1956 Chrysler Windsor Town & Country Wagon

[Matt Harwood]

1 hour ago, neil morse said:

Top notch work all around!  I especially like the tailgate display.  Enjoy the show!

 

Neil

 

Sadly, it was canceled. Melanie was pretty disappointed. Next year, they said...

[neil morse]

Understandable in these crazy times.  Stay healthy and be happy that you're prepared for next year.

[Matt Harwood]

As I mentioned last year, we were having some trouble with the brakes on the Chrysler. They worked well enough, but we just couldn't get a good, high pedal. After pulling all four drums and doing some measuring, I realized it wasn't an internal problem--the shoes were in good shape and using a crude pointer device I made, I was able to check for concentricity. It's pretty close, and an examination of the linings shows that they seem to be wearing consistently. I gave up and figured that they were as good as they were going to get. That was last fall.

 

Since things are slow in the shop, I had our mechanic, Roman, tear into the brakes and have another look. He came to the same conclusion I did about the brakes at each corner. We both checked the master cylinder and it seemed fine, but since everything else was buggered, he pulled it anyway. And sure enough, there's the problem! While it would hold pressure and didn't feel mushy, the pedal was just very low. When Roman pulled out the master he found that it was leaking pretty badly, although the fluid was not going anyplace visible--we don't know where it went, because it wasn't on the floor.

 

Anyway, we ordered a new master cylinder from one of the big suppliers, but it arrived and leaked even worse than the old one. Dang. We returned that and Roman decided to rebuild the existing cylinder himself, so I bought a rebuild kit. He honed the bore slightly to make sure it was clean, used a wire wheel on the housing, painted it, and installed the rebuild kit. All good! With some adjustments, we now have a nice firm pedal.

 

(You're surely wondering why there are no photos of any of these jobs--well, our cloud storage somehow crashed and wiped out megabytes of our photos. I thought the whole point of the cloud was that they did backups so this couldn't happen. Meh.)

 

Anyway, the only thing that is still not right is that the brake lights sometimes stay on. Not all the time, but they will hang and then there's no way to shut them off so we pull a battery cable. Roman disassembled the master cylinder again and found that he had installed something upside down--he described it to me but I don't quite understand what it was and the photos he took are gone. He said there was a little disc with a point and he had installed it with the point aimed at the brake light switch instead of the line out. He thought that might be the problem, but reversing it had no effect. 

 

Any ideas what else it could be? I think the right front brake shoes are a little tight--could that cause some residual pressure in the system? Melanie also says there's a vibration above 50 MPH that wasn't there before. I think we need to back off that wheel a bit.

 

What if we over-extended the pedal adjustment to get a higher pedal? Could that be putting pressure on the system and should we back it off a bit?

 

Or a(nother) new brake light switch?

 

Any suggestions are very welcome.

[Bloo]

I don't recall the pointy thing, unless it it the piece that goes in the end of the return spring. The pointy aluminum thing points up into the master cylinder return spring, and I don't even see how it would fit backwards. It might be the residual pressure valve, but I sort of doubt it because I don't recall a seal on it.

 

There has to be a residual pressure valve somewhere though. It might be under a tube seat where the line attaches, or maybe even in a fitting on the outside. Residual pressure valves are about 12psi, and only the valve (or a leak) affects the pressure. Shoe adjustment would not change the pressure. The shoe return springs are so strong the residual pressure has no effect on the shoes either.

 

3 hours ago, Matt Harwood said:

What if we over-extended the pedal adjustment to get a higher pedal? Could that be putting pressure on the system and should we back it off a bit?

 

I don't know. I don't recall how to set up that bellows-type brake booster. I can tell you how to do it on a more modern can-type booster, and maybe you can sort it out from there. Does the Shop manual have anything? I have a sneaking hunch this might be pretty hard to do by eye on Melanie's car.

 

On a can type booster, the idea is you want the cup as close to the discharge hole as possible without being over it. Any pedal motion going from rest position until the hole is covered is lost motion. Can-type boosters usually have either jam threads on the pushrod, or some shims. The idea is, with no fluid in the cylinder, and a bright light, adjust out (you have to keep taking the cylinder on and off, and bolting it back on solidly) until you see the edge of the rubber cup in the discharge hole, then back off until it just disappears, then go a tiny bit more to account for heat expansion, weather, bad luck, etc.

 

You don't want the cup covering the hole because the brakes won't release. You don't want the cup hanging out in the hole at rest because it would harm the cup over time. You wan't a tiny bit extra, so than no matter what happens, the hole cannot become covered at rest. The key word is tiny though, any extra distance is lost motion, and it is multiplied by the pedal ratio.

 

On manual brake Chryslers of that period, the pedal pushrod is attached to the piston by some rubber. I recall there is a height adjustment on the pedal pushrod itself.

 

Some of those new hydraulic brake light switches engage at a lower pressure than the old ones. I wonder if it could be on the wrong side of the residual pressure valve somehow?

 

 

Edited April 26, 2020 by Bloo (see edit history)

[Matt Harwood]

We seem to have solved the brake problem. Roman had the pedal adjust a little too high--the adjustment rod was putting just a bit of pressure on the master even at full extension. That was why the brakes were dragging a bit and why the brake lights would stay on. It gave us an awesome high pedal, but after backing it off two turns, it seems much better. The pedal is still a little low, but it stops just fine. I'm going to tweak it a bit tomorrow and see if I can get a good compromise between a good pedal and no dragging. 

 

Melanie's horn ring also broke (it was already broken and someone fixed it in the past with JB Weld and a small trim nail) so we're looking for a replacement. '56 Chrysler horn rings are unbelievably difficult to find and very expensive, but 1956 DeSoto horn rings are cheap and plentiful. They aren't the same, of course, but doing some eyeballing, it looks like a DeSoto ring will bolt onto the Chrysler hub--I just can't believe that ChryCo would make two similar cars with unique steering columns and hubs. I found a DeSoto horn ring on eBay for $50 and figure that is a reasonable gamble. I'll have it next week and then we'll find out if they're compatible. It won't be a permanent solution, but it's better than the broken stubs we have now.