Interesting and quite a bit different. Wonder if this is Bendix or a GM copy version. Item 32 & 33 almost looks like there is a cup arrangement, but maybe just a second seal & retainer. If a cup, wonder where the fluid path from the closed end back to outlet would be. At any rate, don't see anything like a compensator valve.

EDIT: Looking at Chilton, it appears to be a cross between the HRT by Bendix and the Moraine version. Not quite either one but more in common with those than the BTV we all know and love. 57-9 Buicks used those units plus one other. Chiltons doesn't mention them using the same as Packard--just those cars on that other list.

I have 2 spare complete treadle Vac Brake Units out of '55 Packard 400's. I will donate ONE of these units to anyone on this list who will:

1.Dissect it. Even if they have to cut it in half and have a working model to re-enact failure.

2.Share this information only on PackardInfo.com (With Pics) with thorough explanations and a possible solution.

PM me with your address and I'll have it on the road and delivered to you within 5 business day. (Continental US Only)

Lets solve this problem before somebody gets killed.