Thanks for the pics Juniper11, really helpful... I have two extra wheel cylinders already, so I'll probably need to pick up two more, and I have new brake shoes also.  Finally grabbed that floor jack from my bro.  Will get on this soon, just been busy.


Dat521gatherer-- thanks, I definitely will!  I checked out your thread(s), and yeah it looks like the same green/beige color.  Yours is a lot cleaner, of course... been too busy to take her somewhere scenic to take some proper pics, but here's some pics from the previous owner's ad--

















She came lowered 2", with some 15x8 steel wheels, L16 with a 4-speed, flow master exhaust, and her radio works... 102k miles... No choke, so it takes 3 or 4 tries to start her in the morning, but then she starts on the first turn of the key for the rest of the day.  While she has some dents, dings, and rust, I love how she looks already.


Was a little hesitant to start a proper intro thread for her because depending on how my finances go during the next few months (had some unexpected expenses), I might not be able to keep her.  I really want to though, I fell in love with her, gave her a name, etc... We'll see how it goes.  If I'm able to keep her, my plan of action is to get her mechanically sound first, then work on freshening up the interior, then work on her exterior.  I've been looking at your 521 and MrBigTanker's 521 for inspiration...

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Finally got her up on jackstands and went underneath to take a look.


Rear wheels and the lines leading to them looked (relatively) clean--

















The front wheels had an incredible amount of caked-on dirt and grime.  I chipped away what I could, here's some before-n-afters--


























Here's most of the crud I cleared out--





I'm wondering if both front wheels had slow leaks, and the grime caked up over time to the leaking brake fluid?  The crud got more gooey when I got closer to the metal, and it was pretty dry on the outside.  Like caked mud.  The gooey stuff was definitely black in color, so I'm not sure if it was brake fluid or oil...

I also seem to have a pretty bad oil leak, it was dripping downward at a couple different points that I could see.  Could the oil have dripped down the steering stuff and collected around the wheels and caked up the road grime?


I'm not sure if I found the brake system leak(s) or not...

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I didn't get the wheels/drums off this time, I'm aiming to do that next... I worked at chipping away at the crud until the sun started to go down, then I had to bring her back down off the jackstands and clear the driveway so my brother could drive home.  Next time the wheels come off.  I'll be taking more pics, asking for advice etc.  ...Man, I'm glad to have this forum!

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