41 Model 1903 Brake Problem

Discussions related to braking systems.
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skemple
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Joined: Wed Aug 29, 2018 12:39 pm

41 Model 1903 Brake Problem

Post by skemple » Tue Nov 06, 2018 2:03 pm

When i got my 41 Packard 160 in August the brakes were very hard and almost did not stop the car. After inspection I found one leaking cylinder and all were rusted. I decided to do a complete brake overhaul including lines. I got the deluxe brake kit from Kanter and went to work. It is now all back together. I think I have chased all of the piping connection issues away, checked for pedal free play and adjusted the brakes. After trying for a few days, I cannot get the brakes bled to a hard pedal. I am not seeing air bubbles, but still I have a soft pedal.

So what did I not do or do incorrectly?

Dave Czirr
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Re: 41 Model 1903 Brake Problem

Post by Dave Czirr » Tue Nov 06, 2018 2:45 pm

Did you bleed starting at the wheel furthest from the master and end with the closest? Did you keep the master full of fluid throughout the bleeding? When bleeding did you power or manual bleed? If the latter were you sure to keep the pedal down until the valve was closed?

Maybe you have a leak in the system.

skemple
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Re: 41 Model 1903 Brake Problem

Post by skemple » Wed Nov 07, 2018 5:55 am

Bleed sequence BR, BL, RF, LF. Master was checked for fluid frequently. Manual bleed using speed bleeders. I can see no system leaks.

Dave Czirr
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Re: 41 Model 1903 Brake Problem

Post by Dave Czirr » Wed Nov 07, 2018 6:38 am

Seems like you've got everything covered on the hydraulic side, I'm at a bit of a loss for further advice though I'm wondering if you are using DOT 5 silicone fluid? Plenty of reports about silicone fluid being a bit "frothy" at times and difficult to bleed, though no personal experience with that. Is it possible your problem is on the mechanical side, if you installed new shoes did you go thru the procedure to adjust the eccentric anchor pin? It can be critical for getting full shoe-to-drum contact.

skemple
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Joined: Wed Aug 29, 2018 12:39 pm

Re: 41 Model 1903 Brake Problem

Post by skemple » Wed Nov 07, 2018 7:04 am

I'm using Dot 3 fluid. I went through the brake adjustment procedure very carefully after an initial false start and I plan to revisit it again. On the anchor pin, the manual said to start with the high nub at the rear of the drum and move it forward to tighten the clearance. All four wheels ended up with the high nub at the top of the drum. I did not bench bleed the master before install. Could this be the problem?

Dave Czirr
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Re: 41 Model 1903 Brake Problem

Post by Dave Czirr » Wed Nov 07, 2018 7:20 am

I just don't know. It's been a very long time since I installed a conventional master cylinder and I don't think I ever bench-bled them and I don't recall ever having problems getting a proper pedal. But maybe at this point it might be worth your effort, if for no other reason than to eliminate it as a potential source of the problem, to do so.

skemple
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Re: 41 Model 1903 Brake Problem

Post by skemple » Wed Nov 07, 2018 8:20 am

Thanks. That's what I'll do. Double check the adjustment and then pull the master. I'll report back in a couple of days

skemple
Posts: 9
Joined: Wed Aug 29, 2018 12:39 pm

Re: 41 Model 1903 Brake Problem

Post by skemple » Wed Nov 07, 2018 11:04 am

I checked the brake adjustment again and made only very minor changes. Then I made two more laps of brake bleeding. No bubbles that I can see. I made a minor adjustment to pedal free movement (a bit less). After the free movement is taken up, the pedal is stiff but not hard until it gets just about even with the gas pedal. Then it is hard with no fading. It is very consistent that way. I had my able assistant (wife) step on the pedal and I checked that all 4 wheels were locked. I then mounted a tire and had her press slowly. The wheel started to get brake pressure shortly after the pedal was pushed and eventually got to the point of not being able to turn it. I have not pulled the master for bench bleeding.

Is this anywhere close to what the pedal is supposed to be like or is there more work to be done? I would have expected a hard pedal much sooner in the stroke. Not used to the 30's 40's technology.

Dave Czirr
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Re: 41 Model 1903 Brake Problem

Post by Dave Czirr » Wed Nov 07, 2018 11:27 am

How soon in the pedal stroke that the shoes firmly contact the drums and limit any further movement of the pedal is purely a matter of the adjustment of the shoes. The further the shoes (any single shoe actually) have to travel before meeting the drum, the more pedal stroke is needed. So it sounds like your problem is simply one of shoe adjustment. Typical with a good brake adjustment is that the pedal travel will be about 1/3 of it's stroke, not more than 1/2.

Question, did you have the drums turned? If so, to get proper shoe-to-drum contact over the full length of the linings you need to have the linings ground to the same new (larger) diameter that the drums have been turned to, though that shouldn't be essential to getting a normal pedal. It is however important for getting good braking action.

skemple
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Joined: Wed Aug 29, 2018 12:39 pm

Re: 41 Model 1903 Brake Problem

Post by skemple » Wed Nov 07, 2018 11:35 am

I Did not have the drums turned. Sounds like I just need to tweak the adjustment a bit. Thanks for the help!!

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