rear master cylinder upgrade

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g2501

Well-Known Member
Joined
Dec 25, 2017
Messages
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Location
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Being an inexperienced rider I made a huge mess with my rear master cylinder.
Long story short :
I've decided to make some maintenance to the rear master cylinder and ordered the kit.
Swapped all the internal parts with the new one and mount it back on the bike.
as soon as I tried to pump on the pedal I felt something strange....the brake pump does not moves. :ummm:
I dissassembled the master cylinder once again and with tears in my eyes I see that I've scretched the internal part. :bang head:

Now, instead of purchase an used rear cylinder I decided to go ahead with a new one, but unfortunately there are only one company that makes a vmax 1200 compatible rear cylinder, and this part cost too much for my pocket.

So, before giving up I made a call to Brembo (an Italian company well known for some of the finest braking systems for cars and motorcycles ) and they told me that theoretically there is a product that can be used to solve this problem.
This is the product :

Brembo_10477683_Rear_Master_Cylinder_Pompa_Freno_Posteriore.jpg


cylinder diameter is 13mm , so it is pretty much the same of the vmax.
size is also very similar, and the only difference is the space from the installation holes and the center of the cylinder.
the original V-max rear master cylinder have a distance of approx. 25mm from the center of the cylinder to the center of the fixing holes, while the Brembo master cylinder only 19mm
here is the diagram :

pdf diagram brembo ps 13

Being this product new , affordable and top quality I decided to purchase this master cylinder and give it a try.

The only annoying difference is that this master cylinder use standard 8mm hoose , so a new 30ml reservoir tank and and a new rubber hoose is needed, but it's not a big issue.

I tried to mount it on the bike and there is plenty of space behing it.

The only trouble is that I need to build a special fixture to mount it perfectly aligned, and I'm strugglin to find out how this can be done without having to harm the bike.

What do you think about?
I still believe that this mod can be a nice upgrade to the vmax.
Looking at the price tag it's a no-brain choice.
I've spent something like 70$ for this and the reservoir tank , and if I had purchased an used vmax master cylinder I could have spent maybe even more considering the shipping fees.
In Italy an used parts can cost from 40 to 90 euros shipping exlcuded.
 
Fabricate an adapter plate.
A piece of aluminum would be the easiest.
Make 2 holes to bolt it to the max frame.

Align the master cylinder as needed so the clevis aligns with the brake pedal. Mount it to the plate.



Sent from my SM-G930V using Tapatalk
 
think of this in the first place, but still arguing on how to do that.
I have 5mm ( more or less ) of difference between the center of the holes, so if I install this plate on the original vmax plate using the master cylinder holes on the frame I do not have enough space to make the 2 new holes to install the new brembo master cylinder.
Also, an adapter plate like this should be at least 3 or 4mm thick, and this will move the center of the pump outside the center of the pedal lever.

Another option could be to modify the brake lever, but I'm really not confident in doing this.
Still looking for a good design to use for the adapter plate, but the more the time pass, the more I belive that I need to cut some metal from the vmax frame, remove the rear nut , enlarge the hole , and then install an "C" shaped adapter .
maybe some of you guys can shed some light on this situation.
 
If you move the new master cylinder up, or down, it should eliminate the problem with the holes being 5mm off. Up is probably the better option. You can lengthen the rod/clevis assembly on the master with a coupling and piece of threaded rod.

If you put spacers between the frame and the adapter plate, you could mount the new master on the front of the plate which would allow it to line up with the brake pedal.

I've done some goofy stuff to switch bikes from drum to disc before. It wasn't pretty but it was functional.

2011-12-31_12-19-19_711.jpg
 
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