lockheed front master cylinder assembly

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dmyena

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Oct 23, 2009
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hi, does anyone have a draw or picture for how is the exactly sequence and order to reassemble the front master cylinder ?
i just received the rebuilt kit and i think there are extra parts that might be there in case you are rebuilding the rear cylinder, ( two gasket a big and a smaller one) my norton is 850 1974 so has only the front disk brake.
I'm in the process to clean all the parts and ready to put it back together would be great to have some reference pics.

thanks

D.y.M.
 
Yes, there are usually some extra parts in the kit which you do not need, so follow the link and assemble it using the parts as shown in the exploded diagram Fig.16:

http://www.classicbike.biz/Norton/Repai ... mmando.pdf -Section H, Fig. H16

If your kit contains two alloy washers, then it's the thinner curved one that should be used between the primary cup and piston, and not the thicker flat one.
 
A picture may help.

This is from my 75 850 front master, I hope I had them in the correct order. The brake works great but check that it matches the diagram.

lockheed front master cylinder assembly


Chuck
 
BTW, putting the secondary cup on the piston assembly is a real PITA but it will go. Let it soak in brake fluid for at least 20 min first and do not use any tools or you may break it.

Chuck
 
If you are referring to the CALIPER, the two big o-rings are for the caliper pistons, the smaller one is for the screw-on CAP.
 
grandpaul said:
If you are referring to the CALIPER, the two big o-rings are for the caliper pistons, the smaller one is for the screw-on CAP.
Click to expand...

There's often two O-ring seals included in the master cylinder rebuild kit which are not used on the Norton Lockheed front master cylinder.

The larger one being the reservoir/saddle to master cylinder body O-ring seal (Norton rear M/Cyl. and Triumph front & rear M/Cyl.) and the smaller one is the saddle retaining nut O-ring seal (Triumph rear M/Cyl.).
 
L.A.B. said:
There's often two O-ring seals included in the master cylinder rebuild kit which are not used on the Norton Lockheed front master cylinder.
Click to expand...

Yep, I read the original post wrong, and have heard calipers called master cylinders 30% of the time...
 
I fear this may be a dumb question, but can anyone tell me what is the function of the rubber/plastic valve assembly shown on the left of ChuckW's photo? I stripped an old spare master cylinder last week, but the rubber valve was in such poor condition that I couldn't work out what it does or how it works.

Thanks

Mitch
 
mitchp said:
what is the function of the rubber/plastic valve assembly shown on the left of ChuckW's photo? I stripped an old spare master cylinder last week, but the rubber valve was in such poor condition that I couldn't work out what it does or how it works.
Click to expand...



Quote from the Triumph T140 manual: "The purpose of the check valve.....is to prevent the re-entry into the master cylinder of fluid pumped into the line during the "bleeding" operation, thus ensuring a fresh charge of fluid at each stroke of the lever"

I believe it also serves a second purpose (again, quoting from the T140 man.)

"On releasing the brake lever the return spring thrust the piston back faster than the fluid is able to return from the wheel cylinders. This creates a partial vacuum in the cylinder which causes fluid to be drawn past the lip of the primary seal from the main reservoir via the main feed port and the small feed holes in the head of the piston."


 
thank you all. the link and the pic was really helpful ,
i think at the end i got the wrong kit, i got the rear master cylinder , i ordered now a new front one... hopefully will fit this time. ( i found one on ebay tha has only the required parts no wired o rings and to big seal cap... cheap and fast shipment)
thanks


D.y.M.
 
L.A.B. said:
mitchp said:
what is the function of the rubber/plastic valve assembly shown on the left of ChuckW's photo? I stripped an old spare master cylinder last week, but the rubber valve was in such poor condition that I couldn't work out what it does or how it works.
Click to expand...



Quote from the Triumph T140 manual: "The purpose of the check valve.....is to prevent the re-entry into the master cylinder of fluid pumped into the line during the "bleeding" operation, thus ensuring a fresh charge of fluid at each stroke of the lever"

I believe it also serves a second purpose (again, quoting from the T140 man.)

"On releasing the brake lever the return spring thrust the piston back faster than the fluid is able to return from the wheel cylinders."
(= due to the valve)



"This creates a partial vacuum in the cylinder which causes fluid to be drawn past the lip of the primary seal from the main reservoir via the main feed port and the small feed holes in the head of the piston."

So it also helps to keep the cylinder fully charged with fluid,-ready for the next brake application.
Click to expand...


That makes perfect sense, thank you very much.

Regards

Mitch
 
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