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PostPosted: Tue Dec 05, 2017 8:29 am 
BoTM Winner
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Looking good!

Quote:
Did you measure to the middle of the brake stud bolt hole or to the upper edge?
Middle to middle.


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PostPosted: Tue Dec 05, 2017 8:56 pm 
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Today I made the bronze bushing sleeve and the "lock nut" that will later hold the spring.

Image

I still don't fully understand how Marinovative dealt with the fact, that brake bosses seem to have slightly different lengths on different bikes or forks. I have seen them from 16mm to 17mm. I made my bushing 16.5mm. This size is perfect for my current project bike (a very sad looking Klein Pinnacle). But they bind on Mag21s.

In my mind, it would be a better design to have the brake arm pivot/slide on the bronze bushing (and have that fixated to the brake stud by that nut) rather than having the bronze bushing pressed into the brake arm and sliding on the brake stud. But this seems to be the way, Marinovative did it.
@stevet1, could you please confirm that for me? :mrgreen:

(Does anybody understand (or even care about :D) my blabbering about those problems ?


Last edited by Thias on Tue Dec 05, 2017 9:37 pm, edited 1 time in total.

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PostPosted: Tue Dec 05, 2017 9:33 pm 
Gold Trader
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cool project, registering for updates! 8)


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PostPosted: Tue Dec 05, 2017 11:22 pm 
BoTM Winner
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Quote:
@stevet1, could you please confirm that for me?

Yep, can't quite remember how they went on but I'll take a look. They certainly work okay on my setup, no binding or vibrating that you might expect if they were loose.


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PostPosted: Thu Dec 07, 2017 10:51 am 
BoTM Winner
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Checked last night. You're correct in that they rotate around the brake boss on the fork/frame, rather than having a separate bush slide over the boss like on e.g. Pauls brakes.
In this respect it is the same setup as most other brakes to be fair, and it doesn't seem to affect performance. Maybe the variation in brake boss lengths isn't as big as you thought so isn't a problem?


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PostPosted: Thu Dec 07, 2017 11:15 am 
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Thank you for your help!
Over at the German forum we have a little discussion about whether it is a problem or not. May well be it is not. Maybe its just all about the tight sliding fit on the bosses.
Someone mentioned there, that e.g. the Grafton cantilevers came new with a few very thin shim rings to eliminate the play. And that those shims got mangled very fast or got lost. Without those shims the owner then had problems with brakes squeal and simply switched back to BR-M732. (But I have those on 2 bikes and those tend to squeal, too...)

I am thinking about changing the design in favour of having a fixed bushing on the brake bosses. We'll see.


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PostPosted: Thu Dec 07, 2017 7:51 pm 
Old School Hero

Joined: Wed Nov 12, 2008 10:52 pm
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Location: manchester uk
Very nice work. Seen as your re making the design to your own spec not a copy of the original you can re design it how you like. You could use a brass bush in the lever that runs on brass top hat on the mount for perfect fit whatever bike there on. Just seems if your doing all this then you might as well make them the way you think would be best. Nice work though Keep it up


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PostPosted: Thu Dec 07, 2017 11:51 pm 
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What a great project. Stuff like this is why I keep coming back to RB!

Looking forward to the updates...


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PostPosted: Fri Dec 08, 2017 9:03 am 
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WandsworthRouleur wrote:
What a great project. Stuff like this is why I keep coming back to RB!

Looking forward to the updates...

Thank you for you kind words. It's comments like this that make me posting here :D

t wild wrote:
Very nice work. Seen as your re making the design to your own spec not a copy of the original you can re design it how you like. You could use a brass bush in the lever that runs on brass top hat on the mount for perfect fit whatever bike there on. Just seems if your doing all this then you might as well make them the way you think would be best. Nice work though Keep it up


Thanks!
In fact this is exactly what I did last night. I made a test-part out of Aluminium (I am low on brass stock...) to go into the arm instead of the brass bushing. It clamps on the brake bosses solid and the brake arm slides on it. That feels so much better! No more wobbling around. I am now sure that's the way to go.

Image


I also started on the brake pad holder. It is the most difficult part to make for me. And sure I messed up the first try. I had to learn that 12.85mm drill is too big if you want to clamp on a 12.7mm rod :facepalm:
But it camps well with one layer of paper warped around the rod :mrgreen: So I will finish the part searching for more problems, I did not think about.
And - while beeing scrap - it still makes for a good progress pic :roll:

Image


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 Post subject: Re:
PostPosted: Fri Dec 08, 2017 10:43 am 
retrobike rider
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Think about switching you bushing setup for some DU or Oilite bushings as used in higher end brakes.

Pretty much all brakes use the separate approach you are now using (you just don't notice it)
Cheaper ones are steel bushings or brass, more expensive are DU coated bushing (a lot seem to use the DU flange ones )

Of course the Marinovate were cheap and cheerful things in reality.


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