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I think the master is made in both 11mm and 12mm piston sizes. 11 is standard.

try and go small on caliper size and then if the amount of travel is too much switch to the 12mm master.
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charlieman22 wrote:
Good questions.
I need help.
Hope y'all weigh in.

Overview:
- I wanna do full hydro.
- I want it to be tied in to front brake - so when I get on the front, rather than allowing the sidecar weight to bear down on the fork, I get some drag from it. This should give me some nice improvement to the sensation of weight when heavy braking.
- which means, it's front master cyl driven & I need a proportioning valve - as u note.
- The swing arm was designed to allow the caliper to be bolted on (radial).
- I expect an empty sidecar to need far less braking force then front wheel of scoot
- my master cyl is same as whodats.
Maybe 9 or 10mm? (MMW).


The questions are many.
1. Can it operate two calipers?
2. If no - why
3. What would ideal master cyl piston and reservoir be? I'm not shy bout modifying stuff…

Welcome some insights/ discussion on this one, before I proceed.
Suck at it later in week.
You should be able to operate two calipers (along with a prop valve in the mix) with a standard master cylinder. What diameter is the caliper piston? And is it single or double piston caliper? And what size caliper (and piston diameter) are you wanting to use on the sidecar?
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Thanks u guys.
I'll take some measures and post some pics.

I'll also sketch up a routing and schematic I'm thinking a bout.

Much appreciated.
Stay tuned!
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I found a master cylinder sizing tool/spreadsheet a guy on a race bike forum built. It's probably overkill for your purposes, but should be useful nevertheless.

I'll share a link later when I'm not working on my phone.
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Great
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some vespa related data on master and caliper size and impact

LX brakes > GTS brakes, NOT!
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This looks like your sort of thing. Apologies about the TinyURL but the Aliexpress url went off the page.

https://tinyurl.com/2b2jbv72
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Thanks for that Ginch. I've seen something similar on Amazon here.
One question I am trying to resolve - how do I put it all together... related to size of fitting - but I think I can sort that out.

Time slipped away this week - so I didn't get a chance to take the measures/ look at what I have.

Below are some pics/ deets.
- My caliper is the std 4 piston type. Believe the piston's are 25mm.
- I purchased some raw brake line. little over 7mm outside, 3.xx ID. The fittings I got seam right on for the ID - but won't work with the OD.
- The proportioning valves like Ginch showed seem to all have 1/8" NPT thread.

Interested to know how you guys might tackle the brake lines. I was thinking double banjo on the front brake inlet - that allows me to run a second line from there to the side car - via a proportioning valve.

Would be cool if I could hide that in the tunnel somehow - perhaps under the seat where the bodges add a hook.
This could allow some on the fly adjustment if I start smoking my tire like a semi pulling up to a random stop sign.
But that seams like a really long set of brake lines.
Not sure how that might affect me.
Bought a splitter.  If I can figure out what size fitting will work with my hose - this could likely mount before the front caliper.
Bought a splitter. If I can figure out what size fitting will work with my hose - this could likely mount before the front caliper.
I bought these.  The brake tube I have fits perfectly on the male portion - but the brass ferrel and nut don't seem to be for 7mm OD tube?
I bought these. The brake tube I have fits perfectly on the male portion - but the brass ferrel and nut don't seem to be for 7mm OD tube?
The ID is about 3.3mm
The ID is about 3.3mm
And of course I have the SIP brake line running to my caliper from my master.  I'm not sure what the ID is on this - and I haven't really figured out how I'm going to find an end that will work.  May need someone to make me up some lines.
And of course I have the SIP brake line running to my caliper from my master. I'm not sure what the ID is on this - and I haven't really figured out how I'm going to find an end that will work. May need someone to make me up some lines.
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Hey pal, once you get things figured out on lengths you could always have Galfer make you custom hoses. Banjo to AN would work for your hose to valve. 1/8 NPT to AN-3 is probably what you need for a fitting coming out of your proportioning valve.
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been thinking about the linked brakes setup, and the more I think about it the more I think it would be better to use the foot brake for the sidecar wheel.

1. you could use a balance bar to split the cable/hydraulic load between the rear and sidecar. I'd let the side car be stronger than the rear.
2. having the front and sidecar brakes separate would let you control yaw as needed regardless of conditions. A proportioning valve will only be "right" in a very narrow set of conditions and likely different for even left and right hand corners.
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oopsclunkthud wrote:
been thinking about the linked brakes setup, and the more I think about it the more I think it would be better to use the foot brake for the sidecar wheel.

