Center plane brakes, ‘61 Plymouth

[Glenner]

Hi again. My ‘61 Plymouth, which has been on the road for about 4 years now (not driven often) is giving me brake issues. I have gone through the brakes with assistance about 3 times in the last few months. I know that using Dot 3 or 4 brake fluid coupled with sporadic driving will produce issues because of the brake fluid attracting moisture. I’m aware the solution is to just keep doing repairs every 3-4 years or to remove all Dot 3 or 4 fluid completely from the system, including either decontamination of the master and wheel cylinders or buying all new, and to start over again with Dot 5. That’s a possibility down the road. I won’t get into the benefits (or not) of the center plane brakes compared to Bendix or Lockheed, but I wouldn’t mind switching over, also down the road. But here’s what’s happening with my brakes…
At first, when backing out of my shop, the right front would lock up solid, leaving a black mark on the floor. I’d have to go ahead, and then reverse and the minute I touched the brake pedal it would lock again. It would take a few minutes to back out as I was always touching the pedal, as there’s not a lot of clearance on either side and I was subconsciously being cautious, therefore lightly touching the brake. There’s black marks on the floor right to the door. Once out the door, there would be one last lockup as I came to a halt on the gravel driveway, then I’d go forward, stop, back up, lock up, and after a couple more times, everything cleared up and I’d go for a drive with no problems occurring. Even if I stopped for a long break there were no brake issues when I’d resume driving. (To be continued)

 

[Glenner]

I did notice that my brake pedal was travelling farther than previous. I pulled the right front wheel apart, and everything was clean and dry. Checked the left front, everything ok. Pulled the rear right apart, found a leaking wheel cylinder. Replaced it. Put everything back together. Did not check the left rear as, in my inexperience I thought I’d found the problem…but I couldn’t figure why the black marks indicated front right was locking up but it was the right rear that seemed to have the problem. Now, I’ve done so much work during this time on the brakes that I can’t remember what I did in some cases nor in what order I did it, so the symptoms changed and I’ll try to remember when and what changed.
After adjusting all the brakes, I was thinking positive and backed out. No issues whatsoever backing out, smooth as silk. (To be continued)

 

[Glenner]

Sorry for this lengthy post…
I put it in drive, went ahead, and I touched the brake pedal, and I mean a feather couldn’t have applied this little pressure, and the right front locked up solid and wouldn’t release with no brake pedal application. As I idled forward, grinding through the gravel, I could feel it releasing then applying again until it finally released. Back into the shop. Jacked it up again and removed the left rear assembly. Another leaking wheel cylinder, but what’s that got to do with the front right? Replaced the leaking cylinder. Bled (again) the entire system and adjusted all the brakes. Yesterday, doing this, I ended up with a great feeling brake pedal and once again, optimism reigned supreme. Rained yesterday so today was test drive day. Backed out, at first it felt like the parking brake was on…..

 

[Glenner]

I had to force it to move and then something released and it moved, although when I put it in drive it still felt like it wasn’t fully free. Drove slowly out the driveway and turned into the road and it seemed to free up. Once up to speed, I applied the brakes hard and it pulled slightly to the left but it wasn’t terrible. The thing that bothered me was the good pedal I had earlier now disappeared. After adjusting the brakes and bleeding the system, the pedal travel was about 1” and the pedal stopped, car sitting in the shop. Now, the pedal was traveling a good 3 inches or so and it felt like I was doing all the stopping, if you know what I mean. Before these problems, the pressure I had to exert seemed to be minimal, as the accordion style booster was doing its job…I think.

 

[Glenner]

Now, I was actually stretching my foot out to get stopped. Back home I came and I thought I’d present the problem to better mechanics than I.
By the way, during one of the many attempts to fix these issues, on one of the test drives, upon application the car would pull to the left and then straighten itself out but more alarming, the first time I did a hard application, it pulled and when I released the brakes, the pedal kept sucking on (poor description, perhaps), it was like it was caught in a vacuum and it slowed the car down and then released on its own. Thanks for any ideas you may have. Glenn

 

[1970cat]

did you change the rubber brake hoses ? it almost sounds like pedal pressure pushes the fluid through but partially clogged hoses wont allow fluid to return. if there is a vent on your reservoir cover , make sure that is clear too.

