Rich, thanks for your tip on checking the actuating rod length ? I probably just put everything back together being rather merry that I managed to get the cross-bolt with locking pin back in place while laying upside down underneath the dash. Otherwise your description of atmospheric pressure flowing back to the brake booster when pedal is released, is exactly the thing that is not happening. I have frowned upon the car now for 10 days not wanting to touch it, but might give it a try again next week. Will keep you all posted. Otherwise, anyone tried modern disc brakes on a 55? Or Ausco-Lambert for the rarest of the rare touch? Narve 29 Chrysler ? contemporary fabulous brakes 40 Chrysler ? contemporary good brakes 52 Chrysler ? contemporary acceptable brakes 55 Chrysler ? rubbish brakes 60 Chrysler ? rubbish brakes, but better than a 55 Fra: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] På vegne av Rich Barber Sendt: 12. august 2012 22:20 Til: 'Narve Nordanger'; Chrysler300@xxxxxxxxxxxxxxx Emne: RE: [Chrysler300] A serious 55 Kelsey Hayes issue - brake failure Narve: I know you are a thorough guy, but the clearance on the actuating rod from the brake pedal to the back of the booster is critical. In theory, retraction of the rod when the pedal is released should allow atmospheric pressure to flow back into the vacuum side of the booster. If the pedal is returned by spring pressure, it should retract the actuator rod. There is a small check valve in the outlet of the master cylinder that is designed to hold a small amount of residual pressure on the system in order to exclude moist air. That small check valve may have been damaged or improperly installed. Other things to check include the check valve on the vacuum inlet line. Progress was made over the years. The brake pedal in the '55 is now wide enough to get both feet on it. Rich Barber Brentwood, CA 1955 C-300 From: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> [mailto:Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> ] On Behalf Of Narve Nordanger Sent: Sunday, August 12, 2012 12:33 PM To: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> Subject: [Chrysler300] A serious 55 Kelsey Hayes issue - brake failure Group, my C-300 has twice this summer had failure on its freshly overhauled brake system. On both occasions the Kelsey Hayes master power brake appear to lock up and not letting out the vacuum after I have released the brake pedal. Brakes stayed locked until I split the master cylinder from the booster. Anyone seen this before, any remedy? Additional information: The lightest of touches on the brake pedal sucks it in and make immediate contact on the shoes, making progressive braking a difficulty. This was evident both with the old (original) and overhauled (x-55 De Soto) K-H MC. Having just gone through the brakes on 29 Chrysler one really wonders if there was any progress at all in the intervening 26 years.. Narve N C-300 in Norway [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: Chrysler300-digest@xxxxxxxxxxxxxxx Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/