1. you could use a balance bar to split the cable/hydraulic load between the rear and sidecar. I'd let the side car be stronger than the rear.
2. having the front and sidecar brakes separate would let you control yaw as needed regardless of conditions. A proportioning valve will only be "right" in a very narrow set of conditions and likely different for even left and right hand corners.
This makes a lot of sense. It's felt wrong to tie the front wheel and the sidecar, but I couldn't pinpoint why. Patrick did.
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Allright - long one - but don't bail on me yet.
Getting a lot from the discussion.
BajaRob wrote:
Hey pal, once you get things figured out on lengths you could always have Galfer make you custom hoses. Banjo to AN would work for your hose to valve. 1/8 NPT to AN-3 is probably what you need for a fitting coming out of your proportioning valve.
Good thought on banjo to AN3.
Agreed first step would be to get everything hard mounted and figure out my lengths.
My front disc is a Galfer - bought it in Germany.
Had no idea they would custom make brake lines.
Just saw on their web site.
Awesome.
Thanks!
Quote:
Here you go…
Safis - thanks!
I think these are the links you posted for me before.
I bought the fittings (M10 AN3) you posted - and thought I got the right brake line.
Just had a closer look - mine is ID:3.2 MM
OD:7.5MM
Yours is ID : 3.5mm
OD :6.35mm
I think what I bought turned out to be incompatible...
Tks.
Quote:
been thinking about the linked brakes setup, and the more I think about it the more I think it would be better to use the foot brake for the sidecar wheel.

1. you could use a balance bar to split the cable/hydraulic load between the rear and sidecar. I'd let the side car be stronger than the rear.
2. having the front and sidecar brakes separate would let you control yaw as needed regardless of conditions. A proportioning valve will only be "right" in a very narrow set of conditions and likely different for even left and right hand corners.
So you probably know why I'm thinking about tying to front brake - but I'll spell it out to see if that changes your thinking at all.

Currently:
When I get on the back brake - it works nicely.
There isn't really any noticeable pull at all - left or right - because it's dragging down my speed and holding the weight from behind.
It slows me a little.
It lets the people behind me know I'm bout to lean into a corner...

When I get on the front brake - there is an initial push from my right.
That inertia of the weight off to the right wants to pass the scoot.
I hardly notice it anymore.
Maybe the damper picks it up.
Maybe I've learned to lean into it a little.
IDK.

Stopping power is pretty good.
Unless its wet out.
In which case, the tiny patch of tire touching at the front is just overwhelmed by the push and weight.

My thinking is - tying in the sidecar brake to front will remove the inertia of the mass to my right. I could be wrong - but that's my thinking.

Your solution for the back brake is very executable.
In fact - Whodat hooked me up with a Grimke semi hydraulic set up that would do the job quite nicely.
I suspect getting the cables set up would be kinda fiddly.
trying to get tension just right in everything.
Not out of the question tho.
I'll ponder it

Last: though I bought a 220mm disc and full size caliper, I am kinda wondering if a mountain bike setup might have been lighter and just as effective for my needs?
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Admittedly all my sidecar experience is with the non-leaning kinds, and that may negate the validity of my observations. I get the thinking of the linking the front to the sidecar as hitting the front does cause the bike to yaw. It's just that the asymmetry of a sidecar always reminded me a bit of flying where you had to actively control yaw, pitch and roll but with very limited and overlapping inputs.

Being able to directly control yaw under braking just seems like it would open up more options.
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oopsclunkthud wrote:
Admittedly all my sidecar experience is with the non-leaning kinds, and that may negate the validity of my observations. I get the thinking of the linking the front to the sidecar as hitting the front does cause the bike to yaw. It's just that the asymmetry of a sidecar always reminded me a bit of flying where you had to actively control yaw, pitch and roll but with very limited and overlapping inputs.

Being able to directly control yaw under braking just seems like it would open up more options.
Unless you're talking about a Stearman with a 985 up front, then it's extreme overlapping inputs! 😄 You fly too?!
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Wait, are you trying to fit the brass ferrel over the OD?? It needs to go on the PTFE tube and between the outside braiding…
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Well, uh, not exactly…
TBH - I flat out couldn't figure out what or how the brass ferrule worked.

