News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

Master cylinder piston stuck...

Started by Edward Kenny, July 24, 2013, 09:05:44 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Edward Kenny

After removing the lock ring from the back of my Delco-Moraine master cylinder for my '62 CDV, the piston does not want to come out of the cylinder bore. It smoothly travels inside the bore but comes to a stop as if something is blocking its way out. I've already removed the stop bolt per the shop manual. Does anyone have any insight as to how I can remove the piston?

Also, the headnut at the front of the MC doesn't not want to loosen. I've used WD40 on it but thus far it has not come loose. Is there a trick I'm missing that will loosen it?

Thanks on advance for the due diligence.






The Tassie Devil(le)

G'day Edward,

As you have done the "normal" things, I can only suggest that you persist on trying to remove the piston via pushing it in and out but make sure that when the piston is in, there is no lip in the bore when the piston is at the rear.

I have had trouble as you mention, and I have used the "hit the MC on the block" method.   That is, without damaging the outer end, raise the cylinder with one hand, and bring it down hard onto a hard unmovable surface.   This will sort of shock the piston out, and it uses the weight of the piston to slide down the bore.

You cannot use reverse pressure, as there are too many orifices to cover.

There is not much else you can do.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Roger Zimmermann

Edward, are you sure that your MC is a Delco-Moraine? According to my parts book, the Delco-Moraine has a plug at the end of the MC, which can be removed to push the piston out.
The 62-63 Bendix MC has no plug and I had myself a very hard time to remove that damn piston. By the way, I still have this MC with the piston out as suddenly the guy who wanted it retracted.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

gene harl

You have rust ring at the top of the bore ,,, try some sand paper with wd-40 around the very top of the bore.... Gene..

pauldridge

Edward,

This is pretty common.  More often than not those pistons aren't just going to drop out.

A very simple solution:  Just take an air gun (preferably with a rubber tip), and give a VERY SHORT blast of air through the brake line port.  It should pop right out.  However, hold something over the receiving end (like maybe point it into a bucket, or just hold with a glove) before pressurizing it, because that piston (and other parts) is going to come out of there like a bullet!

Phil
Phil Auldridge
Austin, TX
1940 60S as well as MGA, Stingray, '39 Ford Coupe, BMW 3.0 CS, '59 Jaguar, '51 Hudson Hornet, '64 and '70 Mercedes roadsters, and Nash-Healey LeMans Coupe
[img]http://www.auldridge.org/images/hdricon.jpg[/img]