Rebuilding a Master Cylinder

[73 gt man]

I am new to this site and I am almost overwhelmed with the amount of info here, so much to read, thank you for your help. I am also trying to find something on rebuilding the master cylinder for my gt I have the rebuild kit and tools just not a diagram, any guidance as to where I could find that would be great, I tried the search function without much luck.

Sean

[benncojr]

When in doubt on any part go to http://www.opelgtsource.com/ for parts and help.

[namba209]

Sean, I just got a rebuild kit from OGTS complete with the instruction sheet. If you want I can scan it to a .jpg file and e-mail it to you. It would be a large file and take a while to down load, but it would be a full 8.5" X 11" pic you could print out and have for future reference. Lemmee know, I'll be back on the site in about an hour or so, gotta finish giving the motorhome a bath.

[kwilford]

Thread Split...

kwilford
"not the Moderator"

[benncojr]

Originally Posted by kwilford Thread Split... kwilford "not the Moderator"

Ya....but old habits are hard to break

[73 gt man]

The picture would be great, I am sorry to all if i caused a problem with my posting in the incorrect section

Sean

[GTJIM]

Here are a couple of diagrams to help you.
It says "Drum Brakes" at the top of the page but is a Disc brake master cylinder - an early Kadett one! The GT disc one is very similar except for the balance cylinder which is piggybacked underneath and is shown in the next diagram.
HTH

[73 gt man]

Thanks alot I got this drawing just in time. I will let you know how it goes.

Sean

[namba209]

Jim, Sean, here's the breakdown on the the rebuild Kit I got from OGTS. It's a little bit more exploded than the one Jim attached to his thread and may be a bit easier to see where all the bits and pieces go. Sean if you have a photoshop program you can explode the pic to about 1650 pixels or to an 8.5" X 11" size you'll get the actual size of the breakdown. Sorry about the stain, it fell on the work area and got brake fluid on it. HTH.

[73 gt man]

Ron or Jim,

I am having a heck of a time getting the insides out I guess I am being a little chicken because i do not want to break anything, plus I am having problems getting the resevoir off I am afraid I will brake it too, any help would as always be appreciated. The pictures have been a great help now I just need to get the old stuff out.

Sean

[baz]

if you have air you can blow the pistons out after you remove the piston stops
some are bolts ,some are like a roll pin with legs and the snap ring from the end

[73 gt man]

Is the stop screw supposed to be screwed into the the first piston and if so how far?

[namba209]

Sean, the reservoir is held in place by a rubber grommet, just remove the hose from the bottom of it and you'll see the fitting on the other end of the hose is also held in by the same size grommet. Just pull straight up and wiggle, it will come right out. There is a bolt in the top of the MC that holds the front brake piston from coming out. Remove that bolt and you'll have double spring pressure to help remove the rear piston out. I used a deep socket that fits inside the bore and tapped it a bunch of times, forcing the spring to compress and rebound, eventually the rear piston seal cleared the bore and the rest slid out. Be careful of the screw that holds the rear piston spring, it can be a bear to re-install. Also note on the breakdown I sent you, the direction of the lips on the seals, if installed backwards, you'll have no brakes. HTH.

[namba209]

The rear stop spring screw goes in all the way, it just preloads the spring a bit so the whold mess will fit inside the bore. Even so it will take a bit of pressure to hold the assembly inside the bore to get the snap ring back in.

[73 gt man]

I assembled per the drawing, but to make sure I understand the screw should be screwed into the rear piston holding the spring tension?

[73 gt man]

so the screw stays in the whole time, mine was undone when I disassembled.

[namba209]

Yes, Sean. When I disassembled my MC last week, I used an old trick, tighten the screw to see if it will turn first, then use the number of turns to stop and you get the preload setting. Mine was turned all the way in so I put it back the same way. It could be, years of vibration loosened up your screw to the point it just came all the way out. HTH.

[73 gt man]

I have it all back together and now I am ready to bleed, the two set screws on the top, how are they used, I am sorry for all the questions but I do not have a manual yet. I appreciate everyones help

Sean

[GTJIM]

The two set screws on top of the master cylinder retain the pistons and position them until the fluid is replaced.
From the Manual: "Push the piston into the housing against the spring pressure (noting that the smaller diameter end of the spring faces the piston) and insert a rod into the feed port to retain it. Fit the stop screw into the housing and tighten it.
Insert the rear piston into the housing and fit the circlip. Checkthe piston for free movement, fitting washers under the head of the stop screw if required to ensure this. Gently push the piston into the housing and remove the thin rod from the feed port in the front brake circuit."

NB: Brookland Books have an "Opel GT Owners Workshop Manual" in print at the moment - ISBN 1 870642 864 - their number, OWM 727, it is a green cover with yellow writing and a drawing of a GT against a yellow & green "grahp" paper background. It is often for sale on eBay and your local bookseller should be able to get it too if you Quote the ISBN number.

HTH

[73 gt man]

I would like to thank everyone who gave me the great help today, unfortunately I have stripped the swivel adapter to the the MC and will have to find another I hope I can find one at the local parts store. If anyone knows a cross reference for that part please let me know.

Sean

[namba209]

Sean, best bet may be OGTS, or maybe "nobody" (Dave) or some of the other folks on the site may have one. Is it the bolt that goes through the banjo, or did you strip the line fitting?

[73 gt man]

I stripped the banjo, I was quite aggravated the whole job of disassembly and cleaning and restoring everything with the MC took 8 hours and then the fiting started leaking very badly and took another hour to figure out what I had done.
If anyone has a banjo please let me know, I am going to try the local stores as well.

[GTJIM]

I hope that it was the brake line thread that stripped and not the one in the Mastercylinder body itself......
The brass banjo fittings are also used on some BMWs 1979-85 plus VWs too, I think as they all used ATE brand brake cylinders on some models. So you may find one at a Pick-a-Part yard - or even a BMW Dealer. A well stocked specialty brake shop that specialises in imports should have them too.
Remember that a thin coper washer goes on either side of the banjo bolt that holds this on to the Mastercylinder to seal it - and: If it does not screw in by finger pressure then something is wrong!
HTH