My brake line OD is a hair too big for the fitting.
But maybe I didn't try hard enough.

So does the brake line just get smashed into the ferrule ?

It's too big to fit the ID of the brake line.
The brake line ID is a net fit to the male tube poking out of the banjo.
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Safis - here is a picture of the components.
The braided line is defiantly too large to go into the cap - so I would need to re-order.

Even if I don't go this way - would like to understand how these lines work.
In the pic - you can see the brass ferrule.

It appears to me that it would fit over the PTFE internal tube - if I could strip back the braided cover.
Is that how you are supposed to assemble these?

Is there a trick to cutting back the braiding if that's the case?
Tks.
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I've been doing this now with all my brake lines. After I install banjos I measure hose length and go pick up hoses. Super easy and your local Harley dealer should stock those hoses in different lengths and banjos if you don't want to order. Boom!
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charlieman22 wrote:
Safis - here is a picture of the components.
The braided line is defiantly too large to go into the cap - so I would need to re-order.

Even if I don't go this way - would like to understand how these lines work.
In the pic - you can see the brass ferrule.

It appears to me that it would fit over the PTFE internal tube - if I could strip back the braided cover.
Is that how you are supposed to assemble these?

Is there a trick to cutting back the braiding if that's the case?
Tks.
Pro tip: unless you're drawing blood from getting pricked multiple times from the braided stainless jacket, you're probably doing it wrong...at least that's been my experiences. The instructions are for Aeroquip lines.

https://static1.squarespace.com/static/56a4243589a60a5d20e455ec/t/5a8d9d760d929746af2adb90/1519230329966/AeroquipHoseInstallation.pdf
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Watch this. This is how I do them too…

*You don't need the tool to press in the ferrel, I tap it lightly with a plastic hammer…

https://youtu.be/m5UUEGT1N2w

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Awesome!
Thanks you guys.

Rob - that's two good solutions you've shared. Tks.

Whodat - I'll prepare my finger tips to be numb (again) for a few days after assembly.

Safis - That video is great! and the assembly part is ok also... 🙂
Thanks!

Ok - I am brake line savvy now.
AN vs PTFE lines and ends, and crimping.

So now I gotta think about my design - and also those lighter weight brakes.
Does anyone wanna weigh in on the idea of using something less than a full motorcycle weight caliper/disc for this thing?
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charlieman22 wrote:
Does anyone wanna weigh in on the idea of using something less than a full motorcycle weight caliper/disc for this thing?
I really like this idea.

One thing (of many things) I don't know about hydraulic bicycle brakes is how they will work with your current master cylinder. I do know they run a very thin hose, presumably they have much smaller piston capacity than the front one you have on at the moment.
If you are running similar calipers then (as I think Patrick pointed out) then you know it will work. But would your M/C overcome the bicycle calipers, effectively only giving you on/off? Dunno. But worth considering.

Something that popped into my head while reading was a rear disc for smallframe - think I posted it up a few years back - operated by cable. If you were linking to the rear then it could work. Obviously linking to the front very difficult and not worth considering.

With both of those options it might be useful to know what the sidecar weighs as a percentage of the overall, assuming the frame weight is shared 50/50. That might tell you whether a less effective brake is up to the job or not... without going to the trouble of fitting the 'full size' setup to the sidecar and finding it always locks up.
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doubled up
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I did some measuring on my KTM front brake calipers and master cylinders.
The KTM 950 and 990 Adventure bikes come with dual disc brakes up front. Each caliper has two 30mm pistons (which happen to be the same diameter as the calipers that come in the Grimeca disc brake kits. The Grimeca also has two opposing 30mm pistons in the caliper. maybe you can use these measurements and convert them to something useful?

KTM 950/990 Adventure double disc brake calipers/rotor.
-total of four 30mm brake pistons (both pistons are on the same side).
-16mm master cylinder bore.
-two 300mm diameter brake rotors
-90/100-21" tire/wheel combo.

KTM 690 Enduro and 950 Super Enduro have a single brake caliper/rotor.
-total of two 30mm brake pistons (both pistons are on the same side).
-11mm master cylinder bore.
-single 300mm diameter brake rotor.
-90/100-21" tire wheel combo.

