Street Twin Brakes

The glossy spots is wet satin hammerite. £60. Pistons look good and clean. Floating disc, HH disc pads and 14mm master cylinder repair kit (for T595 M/C I have in the shed) in the post.

 

After 2 days of reading ratio tables, playing with master cylinder calculators, finding formulas linking piston surface areas with just about everything else that moves on a vehicle I recon the ideal master cylinder is the 12.7mm bore for a 3 pot Nissen caliper.

The optimum size may well be a bit less but given the sizes commonly available in the market (11mm, 12.7mm, 14mm, 16mm, 17mm etc) with suitable brake light switches, look, and a 'standard' lever length I'm going for a 12.7mm bore - basically the master cylinder for the 4 pot Brembo equiped gen2 LC 900 is the one. I'm expecting the lever to have slightly less travel and require a bit more effort than the standard braking system but close.

And of course it's obvious. The 14mm bore supports twin disc, mostly 4 pot caliper fits. 11.7mm does the 2 pot gen1 single disc twins. The 3 pot Nissen has about 20% more piston surface area over the standard twin pot caliper. Working the maths a 12mm may be a ideal pairing but the maths is significant as there is so much to consider including disc size, weight of the machine, momentum etc.. Anywa, as a 12mm isn't available except for custom application such as bespoke racing kit it is the 12.7mm Triumph master cylinder.

I got a second hand one tonight. Given I was going to use a 14mm, off a T595, master cylinder I had in the shed (free) is the whole endeavor worth it over buying a kit?

Floating 310mm EBC Street Cup floating disc = £150
Used 3 pot Nissen Honda Caliper = £60
12.7mm used Triumph Master Cylinder = £85
Second hand but unopened EBC HH pads = £23

Total = £318

That, assuming all work well and the Master cylinder does not need a repair kit, gets you an upgraded braking system that is unlikely to stop you quicker (for want of a better expression) than the 4 pot brembo kit we all have seen. Is the Brenbo upgrade more reliable in the long term? Who knows? Will the kit look better? To me yes - it will all be new and unmarked and have Brembo written on it if that matters to you.

As I write I'm undecided if I would do this again on any future bike. If I fit my solution and it bleeds up easy and works well it make my Triumph a bit more 'mine' and a bit more unique and have a more powerful front brake over standard. I guess I will be happy and forget the fact that I could have saved for another month or two and got a better solution.

I will fit my solution next week now and post the 'on the road' assessment if anyone is interested.

 

Caliper on and 12.7mm (2022, 900 Bonnie) 1/2 inch marked master cylinder on. The mater cylinder is exactly the same except for the bore so mirrors, reservoir and brake swith all go on no problem. First bleed done - took some patience to get rid of the worse of the air pockets - but rain stopped play so I'm gonna bleed it again.

Lever as expected. Very slightly firmer than standard. The old brake fluid was a little cloudy.

I still have an ebc floating disc and new HH disc pads to go but so far so good. I have no centre stand so I'm gonna get an Abba stand or something to help me keep the bike solid so I can get the front wheel out safely.

Photos to come once the job is completed.

 

Nice honest write up, thanks.
Please do post a test ride impression once its all up and running

 

A vacuum bleeder is your friend and once mastered it makes your life easier.

I have one something like this....

https://www.machinemart.co.uk/p/blue-spot-brake-bleeder-and-vacuum-pump-kit/

 

Wow! That does look trick and I'm always looking for more tools! Many thanks for the thought.

 

Make sure the bleed nipple isn't leaking (air) when "your pulling the fluid"?
If it is, remove the nipple and give it x3 wraps of ptfe tape, on the threads only

Job done.

 

Don't forget these can also be used for vacuum (reverse pressure) testing i.e. seals and chambers.

 

You know i have two of those and never used them

 

Good tools @joe mc donald and I've used mine for all sorts.
The younger generation wont have a clue what I'm talking about but it was interesting using one and watching how the advance and retard diaphragm performed on the points baseplate. Any leaky pipework can soon be safely sorted without popping anything i.e. applying compressed air ... oh b0ll0cks, I wish I hadn't done that ...... a few of us have been there no doubt.... moi, oh no .... but maybe

 

@Eldon Perhaps i will get around to trying one out soon. My boy used them on is track bikes 675's so i got one then he got me a second.

 

Bonnie master cylinder.

 

Sorry, lever!!

 

Lever pull

 

On setting #4 yes?

 

On 3 Eldon.

 

Sorry mate, yes 4.

 

I have also bled them again this morning and the lever firmed up a little more. In between the rain I also went out for a 25mile run. Lever consistent, no leaks. Definitely more stopping power. I never thought the standard brake was that bad tbh. 2 up (I'm a 17st fat bastard and the wife is a gorgiously well proportioned 12st) and pulling her down from a ton there was no real reserve power in the brakes - you were using the system, with the rear brake to 90% or so of its potential. Now the engine is done, suspension is done I can ride her swiftly and know I have some 'brakes in my back pocket'. I'm happy - after all, she is no ZXR or Speed Triple and there is a reason why I no longer have such bikes. Basically, I'm getting old and have too many old injuries!!! Lol!!

 

All bedded in now (after about 300 miles). The 3 pot nissen works great and is effortless on the fingers. The caliper, 12.7mm master cylinder (gen 2 900 bonnie) EBC floating disc (for a Street Cup) and HH pads have really made a difference and feels 'factory fitted'. Very happy.