 

[Glenner]

Hi 1970cat, thanks for your reply. The flex lines are fairly new so I’m not sure they would be faulty but it’s always a good thing to double check. The fluid squirted out at a good rate when bleeding, but the issue might be on the return. I’m wondering if the booster might be acting up, or if I have a vacuum leak somewhere.
There’s no vent on the master cylinder lid.
Thanks again.

 

['66 Fury I]

Is it possible that the pushrod is not allowing the master to return far enough to expose the relief port and thus holding pressure in the system? Just a thought. Lindsay

 

[Glenner]

Hi Lindsay. The pushrod seems to be loose and moving freely. I appreciate the idea. Still searching for a solution. On a side note, I’m thinking of a winter project to switch from the center plane system to a Bendix system, which I believe were used from ‘62 and newer. If anyone has an idea of exactly what that entails, and where i might find used or even new Bendix brakes, please let me know. And even if I don’t switch to Bendix, I think I’ll flush out the whole system and switch to Dot 5 fluid to eliminate the moisture attraction issue. I have heard I’ll either have to replace all the wheel cylinders and the master cylinder too..or find some way to decontaminate them to rid them of any Dot3 or 4 fluid. Any thoughts are appreciated.

 

['66 Fury I]

When I got my '66 Fury, it had been stored for some 8 years. The brakes worked well on the 150(?) mile trip home, but I inspected all brake lines, replaced the MC, all wheel cylinders, brake shoes and hardware. The replacement MC is a '69 dual unit so I split the system. I filled it with DOT5 (silicone) fluid and have had no problens for 30 years. This spring, I flushed the system with fresh DOT5 and replaced the brake shoes. Still no problems and no sign of water or rust when I did the flush. That is my experience.
YouTube has a Mopar tech video on the Center Plane Brakes that might be helpful. Lindsay

 

[Glenner]

Thanks Lindsay. Your post definitely steers me towards doing a complete flush of old Dot 3 or 4 fluid and going to Dot 5. Does anyone know if there’s a way to thoroughly clean the master cylinder and all wheel cylinders to remove all traces of the old stuff? I’d hate to have to buy all new if I don’t need to. When you flushed your system the first time, what did you use to clean it out? I’m guessing whatever you used caused you to replace the flexible lines too? Thanks again

 

['66 Fury I]

As i stated, my car had been sitting for 8 years and, although the brakes worked, I replaced everything except the steel lines. They were inspected and I found no rust inside or outside. I blew them out with air, flushed them with lacquer thinner and blew them out again. Flex lines and all cylinders were replaced as age made them suspect IMO. Richard Erinbergh (tech editor at Mopar Action) says to simply flush with DOT5 and enjoy. I have never done this, but I do respect Richard.
Flex lines (rubber) can fail on the inside with no external evidence, and act as a check valve, allowing forward flow while blocking return flow. This baffled me a few years ago! Lindsay

 

[saforwardlook]

Centerplane brakes are self-energizing. What this means is that when you just tap the pedal the brakes will automatically start to self apply. Normally this is a gradual process but if there is any surface rust on either the brake shoes or the drums from sitting a long time outside or even inside under somewhat humid conditions then the accumulated rust will self-energize the brake with just touching the pedal. I normally store my 300C inside my well insulated garage and I am located in a dry climate most of the time. As such, I don't have the problem you describe.

However, I do store my 1958 Dodge Custom Royal Lancer outside under a cover for long periods and I too have this exact problem. What I do is remove the drum from any offending wheel and sand the drum and shoes down and clean them with a brake cleaner. Usually this takes care of the problem.

Perhaps if there is enough room, you might be able to back up for a relatively long distance with the brakes applied to allow the drums/shoes to clean off the rust after some significant distance.

I really do not know how Chrysler got along with these brakes for so long but the bendix "normal" brakes came along in 1963. Unless you are a purist, you would eliminate a lot of headaches down the road by changing over to those.

I am a purist and live in California so I usually get away with the center plane brakes if my cars with them are stored indoors. Otherwise, they are hard to live with. They are relatively unsafe too with only a single master cylinder so if any wheel cylinder fails, you have no more brakes except for the worthless parking brake mounted on the output shaft of the cast iron Torqueflite transmission.