Vespa PX disc have a single brake caliper/rotor.
-total of two 30mm brake pistons (on the opposite side of each other).
-12mm master cylinder bore.
-single 200mm diameter brake rotor.
-3.5x10'' tire wheel combo (or 3x10" for smallframe disc conversion).


A common modification for us KTM 9x0 Adventure owners is to remove extra unsprung weight from our front end. Remove the right side brake rotor and caliper, then swap on a 690 Enduro master cylinder. It removes about 13lbs of unwanted weight from the wheel.

Use a master cylinder that has too small of a bore diameter, and the lever will feel mushy.
Use a master cylinder that has too large of a bore diameter, and the lever will be hard with a woody feel to it with less braking force.

Spiegler USA or Core Moto can build you custom brake lines. Orange is a common color that they both sell. You can also go with what Rob did on his Harley. Buy the banjo fittings, then buy the -3AN hydro hose from wherever online (such as Summit racing). The only problem with that is the -3 female fittings might be too large for some scooter applications. The Spieger hoses can be made with a smaller diameter female fitting. A standard Aeroquip -3AN brake line can be fished through pretty much any hole. The only downside is that it can be a bear to install the fittings. Plus it's more of a semi-permanent attachment once that fitting is assembled.

For my old 71 Ford highboy 4x4 with a front disc brake conversion and a vacuum master cylinder (now hydroboost mc), i ditched my drum brake proportioning valve and installed a Wilwood adjustable prop valve (that's leading to the rear drum brakes). It's mounted under the dash so that i can turn the adjustment knob while i'm driving.
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Tips for brake piston area ratios:
when the pistons sit opposed only count the area of one side. so the piston area of a 4 piston caliper where there are two on each side would include the area of two pistons. The px caliper is a fixed caliper with 30mm piston on each side, so count the area of one piston.

On a floating caliper where there are only pistons on one side and a fixed pad on the other (like the GTS front) then the area of all this pistons are counted.

In addition to the disk diameter you also have to factor in the ratio of disk to wheel diameter.

It's not hard but some diagrams and a spreadsheet makes it easier.
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Man you guys.
A lota good stuff in here.
I think my master cylinder is 12mm.
My current caliper is 4 piston - but from both sides rather than floating - so as per OCT - it counts as 2x25mm. I would be adding a second.

Since I have the master on there already - I am inclined to try it.
If it's too small - I could either replace - or perhaps even bore out.
¯\_(ツ)_/¯

The unsprung weight is what I'm focused on, and as Whodat rightly points out - I may be able to apply my usual math and shave some off using orange.
🙂

Kidding aside - at closer look - most the mountain bike discs just look a bit too delicate for my use - but I am seeing some 200MM ones that might do the trick.

The largest component of weight in my braking system is the disc rotor - rather than the brake caliper - so its my #1 focus for lightening up.
(My current one might be heavier than the wheel itself - its kinda beastly).
This one looks to be less than 1/2 the weight of the one I bought.  I'm guessing I could save another 1/3 of 1/2 if I can find it in orange.
This one looks to be less than 1/2 the weight of the one I bought. I'm guessing I could save another 1/3 of 1/2 if I can find it in orange.
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for reduced weight:

smaller diameter, not thinner.
Aluminum not steel https://www.motobi.com/catalog/
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Wait - am I about to make my own aluminum rotors?!?

@oopsclunkthud avatar
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@oopsclunkthud avatar
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UTC quote
not unless you know how to bond an iron surface to the aluminum core like ZANZANI does.

Just saying they make one in 200mm diameter that could likely be adapted to work.
OP
@charlieman22 avatar
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Nedminder
62 VBB1T Round Tail W/ leaner sidecar
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Nedminder
@charlieman22 avatar
62 VBB1T Round Tail W/ leaner sidecar
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Location: california
UTC quote
Chuckled.
I think everyone is breathing a sigh of relief.

Adapter would be fairly easy by the looks.

Not sure the science of it all - smaller rather than thinner - but assume heat is involved.

Cool rotors. (Pun intended)

Wonder if I could machine my rotors to have a wavy edge and smaller circumference. I think they are a stainless, likely surface hardened in some fashion. Not sure if I could successfully machine or I would just get Sparks.
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parallelogramerist
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parallelogramerist
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This place could cut whatever shape you wanted...
https://sendcutsend.com/
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