MKIII master cylinder rebuild

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nberg

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Hi, I am rebuilding my mkiii master cylinder for the first time and purchased Andover Norton rebuild kit 19-4700. The other available kit includes everything in this one plus the bellows and trap valve.

My question is....does anyone have pictures of the components in their assembly order? Besides what is on Old Britts. There is a rubber component in the rebuild kit that I can't match to my parts....and my trap valve has a rubber seal that is not in any kit. And no...they are not similar.

Thanks for any help.
 
nberg said:
does anyone have pictures of the components in their assembly order?
Click to expand...

http://britmoto.com/manuals/Manuals/750_man.pdf
Section H, Fig. H16.


nberg said:
There is a rubber component in the rebuild kit that I can't match to my parts....and my trap valve has a rubber seal that is not in any kit.
Click to expand...

MKIII master cylinder rebuild
MKIII master cylinder rebuild


Lockheed Brake service Manual:
http://www.classicbike.biz/Triumph/Main ... Norton.pdf
 
L.A.B. Thank you very much! This clears up the extra rubber part. Now to figure out the trap valve.
 
nberg said:
Now to figure out the trap valve.
Click to expand...

Why, what's the difficulty?
Also, I assumed you were talking about the front master cylinder-but I think perhaps you mean the rear, in which case I suggest you refer to the rear unit diagram in the Lockheed manual link rather than the Fig. H16 diagram from the factory manual.

Also note that the Old Britts Tech article shows both metal washers supplied in the rebuild kit included in the assembly-but only the thin curved washer is used.
 
IMPORTANT!
The thin curved primary cup/piston washer MUST be assembled with the concave side in and against the rubber primary cup. The convex side to be facing out and against the steel piston with the three small holes. If you get that bit backwards you may find you initially have a good brake, but pressure will bleed of with light to moderate application (as when holding at a stop light or slight incline).
 
Also, on the rear assembly, the way the cylinder screws into the body has to be done just right. I don't have the info handy, but the factory manual is the only place that has this info
that I know of.
 
milfordite said:
Also, on the rear assembly, the way the cylinder screws into the body has to be done just right. I don't have the info handy, but the factory manual is the only place that has this info
that I know of.
Click to expand...

That information is given in the Lockheed Service Manual link I posted above.
 
The complete rear m/c rebuild kit I got from Old Britts included a part not shown in the Lockheed diagram. It's a flat rubber washer with a small hole in the center. No idea what it's for.
 
Danno said:
The complete rear m/c rebuild kit I got from Old Britts included a part not shown in the Lockheed diagram. It's a flat rubber washer with a small hole in the center. No idea what it's for.
Click to expand...

The Lockheed diagram show everything that's in the piston assembly. The one rubber part not shown is one that seals the plastic reservoir to the body. That it?
 
Biscuit said:
Danno said:
The complete rear m/c rebuild kit I got from Old Britts included a part not shown in the Lockheed diagram. It's a flat rubber washer with a small hole in the center. No idea what it's for.
Click to expand...

The Lockheed diagram show everything that's in the piston assembly. The one rubber part not shown is one that seals the plastic reservoir to the body. That it?
Click to expand...


No, that comes as an O ring that fits in the groove in the underside of the reservoir. This piece looks almost like a faucet washer. About 1/8-3/32" thick, same general diameter as the master cylinder bore and a very small hole in the middle.
 
On the AP drawing that L.A.B. Posted, there is reference to 2 different designs using different rubber components. I assume the rebuild kits contain either option. I couldn't figure out that extra washer....and that prompted me to post this thread.
 
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