Good luck.................

 

[Glenner]

Thanks for that info. I’ve sanded down the shoes and drums and wiped everything clean….numerous times. I’d like to switch to Bendix…being a purist has its limits, in my books…so I’m wondering if it’s a simple process to switch? What all is needed? I’m still hoping someone can tell me how to clean up master and wheel cylinders of the old Dot 3/4 fluid so nothing contaminates the new Dot 5. I’ve been told to put them in a wood stove (if one has a wood stove) until they glow red and remove them, job done. I don’t have a wood stove.
I’ll keep plugging away and hopefully there’s a light at the end of the tunnel.
So…if anyone has the parts that will enable to me to convert from center plane brakes to Bendix, please let me know. And…if anyone knows how to clean up all the cylinders so I don’t have to buy all new, please let me know.
Thank you

 

[shooter65]

Just my 2 cents but I think you're stressing too much about switching from DOT 3 or 4 to DOT 5. IMO if you purged your system of the old fluid, filled it with DOT 5, bleed the entire system, purged the DOT 5 and repeated the fill and bleed the entire system a second time with the DOT 5 there wouldn't be enough DOT 3 or 4 remaining to cause any issues.

 

[Mike66Chryslers]

Whatever your problem is, I suspect it's not water contamination of the brake fluid, unless you don't drive your car for YEARS at a time. The only place that the system exposed to atmosphere is at the master cylinder, which has a cap with a seal on it. So IMO switching to DOT5 isn't going to solve your problem.

I had a problem when I first got my '66 that you'd tap on the brakes and the pedal would suck itself to the floor and lock the brakes up, something you described in one of your posts. If I put my foot below the brake pedal and lifted it, it would go back up on its own. To use the brakes I had to put one foot below the brake pedal and one above, and the pedal would oscillate between them. (Obviously I didn't drive it far like that!) There was a checkvalve inside the booster that was stuck. I replaced the booster. So you may have a defective booster, though that doesn't explain just one wheel locking-up.

Even the later drum brakes are self-energizing on one of the shoes. When my Chryslers have been sitting for a couple weeks, especially the one that has front drums, and I go to get it out of the garage, the brakes are VERY touchy/grabby. It's impossible to feather the brakes; they're either off or ON. Getting that car out of the garage after it's been sitting wahile looks very awkward and jerky. Once I have applied the brakes while it's actually driving down the road it's fine from then on. This has to do with moisture and surface rust on the inside of the drums, same as what @saforwardlook described.

Possibly you're setting your adjustment too tight so the shoes are dragging on the drum a bit? After the car has sat for awhile, the moisture and possibly surface rust on the components causes them to self-energize.

After a bit of google searching, I see that setting the adjustment on center-plane drums is more involved than with later drum brakes. Maybe you'd consider swapping your center-plane front brakes for some later-style ones? Here's a write-up from someone who did that: http://www.chrysler300clubinc.com/project300f.pdf

 

[Glenner]

Thanks Mike. You’ve definitely described some of the symptoms my car is having. I’ve been getting information and suggestions from a few different people and yes, as shooter pointed out, I’m a little obsessed with how to flush and clean a Dot 3 or 4 system to make it work for Dot 5…and that’s because I heard that from a reputable source that’s in his 80s that was a Chrysler mechanic his whole working life and has done many Dot 3 or 4 to Dot 5 conversions, using the method involving high heat etc. So, I’m open to all suggestions and certainly like the idea of just flushing the system with Dot 5 until it looks good and being done with it. And I’ve just read an article that talks about Dot 5.1 that is compatible with 3 and 4…so maybe that’s the answer. I’m just heading out to my shop to lift the car onto Jack stands again for yet another system check. By the way, the article from the Chrysler 300 club about converting from CP brakes to Bendix was very thorough and a bit overwhelming for a guy like me, but I’ll read it again and again until it gets more clear. Thanks for forwarding it to me.

