Re: IML: 1960 Imperial brake bleeding

I believe that if you go to a larger diameter piston you get less pressure.

----- Original Message -----
From: sosmi@xxxxxxxxxxx
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: Re: IML: 1960 Imperial brake bleeding
Date: Mon, 22 Oct 2007 15:32:09 +0000

Richard, if the short comings you described are common with the brake system, then logic would say a master cylinder with a larger diameter piston would help. It would be interesting, to find a M/C with a larger piston, or modify one. Since the applied volume of fluid would be greater, for the same distance of peddle stroke, it may be enough to compensate for adjustment/ shoe ware. Just a thought. Ya'll have a nice day, Dave.

-------------- Original message --------------
From: richard burgess <lecrown60@xxxxxxxxx>

Hi Folks,

After spending countless hours working on the brakes on my '60 Crown they are finally working properly. I think we bled them entirely three times before getting everything repaired properly. The shop that "restored" my chasis did not double flare the brake lines correctly and had overtightened the flares at the bronze blocks creating distortion and leaks. We ended up replacing all of the lines again and the blocks as well, at the front frame and on top of the axle. The IML web site was helpful but did not really address the issue of pedal going to the floor. See below. Another tip, we elevated our brake bleeding bottle on a small step ladder, that really helped keeep the air from returning to the cylinders during the bleeding process. After all of this my father had this to say:

For Imperial Club under "Repair" , "Brakes", "Brake Bleeding".

The 1960 Imperial and like years brake systems can be perfectly bled and the pedal still go to the floor if the brake shoes are not adjusted to require minimal movement to brake the drum. The bottom line is that with six cylinders to provide fluid too, the master cylinder will be at the end of its stroke (to the floor) before the wheel cylinders have enough fluid (pressure) to push the shoes tight against the drums. Chrysler knew this, as in the Maintenance Manual under "Pedal goes to Floor" you (a) check fluid in master cylinder and (b) adjust for worn linings. The obvious implication is that it does not take much slack at the brake shoes to allow the pedal to go to the floor. With the shoes properly adjusted tight against the drum and just loosened enough to allow the wheel to turn freely you still will not have a firm pedal until you almost reach the floor. That's just the way it is. If you want to see this then tighten all the shoes against the drums and then see how much pedal you have. You cannot see this by pumping the pedal as the strong shoe return springs will push the fluid back out of the wheel cylinders faster than you can stroke the master cylinder. Adjust the shoes properly and frequently and you can get good braking.

Richard Burgess

'60 Crown

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