Ironhead what brake master cylinder can I use?

[Roane]

I posted this question in another thread about an electrical problem I am having but thought I should probably separate it as it is related to me but unrelated to you.

Any idea the bore size of this master cylinder (is OEM for my bike I think... 1977 sporty) but it’s running to dual calipers (no idea the number of pistons and there are no markings anywhere I can find stating bore size anywhere).
The calipers look like they might be V-Twin.
https://www.jpcycles.com/product/241...left-and-right

This is the pricey master I want to use, which comes in 9/16" or 11/16"
https://www.rolandsands.com/product/...r-mount/chrome

Here are the links to the pics from my bike.
http://xlforum.net/forums/attachment...5&d=1558298552

http://xlforum.net/forums/showthread...2072109&page=3

[mickey t]

72xlh....where are ya I need ya...cashh is waiting n did they make headlights like thos

Sent from my LM-X210APM using Tapatalk

[Roane]

nice bike mike... any thoughts on my master cylinder possibilities...

[just1pepsi]

https://www.joesracing.com/master-cylinder-math/

The link above contains probably everything you could ever want/need to know about brakes.

Basically: Smaller bore's are more difficult to push, and must be pushed farther to move the same amount of fluid as a larger bore.

The bore size on a 1983' that came with dual disc's from the factory is: 3/4" (12/16")

I ran the 70's style Master Cylinder for years, and it was admittedly more difficult to pull, but did the job - It did however, eventually seize up, but that I attribute more to it being a Chinese copy.

GMA makes some fairly priced USA made master cylinders in several bore sizes with various finishes and switch options. When I replaced my Chinese knock-off 70's style MC, I used a GMA with a 5/8" (10/16") bore - It works fine for me.

Here is their part list - Look for the part numbers starting at: GMA-HC

http://beltdrives.com/wp-content/upl...st-For-CCI.pdf

[Roane]

Thanks,
I'm not sure what's on there now but the connection to the brake lines is pretty small diameter. Is it advisable to get new connection hardware? I've not done this before so apologies if this is usual.

[Iron Mike]

Single disc requires less displacement of fluid per amount of lever travel---smaller bore
Dual requires more--larger bore
Large bore with single disc will displace more than enough fluid required in less lever travel resulting in very firm short travel
Small bore with dual will result in long travel and softer lever

[Roane]

So, I bit the bullet and got an 11/16 master cylinder. I neglected to get a banjo fitting though. Any idea which size I need?

[ryder rick]

I use a small master with dual single piston calipers on the FXR.
If I use more than 2 fingers on it I will lock the front wheel.

[Sadsack]

Originally Posted by Roane

So, I bit the bullet and got an 11/16 master cylinder. I neglected to get a banjo fitting though. Any idea which size I need?

No way of telling for sure without seeing it. Any auto parts will have what you need and will be able to match your parts.

[ryder rick]

10mm or 3/8" banjo bolt threads (not interchangeable)