New Rear Master Cylinder not performing well

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Thank you LAB for looking at my details. I simply keep putting items back as found.
I ordered the big 7/16" nut with shoulder.
I will switch the clevis pin if possible.
Thanks again for all your technical expertise and time on this forum.
 
Looking at my technique of holding the rear brake pedal down with finger pressure,
what pedal travel distance is found on a 5/8" OEM cyl?
What pedal travel distance is found on a new 13mm cyl?

New Rear Master Cylinder not performing well
 
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Can anyone report on what a Mk3 13mm rear master brake pedal travel is typical?
See photos above to set your tape measure
Thank you,
 
I'm making 36mm of travel on a 13mm cylinder at the moment. Though not ruling out possibility that calliper would benefit from an overhaul :-)
 
Thank you, i too am considering an overhaul on rear caliper.
The inboard piston doesnt seem to move or simply looks suspicious.
 
Some of the latest pistons in the Triumph master cylinders are now different in manufacture to the piston found in the original master cylinders. This results in the operating rod locking prior to screwing in the assembly into the mounting.
 
Is 'caliper' like 'color', one of those words written differently either side of the Atlantic? If I use one 'L' in the former here I get the red wavy line indicating a mis-spell until I add another...
 
Madnorton said:
Some of the latest pistons in the Triumph master cylinders are now different in manufacture to the piston found in the original master cylinders.
Click to expand...


Presumably, you are referring to 5/8" master cylinders (as there were no original 13mm master cylinders) so how exactly do "some of the latest pistons" differ in manufacture?

Madnorton said:
This results in the operating rod locking prior to screwing in the assembly into the mounting.
Click to expand...

That seems to make no sense so perhaps you could explain?
 
Just ratioing areas, a 13mm cyl would increase stroke by factor of about 1.5 for the same volume of fluid. So if my 3/4" is typical for 5/8, then a 13mm cyl would yield a 1.1" pedal travel. Not as much difference as I had expected.
Jaydee
 
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Measured mine at less than 1 " of travel before good brake engagement. Seeing as I have the Cdn. MK 111 model and seeing as I now work in milimeters. (by law) that's help for you/ our good neighbours just south of us. Spellcheck on both words seeing as I am in Canada.
 
Thanks all, today I did a 100 mile ride on this newly reset 13mm rear master and I found it much nicer to use.
It had been in service about a year with longer pedal travel and not the safest bike for me to ride, but i did a couple thousand miles.
I also finished a clutch/primary rebuild just this week and , as a result of todays ride, need to reset the shift lever down one spline, i think also i will lower the brake pedal.

The Mk3 brakes are underwhelming compared to modern, and I have 13mm cylinders on both brakes.

20200819_192549.jpg


Two Mk3 and an Indian pausing at an upcoming equipment sale.
 
I found the front 13mm upgrade more than adequate, though didn't find the rear to be such a quantum leap forward (or should that be 'backwards?'). Perhaps one is 13 milimeter and t'other 13 millimetre :-)
 
L.A.B. said:
Presumably, you are referring to 5/8" master cylinders (as there were no original 13mm master cylinders) so how exactly do "some of the latest pistons" differ in manufacture?



That seems to make no sense so perhaps you could explain?
Click to expand...
Yes, both. The 13mm rears we used to make up would use the same rod as the standard bore, but the recent batches of the 13mm assembly we get in have a different piston in them compared to the 13mm assemblies of old, this latest version needs the rod shortening so the assembly can be screwed into the body to get the grub screw to correctly.

I will try and get photos tonight of old my 13mm version and the new version.
 
Madnorton said:
Yes, both.
Click to expand...

How is it "both" (5/8 and 13mm) as it appears to be only the 13mm rear master cylinder? Why specifically "Triumph" as you stated previously or does "both" refer to Triumph and Norton 13mm rear master cylinder assemblies?

Madnorton said:
The 13mm rears we used to make up would use the same rod as the standard bore, but the recent batches of the 13mm assembly we get in have a different piston in them compared to the 13mm assemblies of old, this latest version needs the rod shortening so the assembly can be screwed into the body to get the grub screw to correctly.
Click to expand...

...to correctly...?
Well, I think I understand what you mean which doesn't sound as drastic as what you said previously but then as far as I'm aware the 13mm Triumph and Norton rear master cylinder parts have never been available separately anyway, or, if they are, what are the part numbers or in what section can they be found on the AN website?

Edit: A different piston length would seem to mean the 13mm master cylinder could not be fitted to Triumph front brake assemblies without modifying the lever pushrod.
 
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