 

[michiganhotrod1]

I have the same problem with my '58 Imperial, that sat for two years getting an engine electrical problem fixed. The brakes are very sensitive to rust or moisture; when these cars were daily drivers this was not so bad but that is not the case now. Hard use will help free them up.
That said, if your old linings were oil or brake fluid contaminated, throw them away, you cant clean them up enough. Also, if you removed the wheel cylinders make sure you replace that foam gasket to the backing plate or use "dum-dum" to reseal to keep water out.
For the DOT 5, just flush the system with the new fluid, as in- run a couple of pints thru by bleeding, the residual dot 3 wont cause any problem. I did this on my 64 D100 in about 1987; I got about 30 years of very occasional use before I had to replace the wheel cylinders again.
Mark

 

[cantflip]

Thanks Mike. You’ve definitely described some of the symptoms my car is having. I’ve been getting information and suggestions from a few different people and yes, as shooter pointed out, I’m a little obsessed with how to flush and clean a Dot 3 or 4 system to make it work for Dot 5…and that’s because I heard that from a reputable source that’s in his 80s that was a Chrysler mechanic his whole working life and has done many Dot 3 or 4 to Dot 5 conversions, using the method involving high heat etc. So, I’m open to all suggestions and certainly like the idea of just flushing the system with Dot 5 until it looks good and being done with it. And I’ve just read an article that talks about Dot 5.1 that is compatible with 3 and 4…so maybe that’s the answer. I’m just heading out to my shop to lift the car onto Jack stands again for yet another system check. By the way, the article from the Chrysler 300 club about converting from CP brakes to Bendix was very thorough and a bit overwhelming for a guy like me, but I’ll read it again and again until it gets more clear. Thanks for forwarding it to me.

A little food for thought... DOT 3,4 and 5.1 are compatible in that they are glycol based and the main difference is in the minimum boiling point of the fluid... that said, minimum boiling point rated fluids are poor quality and often what is found on store shelves. Ford used to have a heavy duty DOT 3 which exceeded the minimum boiling point of DOT 5.1, but I understood it to be no longer available last I looked.

The purpose for many who change to DOT 5 in classic cars is split between those who value it's safety for their paint and those who value it's inability to absorb moisture. Glycol based fluids will attack painted surfaces, even epoxy floors. Glycol fluids are recommended by manufacturers to be flushed every 2-3 years in part due to their moisture absorbing tendencies, in part to get rid of suspended particles. When flushing, it is easy to saturate the fluid with moisture, as a new bottle will absorb all it can if left open for about an hour.

DOT 5 is silicone based and not compatible with the others at all. It is far less likely to cause paint damage and will not absorb moisture... if water condenses in a DOT 5 system, it has a tendency to collect in a low point of the system and cause corrosion concentrated to that area only. To help prevent this and to remove any particles, DOT 5 should still be flushed, but longer intervals are acceptable. DOT 5 aerates more easily than glycol based fluids and tends to offer a slightly softer pedal feel. It also has been considered questionable for ABS use due to that property, but that isn't much concern to many classic car owners.

Bottom line, you are unlikely to effect much performance change regardless of which fluid you chose, provided your car began life with DOT 3. With any brake fluid, observing the full line, or fill recommendation to prevent heat expansion from applying the brakes as you drive and assuring the master cylinder cover gasket seals out moisture are critical to general servicing or checking of the fluid.

New brake components are likely assembled with glycol compatible lubricant, which is also not silicone compatible. The better you do at cleaning the glycol products from the system, the better your conversion, but be cautious that solvents which can harm the soft parts of the system will eventually cause failures. I am not too sure about metal distortion created by glowing iron parts, but agree that it would be an effective way to remove all traces of the glycol fluid. If attempted, the iron pieces MUST be empty cores and clean of any visual contamination... then I would expect there to be some possibility of warping and loss of the parts. I would expect honing/measuring of the bores to be part of reassembly.

 

[Glenner]

Thanks for your well thought out responses. I learn more with each reply. I’m leaning towards Dot 5 simply to get away from the attraction to moisture. And I’m going with the more popular “just flush the old stuff out until it’s all gone “ theory rather than the wood stove theory…mostly because I don’t have a wood stove. As stated before, I’m not a purist to the nth degree so will replace the CP system with Bendix if the opportunity arises. Thanks again for all your help and great information.