Measured brake force

Maestro, SEI-V
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RobinSF1
Posts: 35
Joined: 29 Jun 2020 06:05
Location: Merthyr Tydfil Wales

Measured brake force

Post by RobinSF1 »

My SEI-V had it's final mandatory MOT today, it will be historic next year.

It passed, but the tester commented that the brakes were about half as effective as a modern 125 learner bike. 55Kg force was measured both front and back.

I was wondering if anyone else has data from their brake tests?

The tester commented that modern riders wouldn't be able to ride it safely, but 'experienced old guys were OK'!

In 1980 with my first 500 I considered it one of the best braked bikes on the road being fairly light and unusually for those days, triple disks, I could easily out brake friends on other bikes.

Nowadays with this 500, braking is clearly not as good as the 4 pot brembos on my BMW, but much better then my Laverda TLS drum brakes, I would still rate them adequate to good.

This has set me thinking is it time and memory + technology changes which make me think these brakes are maybe not as good as my first 500 or are they suboptimal for Morini disks? Also how would a single disk front brake on a 3 1/2 measure up?

I'm aware of improvements from fitting smaller master cylinders, though that is presumably not improving the brake force, just reducing the effort required.

I've not checked my pads other than a visual inspection of the thickness, nor stripped calipers or master cylinder. I have fitted new hoses and fluid without noticing significant difference.

Just a curiosity at this time.
3potjohn
Posts: 1243
Joined: 02 Jun 2007 13:58
Location: Devon

Re: Measured brake force

Post by 3potjohn »

My triple disc Sport master cylinder failed en route about 12 years ago.
When I got back I fitted a spare smaller bore one. The brakes are very good. I subsequently discovered the old one ( I think it is 19mm, but it was ages ago) had an old seal stuck inside in addition to another.
These are the best brakes on a bike I have ever had. It has two Hel brake lines coming off the master cylinder with no splitter.
John
RobinSF1
Posts: 35
Joined: 29 Jun 2020 06:05
Location: Merthyr Tydfil Wales

Re: Measured brake force

Post by RobinSF1 »

Thanks for that. Both of my 500's have had a splitter, so that maybe not a factor. I replaced the Venhill hoses fitted when I bought it with Speedflow . I didn't notice any difference from that. Amongst the receipts which came with the bike last year were seal kits for front and rear callipers, 2 owners 6 years previous and 200 miles earlier. I presume the callipers were overhauled then. Fluid looked fresh when I replaced the hoses.

More of a curiosity and wondering whether anybody knew what the their braking force was. I find the brakes perfectly adequate for me. I will do a visual inspection of the callipers and pads next time I change tyres.
Emmohaswheelsagain
Posts: 358
Joined: 28 Jun 2008 21:13
Location: Lincolnshire

Re: Measured brake force

Post by Emmohaswheelsagain »

Whilst my 500 has already achieved historic status, I have like you pondered over the efficiency of the brakes.
It is of course all relative, back in 1979 when my 500 was first registered I owned a 350 sport, some of us opted for the twin discs up front, however cars braking abilities were different too, I owned (for work only) an Austin 1100, now compare this vehicle with my latest car, a Toyota Yaris Cross, this has large discs front and rear and can stop very quickly, Indeed the braking ability of cars/traffic generally are far superior to most 40 year old motorcycles. I have therefore adopted a very passive riding style, allowing a generous gap between me and the car ahead. That doesn’t mean that I won’t try and improve the brakes, but when it comes down to straight comparison I have no chance against the modern car. I guess we must rely on our riding experience.
MickeyMoto
Posts: 2415
Joined: 22 Nov 2008 17:41
Location: Even further oop North

Re: Measured brake force

Post by MickeyMoto »

Robin,

I believe you are a member of ILOC. I'll ask your new chairman, he may have some useful data.
norbert
Posts: 750
Joined: 15 May 2007 15:15
Location: Lübeck/Germany

Re: Measured brake force

Post by norbert »

Going down with the bore of the master cilinder changes everything! I´ve put a 13mm Grimeca pump (two discs) and it´s a two finger brake. I think 14 mm would be the way to go with two discs, 13 mm will do perfectly with one disc.
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